WO2020077285A1 - Réseau de coupleurs optiques à alignement passif - Google Patents

Réseau de coupleurs optiques à alignement passif Download PDF

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Publication number
WO2020077285A1
WO2020077285A1 PCT/US2019/055965 US2019055965W WO2020077285A1 WO 2020077285 A1 WO2020077285 A1 WO 2020077285A1 US 2019055965 W US2019055965 W US 2019055965W WO 2020077285 A1 WO2020077285 A1 WO 2020077285A1
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Prior art keywords
optical
waveguide
housing structure
waveguides
array
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PCT/US2019/055965
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English (en)
Inventor
Victor Il'ich Kopp
Daniel Neugroschl
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Chiral Photonics Inc
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Chiral Photonics Inc
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Priority claimed from US16/159,310 external-priority patent/US10564348B2/en
Application filed by Chiral Photonics Inc filed Critical Chiral Photonics Inc
Publication of WO2020077285A1 publication Critical patent/WO2020077285A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/30—Optical coupling means for use between fibre and thin-film device
    • G02B6/305—Optical coupling means for use between fibre and thin-film device and having an integrated mode-size expanding section, e.g. tapered waveguide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4249—Packages, e.g. shape, construction, internal or external details comprising arrays of active devices and fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02042—Multicore optical fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/024—Optical fibres with cladding with or without a coating with polarisation maintaining properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/04—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
    • G02B6/2856—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers formed or shaped by thermal heating means, e.g. splitting, branching and/or combining elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/36—Mechanical coupling means
    • G02B6/3628—Mechanical coupling means for mounting fibres to supporting carriers
    • G02B6/3632—Mechanical coupling means for mounting fibres to supporting carriers characterised by the cross-sectional shape of the mechanical coupling means
    • G02B6/3636—Mechanical coupling means for mounting fibres to supporting carriers characterised by the cross-sectional shape of the mechanical coupling means the mechanical coupling means being grooves
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
    • G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
    • G02B6/423—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using guiding surfaces for the alignment

Definitions

  • the present disclosure relates generally to an optical coupler array, e.g., a multichannel optical coupler array, for coupling, e.g., a plurality of optical fibers to at least one optical device.
  • Some embodiments can relate to coupling light to and from a plurality of fibers, such as to and from one or more single mode fibers, few-mode fibers, multimode fibers, multicore single mode fibers, multicore few -mode fibers, and/or multicore multimode fibers.
  • Some embodiments can relate to coupling light to and from photonic integrated circuits (PICs) and to and from multicore fibers (MCFs).
  • PICs photonic integrated circuits
  • MCFs multicore fibers
  • Optical waveguide devices are useful in various high technology industrial applications, and especially in telecommunications.
  • these devices including planar waveguides, two or three dimensional photonic crystals, multi-mode fibers, multicore single-mode fibers, multicore few-mode fibers, and multicore multi-mode fibers are being employed increasingly in conjunction with conventional optical fibers.
  • optical waveguide devices based on refractive index contrast or numerical aperture (NA) waveguides that are different from that of conventional optical fibers and multichannel devices are advantageous and desirable in applications in which conventional optical fibers are also utilized.
  • NA numerical aperture
  • Example embodiments described herein have innovative features, no single one of which is indispensable or solely responsible for their desirable attributes. Without limiting the scope of the claims, some of the advantageous features will now be summarized.
  • a plurality of optical couplers individual ones of the plurality of optical couplers configured to optically couple at least one optical fiber waveguide to at least one waveguide of an optical device and comprising:
  • Example 11 The multifiber array of Example 9 or 10, wherein said alignment carrier is configured not to sit on the top surface of the v-groove.
  • optical coupler configured to optically couple one end of at least one multicore optical fiber waveguide to at least one waveguide of an optical device.
  • optical couplers configured to optically couple a plurality of optical fibers to the optical device, the elongated optical element having the first end operable to optically couple with said plurality of optical fibers, an intermediate cross section, and the second end operable to optically couple with said optical device, and comprising:
  • an outer cladding longitudinally surrounding said outer core, having a third refractive index (N-3), a first cladding size at said first end, and a second cladding size at said second end,
  • said common single coupler housing structure comprises a transversely contiguous medium having a fourth refractive index (N-4) surrounding said plurality of longitudinal waveguides, wherein a relative magnitude relationship between said first, second, third and fourth refractive indices (N-l, N-2, N-3, and N-4, respectively), comprises the following magnitude relationship: (N-l > N-2 > N-3), wherein a total volume of said medium of said common single coupler housing structure is greater than a total volume of all said vanishing core waveguides inner cores and said outer cores confined within said common single coupler housing structure, and wherein said first inner vanishing core size (ICS-l), said first outer core size (OCS-l), and said spacing between said plurality of longitudinal waveguides, are simultaneously and gradually reduced, in accordance with a reduction profile, between said first end and said second end along said optical element, until said second inner vanishing core size (ICS- 2) and said second outer core size (OCS-2) are reached, wherein said intermediate inner vanishing core size
  • At least one waveguide mode of light traveling from said second end to said first end moves from the combined waveguide formed by at least two outer cores into said outer core proximally to said intermediate cross section, and moves from said outer core into said corresponding inner vanishing core proximally to said first end,
  • said common single coupler housing structure has the outer cross sectional shape comprising the first side comprising one or more curved portions, wherein said second side is disposed at a distance from said plurality of longitudinal waveguides such that waveguiding properties are preserved and not disturbed.
  • An optical coupler array for optical coupling of a plurality of optical fibers to an optical device comprising:
  • optical coupler array of Example 1 or 2 further comprising an alignment carrier comprising one or more flat portions configured to be coupled with said second side such that said alignment carrier extends beyond said second side in the transverse direction on at least one side.
  • a common single coupler housing structure and at least one longitudinal waveguide having a capacity for at least one optical mode, each embedded in said common single housing structure,
  • said common single coupler housing structure has an outer cross sectional shape comprising a first side and a second side
  • a common single coupler housing structure a plurality of longitudinal waveguides each positioned at a predetermined spacing from one another, each having a capacity for at least one optical mode of a predetermined mode field profile, each embedded in said common single housing structure proximally to said second end, wherein at, least one of said plural longitudinal waveguides is a vanishing core waveguide, each said at least one vanishing core waveguide comprising:
  • said common single coupler housing structure proximally to said first end has one of the following cross sectional configurations: a ring surrounding said plurality of longitudinal waveguides, a transversely contiguous structure with plurality of holes, wherein at least one said hole contains at least one of said plurality of longitudinal waveguides.
  • a multichannel optical coupler array comprising:
  • an elongated optical element having a first end and a second end, wherein said first and second ends are operable to optically couple with a plurality of optical fibers, an optical device, or combinations thereof, the optical element further comprising: a coupler housing structure; and
  • an inner vanishing core having a first refractive index (N-l), and having an inner core size;
  • an outer core longitudinally surrounding said inner core, having a second refractive index (N-2), and having an outer core size
  • an outer cladding longitudinally surrounding said outer core, having a third refractive index (N-3), and having a cladding size
  • said coupler housing structure comprises a medium having a fourth refractive index (N-4) surrounding said plurality of longitudinal waveguides, wherein N-l>N-2>N-3,
  • said inner core size, said outer core size, and spacing between said plurality of longitudinal waveguides reduces along said optical element from said first end to said second end such that at said second end, said inner core size is insufficient to guide light therethrough, and said outer core size is sufficient to guide at least one optical mode, and
  • optical coupler array of any of the preceding Examples wherein proximate the first end, one of the plurality of longitudinal waveguides extends outside the coupler housing structure. 5. The optical coupler array of any of the preceding Examples, wherein proximate the first end, one of the plurality of longitudinal waveguides is disposed within the coupler housing structure and does not extends beyond the coupler housing structure.
  • optical coupler array of any of Examples 2-8 wherein said inner core size, said outer core size, and spacing between said plurality of longitudinal waveguides simultaneously and gradually reduces from said first end to said second end.
  • the coupler array comprises substantially no gap between the coupler housing structure and the plurality of longitudinal waveguides.
  • optical coupler array of any of the preceding Examples wherein the one of the cross sectional configurations is the ring surrounding said plurality of longitudinal waveguides.
  • a multichannel optical coupler array comprising:
  • an elongated optical element having a first end and a second end, wherein said first and second ends are operable to optically couple with a plurality of optical fibers, an optical device, or combinations thereof, the optical element further comprising:
  • an inner vanishing core having a first refractive index (N-l), and having an inner core size;
  • an outer core longitudinally surrounding said inner core, having a second refractive index (N-2) and having an outer core size
  • an outer cladding longitudinally surrounding said outer core, having a third refractive index (N-3), and having a cladding size
  • said inner core size, said outer core size, and spacing between said plurality of longitudinal waveguides reduces along said elongated optical element from said first end to said second end such that at said second end, said inner core size is insufficient to guide light therethrough, and said outer core size is sufficient to guide at least one optical mode, and
  • said coupler housing structure at a proximity to the first end has a cross sectional configuration comprising at least one hole, the at least one hole containing at least one of said plurality of longitudinal waveguides, wherein the hole is larger than the at least one of said plurality of longitudinal waveguides such that the at least one of said plurality of longitudinal waveguides is movable with respect to the coupler housing structure in a lateral direction.
  • optical coupler array of any of Examples 36-38 wherein proximate the first end, one of the plurality of longitudinal waveguides is disposed within the coupler housing structure.
  • optical coupler array of any Examples 36-43 wherein the at least one hole comprises a single hole and the at least one of said plurality of longitudinal waveguides comprises a plurality of longitudinal waveguides.
  • Example 60 The optical coupler array of Example 60, wherein the non-circular cross section is D-shaped.
  • a multichannel optical coupler array for optical coupling a plurality of optical fibers to an optical device comprising:
  • an elongated optical element having a first end operable to optically couple with said plurality optical fibers and a second end operable to optically couple with said optical device, and comprising:
  • a common single coupler housing structure a plurality of longitudinal waveguides each positioned at a predetermined spacing from one another, each having a capacity for at least one optical mode of a predetermined mode field profile, each embedded in said common single housing structure, wherein at, least one of said plural longitudinal waveguides is a vanishing core waveguide, each said at least one vanishing core waveguide comprising:
  • an inner vanishing core having a first refractive index (N-l), and having a first inner core size (ICS-I) at said first end, and a second inner core size (ICS-2) at said second end; an outer core, longitudinally surrounding said inner core, having a second refractive index (N-2), and having a first outer core size (OCS-I) at said first end, and a second outer core size (OCS-2) at said second end, and an outer cladding, longitudinally surrounding said outer core, having a third refractive index (N-3), a first cladding size at said first end, and a second cladding size at said second end; and wherein said common single coupler housing structure comprises a transversely contiguous medium having a fourth refractive index (N-4) surrounding said plural longitudinal waveguides, wherein a predetermined relative magnitude relationship between said first, second, third and fourth refractive indices (N-l, N-2, N-3, and N-4, respectively), comprises the following magnitude relationship: (N-l
  • ultichannel optical coupler array for optical coupling a plurality of optical fibers to an op tical device, comprising:
  • a coupler housing structure a plurality of longitudinal waveguides each positioned at a spacing from one another, each having a capacity for at least one optical mode, each embedded in said housing structure, wherein at, least one of said plural longitudinal waveguides is a vanishing core waveguide, each said at least one vanishing core waveguide comprising:
  • said first inner vanishing core size (ICS-I), said first outer core size (OCS-I), and said spacing between said plural longitudinal waveguides reduces between said first end and said second end along said optical element, until said second inner vanishing core size (ICS-2) and said second outer core size (OCS-2) are reached, wherein said second inner vanishing core size (ICS-2) is insufficient to guide light therethrough, and said second outer core size (OCS-2) is sufficient to guide at least one optical mode, such that:
  • a multichannel optical coupler array for optical coupling of a plurality of optical fibers to an optical device comprising:
  • an elongated optical element having a first end operable to optically couple with said plurality optical fibers, an intermediate cross section, and a second end operable to optically couple with said optical device, and comprising:
  • an inner vanishing core having a first refractive index (N-l), and having a first inner core size (ICS-I) at said first end, an intermediate inner core size (ICS-IN) at said intermediate cross section, and a second inner core size (ICS-2) at said second end; an outer core, longitudinally surrounding said inner core, having a second refractive index (N-2), and having a first outer core size (OCS-I) at said first end, an intermediate outer core size (OCS-IN) at said intermediate cross section, and a second outer core size (OCS-2) at said second end, and an outer cladding, longitudinally surrounding said outer core, having a third refractive index (N-3), a first cladding size at said first end, and a second cladding size at said second end; and wherein said common single coupler housing structure comprises a transversely contiguous medium having a fourth refractive index (N-4) surrounding said plural longitudinal waveguides, wherein a predetermined relative magnitude relationship between said first, second, third and fourth
  • said common single coupler housing structure proximally to said first end has a cross sectional configuration comprising a transversely contiguous structure with at least one hole, wherein the at least one hole contains at least one of said plurality of longitudinal waveguides creating a gap between the coupler housing structure and the at least one of said plurality of longitudinal waveguides.
  • a multichannel optical coupler array comprising:
  • an inner vanishing core having a first refractive index (N-l), and having a first inner core size (ICS-I) at said first end, an intermediate inner core size (ICS-IN) at said intermediate cross section, and a second inner core size (ICS-2) at said second end; an outer core, longitudinally surrounding said inner core, having a second refractive index (N-2), and having a first outer core size (OCS-I) at said first end, an intermediate outer core size (OCS-IN) at said intermediate cross section, and a second outer core size (OCS-2) at said second end, and an outer cladding, longitudinally surrounding said outer core, having a third refractive index (N-3), a first cladding size at said first end, and a second cladding size at said second end; and wherein said coupler housing structure comprises a medium having a fourth refractive index (N-4) surrounding said plural longitudinal waveguides, wherein a relative magnitude relationship between said first, second, third and fourth refractive indices (N-l
  • At least one waveguide mode of light traveling from said second end to said first end moves from the combined waveguide formed by at least two neighboring outer cores into said outer core proximally to said intermediate cross section, and moves from said outer core into said corresponding inner vanishing core proximally to said first end.
  • FIG. 1A is a schematic diagram of a side view of a first example embodiment of an optical fiber coupler array, which comprises at least one vanishing core waveguide (VC waveguide), illustrated therein by way of example as a single VC waveguide, and at least one Non-VC waveguide, illustrated therein by way of example as a plurality of Non-VC waveguides, disposed symmetrically proximally to the example single VC waveguide;
  • VC waveguide vanishing core waveguide
  • Non-VC waveguide illustrated therein by way of example as a plurality of Non-VC waveguides, disposed symmetrically proximally to the example single VC waveguide
  • FIG. 1C is a schematic diagram of a side view of a third example embodiment of an optical fiber coupler array, which comprises a plurality of VC waveguides, and a plurality of Non-VC waveguides, disposed longitudinally and asymmetrically to one another, and where at least a portion of the plural Non-VC waveguides are of different types and/or different characteristics;
  • FIG. 1D is a schematic diagram of a side view of a fourth example embodiment of an optical fiber coupler array, configured for fan-in and fan-out connectivity and comprising a pair of optical fiber coupler components with a multi-core optical fiber element connected between the second (smaller sized) ends of the two optical fiber coupler components;
  • FIG. 2A is a schematic diagram of a side view of a fifth example embodiment of an optical fiber coupler array, which comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure, wherein each plural VC waveguide is spliced, at a particular first splice location, to a corresponding elongated optical device (such as an optical fiber), at least a portion of which extends outside the single common housing structure by a predetermined length, and wherein each particular first splice location is disposed within the single common housing structure;
  • a elongated optical device such as an optical fiber
  • FIG. 2C is a schematic diagram of a side view of a seventh example embodiment of an optical fiber coupler array, which comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure, wherein each plural VC waveguide is spliced, at a particular third splice location, to a corresponding elongated optical device (such as an optical fiber), at least a portion of which extends outside the single common housing structure by a predetermined length, and wherein each particular third splice location is disposed outside the single common housing structure;
  • a elongated optical device such as an optical fiber
  • FIG. 2D is a schematic diagram of a side view of an alternative embodiment of an optical fiber coupler array, comprising a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure, that is configured at its second end, to increase, improve, and/or optimize optical coupling to a free- space-based optical device, wherein a free-space-based device may include (1) a standalone device, e.g., a lens followed by other optical components as shown in FIG. 2D, or (2) a device, which is fusion spliceable to the second coupler’s end, e.g. a coreless glass element, which can serve as an end cup for power density redaction at the glass-air interface, or as a Talbot mirror for phase synchronization of coupler’s waveguides in a Talbot cavity geometry;
  • a standalone device e.g., a lens followed by other optical components as shown in FIG. 2D
  • FIG. 3A is a schematic diagram of a cross-sectional view of a first alternative embodiment of the optical fiber coupler arrays of FIGs. 1D to 2D, above, and optionally comprising a fiducial element operable to provide a visual identification of waveguide arrangement / characteristics (such as alignment), which may be disposed in one of several categories of cross-sectional regions;
  • FIG. 3B is a schematic diagram of a cross-sectional view of a first alternative embodiment of the optical fiber coupler array of FIG. 1A, above, in which at least one VC waveguide, illustrated therein by way of example as a single VC waveguide, is positioned along a central longitudinal axis of the single common housing structure, and surrounded by a plurality of parallel proximal symmetrically positioned Non-VC waveguides;
  • FIG. 3C is a schematic diagram of a cross-sectional view of a first alternative embodiment of the optical fiber coupler array of FIG. 3B above, in which a volume of the single common housing structure medium surrounding the sections of all of the waveguides embedded therein, exceeds a total volume of the inner and outer cores of the section of the VC waveguide that is embedded within the single common housing structure;
  • FIG. 3D is a schematic diagram of a cross-sectional view of a second alternative embodiment of the optical fiber coupler array of FIG.
  • FIG. 3E is a schematic diagram of a cross-sectional view of a first alternative embodiment of the optical fiber coupler array of FIG. 3D, further comprising a central waveguide channel operable to provide optical pumping functionality therethrough;
  • FIG. 3F is a schematic diagram of a cross-sectional view of a second alternative embodiment of the optical fiber coupler array of FIG. 3D, in which the VC waveguide that is positioned along the central longitudinal axis of the single common housing structure, is of a different type, and/or comprises different characteristics from the remaining plural VC waveguides, which, if selected to comprise enlarged inner cores, may be advantageously utilized for increasing or optimizing optical coupling to different types of optical pump channels of various optical devices;
  • FIG. 3H is a schematic diagram of a cross-sectional view of a first alternative embodiment of the optical fiber coupler array of FIG. 3G, above, in which the at least one VC waveguide, illustrated therein by way of example as a side-channel off-center positioned single VC waveguide, comprises polarization maintaining properties and comprises a polarization axis that is aligned with respect to its transverse off-center location;
  • FIG. 3K is a schematic diagram of a cross-sectional view of a fifth alternative embodiment of the optical fiber coupler array of FIG. 3B, above, wherein the centrally positioned single VC waveguide, comprises polarization maintaining properties (shown by way of example only as being induced by rod stress members and which may readily and alternately be induced by various other stress or equivalent designs), and a corresponding polarization axis, and optionally comprising a plurality of optional waveguide arrangement indication elements of the same or of a different type, as described in connection with FIG. 3J;
  • polarization maintaining properties shown by way of example only as being induced by rod stress members and which may readily and alternately be induced by various other stress or equivalent designs
  • a corresponding polarization axis and optionally comprising a plurality of optional waveguide arrangement indication elements of the same or of a different type, as described in connection with FIG. 3J;
  • FIG. 5 is a schematic isometric view diagram illustrating an example connection of a second end (i.e.“tip”) of the optical fiber coupler array connected to plural edge coupling elements of an optical device in a butt-coupled configuration, that may be readily shifted into one of several alternative coupling configurations, including a proximal open air optical coupling alignment configuration, and or an angled alignment coupling configuration;
  • a second end i.e.“tip”
  • edge coupling elements of an optical device in a butt-coupled configuration
  • FIG. 6 is a schematic diagram of a cross-sectional view of a previously known optical fiber coupler having various drawbacks and disadvantages readily overcome by the various embodiments of the optical fiber coupler array of FIGs. 1A to 5;
  • FIG. 8 is a schematic diagram of a cross-sectional view of an example configuration of the housing structure at a proximity to a first end of the optical coupler array.
  • the cross-sectional view is orthogonal to the longitudinal direction or length of the optical coupler array;
  • FIG. 12C is a schematic diagram of example mechanical features in a v- groove of the optical device illustrated in FIG. 12A.
  • FIGs. 13, 14 and 15 schematically illustrate examples of a multifiber array positioned over an optical device.
  • Packaging of photonic integrated circuits uses optical and electronic interfaces as well thermomechanical management.
  • One primary challenge in PIC packaging includes fiber coupling from a fiber optic infrastructure to an individual optical waveguide, or multiple waveguides, of a particular PIC.
  • Various embodiments described herein relate to optical coupler arrays configured to couple light from one or more optical fibers to waveguides at the edge of a PIC.
  • the optical coupler array can be configured to passively align with one or more waveguides of the PIC.
  • the housing structure e.g., a common single coupler housing structure in some cases
  • the housing structure can allow for self-aligning waveguide arrangement at a close proximity to a first end (e.g., hexagonal close packed arrangement in a housing structure having circular (as shown in FIG. 8) or hexagonal inner cross section) and improved (precise or near precise in some cases) cross sectional positioning of the waveguides at a second end.
  • Certain embodiments are directed to an optical fiber coupler array capable of providing a low-loss, high-coupling coefficient interface with high accuracy and easy alignment between a plurality of optical fibers (or other optical devices) with a first channel- to-channel spacing, and an optical device having a plurality of waveguide interfaces with a second, smaller channel-to-channel spacing.
  • each of a larger size end and a smaller size end of the optical fiber coupler array is configurable to have a correspondingly different (i.e., larger vs.
  • the optical coupler array includes a plurality of waveguides (at least one of which may optionally be polarization maintaining), that comprises at least one gradually reduced “vanishing core fiber”, at least in part embedded within a common housing structure.
  • the coupler array may be configured for utilization with at least one of an optical fiber amplifier and an optical fiber laser.
  • optical device applies to virtually any single channel or multi-channel optical device, or to any type of optical fiber, including, but not being limited to, standard / conventional optical fibers.
  • optical devices with which the coupler array may advantageously couple may include, but are not limited to, one or more of the following:
  • fusion splice is utilized in the various descriptions of the example embodiments of the coupler array provided below, in reference to interconnections between various optical coupler array components, and connections between various optical coupler array components and optical device(s), it should be noted, that any other form of waveguide or other coupler array component connectivity technique or methodology may be readily selected and utilized as a matter of design choice or necessity, without departing from the spirit of the invention, including but not limited to mechanical connections.
  • an optical coupler array 10A which comprises a common housing structure 14A (described below), at least one VC waveguide, shown in FIG. 1A by way of example, as a single VC waveguide 30A, and at least one Non-VC waveguide, shown in FIG. 1A by way of example, as a pair of Non-VC waveguides 32A-1, 32A-2, each positioned symmetrically proximally to one of the sides of the example single VC waveguide 30A, wherein the section of the VC waveguide 30A, located between positions B and D of FIG. 1A is embedded in the common housing structure 14A.
  • the outer core 22A serves as the effective cladding at the VC waveguide 30A large end at which the VC waveguide 30A supports“Ml” spatial propagating modes within the inner core 20A, where Ml is larger than 0.
  • the indices of refraction N-l and N-2, are preferably chosen so that the numerical aperture (NA) at the VC waveguide 30A large end matches the NA of an optical device (e.g.
  • an optical fiber) to which it is connected such as an optical device 34A-1, for example, comprising a standard / conventional optical fiber connected to the VC waveguide 30A at a connection position 36A-1 (e.g., by a fusion splice, a mechanical connection, or by other fiber connection designs), while the dimensions of the inner and outer cores (20A, 22A), are preferably chosen so that the connected optical device (e.g., the optical device 34A-1), has substantially the same mode field dimensions (MFD).
  • mode field dimensions instead of commonly used mode field diameter (also MFD) due to the case that the cross section of the VC or Non-VC waveguides may not be circular, resulting in a non-circular mode profile.
  • the mode field dimensions include both the mode size and the mode shape and equal to the mode field diameter in the case of a circularly symmetrical mode.
  • the coupler array 10A During fabrication of the coupler array 10A from an appropriately configured preform (comprising the VC waveguide 30A preform having the corresponding inner and outer cores 20A, 22A, and cladding 24A), as the coupler array 10A preform is tapered in accordance with at least one predetermined reduction profile, the inner core 20A becomes too small to support all Ml modes.
  • the number of spatial modes, supported by the inner core at the second (tapered) end is M2, where M2 ⁇ Ml.
  • M2 0 meaning that inner core is too small to support light propagation.
  • the VC waveguide 30A then acts as if comprised a fiber with a single core of an effective refractive index close to N-2, surrounded by a cladding of lower index N-3.
  • a channel-to-channel spacing S-l at the coupler array 10A larger end decreases in value to a channel-to-channel spacing S-2 at the coupler array 10A smaller end (at position C, FIG. 1A), in proportion to a draw ratio selected for fabrication, while the MFD value (or the inversed NA value of the VC waveguide 30A) can be either reduced, increased or preserved depending on a selected differences in refractive indices, (N-l - N-2) and (N-2 - N-3), which depends upon the desired application for the optical coupler array 10A, as described below.
  • the property of the VC waveguide permitting light to continue to propagate through the waveguide core along the length thereof when its diameter is significantly reduced advantageously, reduces optical loss from interfacial imperfection or contamination, and allows the use of a wide range of materials for a medium 28A of the common housing structure 14A (described below), including, but not limited to:
  • pure-silica e.g., the same material as is used in most standard / conventional fiber claddings, to facilitate splicing to multi-core, double- clad, or multi-mode fiber.
  • the desired relative values of NA-l and NA-2 (each at a corresponding end of the coupler array 10A, for example, NA-l corresponding to the coupler array 10A large end, and NA-2 corresponding to the coupler array 10A small end), and, optionally, the desired value of each of NA-l and NA- 2), may be determined by selecting the values of the refractive indices Nl, N2, and N3 of the coupler array 10 A, and configuring them in accordance with at least one of the following relationships, selected based on the desired relative numerical aperture magnitudes at each end of the coupler array 10A :
  • NA-l (lrg. end) ⁇ NA-2 (sm. end) (Nl - N2 ⁇ N2 - N3)
  • NA of any type of fiber is determined by the following expresslon: where «core and n c iad are the refractive indices of fiber core and cladding respectively.
  • NA single-mode
  • the common coupling structure 14A comprises the medium 28A, in which the section of the VC waveguide 30A located between positions B and D of FIG. 1A is embedded, and which may include, but is not limited to, at least one of the following materials:
  • the VC waveguide 30A is spliced, at a particular splice location 36A-1 (shown by way of example as positioned inside the common housing structure 14A), to a corresponding respective elongated optical device 34A-1 (for example, such as an optical fiber), at least a portion of which extends outside the common housing structure 14A by a predetermined length 12A, while the Non- VC waveguides 32A-1, 32A-2 are spliced, at particular splice locations 36A-2, 36A-3, respectively (disposed outside of the common housing structure 14A), to corresponding respective elongated optical devices 34A-2, 34A-3 (such as optical fibers), and extending outside the common housing structure 14A by a predetermined length 12A.
  • a particular splice location 36A-1 shown by way of example as positioned inside the common housing structure 14A
  • a corresponding respective elongated optical device 34A-1 for example, such as an optical fiber
  • the optical device 40A comprises a double- clad fiber
  • the small end of the coupler array 10A is coupled (for example, fusion spliced) to the optical device interface 42A
  • at least a portion of the common housing structure 14A proximal to the splice position may be coated with a low index medium (not shown), extending over the splice position and up to the double-clad fiber optical device 40A outer cladding (and optionally extending over a portion of the double-clad fiber optical device 40A outer cladding that is proximal to the splice position).
  • FIG. 1B by way of example, as a single Non-VC waveguide 32B, disposed in parallel proximity to the VC waveguide 30B, where a portion of the optical coupler array 10B, has been configured to comprise a larger channel-to-channel spacing value S2’ at its small end, than the corresponding channel-to-channel spacing value S2 at the small end of the optical coupler array 10A, of FIG. 1A.
  • This configuration may be readily implemented by transversely cutting the optical fiber array 10A at a position C’, thus producing the common housing structure 14B that is shorter than the common housing structure 14A and resulting in a new, larger diameter array interface 18B, having the larger channel-to-channel spacing value S2 ⁇
  • FIG. 1C a third example embodiment of the optical fiber coupler array, is shown as a coupler array 10C.
  • the coupler array 10C comprises a plurality of VC waveguides, shown in FIG. 1C as VC waveguides 30C-1, and 30C-2, and a plurality of Non-VC waveguides, shown in FIG.
  • FIG. 1D a fourth example embodiment of the optical fiber coupler array that is configured for multi-core fan-in and fan-out connectivity, and shown as a coupler array 50.
  • the coupler array 50 comprises a pair of optical fiber coupler array components (10D-1 and 10D-2), with a multi-core optical fiber element 52 connected (e.g., by fusion splicing at positions 54-1 and 54-2) between the second (smaller sized) ends of the two optical fiber coupler array components (10D-1, 10D-2).
  • the coupler array 100A comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure 104A, shown by way of example only, as plural VC waveguides 130A-1, 130A-2.
  • Each plural VC waveguide 130A-1, 130A-2 is spliced, at a particular splice location 132A-1, 132A-2, respectively, to a corresponding respective elongated optical device 134A-1, 134A-2 (such as an optical fiber), at least a portion of which extends outside the common housing structure 104A by a predetermined length 102A, and wherein each particular splice location 132A-1, 132A-2 is disposed within the common housing structure 104A.
  • FIG. 2B a sixth example embodiment of the optical fiber coupler array, is shown as a coupler array 100B.
  • the coupler array 100B comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure 104B, shown by way of example only, as plural VC waveguides 130B-1, 130B-2.
  • Each plural VC waveguide 130B-1, 130B-2 is spliced, at a particular splice location 132B-1, 132B-2, respectively, to a corresponding respective elongated optical device 134B-1, 134B-2 (such as an optical fiber), at least a portion of which extends outside the common housing structure 104B by a predetermined length 102B, and wherein each particular splice location 132B-1, 132B-2 is disposed at an outer cross-sectional boundary region of the common housing structure 104B.
  • FIG. 2C a seventh example embodiment of the optical fiber coupler array, is shown as a coupler array 100C.
  • the coupler array 100C comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure 104C, shown by way of example only, as plural VC waveguides 130C-1, 130C-2.
  • Each plural VC waveguide 130C-1, 130C-2 is spliced, at a particular splice location 132C-1, 132C-2, respectively, to a corresponding respective elongated optical device 134C-1, 134C-2 (such as an optical fiber), at least a portion of which extends outside the common housing structure 104C by a predetermined length 102C, and wherein each particular splice location 132C-1, 132C-2 is disposed outside of the common housing structure 104C.
  • the coupler array 150 comprises a plurality of longitudinally proximal VC waveguides at least partially embedded in a single common housing structure, that is configured at its second end, to increase or optimize optical coupling to a free- space-based optical device 152.
  • the free-space-based optical device 152 may comprise a lens 154 followed by an additional optical device component 156, which may comprise, by way of example, a MEMS mirror or volume Bragg grating.
  • the combination of the coupler and the free-space-based optical device 152 may be used as an optical switch or WDM device for spectral combining or splitting of light signals l60b (representative of the light coupler array 150 output light signals l60a after they have passed through the lens 154.)
  • one of the fibers may be used as an input and all others for an output or vice versa.
  • a free- space-based device 152 can be fusion spliceable to the second coupler’s end.
  • This device may be a coreless glass element, which can serve as an end cup for power density redaction at the glass-air interface.
  • the coreless element can serve as a Talbot mirror for phase synchronization of coupler’s waveguides in a Talbot cavity geometry
  • single or individual coupler array components/elements are identified by a single reference number, while each plurality of the coupler component/elements is identified by a reference number followed by a“(l..n)” designation, with“n” being a desired number of plural coupler elements/components (and which may have a different value in any particular coupler array embodiment described below).
  • all the waveguides VC and Non-VC are shown with a circular cross- section of the inner and outer core and cladding only by example.
  • Other shapes of the cross- sections of the inner and outer core and cladding may be utilized without departure from the current invention.
  • the specific choice of shape is based on various requirements, such as channel shape of the optical device, channel positional geometry (for example, hexagonal, rectangular or square lattice), or axial polarization alignment mode.
  • the sizes, relative sizes, relative positions and choices of composition materials are not limited to the example sizes, relative sizes, relative positions and choices of composition materials, indicated below in connection with the detailed descriptions of the coupler array embodiments of FIGs. 3A to 3L, but rather they may be selected by one skilled in the art as a matter of convenience or design choice, without departing from the spirit of the present invention.
  • each of the various single common housing structure components 202A to 202L, of the various coupler arrays 200A to 200L of FIGs. 3A to 3L, respectively, may be composed of a medium having the refractive index N-4 value in accordance with an applicable one of the above-described relationships with the values of other coupler array component refractive indices N-l, N-2, and N-3, and having properties and characteristics selected from the various contemplated example medium composition parameters described above in connection with medium 28A of FIG. 1A.
  • FIG. 3A a first alternative embodiment of the optical fiber coupler array embodiments of FIGs. 1D to 2D, is shown as a coupler array 200A in which all waveguides are VC waveguides.
  • the coupler array 200A comprises a single common housing 202A, and plurality of VC waveguides 204A-(l..n), with n being equal to 19 by way of example only, disposed centrally along the central longitudinal axis of the housing 202A.
  • the coupler array 200A may also comprise an optional at least one fiducial element 210A, operable to provide one or more useful properties to the coupler array, including, but not limited to:
  • a fiducial element when deployed in optical coupler array embodiments that comprise at least one polarization maintaining VC waveguide (such as the optical coupler array embodiments described below in connection with FIGs. 3H - 3L), a fiducial element is further operable to:
  • the fiducial element 210A may comprise any of the various types of fiducial elements known in the art, selected as a matter of design choice or convenience without departing from the spirit of the invention - for example, it may be a dedicated elongated element positioned longitudinally within the common housing structure 202A in one of various cross-sectional positions (such as positions X or Y, shown in FIG. 3A.
  • the fiducial element 210A may comprise a dedicated channel not used for non- fiducial purposes, for example, replacing one of the waveguides 204A-(l..n), shown by way of example only at position Z in FIG. 3 A.
  • a first alternative embodiment of the optical fiber coupler array 10A of FIG. 1A, above, is shown as a coupler array 200B, that comprises a single housing structure 202B, and at least one VC waveguide, shown in FIG. 3B by way of example as a VC waveguide 204B, and a plurality of Non-VC waveguides 206B-(l..n), with n being equal to 18 by way of example only.
  • the VC waveguide 204B is positioned along a central longitudinal axis of the common housing structure 202B, and circumferentially and symmetrically surrounded by proximal parallel plural Non-VC waveguides 206B- (l..n).
  • FIG. 3C a first alternative embodiment of the optical fiber coupler array 200B of FIG. 3B, above, is shown as a coupler array 200C that comprises a single housing structure 202C, a VC waveguide 204C, and a plurality of Non-VC waveguides 206C-(l..n), with n being equal to 18 by way of example only.
  • the VC waveguide 204C is positioned along a central longitudinal axis of the common housing structure 202C, and circumferentially and symmetrically surrounded by proximal parallel plural Non-VC waveguides 206C-(l..n).
  • the coupler array 200C is configured such that a volume of the common housing structure 202C medium, surrounding the sections of all of the waveguides embedded therein (i.e., the VC waveguide 204C and the plural Non-VC waveguides 206C-(l..n)), exceeds a total volume of the inner and outer cores of the section of the VC waveguide 204C that is embedded within the single common housing structure 202C.
  • the plural VC waveguides 204D-(l..N) are positioned along a central longitudinal axis of the common housing structure 202D, and circumferentially and symmetrically surrounded by proximal parallel plural Non- VC waveguides 206D-(l..n).
  • the coupler array 200D is configured such that a volume of the common housing structure 202D medium, surrounding the sections of all of the waveguides embedded therein (e.g., the plural VC waveguides 204D-(l..N), and the plural Non-VC waveguides 206D-(l..n)), exceeds a total volume of the inner and outer cores of the section of the plural VC waveguides 204D-(l..N) that are embedded within the single common housing structure 202D.
  • a first alternative embodiment of the optical fiber coupler array 200D of FIG. 3D, above, is shown as a coupler array 200E, that comprises a single housing structure 202E, a plurality of VC waveguides 204E-(l..N), with N being equal to 6 by way of example only, a plurality of Non-VC waveguides 206E-(l..n), with n being equal to 12 by way of example only, and a separate single Non-VC waveguide 206E’.
  • the Non- VC waveguide 206E’ is preferably operable to provide optical pumping functionality therethrough, and is positioned along a central longitudinal axis of the common housing structure 202E and circumferentially and symmetrically surrounded by proximal parallel plural VC waveguides 204E-(l..N), that are in turn circumferentially and symmetrically surrounded by proximal parallel plural Non- VC waveguides 206E-(l..n).
  • a second alternative embodiment of the optical fiber coupler array 200B of FIG. 3B, above, is shown as a coupler array 200F, that comprises a single housing structure 202F, a plurality of VC waveguides 204F-(l..N), with N being equal to 6 by way of example only, a separate single VC waveguide 204F’, and a plurality of Non-VC waveguides 206F-(l..n), with n being equal to 12 by way of example only, that preferably each comprise enlarged inner cores of sufficient diameter to increase or optimize optical coupling to different types of optical pump channels of various optical devices, to which the coupler array 200F may be advantageously coupled.
  • the VC waveguide 204F’ is positioned along a central longitudinal axis of the common housing structure 202F, and circumferentially and symmetrically surrounded by proximal parallel plural VC waveguides 204F-(l..N), that are in turn circumferentially and symmetrically surrounded by proximal parallel plural Non- VC waveguides 206F-(l..n).
  • FIG. 3G a third alternative embodiment of the optical fiber coupler array 200B of FIG. 3B, above, is shown as a coupler array 200G, that comprises a single housing structure 202G, and at least one VC waveguide, shown in FIG. 3G by way of example as a VC waveguide 204G, and a plurality of Non-VC waveguides 206G-(l..n), with n being equal to 18 by way of example only.
  • a double-clad fiber is a fiber in which both the core and the inner cladding have light guiding properties
  • most optical fiber types such as SM, MM, LMA, or MC (multi core), whether polarization maintaining or not, and even standard (e.g., conventional) single mode optical fibers, can be converted into a double-clad fiber by coating (or recoating) the fiber with a low index medium (forming the outer cladding).
  • the second end of the coupler array 200G when the second end of the coupler array 200G is spliced to a double-clad fiber (not shown), at least a portion of the common housing structure 202G proximal to the splice point with the double-clad fiber (not-shown), may be coated with a low index medium extending over the splice point and up to the double-clad fiber’ s outer cladding (and optionally extending over a portion of the outer cladding that is proximal to the splice point).
  • At least one of the VC waveguides utilized therein, and, in certain embodiments, optionally at least one of the Non-VC waveguides may comprise a polarization maintaining (PM) property.
  • the PM property of a VC waveguide may result from a pair of longitudinal stress rods disposed within the VC waveguide outside of its inner core and either inside, or outside, of the outer core (or through other stress elements), or the PM property may result from a noncircular inner or outer core shape, or from other PM-inducing optical fiber configurations (such as in bow-tie or elliptically clad PM fibers).
  • an axial alignment of the PM waveguides (or waveguide), in accordance with a particular polarization axes alignment mode may be involved.
  • a polarization axes alignment mode may comprise, but is not limited to, at least one of the following:
  • the single common housing structure of the optical coupler comprises a non-circular geometric shape (such as shown by way of example in FIG. 3L): axial alignment of a PM waveguide’s polarization axis to a geometric feature of the common housing structure outer shape;
  • optical coupler embodiments comprising one or more waveguide arrangement indicators, described below, in connection with FIGs. 3J-3L: axial alignment of a PM waveguide’s polarization axis to at least one geometric characteristic thereof;
  • optical coupler embodiments comprising at least one fiducial element 210A, as described above in connection with FIG. 3A: axial alignment of a PM waveguide’s polarization axis to a geometric position of the at least one fiducial element 210A;
  • the selection of a specific type of polarization axes alignment mode for the various embodiments of the optical coupler is preferably governed by at least one axes alignment criterion, which may include, but which is not limited to: alignment of PM waveguides’ polarization axes in a geometric arrangement that increases or maximizes PM properties thereof; and/or satisfying at least one requirement of one or more intended industrial application for the coupler array.
  • FIG. 3H a first alternative embodiment of the optical fiber coupler array 200G of FIG. 3G, above, is shown as a coupler array 200H, that comprises a single housing structure 202H, and at least one VC waveguide, shown in FIG. 3H by way of example as a PM VC waveguide 204H having polarization maintaining properties, and a plurality of Non-VC waveguides 206H-(l..n), with n being equal to 18 by way of example only.
  • the PM VC waveguide 204H is positioned as a side-channel, off-set from the central longitudinal axis of the single common housing structure 202H, and comprises a polarization axis that is aligned, by way of example, with respect to the transverse off-center location of the PM VC waveguide 204H.
  • the PM VC waveguide 2041 is positioned along a central longitudinal axis of the common housing structure 2021, and circumferentially and symmetrically surrounded by proximal parallel plural PM Non-VC waveguides 206I-(l..n).
  • the coupler array 2001 comprises a polarization axes alignment mode in which the polarization axes of each of the PM VC waveguide 2041 and of the plural PM Non-VC waveguides 206I-(l ..n) are aligned to one another.
  • the PM properties of the PM VC waveguide 2041 and of the plural PM Non-VC waveguides 206I-(l..n) are shown, by way of example only, as being induced by rod stress members (and which may readily and alternately be induced by various other stress, or equivalent designs)).
  • the coupler array 200J optionally comprises at least one waveguide arrangement indication element 208J, positioned on an outer region of the common housing structure 202J, that is representative of the particular cross-sectional geometric arrangement of the optical coupler array 200J waveguides (i.e., of the PM VC waveguide 204J and of the plural PM Non-VC waveguides 206J-(l..n)), such that a particular cross-sectional geometric waveguide arrangement may be readily identified from at least one of a visual and physical inspection of the common coupler housing structure 202J that is sufficient to examine the waveguide arrangement indication element 208 J.
  • the waveguide arrangement indication element 208J may be configured to be further operable to facilitate passive alignment of a second end of the optical coupler array 200J to at least one optical device (not shown).
  • the waveguide arrangement indication element 208J may comprise, but is not limited to, one or more of the following, applied to the common housing structure 202J outer surface: a color marking, and/or a physical indicia (such as an groove or other modification of the common housing structure 202J outer surface, or an element or other member positioned thereon).
  • the waveguide arrangement indication element 208J may actually comprise a specific modification to, or definition of, the cross-sectional geometric shape of the common housing structure 202J (for example, such as a hexagonal shape of a common housing structure 202L of FIG. 3 L, below, or another geometric shape).
  • the coupler array 200J may comprise a polarization axes alignment mode in which the polarization axes of each of the PM VC waveguide 204J and of the plural PM Non-VC waveguides 206J-(l..n) are aligned to one another, or to the waveguide arrangement indication element 208 J.
  • a fifth alternative embodiment of the optical fiber coupler array 200B of FIG. 3B, above, is shown as a coupler array 200K, that comprises a single housing structure 202K, and at least one VC waveguide, shown in FIG. 3K by way of example as a PM VC waveguide 204K having polarization maintaining properties, and a plurality of Non-VC waveguides 206K-(l..n), with n being equal to 18 by way of example only.
  • the PM VC waveguide 204K is positioned along a central longitudinal axis of the common housing structure 202K, and circumferentially and symmetrically surrounded by proximal parallel plural PM Non-VC waveguides 206K-(l..n).
  • the PM properties of the PM VC waveguide 204K are shown, by way of example only, as being induced by rod stress members (and which may readily and alternately be induced by various other stress, or equivalent approaches)).
  • the coupler array 200K may optionally comprise a plurality of waveguide arrangement indication elements — shown by way of example only, as waveguide arrangement indication elements 208K-a and 208K-b, which may each be of the same, or of a different type, as described above, in connection with the waveguide arrangement indication element 208J of FIG. 3J.
  • FIG. 3L a second alternative embodiment of the optical fiber coupler array 2001 of FIG. 31, above, is shown as a coupler array 200L, that comprises a single housing structure 202L comprising a cross section having a non-circular geometric shape (shown by way of example as a hexagon), and at least one VC waveguide, shown in FIG. 3L by way of example as a PM VC waveguide 204L having polarization maintaining properties, and a plurality of PM Non-VC waveguides 206L-(l..n), with n being equal to 18 by way of example only, each also having polarization maintaining properties.
  • a coupler array 200L that comprises a single housing structure 202L comprising a cross section having a non-circular geometric shape (shown by way of example as a hexagon), and at least one VC waveguide, shown in FIG. 3L by way of example as a PM VC waveguide 204L having polarization maintaining properties, and a plurality of PM Non-VC waveguides 206L-(
  • the PM VC waveguide 204L is positioned along a central longitudinal axis of the common housing structure 202L, and circumferentially and symmetrically surrounded by proximal parallel plural PM Non-VC waveguides 206L-(l..n).
  • the coupler array 200L comprises a polarization axes alignment mode in which the polarization axes of each of the PM VC waveguide 204L and of the plural PM Non-VC waveguides 206L-(l ..n) are aligned to one another, and to the common housing structure 202L cross-sectional geometric shape.
  • the PM properties of the PM VC waveguide 204L and of the plural PM Non-VC waveguides 206L-(l..n) are shown, by way of example only, as being induced by rod stress members (and which may readily and alternately be induced by various other stress, or equivalent designs)).
  • the coupler array 200K may optionally comprise a waveguide arrangement indication element 208L-a which may comprise any of the configurations described above, in connection with the waveguide arrangement indication element 208J of FIG. 3J.
  • a second end 302 i.e. “tip” of the optical fiber coupler array is shown, by way of example, as being in the process of connecting to plural vertical coupling elements 306 of an optical device 304 in a proximal open air optical coupling alignment configuration, that may be readily shifted into a butt-coupled configuration through full physical contact of the optical fiber coupler array second end 302 and the vertical coupling elements 306.
  • a second end 322 (i.e.“tip”) of the optical fiber coupler array is shown, by way of example, as being in the process of connecting to plural edge coupling elements 326 of an optical device 324 in a butt-coupled configuration, that may be readily shifted into one of several alternative coupling configuration, including a proximal open air optical coupling alignment configuration, and or an angled alignment coupling configuration.
  • the optical coupler array (i.e., such as optical coupler arrays 200D to 200L of FIGS. 3C to 3L) may be readily configured to pump optical fiber lasers, and/or optical fiber amplifiers (or equivalent devices).
  • a pumping-enabled coupler array comprises a central channel (i.e., waveguide), configured to transmit a signal (i.e., serving as a“signal channel”) which will thereafter be amplified or utilized to generate lasing, and further comprises at least one additional channel (i.e., waveguide), configured to provide optical pumping functionality (i.e., each serving as a “pump channel”).
  • the pumping-enabled coupler array may comprise the following in any desired combination thereof:
  • a single mode signal channel configured for increased or optimum coupling to a single mode amplifying fiber at at least one predetermined signal or lasing wavelength
  • a multimode signal channel configured for increased or optimum coupling to a multimode amplifying fiber at at least one predetermined signal or lasing wavelength
  • a single mode pumping channel configured for increased or optimum coupling to a single mode pump source at at least one predetermined pumping wavelength
  • a multimode pumping channel configured for increased or optimum coupling to a multimode pump source at at least one predetermined pumping wavelength
  • the pumping- enabled coupler array may be configured to selectively utilize less than all the available pumping channels. It should also be noted that, as a matter of design choice, and without departing from the spirit of the invention, the pumping-enabled coupler array may be configured to comprise:
  • At least one signal channel each disposed in a predetermined desired position in the coupler array structure
  • At least one pumping channel each disposed in a predetermined desired position in the coupler array structure
  • at least one additional waveguide for at least one additional purpose other than signal transmission or pumping e.g., such as a fiducial marker for alignment, for fault detection, for data transmission, etc.
  • the pump channels could be positioned in any transverse position within the coupler, including along the central longitudinal axis.
  • the pump channels may also comprise, but are not limited to, at least one of any of the following optical fiber types: SM, MM, LMA, or VC waveguides.
  • any of the optical fiber(s) being utilized as an optical pump channel (regardless of the fiber type) in the coupler may comprise polarization maintaining properties.
  • the pumping-enabled coupler array may be configured to be optimized for coupling to a double-clad fiber - in this case, the signal channel of the coupler array would be configured or optimized for coupling to the signal channel of the double-clad fiber, while each of the at least one pumping channels would be configured or optimized to couple to the inner cladding of the double-clad fiber.
  • the optical coupler arrays shown by way of example in various embodiments, may also be readily implemented as high density, multi-channel, optical input/output (I/O) for fiber-to-chip and fiber- to-optical waveguides.
  • the optical fiber couplers may readily comprise at least the following features:
  • optical fiber couplers may be advantageously utilized for at least the following applications, as a matter of design choice or convenience, without departing from the spirit of the invention:
  • Chip processing needs / waveguide up-tapering Polarization maintaining properties may be readily configured
  • the various example embodiments of the optical fiber couplers comprise at least the following advantages, as compared to currently available competitive solutions:
  • FIG. 7 at least one example embodiment of a flexible optical coupler array is shown as a flexible pitch reducing optical fiber array (PROFA) coupler 450.
  • PROFA flexible pitch reducing optical fiber array
  • FIG. 7 any feature described above can be implemented in any combination with a flexible PROFA coupler.
  • any of the features described with respect to FIGs. 1A-5 may be utilized in a flexible PROFA coupler.
  • any feature described with respect to FIGs. 1A-5 may be combined with any feature described with respect to FIG. 7.
  • the example flexible PROFA coupler 450 shown in FIG. 7 can be configured for use in applications where interconnections with low crosstalk and sufficient flexibility to accommodate low profile packaging are desired.
  • the vanishing core approach allows for the creation of a pitch reducing optical fiber array (PROFA) coupler / interconnect operable to optically couple, for example, a plurality of optical fibers to an optical device (e.g., a PIC), which can be butt- coupled to an array of vertical grating couplers (VGCs).
  • a pitch reducing optical fiber array (PROFA) coupler / interconnect operable to optically couple, for example, a plurality of optical fibers to an optical device (e.g., a PIC), which can be butt- coupled to an array of vertical grating couplers (VGCs).
  • VOCs vertical grating couplers
  • the vanishing core approach can be utilized once more to reduce the outside diameter further without substantially compromising the channel crosstalk. This further reduction can advantageously provide certain embodiments with a flexible region which has a reduced cross section between a first and second end.
  • the difference (N-2A minus N-3) is larger than the differences ( N-2 minus N-2A) or ( N-l minus N-2), resulting in a high NA, bend insensitive waveguide, when the light is guided by the additional layer having refractive index N-2A.
  • the outer diameter can then be expanded along the longitudinal length toward the second end, resulting in a lower NA waveguide with larger coupling surface area at the second end.
  • an optical coupler array 450 can comprise an elongated optical element 1000 having a first end 1010, a second end 1020, and a flexible portion 1050 therebetween.
  • the optical element 1000 can include a coupler housing structure 1060 and a plurality of longitudinal waveguides 1100 embedded in the housing structure 1060.
  • the waveguides 1100 can be arranged with respect to one another in a cross-sectional geometric waveguide arrangement.
  • FIG. 7 the example cross-sectional geometric waveguide arrangements of the waveguides 1100 for the first end 1010, the second end 1020, and at a location within the flexible portion 1050 are shown.
  • the cross-sectional geometric waveguide arrangement of the waveguides 1100 for an intermediate location 1040 between the first end 1010 and the flexible portion 1050 is also shown. As illustrated by the shaded regions within the cross sections and as will be described herein, light can be guided through the optical element 1000 from the first end 1010 to the second end 1020 through the flexible portion 1050. As also shown in FIG. 7, this can result in a structure, which maintains all channels discretely with sufficiently low crosstalk, while providing enough flexibility (e.g., with the flexible portion 1050) to accommodate low profile packaging.
  • the level of crosstalk and/or flexibility can depend on the application of the array. For example, in some embodiments, a low crosstalk can be considered within a range from -45 dB to -35 dB, while in other embodiments, a low crosstalk can be considered within a range from -15 dB to -5 dB. Accordingly, the level of crosstalk is not particularly limited.
  • the crosstalk can be less than or equal to -55 dB, -50 dB, -45 dB, -40 dB, -35 dB, -30 dB, -25 dB, -20 dB, -15 dB, -10 dB, 0 dB, or any values therebetween (e.g., less than or equal to -37 dB, -27 dB, -17 dB, -5 dB, etc.)
  • the crosstalk can be within a range from -50 dB to -40 dB, from -40 dB to -30 dB, from -30 dB to -20 dB, from -20 dB to -10 dB, from -10 dB to 0 dB, from -45 dB to -35 dB, from -35 dB to -25 dB, from -25 dB to -15 dB, from -15 d
  • the flexibility can also depend on the application of the array.
  • good flexibility of the flexible portion 1050 can comprise bending of at least 90 degrees, while in other embodiments, a bending of at least 50 degrees may be acceptable. Accordingly, the flexibility is not particularly limited. In some embodiments, the flexibility can be at least 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 90 degrees, 100 degrees, 110 degrees, 120 degrees, or at least any value therebetween.
  • the flexible portion 1050 can bend in a range formed by any of these values, e.g., from 45 to 55 degrees, from 50 to 60 degrees, from 60 to 70 degrees, from 70 to 80 degrees, from 80 to 90 degrees, from 90 to 100 degrees, from 100 to 110 degrees, from 110 to 120 degrees, or any combinations of these ranges, or any ranges formed by any values within these ranges (e.g., from 50 to 65 degrees, from 50 to 85 degrees, from 65 to 90 degrees, etc.) In other embodiments, the flexible portion 1050 can bend more or less than these values. Bending can typically be associated with light scattering. However, various embodiments can be configured to bend as described herein (e.g., in one of the ranges described above) and achieve relatively low crosstalk as described herein (e.g., in one of the ranges described above).
  • the flexible portion 1050 might not bend in use, however the flexibility can be desired for decoupling the first 1010 or second 1020 end from other parts of the coupler array 450.
  • the flexible portion 1050 of the flexible PROFA coupler 450 can provide mechanical isolation of the first end 1010 (e.g., a PROFA- PIC interface) from the rest of the PROFA, which results in increased stability with respect to environmental fluctuations, including temperature variations and mechanical shock and vibration.
  • the coupler array 450 can be operable to optically couple with a plurality of optical fibers 2000 and/or with an optical device 3000.
  • the optical fibers 2000 and optical device 3000 can include any of those described herein.
  • the coupler array 450 can couple with the optical fibers 2000 via the plurality of waveguides 1100 at the first end 1010.
  • the coupler array 450 can couple with the optical device 3000 via the plurality of waveguides 1100 at the second end 1020.
  • the plurality of waveguides 1100 can include at least one VC waveguide 1101.
  • FIG. 7 illustrates all of the waveguides 1100 as VC waveguides. However, one or more Non-VC waveguides may also be used.
  • FIG. 7 illustrates 7 VC waveguides, yet any number of VC and/or Non- VC waveguides can be used.
  • each of the waveguides 1100 can be disposed at an individual corresponding cross-sectional geometric position, relative to other waveguides of the plurality of waveguides 1100.
  • FIG. 7 shows a waveguide surrounded by 6 other waveguides
  • the cross-sectional geometric waveguide arrangement is not limited and can include any arrangement known in the art or yet to be developed including any of those shown in FIGs. 3A-3L.
  • the VC waveguide 1101 can include an inner core (e.g., an inner vanishing core) 1110, an outer core 1120, and an outer cladding 1130 with refractive indices N-l, N-2, and N-3 respectively.
  • the VC waveguide 1101 can also include a secondary outer core 1122 (e.g., between the outer core 1120 and the outer cladding 1130) having refractive index N-2A.
  • the outer core 1120 can longitudinally surround the inner core 1110
  • the secondary outer core 1122 can longitudinally surround the outer core 1120 with the outer cladding 1130 longitudinally surrounding the secondary outer core 1122.
  • the relationship between the refractive indices of the inner core 1110, outer core 1120, secondary outer core 1122, and outer cladding 1130 can advantageously be N-l > N-2 > N2-A > N-3.
  • each surrounding layer can serve as an effective cladding to the layers within it (e.g., the outer core 1120 can serve as an effective cladding to the inner core 1110, and the secondary outer core 1122 can serve as an effective cladding to the outer core 1120).
  • the use of the secondary outer core 1122 can provide an additional set of core and cladding.
  • the secondary outer core 1122 By including the secondary outer core 1122 with a refractive index N-2A, certain embodiments can achieve a higher NA (e.g., compared to without the secondary outer core 1122).
  • the difference (N-2A minus N-3) can be larger than the differences ( N-2 minus N-2A) or ( N-l minus N-2) to result in a relatively high NA.
  • Increasing NA can reduce the MFD, allowing for the channels (e.g., waveguides 1100) to be closer to each other (e.g., closer spacing between the waveguides 1100) without compromising crosstalk.
  • the coupler array 450 can be reduced further in cross section (e.g., compared to without the secondary outer core 1122) to provide a reduced region when light is guided by the secondary outer core 1122.
  • certain embodiments can include a flexible portion 1050 which can be more flexible than the regions proximal to the first end 1010 and the second end 1020.
  • the inner core 1110 size, the outer core 1120 size, and the spacing between the waveguides 1100 can reduce (e.g., simultaneously and gradually in some instances) along the optical element 1000 from the first end 1010 to the intermediate location 1040 such that at the intermediate location 1040, the inner core 1110 size is insufficient to guide light therethrough and the outer core 1120 size is sufficient to guide at least one optical mode.
  • each waveguide 1100 can have a capacity for at least one optical mode (e.g., single mode or multi-mode).
  • the VC waveguide 1101 can support a number of spatial modes (Ml) within the inner core 1110.
  • the outer core 1120 size, the secondary outer core 1122 size, and the spacing between the waveguides 1100 can reduce (e.g., simultaneously and gradually in some instances) along said optical element 1000, for example, from the intermediate location 1040 to the flexible portion 1050 such that at the flexible portion 1050, the outer core 1120 size is insufficient to guide light therethrough and the secondary outer core 1122 size is sufficient to guide at least one optical mode therethrough.
  • the VC waveguide 1101 can support all the Ml modes within the outer core 1120.
  • the outer core 1120 may be no longer able to support all the Ml modes (e.g., cannot support light propagation).
  • the secondary outer core 1122 can be able to support all the Ml modes (and in some cases, able to support additional modes).
  • light traveling within the outer core 1120 from the intermediate location 1040 to the flexible portion 1050 can escape from the outer core 1120 into the secondary outer core 1122 such that light can propagate within the inner core 1110, the outer core 1120, and secondary outer core 1122.
  • the outer core 1120 size, the secondary outer core 1122 size, and the spacing between the waveguides 1100 can expand (e.g., simultaneously and gradually in some instances) along the optical element 1000 from the flexible portion 1050 to the second end 1020 such that at the second end 1020, the secondary outer core 1122 size is insufficient to guide light therethrough and the outer core 1120 size is sufficient to guide at least one optical mode therethrough.
  • the secondary outer core 1122 may no longer be able to support all the Ml modes (e.g., cannot support light propagation).
  • the outer core 1120 can be able to support all the Ml modes (and in some cases, able to support additional modes).
  • light traveling within the secondary outer core 1122 from the flexible portion 1050 to the second end 1020 can return and propagate only within the inner core 1110 and the outer core 1120.
  • the outer core 1120 size, the secondary outer core 1122 size, and spacing between the waveguides 1100 can reduce (e.g., simultaneously and gradually in some instances) along the optical element 1000 from the second end 1020 to the flexible portion 1050 such that at the flexible portion 1050, the outer core 1120 size is insufficient to guide light therethrough and the secondary outer core 1122 size is sufficient to guide at least one optical mode therethrough.
  • the reduction in cross-sectional core and cladding sizes can advantageously provide rigidity and flexibility in a coupler array 450. Since optical fibers 2000 and/or an optical device 3000 can be fused to the ends 1010, 1020 of the coupler array 450, rigidity at the first 1010 and second 1020 ends can be desirable. However, it can also be desirable for coupler arrays to be flexible so that they can bend to connect with low profile integrated circuits.
  • the flexible portion 1050 between the first 1010 and second 1020 ends can allow the first 1010 and second 1020 ends to be relatively rigid, while providing the flexible portion 1050 therebetween.
  • the flexible portion can extend over a length of the optical element 1000 and can mechanically isolate the first 1010 and second 1020 ends.
  • the flexible portion 1050 can mechanically isolate the first end 1010 from a region between the flexible portion 1050 and the second end 1020.
  • the flexible portion 1050 can mechanically isolate the second end 1020 from a region between the first end 1010 and the flexible portion 1050.
  • Such mechanical isolation can provide stability to the first 1010 and second 1020 ends, e.g., with respect to environmental fluctuations, including temperature variations and mechanical shock and vibration.
  • the length of the flexible portion 1050 is not particularly limited and can depend on the application.
  • the length can be in a range from 2 to 7 mm, from 3 to 8 mm, from 5 to 10 mm, from 7 to 12 mm, from 8 to 15 mm, any combination of these ranges, or any range formed from any values from 2 to 20 mm (e.g., 3 to 13 mm, 4 to 14 mm, 5 to 17 mm, etc.).
  • the length of the flexible portion 1050 can be shorter or longer.
  • the flexible portion 1050 can provide flexibility.
  • the flexible portion 1050 can have a substantially similar cross-sectional size (e.g., the cross-sectional size of the waveguides 1100) extending over the length of the flexible portion 1050.
  • the cross-section size at the flexible portion 1050 can comprise a smaller cross-sectional size than the cross-sectional size at the first 1010 and second 1020 ends. Having a smaller cross-sectional size, this flexible portion 1050 can be more flexible than a region proximal to the first 1010 and second 1020 ends.
  • the smaller cross- sectional size can result from the reduction in core and cladding sizes.
  • An optional etching post-process may be desirable to further reduce the diameter of the flexible length of the flexible PROFA coupler 450.
  • the flexible portion 1050 can be more flexible than a standard SMF 28 fiber. In some embodiments, the flexible portion 1050 can bend at least 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 90 degrees, 100 degrees, 110 degrees, 120 degrees, or at least any value therebetween.
  • the flexible portion 1050 can bend in a range formed by any of these values, e.g., from 45 to 55 degrees, from 50 to 60 degrees, from 60 to 70 degrees, from 70 to 80 degrees, from 80 to 90 degrees, from 90 to 100 degrees, from 100 to 110 degrees, from 110 to 120 degrees, or any combinations of these ranges, or any ranges formed by any values within these ranges (e.g., from 50 to 65 degrees, from 50 to 85 degrees, from 65 to 90 degrees, etc.) In other embodiments, the flexible portion 1050 can bend more or less than these values. As described herein, in various applications, the flexible portion 1050 might not bend in use, however the flexibility can be desired for decoupling the first 1010 or second 1020 end from other parts of the coupler array 450.
  • the coupler array 450 can include a coupler housing structure 1060.
  • the coupler housing structure 1060 can include a common single coupler housing structure.
  • the coupler housing structure 1060 can include a medium 1140 (e.g., having a refractive index N-4) surrounding the waveguides 1100.
  • N-4 is greater than N-3. In other examples, N-4 is equal to N-3.
  • the medium 1140 can include any medium as described herein (e.g., pure-silica).
  • the medium can also include glass such that the coupler array 450 can be an all-glass coupler array.
  • the waveguides 1100 can be embedded within the medium 1040 of the housing structure 1060.
  • a total volume of the medium 1140 of the coupler housing structure 1060 can be greater than a total volume of all the inner and outer cores 1110, 1120, 1122 of the VC waveguides confined within the coupler housing structure 1060.
  • each waveguide can couple to the optical fibers 2000 and/or optical device 3000 at a location inside, outside, or at a boundary region of the coupler housing structure 1060, e.g., as shown in FIGs. 1A to 2D. Because the optical fibers 2000 and optical device 3000 can be different at each end, the first end 1010 and the second end 1020 can each be configured for the optical fibers 2000 or optical device 3000 with which it is coupled.
  • the MFD of the VC waveguide at the first 1010 and/or second 1020 ends can be configured (e.g., using the sizes of the cores) to match or substantially match the MFD of the optical fiber 2000 or optical device 3000 with which it is coupled.
  • the NA of the VC waveguide at the first 1010 and/or second 1020 ends can be configured (e.g., using the refractive indices) to match or substantially match the NA of the optical fiber 2000 or optical device 3000 with which it is coupled.
  • the refractive indices can be modified in any way known in the art (e.g., doping the waveguide glass) or yet to be developed.
  • the core and cladding (1110, 1120, 1122, 1130) sizes are not particularly limited.
  • the inner 1110 and/or outer 1120 core sizes can be in a range from 1 to 3 microns, from 2 to 5 microns, from 4 to 8 microns, from 5 to 10 microns, any combination of these ranges, or any range formed from any values from 1 to 10 microns (e.g., 2 to 8 microns, 3 to 9 microns, etc.). However, the sizes can be greater or less.
  • the inner 1110 and/or outer 1120 core sizes can range from submicrons to many microns, to tens of microns, to hundreds of microns depending, for example, on the wavelength and/or number of modes desired.
  • the difference in the refractive indices e.g., between N-l and N-2, between N-2 and N-2A, and/or between N-2A and N-3) is not particularly limited.
  • the index difference can be in a range from 1.5 x 10 3 to 2.5 x 10 3 , from 1.7 x 10 3 to 2.3 x 10 3 , from 1.8 x 10 3 to 2.2 x 10 3 , from 1.9 x 10 3 to 2.1 x 10 3 , from 1.5 x 10 3 to 1.7 x 10 3 , from 1.7 x 10 3 to 1.9 x 10 3 , from 1.9 x 10 3 to 2.1 x 10 3 , from 2.1 x 10 3 to 2.3 x 10 3 , from 2.3 x 10 3 to 2.5 x 10 3 , any combination of these ranges, or any range formed from any values from 1.5 x 10 3 to 2.5 x 10 3 .
  • the index difference can be greater or less.
  • the optical device 3000 can include a PIC.
  • the PIC can include an array of VGCs.
  • multiple flexible PROFA couplers (such as the coupler 450), each having multiple optical channels, can be combined together to advantageously form an optical multi-port input/output (IO) interface.
  • an optical multi-port IO interface can include a plurality of optical coupler arrays, at least one of the optical coupler arrays can include an optical coupler array 450 as described herein.
  • first (larger) end there are two ends of the coupler array: a first (larger) end, and a second (smaller) end.
  • the two ends are spaced apart in the longitudinal direction (along the z direction).
  • the first end is proximate to position B and the second end is proximate to positions C and D.
  • one of the functions of the first end is to encapsulate the waveguides 30A, 32A-1, 32A-2 with increased or approximate positioning accuracy.
  • the coupler housing structure 14A at a proximity to the first end may encapsulate, e.g., circumferentially surround a portion of the length of the waveguides 30A, 32A-1, 32A-2, but not necessarily completely enclose the ends of the waveguides 30A, 32A-1, 32A-2.
  • the waveguides 30A, 32A-1, 32A-2 may or may not extend (e.g., longitudinally) outside the coupler housing structure 14A.
  • the end of waveguide 30A is disposed within the coupler housing structure 14A, but the ends of waveguides 32A-1 and 32A-2 extend, e.g., longitudinally (in a direction parallel to the z-direction) outside of the coupler housing structure 14A.
  • the ends of waveguides 130B-1, 130B-2 are disposed at an outer cross sectional boundary region of the coupler housing structure 14A and do not extend, e.g., longitudinally (in a direction parallel to the z-direction) outside of the coupler housing structure 14 A.
  • one of the functions of the second end is to have the waveguides 30A, 32A-1, 32A-2 embedded in a housing structure (e.g., a common housing structure in some instances) with improved (precise or near precise in some cases) cross sectional positioning.
  • a housing structure e.g., a common housing structure in some instances
  • the waveguides 30A, 32A-1, 32A-2 at a proximity to the second end may be embedded, e.g., be circumferentially surrounded by the contiguous coupler housing structure 14A.
  • the ends of waveguides 30A, 32A-1, 32A-2 are longitudinally disposed at an outer cross sectional boundary region of the coupler housing structure 14A.
  • one or more ends of the waveguides may be disposed within or may longitudinally extend outside the coupler housing structure 14A.
  • some embodiments can include the example cross sectional configuration of the housing structure shown in FIG. 8 at a proximity to the first end. The cross section is orthogonal to the longitudinal direction or length of the optical coupler array. As shown in FIG.
  • the coupler array 800 can include a housing structure 801 having a transverse (or lateral) configuration of a ring surrounding the plurality of longitudinal waveguides 805 at a close longitudinal proximity to the first end.
  • a gap such as an air gap, may separate the plurality of longitudinal waveguides 805 from the surrounding ring.
  • Some such configurations may allow for self-aligning waveguide arrangement at a close proximity to a first end (e.g., hexagonal close packed arrangement in a housing structure having circular (as shown in FIG. 8) or hexagonal inner cross section)
  • the waveguides 805 are in a hexagonal arrangement. Other arrangements are possible, e.g., square, rectangular, etc.
  • the ring may have an inner cross section 80 la (in the transverse direction, i.e., orthogonal to the longitudinal direction or length of the optical coupler array) that is circular or non-circular.
  • the inner cross section 80 la may be circular, elliptical, D-shaped, square, rectangular, hexagonal, pentagonal, octagonal, other polygonal shape, etc.
  • the inner cross section 80 la does not necessarily follow the arrangement of the waveguides 805.
  • four waveguides arranged in a square arrangement can be confined in an inner circular cross section.
  • the inner cross section 80la is circular, while the waveguides 805 are hexagonally arranged.
  • a circular inner cross section may be a preferred shape, which can allow for a close-pack hexagonal arrangement.
  • other inner cross sectional shapes may also be used, such as square or rectangular, which can allow for non-hexagonal waveguide arrangements.
  • the inner cross section 80la may be similar as the arrangement of the waveguides 805 to reduce empty space.
  • the inner cross section 80 la of the ring may be hexagonal to reduce empty space between the inner cross section 80 la and the waveguides 805.
  • the outer cross section 80lb (in the transverse direction, e.g., orthogonal to the longitudinal direction or length of the optical coupler array) may be circular or non-circular.
  • the outer cross section 80 lb may be circular, elliptical, hexagonal, D-shaped (e.g., to provide for passive axial alignment of the coupler since the flat surface allow for an easy rotational alignment), square, rectangular, pentagonal, octagonal, other polygonal shape, etc.
  • the outer cross section 80lb (e.g., circular) follows the shape of the inner cross section 80la (e.g., circular).
  • the outer cross section 80lb need not be similar as the inner cross section 80la.
  • One of the functions of the inner cross sectional shape is to allow for an improvement in the transverse positional accuracy at the proximity to the second end, while one of the functions of the outer cross sectional shape is to allow for a passive axial alignment of the coupler (e.g., the alignment can be done without launching light into the coupler). In some configurations it may be preferred to substantially preserve the outer cross sectional shape from the first end to the second end to facilitate the passive alignment at one of the ends or at both ends of the coupler array.
  • FIG. 9 shows another example cross sectional configuration of the housing structure at a proximity to the first end.
  • the coupler array 850 can include a housing structure 851 having a configuration of a structure (e.g., a contiguous structure in some cases) with a plurality of holes 852. At least one of the holes 852 may contain at least one of the longitudinal waveguides 855. A gap, such as an air gap, may separate the plurality of longitudinal waveguides 855 from the surrounding housing structure 851.
  • the outer cross section may be circular, elliptical, hexagonal, D- shaped, square, rectangular, pentagonal, octagonal, other polygonal shape, etc. Some of such configurations may allow for passive alignment at one of the ends or at both ends of the coupler array. While the example configuration shown in FIG. 8 may allow for simpler fabrication in some cases, the example configuration shown in FIG. 9 may allow for arbitrary transverse waveguide positioning.
  • FIG. 9 shows an example configuration with six holes 852, yet other number of holes is possible.
  • the holes 852 in this example configuration may be isolated or some or even all holes 852 may be connected.
  • a first hole 852-1 is isolated from a second hole 852-2.
  • the first hole 852-1 may be connected to at least one second hole 852-2.
  • the arrangement of the holes 852 is shown as a 3 x 2 array, yet other arrangements are possible.
  • the hole arrangement pattern may be hexagonal, square, rectangular, or defined by an XY array defining positions of the holes in the transverse plane.
  • Figure 9 shows all the holes 852 with a waveguide 855 illustrated as a vanishing core (VC) waveguide.
  • VC vanishing core
  • one or more of the holes 852 may be identical or different than another hole 852 to accommodate, for example, waveguides 855 of different shapes and dimensions (e.g., cross sectional shapes, diameters, major/minor elliptical dimensions, etc.).
  • the cross sections of the holes 852 may be circular or non-circular.
  • the cross section may be circular, elliptical, hexagonal or D-shaped (e.g., to provide for passive axial alignment of polarization maintaining (PM) channels), square, rectangular, pentagonal, octagonal, other polygonal shape, etc.
  • the cross section of the hole 852 at close proximity to the first end is larger than the cross section of the waveguides 855 such that a gap is disposed between an inner surface 85 la of the coupler housing structure 851 and the waveguide 855.
  • the coupler housing structure (e.g., 801 in FIG. 8 or 851 in FIG. 9) can include a medium from a wide range of materials as described herein.
  • the medium of the coupler housing structure 801, 851 can have refractive index (N-4).
  • the medium can be a transversely contiguous medium. This can allow for a robust housing structure with improved transverse positioning accuracy in some embodiments.
  • the total volume of the medium of the coupler housing structure 801, 851 can be greater than a total volume of all the inner and outer cores of the VC waveguides confined within the coupler housing structure 801, 851 to provide that in some embodiments, all VC waveguides are reliably embedded in the housing structure allowing for stable performance).
  • the example configurations shown in FIG. 8 and FIG. 9 may allow for improved manufacturability of the devices with improved cross sectional (transverse) positioning of the waveguides e.g., at the second end.
  • This transverse position may for example, be defined in the x and/or y directions, while z is the direction along the length coupler array (e.g., from the first end to the second end).
  • the assembly comprising the waveguides (e.g., 805 in FIG. 8 and 855 in FIG. 9) and coupler housing structure (e.g., 801 in FIG. 8 or 851 in FIG.
  • the waveguides 805 can be inserted into the coupler housing structure 801 having a configuration of a ring (in the cross section orthogonal to the longitudinal direction or length of the optical coupler array, e.g., in the x-y plane shown).
  • a gap such as an air gap can be disposed between the coupler housing structure 801 and the waveguide 805 to permit lateral movement (in x and/or y directions) of the waveguide with respect to the coupler housing structure 801.
  • one or more waveguides 855 can be inserted into the coupler housing structure 851 having a plurality of holes 852 (e.g., as seen in the cross section orthogonal to the longitudinal direction or length of the optical coupler array, e.g., in the x-y plane shown) where the waveguides 855 can be passively aligned within the housing structure 851.
  • a gap such as an air gap can be disposed between the coupler housing structure 851 and the waveguide 855 to permit transverse movement (in x and/or y directions) of the waveguide with respect to the coupler housing structure 851.
  • close packed waveguide arrangement e.g., hexagonal
  • the coupler array can include a plurality of longitudinal waveguides 30A, 32A-1, 32A-2 with at least one VC waveguide 30A having an inner core 20A and an outer core 22A.
  • the inner core 20A, the outer core 22A, and the spacing between the plurality of waveguides 30A, 32A-1, 32A-2 can reduce (e.g., simultaneously and gradually in some cases) from the first end (proximate to position B) to the second end (proximate to positions C and D), e.g., from S-l to S-2.
  • the cross sectional configuration at the first end (proximate position B) is shown as in FIG. 8 or FIG.
  • FIGs. 3A-3L or FIG. 7 there is substantially no gap between the coupler housing structure and the waveguides, some gaps being filled by housing material and some gaps being filled by waveguide cladding material.
  • the cross sectional or transverse positioning of the waveguides at the second end can be improved.
  • the waveguides at the second end can thus be properly aligned in the transverse direction (e.g., x and/or y direction) with an optical device.
  • the coupler arrays 4000, 5000 can be configured to couple to and from a plurality of optical fibers, such as to and from optical fibers with different mode fields and/or core sizes.
  • the coupler arrays 4000, 5000 can be configured to provide coupling between a set of individual isolated optical fibers 2000 and an optical device 3000 having at least one optical channel allowing for propagation of more than one optical mode.
  • all isolated optical fibers 2000 can be identical (or some different in some instances) and the optical device 3000 can include at least one few-mode fiber, multimode fiber, multicore single mode fiber, multicore few-mode fiber, and/or multicore multimode fiber.
  • various embodiments 4000, 5000 can include a further reduction of the taper diameter, which can allow light to escape the outer core 4120, 5120 and propagate in a combined waveguide 4150, 5150, formed by at least two neighboring cores. Accordingly, various embodiments described herein can be configured to optically couple between fibers with dissimilar mode fields and/or core shapes or sizes.
  • some embodiments of the coupler arrays can improve and/or optimize optical coupling between one or more of single mode fibers, few-mode fibers, multimode fibers, multicore single mode fibers, multicore few-mode fibers, and/or multicore multimode fibers.
  • any described feature can be implemented in any combination with the coupler arrays described with respect to FIGs. 1A-5 and 7. Further, any feature described with respect to FIGs. 1 A- 5 and 7 may be combined with any feature described with respect to FIGs. 10 and 11.
  • the example coupler arrays 4000, 5000 are illustrated utilizing housing structures 4060, 5060 similar to the housing structures 801, 851 shown in FIGs. 8-9.
  • the cross sectional configuration of the housing structure 4060, 5060 may include a structure with a plurality of holes (e.g., multi-hole) as shown in FIG.10, or may include one hole (e.g., single-hole surrounded by a ring), as shown in FIG. 11.
  • other housing structures can also be used.
  • the housing structures described with respect to FIGs. 1A-5 and 7 may be used.
  • certain embodiments of a multichannel optical coupler array 4000 can include an elongated optical element 4001 having a first end 4010, an intermediate location or cross section 4050, and a second end 4020.
  • the housing structure 4060 proximally (e.g. proximately) to the first end 4010, can have a cross sectional configuration of a structure (e.g., transversely contiguous structure in some cases) with a plurality of holes 4062.
  • FIG. 10 shows an example configuration with three circular holes 4062- 1 , 4062-2, 4062-3.
  • the shape of the holes, number of holes, and/or arrangement of the holes are not particularly limited and can include any other shape, number, and/or arrangement including those described with respect to FIG. 9.
  • At least one of the holes 4062 may contain at least one of the longitudinal waveguides 4100.
  • a gap such as an air gap, may separate the plurality of longitudinal waveguides 4100 from the surrounding housing structure 4060 proximally to the first end 4010.
  • one or more gaps may be filled by housing material and/or waveguide cladding material.
  • proximate to the first end 4010 there may be a gap between the coupler housing structure 4060 and the waveguides 4100, but proximate to the second end 4020, there may be substantially no gap between the coupler housing structure 4060 and the waveguides 4100 (or vice versa).
  • the coupler array 4000 can be operable to optically couple with a plurality of optical fibers 2000 and/or with an optical device 3000.
  • the coupler array 4000 can couple with the optical fibers 2000 via the plurality of waveguides 4100 proximate the first end 4010 (e.g., via a fusion splice 2001), and/or with the optical device 3000 via the plurality of waveguides 4100 proximate the second end 4020 (e.g., via a fusion splice not shown).
  • the number of waveguides 4100 may equal the number of optical fibers 2000 (e.g., 9 waveguides to couple with 9 optical fibers).
  • the number of waveguides 4100 in at least one hole may equal the number of optical modes supported by a corresponding few-mode or multi-mode waveguide of the device 3000 (e.g. 3 waveguides in each of 3 holes to couple with three 3-mode cores of a multicore fiber).
  • a total volume of the medium 4140 of the coupler housing structure 4060 can be greater than a total volume of all the inner and outer cores 4110, 4120 of the VC waveguides confined within the coupler housing structure 4060.
  • the waveguides 4100 may be embedded in the housing structure 4060 (e.g., proximate the second end 4020).
  • some of the outer cores 4120 can be made with a non-circular cross section (e.g., elliptical as shown in FIG. 10) and a particular orientation of the outer cores 4120 can be used to increase and/or optimize optical coupling.
  • Various embodiments described herein can also include features of any of the optical polarization mode couplers described in U.S. Application Number 15/617,684, entitled“CONFIGURABLE POLARIZATION MODE COUPLER”, which is incorporated herein in its entirety.
  • the inner core 4110 size, the outer core 4120 size, the cladding 4130 size, and/or the spacing between the waveguides 4100 can reduce (e.g., simultaneously and gradually in some instances) along the optical element 4001 from the first end 4010 to an intermediate location or cross section 4050.
  • a predetermined reduction profile may be used.
  • the inner core 4110 may be insufficient to guide light therethrough and the outer core 4120 may be sufficient to guide at least one optical mode (e.g., spatial mode).
  • each core of a waveguide 4100 can have a capacity for at least one optical mode (e.g., single mode, few-mode, or multi-mode).
  • the VC waveguide 4101 can support a number of spatial modes (Ml) within the inner core 4110.
  • Ml spatial modes
  • the inner core 4110 may no longer be able to support all the Ml modes (e.g., cannot support light propagation).
  • the outer core 4120 can be able to support all the Ml modes (and in some cases, able to support additional modes).
  • light traveling within the inner core 4110 from the first end 4010 to the intermediate location 4050 can escape from the inner core 4110 into the outer core 4120 such that light can propagate within the outer core 4120.
  • the inner core 4110 size, the outer core 4120 size, the cladding 4130 size, and/or the spacing between the waveguides 4100 can be further reduced (e.g., simultaneously and gradually in some instances) along the optical element 4001 from the intermediate location 4050 to the second end 4020.
  • the outer core 4120 may be insufficient to guide light therethrough.
  • the VC waveguide 4101 can support all the Ml modes within the outer core 4120.
  • the outer core 4120 may be no longer able to support all the Ml modes (e.g., cannot support light propagation).
  • a combined core 4150 of at least two cores may be able to support all the Ml modes of all waveguides 4101 combined (and in some cases, able to support additional modes).
  • each of the combined waveguides 4150 is formed by three outer cores.
  • the combined waveguides 4150 may be formed with another number of outer cores.
  • light travelling from the second end 4020 to the first end 4010 can behave in the reverse manner.
  • light can move from the combined waveguide 4150 formed by at least two neighboring outer cores into the at least one outer core 4120 proximally to the intermediate cross section 4050, and can move from the outer core 4120 into corresponding inner core 4110 proximally to the first end 4010.
  • each of the combined waveguides 4150 can support three propagation modes.
  • a gap may separate the plurality of longitudinal waveguides 5100 from the surrounding housing structure 5060.
  • the inner core 5110 waveguide dimensions, the outer core 5120 waveguide dimensions, the cladding 5130 dimensions, refractive indices, and/or the numerical apertures (NAs) can be selected to increase and/or optimize coupling to the individual fibers 2000 and/or optical device 3000.
  • the inner core 5110 size, the outer core 5120 size, the cladding 5130 size, and/or the spacing between the waveguides 5100 can reduce along the optical element 5001 from the first end 5010 to the second end 5020. In the example shown in FIG.
  • each of the combined waveguides 5150 is formed by three outer cores, the combined waveguides 5150 may be formed by another number of outer cores.
  • the remaining cores e.g., cores of waveguides or dummy fibers
  • Light travelling from the second end 5020 to the first end 5010 can behave in the reverse manner.
  • optical coupler arrays configured to couple light from one or more optical fibers to an optical device, e.g., a photonic integrated circuit (PIC), or vice versa from an optical device to one or more optical fibers.
  • one or more optical coupler arrays can include one or more features configured to passively align (e.g., laterally and/or axially) with one or more features of the optical device.
  • Some such embodiments can advantageously provide passive alignment without time-consuming and costly active alignment, which may entail for example, transmitting light through the waveguide structures, detecting coupling efficiency, and optimizing the alignment between waveguides of the coupler array and the optical device to optimize light coupling.
  • FIG. 12A schematically illustrates an example optical coupler array configured to provide passive alignment with an optical device such as a PIC.
  • the example optical coupler array 900 can include one or more longitudinal waveguides 930 within a housing structure 914.
  • the housing structure 914 can have an outer cross sectional shape comprising a first side 914A and a second side 914B.
  • the first side 914A can be configured to align with a feature 945 of the optical device 940.
  • the second side 914B can, in some implementations, be configured to align with the top surface 945B of the optical device’s feature 945 and/or optical device 940.
  • the second side 914B can be substantially parallel and in a substantially straight line with the top surface 945B of the optical device’s feature 945.
  • the second side 914B can be higher or lower (e.g., in a vertical direction) than the top surface 945B of the optical device’s feature 945, but still substantially parallel with the top surface 945B.
  • the housing structure 914 has a D-shaped outer cross sectional shape with a first side 914A comprising a curved portion and a second side 914B comprising a flat portion.
  • the curved side 914A can align with a feature 945 (e.g., a v-groove) of the optical device 940, and the flat side 914B can align (e.g., be substantially parallel) with the top surface 945B of the optical device’s feature 945 and/or optical device 940.
  • an alignment carrier 920 e.g., a plate, a block, wedge, etc.
  • FIG. 12B schematically illustrates the example optical coupler array 900 aligned and coupled with the optical device 940 shown in FIG. 12A.
  • the optical coupler array 900 can be any optical coupler array known in the art or yet to be developed.
  • the optical coupler array 900 can include any optical coupler array described herein, e.g., any optical coupler array in Figs. 1A-11.
  • the optical coupler array 900 can include a pitch reducing optical fiber array (PROFA) as described herein.
  • PROFA pitch reducing optical fiber array
  • a PROFA may advantageously be used to provide access to individual channels.
  • the optical coupler array 900 can have a first end 901 and a second end 902.
  • the optical coupler array 900 can be configured to optically couple at the first end 901 with a plurality of optical fibers (not shown), and can be configured to optically couple at the second end 902 with the optical device 940.
  • the optical coupler array 900 can include one or more optical waveguides 930.
  • the number of waveguides is not particularly limited (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, 50, 75, 80, 90, 100, etc., or any range formed by such values).
  • the optical waveguide 930 can be any optical waveguide known in the art or yet to be developed.
  • the optical waveguides 930 can include any waveguide described herein, e.g., a vanishing core waveguide or a non-vanishing core waveguide.
  • the waveguides 930 can include optical fibers and are not limited as to the type of optical fibers but may include any optical fibers, e.g., single mode fibers, few-mode fibers, multimode fibers, polarization maintaining fibers, and/or any combination thereof.
  • the one or more optical waveguides 930 can be disposed in a housing structure 914, e.g., a common single coupler housing structure. In some instances, one or more optical waveguides 930 can be embedded in the housing structure 914.
  • the waveguides 930 can comprise cores of a fiber, and the housing 914 can comprise a fiber cladding.
  • a multi-core fiber MCF
  • the waveguides 930 are cores of the MCF
  • the housing 914 is the cladding.
  • the MCF fiber may be fabricated separately and fusion-spliced to an end of a PROFA coupler or a PROFA coupler may be fabricated with an MCF as an integral part of the PROFA coupler.
  • an MCF can be formed as a relatively long and flexible end section of a PROFA coupler.
  • a PROFA coupler may or may not be used.
  • the optical coupler array 900 may be optically coupled at the first end 901 with a MCF (not shown).
  • the MCF may be operable to optically couple with at least one optical fiber waveguide (e.g., a plurality of optical fibers or another optical device).
  • the MCF can be optically coupled (at the end opposite the optical coupler array 900) with a second optical coupler array operable to optically couple with at least one optical fiber waveguide (e.g., a plurality of optical fibers or another optical device).
  • the second optical coupler array can be any optical coupler array disclosed herein, including any optical coupler array in FIGs. 1A-11 or optical coupler array 900 shown in FIG. 12A. Other examples are possible.
  • the optical coupler array 900 can have one or more features configured to passively align with one or more features of the optical device 940 (or with one or more features of a carrier or substrate of the coupler array 900 and/or the optical device 940). In some examples, the optical coupler array 900 can have one or more features that can passively align with one or more features of a common carrier/ substrate of the coupler array 900 and optical device 940.
  • the feature of the optical coupler array 900 can be positionally registered with one or more waveguides 930 of the optical coupler array 900 (e.g., a position of the first side 914A can be registered relative to a position of a waveguide 930 of the optical coupler array 900), and the feature of the optical device 940 can be positionally registered with one or more of the waveguides 950 of the optical device 940 (e.g., a position of a v-groove 945 can be registered relative to a position of a waveguide 950 of the optical device 940).
  • the waveguides 930 of the optical coupler array 900 are aligned (e.g., laterally and/or axially at the second end 902) with the waveguides 950 of the optical device 940.
  • the feature of the optical device 940 can accept a reciprocally or complementary designed feature in the optical coupler array 900.
  • the feature of the optical coupler array 900 can accept a reciprocally or complementary designed feature in the optical device 940.
  • the feature of the optical coupler array 900 can include a particular shape of the housing structure 914, such as a shape complementary with a feature 945 of the optical device 940 (or with a feature of a carrier or substrate of the coupler array 900 and/or the optical device 940).
  • the housing structure 914 can have an outer cross sectional shape with a first side 914A comprising one or more curved portions (e.g., a portion or portions of a circular shape or ellipse).
  • the outer cross sectional shape can include a second side 914B comprising one or more flat portions (e.g., a portion or portions of a flat or planar shape).
  • the housing structure 914 can have a D-shaped outer cross sectional shape.
  • the housing structure 914 can have a curved side 914A and a flat side 914B.
  • Other shapes including any shape with planar and/or curved portions can also be used (e.g., square, rectangular, pentagonal, hexagonal, octagonal, any other polygonal shape, circular with a flat section, etc.).
  • the second side 914B can be disposed at a distance from the waveguides 930 such that the waveguiding properties are preserved and not disturbed.
  • the second side 914B can be disposed 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 wavelengths distance (or any range formed by such values) from the waveguides 930.
  • the second side 914B can be disposed such that the insertion loss is low (e.g., minimized in some cases). In some instances, the second side 914B can be disposed such that the polarization extinction ratio is high (e.g., maximized in some cases). The second side 914B can also be registered with the optical device 940 (e.g., in height).
  • the chip/die edge 947 can be faceted to integrate a registered v-groove 945 feature.
  • the v-groove 945 can include angled walls 945A forming a v-shape.
  • the v-groove 945 (or the optical device 940) can also include a top surface 945B, e.g., configured to align (e.g., be substantially parallel) with the second side 914B of the housing structure 914 of the optical coupler array 900.
  • the top surface 945B of the v-groove 945 and/or the optical device 940 can be substantially parallel and in a substantially straight line with the second side 914B of the housing structure 914 of the optical coupler array 900.
  • the top surface 945B of the v-groove 945 and/or the optical device 940 can be substantially parallel, but lower or higher (e.g., in a vertical direction) than the second side 914B of the housing structure 914 of the optical coupler array 900.
  • the v-groove 945 feature with a chip/die edge 947 can include one or more features for coupling and/or index matching/ filling.
  • the features can include grooves 946A within the v-groove 945 (e.g., on a wall 945A of the v-groove 945) that can allow an epoxy to flow and better adhere to the optical device 940.
  • the features can include features 946B (e.g., protrusions, holes, pits, grooves, etc.) that can enable the index matching adhesive to have better mechanical adhesion to the chip/die edge 947.
  • Other example features of the optical device 940 can include other shapes with planar surfaces (e.g., a square- or rectangularly-trenched structure or a hexagonally- or octogonally-trenched structure) and/or with curved surfaces. Some such examples can help facilitate preferential or multiple orientations of, e.g., a MCF.
  • the v-groove 945 of the optical device 940 can accept the shaped housing structure 914 (e.g., D-shaped) of the optical coupler array 900.
  • the first side 914A of the housing structure 914 can be configured to be positioned in the v-groove 945 such that the shaped (e.g., curved in this example) portion of the first side 914A can contact and/or align with the shape (e.g., walls 945A of the v-groove 945) of the optical device 940.
  • the second side 914B can be configured to align with the top surface 945B (e.g., substantially parallel) of the v-groove 945 and/or the optical device 940.
  • the second side 914B can be substantially parallel and in a substantially straight line with the top surface 945B of the v-groove 945 and/or the optical device 940.
  • the second side 914B can higher or lower (e.g., in a vertical direction) than the top surface 945B of the v-groove 945 and/or the optical device 940, but still substantially parallel with the top surface 945B.
  • the optical coupler array 900 can advantageously self-align (e.g., automatically align) with the optical device 940 such that the waveguides 930 of the optical coupler array 900 can be aligned with the waveguides 950 of the optical device 940 laterally and axially.
  • the waveguides 930 of the optical coupler array 900 can be aligned with the waveguides 950 of the optical device 940 with an optical coupling efficiency between 50% and 100% (e.g., between 60% and 100%, between 70% and 100%, between 80% and 100%, between 90% and 100%).
  • one or more of the waveguides 930, 950 or surface thereof can be angled at the interface to reduce back reflections.
  • the optical coupler array 900, the optical device 940, and/or a carrier/substrate can include alignment fiducials.
  • the optical coupler array 900 can include a polarization maintaining (PM) MCF configured to couple with polarization sensitive waveguides of a PIC.
  • PM polarization maintaining
  • Alignment fiducials can be incorporated on the MCF, PIC, a carrier/substrate, and/or any combination thereof. Alignment fiducials can be used by machine vision for rough alignment and the self-aligning features accomplish the fine alignment.
  • the fiducials can be, for example, any kind of visually discernible features such as lithographically formed possibly metallic geometric shapes (e.g. lines, comers, crosses, etc.).
  • mechanical coupling features can be used to facilitate, for example, compression bonding, solder bonding, laser welding, and/or flow and retention of optical or mechanical adhesives. These can, for example, be copper bond pads, metallization for acceptance of solder bumps, metal pads or lines for laser welding, grooves that increase surface or roughness for enhanced mechanical adhesion, etc.
  • Mechanical coupling features e.g., reciprocal features in the optical coupler array 900 and optical device 940
  • fibers can transmit light but also can have electrical (e.g. metallic) and/or fluid (e.g. holes) waveguides that also transmit electricity or fluids.
  • electrical e.g. metallic
  • fluid e.g. holes
  • PICs that are used in microfluidics or biological analysis or gas sensing
  • PICs that may have varied input/output needs - e.g., for electricity, fluids/gases and/or light.
  • An array of waveguides in the optical coupler array 900 and/or optical device 940 could be heterogeneous to include other mechanical or transmission coupling modes.
  • the optical coupler array 900 can include an alignment carrier 920 (e.g., a plate, a block, wedge, etc.) disposed and/or coupled with the second side 914B of the housing structure 914.
  • the alignment carrier 920 can have a first side 920A and a second side 920B.
  • the alignment carrier 920 can include one or more features configured to align with one or more features of the second side 914B of the housing structure 914, such as one or more features complementary with one or more features of the second side 914B of the housing structure 914.
  • the first side 920A of the alignment carrier 920 can include one or more flat portions (e.g., a portion or portions of a flat or planar shape) configured to align with one or more flat portions of the second side 914B of the housing structure 914.
  • the flat portions of the first side 920A (e.g., bottom side) of an alignment carrier 920 can be disposed on the flat portions of the second side 914B (e.g., top side) of a housing structure 914.
  • the shape of the second side 920B of the alignment carrier 920 is not particularly limited.
  • the second side 920B can include one or more flat and/or curved portions.
  • the second side 920B can include a regular or irregular shape.
  • the alignment carrier 920 can be configured to advantageously provide an axial alignment tool and allow a pick-and-place machine to appropriately position the optical coupler array 900, e.g., to provide alignment with the top surface of the v-groove 945 and/or optical device 940.
  • the housing structure 914 can be designed such that the waveguides 930 are axially aligned with the PIC’s waveguides 950 when the top surface 945B of the PIC and top surface 914B of the housing structure 914 of the optical coupler array 900 are substantially parallel.
  • a pick-and-place tool can, for example, pick up the alignment carrier 920 by applying a vacuum to the top side 920B and then place it on the housing structure 914.
  • the top surface 914B of the housing structure 914 of the optical coupler array 900 and/or the bottom surface 920A of the alignment carrier 920 can include an adhesive (e.g., a pre-applied adhesive). Pressing the alignment carrier 920 onto the housing structure 914, possibly also residing in an appropriate carrier, can adhere the alignment carrier 920 and housing structure 914 and can align the housing structure 914 axially such that it can be lifted and placed into the v-groove 945, adhered within that v-groove 945, and waveguides 930 and 950 can be thereby aligned. In some instances, the alignment carrier 920 can extend beyond the second side 914B of the housing structure 914 in the transverse direction on at least one side or on both sides.
  • an adhesive e.g., a pre-applied adhesive
  • the alignment carrier 920 can be configured to sit over (e.g., disposed above and/or on) the top surface 945B of the v-groove 945 or optical device 940. In some instances, the alignment carrier 920 might not sit on and/or contact the top surface 945B of the v-groove 945 and/or optical device 940.
  • the housing structure 914 of the optical coupler array 900 can have a second side 914B having a curved portion
  • the alignment carrier 920 can have a first side 920A having a V-shape or curved portion.
  • the optical coupler array 900 can have a housing structure 914 with a first side 914A (e.g., bottom side) with a shape complementary with a feature 945 of the optical device 940 to provide passive alignment.
  • the optical coupler array 900 can include an alignment carrier 920 with a first side 920A (e.g., bottom side) having a shape complementary with the second side 914B (e.g., top side) of the housing structure 914 of the optical coupler array 900.
  • FIG. 13 schematically illustrates an example multifiber array 1300 positioned over an optical device 1340.
  • the example multifiber array 1300 includes a plurality of optical couplers 1301.
  • the multifiber array 1300 can include 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. optical couplers 1301.
  • the number of optical couplers 1301 is not particularly limited.
  • FIG. 13 shows four optical couplers 1301 for illustration purposes only.
  • the optical couplers 1301 can include any of the optical coupler arrays described herein (including for example, optical coupler array 900).
  • the optical coupler 1301 can include one or more longitudinal waveguides 1330.
  • the waveguides 1330 can include any of the waveguides described herein (including for example, waveguide 930) including any vanishing core and/or non- vanishing core waveguides. In some instances, the waveguides 1330 can include cores of multicore fiber. Some fibers can be flexible.
  • the waveguides 1330 of the optical coupler 1301 can be embedded in a common single housing structure 1314.
  • the housing structure 1314 can include any of the housing structures described herein (including for example, housing structure 914). In some instances, the housing structure 1314 can include cladding.
  • the housing structure 1314 has a first side 1314A, which can comprise one or more curved portions.
  • the housing structure 1314 has a second side 1314B, which can comprise one or more flat portions.
  • the flat portion(s) of the second side 1314B can be disposed at a distance from the waveguide 1330 such that insertion loss is low from one end to the other end of the waveguide 1330.
  • the flat portion(s) of the second side 1314B can be disposed at a distance from the waveguide 1330 such that waveguiding properties are preserved from one end to the other end of the waveguide 1330.
  • the optical couplers 1301 can be coupled together with an alignment carrier 1320.
  • the alignment carrier 1320 can include any of the alignment carriers described herein (including for example, alignment carrier 920).
  • the alignment carrier 1320 can include, for example, a plate, a block, a wedge, etc.
  • the alignment carrier 1320 can have a first side 1320A and a second side 1320B, and can be disposed over the second side 1314B of the housing structure 1314 of the optical coupler 1301.
  • the first side 1320A of the alignment carrier 1320 can comprise one or more flat portions 1320A-1 coupled with one or more flat portions of the second side 1314B of the housing structure 1314 of the optical coupler 1301.
  • the flat portions 1320A-1 of the alignment carrier 1320 may be adhered (e.g., with adhesive) with the flat portions of the second side 1314B of the housing structure 1314 of the optical coupler 1301.
  • the alignment carrier 1320 can extend beyond the second side 1314B of the housing structure 1314 of the optical coupler 1301 in the transverse direction on at least one side (e.g., extend on both sides as shown in FIG. 13).
  • the multifiber array 1300 is positioned over an example optical device 1340.
  • the optical device 1340 can include any of the optical devices described herein (including for example, optical device 940).
  • the optical device 1340 or a carrier of the optical device 1340 can include walls 1345 A and a top surface 1345B of a v-groove 1345 and/or the optical device 1340.
  • the first side 1314A of the housing structure 1314 of the optical coupler 1301 can be positioned in the v-groove 1345.
  • the first side 1314A of the housing structure 1314 can contact the walls 1345A of the v-groove 1345.
  • other reciprocally or complementary designed shapes of the optical coupler 1301 and optical device 1340 are possible.
  • the alignment carrier 1320 can be configured to align (e.g., be substantially parallel) with the top surface 1345B of the optical device 1340 (e.g., the v-groove 1345).
  • the first side 1320A of the alignment carrier 1320 can be configured to sit over the top surface 1345B of the optical device 1340.
  • the alignment carrier 1320 can be configured to sit on the top surface 1345B of the optical device 1340.
  • the alignment carrier 1320 can be configured to not sit on the top surface 1345B of the optical device 1340.
  • the alignment carrier 1320 may be shaped such that it does not contact the top surface 1345B of the optical device 1340.
  • the second side 1314B of the housing structure 1314 of the optical coupler 1301 may be higher (e.g., in a vertical direction) than the top surface 1345B of the optical device 1340 such that the alignment carrier 1320 may also be higher than the top surface 1345B of the optical device 1340.
  • the alignment carrier 1320 can be aligned (e.g., be substantially parallel) with the top surface 1345B of the optical device 1340 even though it might not contact the top surface 1345B of the optical device 1340.
  • the optical coupler 1301 can be configured to optically couple with at least one waveguide of the optical device 1340.
  • a position of the optical device 1340 e.g., the v-groove 1345
  • a waveguide 1330 of the optical coupler 1301 can be aligned with a waveguide of the optical device 1340.
  • the waveguide 1330 of the optical coupler 1301 can be aligned with the waveguide of the optical device 1340 with an optical coupling efficiency from 50% to 100% (e.g., from 60% to 100%, from 70% to 100%, from 80% to 100%, from 90% to 100%, etc. or any range between any of these values).
  • individual ones of the optical couplers 1301 can be configured to optically couple one end of at least one optical fiber waveguide (e.g., one or more single mode fibers, few-mode fibers, multimode fibers, multicore single mode fibers, multicore few-mode fibers, and/or multicore multimode fibers) to a waveguide or waveguides of the optical device 1340.
  • optical fiber waveguide e.g., one or more single mode fibers, few-mode fibers, multimode fibers, multicore single mode fibers, multicore few-mode fibers, and/or multicore multimode fibers
  • the first side 1414A of the housing structure 1414 of the optical coupler 1401 can be positioned in the optical device 1440.
  • the first side 1414A of the housing structure 1414 can comprise one or more curved portions configured to be positioned within walls 1445A of a v-groove 1445 in the optical device 1440.
  • the first side 1420A of the alignment carrier 1420 can comprise one or more v-grooves 1420A-1
  • the second side 1414B of the housing structure 1414 of the optical coupler 1401 can comprise one or more curved portions.
  • a curved portion of the housing structure 1414 can be disposed within a v-groove 1420A-1 of the alignment carrier 1420.
  • the number of v-grooves 1420A-1 is not particularly limited.
  • the number of v-grooves 1420A-1 in the alignment carrier 1420 can be at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. (or any range formed by such values).
  • the number of v-grooves 1420A-1 in the alignment carrier 1420 may correspond with the number of optical couplers 1401.
  • v-grooves 1420A-1 in the alignment carrier 1420 there may be more v-grooves 1420A-1 in the alignment carrier 1420 than the number of optical couplers 1401. In some implementations, there may be less v-grooves 1420A- 1 in the alignment carrier 1420 than the number of optical couplers 1401.
  • the v-grooves 1420A-1 in the alignment carrier 1420 can be the same or different in shape (e.g., slope of walls) and/or size with the other v-grooves 1420A-1 in the alignment carrier.
  • the v-grooves 1420A- 1 in the alignment carrier 1420 can also be the same or different in shape (e.g., slope of walls) and/or size with the v-grooves 1445 in the optical device 1440.
  • the v-grooves 1420A-1 in the alignment carrier 1420 are not the same in size as the v-grooves 1445 in the optical device 1440.
  • the v-grooves 1420A-1 in the alignment carrier 1420 may be the same size as the v-grooves 1445 in the optical device 1440.
  • individual ones of the optical couplers 1401 can be configured to optically couple one end of at least one optical fiber waveguide to a waveguide or waveguides of the optical device 1440.
  • the first side 1420A of the alignment carrier 1420 may sit over the top surface 1445B (e.g., top surface of v-groove 1445) of the optical device 1440.
  • the alignment carrier 1420 may or may not contact the top surface 1445B of the optical device 1440.
  • FIG. 15 schematically illustrates another example multifiber array 1500 positioned over an optical device 1540.
  • the multifiber array 1500 has a plurality of optical couplers 1501 and an alignment carrier 1520.
  • One or more of the optical couplers 1501 can include one or more longitudinal waveguides 1530 in a housing structure 1514.
  • the alignment carrier 1520 has a first side 1520A and a second side 1520B.
  • the optical couplers 1501 and alignment carrier 1520 can include any of the features and/or combination of features described herein, and are not all repeated herein.
  • the first side 1514A of the housing structure 1514 of the optical coupler 1501 can be positioned in the optical device 1540.
  • the first side 1514A of the housing structure 1514 can comprise one or more curved portions configured to be positioned within walls 1545 A of a v-groove 1545 in the optical device 1540.
  • the first side 1520A of the alignment carrier 1520 can comprise multiple flat portions 1520A-1, and the second side 1514B of the housing structure 1514 of the optical coupler 1501 can comprise multiple flat portions configured to couple with the multiple flat portions of the alignment carrier 1520.
  • the number of flat portions in an optical coupler 1501 may be same as the number of corresponding flat portions 1520A-1 in the alignment carrier 1520.
  • the number of flat portions in a given optical coupler 1501 and/or the number of corresponding flat portions 1520A-1 in the alignment carrier 1520 is not particularly limited.
  • the number of flat portions can be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. (or any range formed by such values).
  • the number of flat portions in an optical coupler 1501 may be different than the number of corresponding flat portions 1520A-1 in the alignment carrier 1520.
  • an optical coupler 1501 with a second side 1514B having two flat portions may be positioned within three flat portions in the alignment carrier 1520.
  • the number, shape, and/or size of flat portions for one optical coupler 1501 (and/or the number, shape, and/or size of corresponding flat portions 1520A-1 in the alignment carrier 1520) may be the same or different than the number, shape, and/or size of flat portions for another optical coupler 1501 (and/or the number, shape, and/or size of corresponding flat portions 1520A-1 in the alignment carrier 1520).
  • individual ones of the optical couplers 1501 can be configured to optically couple one end of at least one optical fiber waveguide to a waveguide or waveguides of the optical device 1540.
  • the first side 1520A of the alignment carrier 1520 may sit over the top surface 1545B (e.g., top surface of v-groove 1545) of the optical device 1540.
  • the alignment carrier 1520 may or may not contact the top surface 1545B of the optical device 1540.
  • the reciprocally or complementary designed shapes of the alignment carrier and the housing structures of the optical couplers are similar for different optical couplers in the multifiber array.
  • reciprocally or complementary designed shapes can be combined with other reciprocally or complementary designed shapes.
  • any of the designed shapes shown in FIGs. 13, 14, and/or 15 can be combined with any of the other designed shapes shown in FIGs. 13, 14, and/or 15.
  • Other reciprocally or complementary designed shapes can also be used.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un réseau de coupleurs optiques pouvant comprendre un élément optique allongé ayant une structure de logement de coupleurs et au moins un guide d'ondes longitudinal intégré dans ladite structure de logement. La structure de logement peut avoir une forme de section transversale externe comprenant un premier côté comportant une ou plusieurs parties incurvées et un second côté comportant une ou plusieurs parties plates. Le second côté peut être disposé à une certaine distance dudit guide d'ondes longitudinal de sorte que les propriétés de guidage d'ondes soient conservées et non perturbées.
PCT/US2019/055965 2018-10-12 2019-10-11 Réseau de coupleurs optiques à alignement passif Ceased WO2020077285A1 (fr)

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US16/159,310 US10564348B2 (en) 2013-06-14 2018-10-12 Passive aligning optical coupler array
US16/159,310 2018-10-12

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WO2020077285A1 true WO2020077285A1 (fr) 2020-04-16

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US10838155B2 (en) 2013-06-14 2020-11-17 Chiral Photonics, Inc. Multichannel optical coupler
US10914891B2 (en) 2013-06-14 2021-02-09 Chiral Photonics, Inc. Multichannel optical coupler
US11022762B2 (en) 2019-08-05 2021-06-01 Chiral Photonics, Inc. Optical fiber connectors for rotational alignment
US11156781B2 (en) 2013-06-14 2021-10-26 Chiral Photonics, Inc. Passive aligning optical coupler array
US11280971B2 (en) * 2020-08-10 2022-03-22 Nokia Solutions And Networks Oy Optical coupling with undercut protection from underfill
WO2022254290A1 (fr) 2021-05-31 2022-12-08 Picadvanced S.A. Appareil d'hébergement auto-entretenu multifonctionnel et sous-ensemble optique bidirectionnel associé basé sur un circuit intégré photonique
US11609376B2 (en) 2020-02-24 2023-03-21 Chiral Photonics, Inc. Space division multiplexers
US11966091B2 (en) 2013-06-14 2024-04-23 Chiral Photonics, Inc. Multichannel optical coupler array
US12210185B2 (en) 2020-02-24 2025-01-28 Chiral Photonics, Inc. Wavelength division multiplexers for space division multiplexing (SDM-WDM devices)
TWI871618B (zh) * 2022-04-28 2025-02-01 日商京瓷股份有限公司 光迴路基板及光學零件安裝構造體

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US20170205583A1 (en) * 2016-01-18 2017-07-20 Corning Incorporated Polymer clad fiber for evanescent coupling
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US20180188454A1 (en) * 2012-10-17 2018-07-05 Cornell University Fiber-waveguide evanescent coupler
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Publication number Priority date Publication date Assignee Title
US10838155B2 (en) 2013-06-14 2020-11-17 Chiral Photonics, Inc. Multichannel optical coupler
US10914891B2 (en) 2013-06-14 2021-02-09 Chiral Photonics, Inc. Multichannel optical coupler
US11156781B2 (en) 2013-06-14 2021-10-26 Chiral Photonics, Inc. Passive aligning optical coupler array
US12487418B2 (en) 2013-06-14 2025-12-02 Chiral Photonics, Inc. Multichannel optical coupler array
US11966091B2 (en) 2013-06-14 2024-04-23 Chiral Photonics, Inc. Multichannel optical coupler array
US11022762B2 (en) 2019-08-05 2021-06-01 Chiral Photonics, Inc. Optical fiber connectors for rotational alignment
US11609376B2 (en) 2020-02-24 2023-03-21 Chiral Photonics, Inc. Space division multiplexers
US12210185B2 (en) 2020-02-24 2025-01-28 Chiral Photonics, Inc. Wavelength division multiplexers for space division multiplexing (SDM-WDM devices)
US11280971B2 (en) * 2020-08-10 2022-03-22 Nokia Solutions And Networks Oy Optical coupling with undercut protection from underfill
KR20240014497A (ko) 2021-05-31 2024-02-01 픽어드밴스드 에스.에이. 광자 집적 회로 기반 다중기능 자가 지속 호스팅 장치 및 관련 양방향 광학 서브 어셈블리
WO2022254290A1 (fr) 2021-05-31 2022-12-08 Picadvanced S.A. Appareil d'hébergement auto-entretenu multifonctionnel et sous-ensemble optique bidirectionnel associé basé sur un circuit intégré photonique
US12619028B2 (en) 2021-05-31 2026-05-05 Picadvanced S.A. Multifunctional self-sustained hosting apparatus and related bidirectional optical sub assembly based on photonic integrated circuit
TWI871618B (zh) * 2022-04-28 2025-02-01 日商京瓷股份有限公司 光迴路基板及光學零件安裝構造體

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