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
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/12004—Combinations of two or more optical 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
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/12002—Three-dimensional structures
• • 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
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
• • 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
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B2006/12083—Constructional arrangements
  • G02B2006/12107—Grating
• • 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
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/122—Basic optical elements, e.g. light-guiding paths
  • G02B6/124—Geodesic lenses or integrated gratings
• • 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
  • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
  • G02B6/29331—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by evanescent wave coupling
  • G02B6/29332—Wavelength selective couplers, i.e. based on evanescent coupling between light guides, e.g. fused fibre couplers with transverse coupling between fibres having different propagation constant wavelength dependency
  • G02B6/29334—Grating-assisted evanescent light guide couplers, i.e. comprising grating at or functionally associated with the coupling region between the light guides, e.g. with a grating positioned where light fields overlap in the coupler

Definitions

• Optical substrate with integrated antennas and spectrometer comprising it
• the present invention relates to the field of integrated optics, and relates more particularly to an optical substrate with integrated antennas and to a spectrometer comprising it.
• an optical detector in particular of the infrared (IR) or camera type, outside the optical component, in a direction close to the normal to the surface of the optical component, the light will diverge naturally from the emission point to the detection point.
• the signal coming from these distinct sources will be spread over several pixels. This induces a superposition on a pixel (or group of pixels) of signals from the different sources at the optical detector, creating crosstalk and reducing the signal-to-noise ratio.
• This large angular divergence is due to the source points, considered punctual and therefore very divergent, and to the active zone in optical detectors (particularly of the IR type), which can be several hundred micrometers below the physical surface of the detector. optical.
• a first solution to overcome these drawbacks is to space out the source points. However, the density of information that can be processed is thus reduced.
• Another solution is to act on the extraction of light from the waveguide to the optical detector.
• We can thus use, for example, a Bragg grating (physical alternation of zones with high/low refractive index) placed on the surface in the waveguide.
• This principle is widely known in integrated optics.
• Most solutions for improving the directivity of the radiated flux are thus based on two-dimensional antennas of the surface array type, by electron beam lithography, a focused ion beam, or polymerization.
• the following publications disclose such solutions: - YagiUda 3D optical nanoantenna array, (3D optical YagiUda nanoantenna array), Dregely D.
• Another possibility of manufacturing the Bragg grating is to produce periodically spaced nano "holes" of air (which are similar to air cylinders), in the material constituting the component.
• Such a technique for forming nano-holes is for example described in the following publications: - Machining of high aspect ratio nanochannel machining using single shot femtosecond Bessel beams (High aspect ratio nanochannel machining using single shot femtosecond Bessel beams), Bhuyan et al., Appl. Phys. Lett. 97, 081102 (2010), - Single shot high aspect ratio bulk nanostructuring of fused silica using chirp controlled ultrafast laser Bessel beams), Bhuyan et al., Appl. Phys. Lett.
• a non-diffractive irradiation procedure is used to photo-inscribe nano-holes in the optical substrate comprising a waveguide using focused Bessel beams which locally generate a concentration of energy in the optical substrate sufficient to create localized one-dimensional microexplosions, the lateral release of pressure creating one-dimensional axially uniform cavities, to create extended uniform nano-holes (sometimes called Bessel nano-holes). It is possible according to this technique to use two lasers which face each other with the optical substrate in the middle, or a single laser aimed at the substrate.
• the main advantage of laser inscription for the fabrication of elongated nano-holes is that it is possible to cover a sampling length of 1 cm, without mask replacement, in a very short time (a few seconds).
• the position of the hole can be adjusted relative to the waveguide.
• the geometry and length of the nano-holes can be controlled “at will”, but with a compromise between length and diameter.
• the manufacture of nano-air holes using laser photo-inscription techniques makes it possible, for example, to produce this type of planar network. As with the two-dimensional antennas described above, only the period or the duty cycle of the periods can be modified to control the extraction power of the network.
• pp.82, ⁇ 10.1117/12.2562179> describes the use of nano-holes for the extraction of optical flow in a waveguide.
• the present invention aims to optimize the extraction of an optical flow confined in a waveguide integrated in an optical substrate in order to direct it towards a detector located on the surface of the optical substrate integrating the waveguide, using nano -three-dimensional nano-air hole type antennas formed by laser photo-inscription.
• classic lithographic technologies which are surface techniques
• a photo-sensitive resin is deposited on a waveguide in surface, then is exposed with a laser, for example a UV laser (simpler than the femto-second lasers of the laser photo-inscription technique), then degraded in the exposed locations, which are then removed with a solvent to also form nano-air holes.
• a laser for example a UV laser (simpler than the femto-second lasers of the laser photo-inscription technique)
• the result can be compared to three-dimensional stacks which can be produced by the Microlight 3D ® or Nanoscribe ® tools in polymers, by two-photon absorption for example.
• the nanoantennas are thus formed directly in the material in which the waveguide is located, without requiring an additional resin deposition step as in the case of Microlight 3D ®.
• the invention provides access to an additional degree of freedom. Indeed, the nano-holes can be made at different heights relative to each other.
• the extraction of the optical flow from the waveguide by these three-dimensional antennas made up of nano-holes can therefore be controlled by several parameters: the period, the cyclical ratio with the diameter of the nano- holes, the offset, spacing or superposition of periodic nano-holes in height.
• the period of the nano-holes is in this case preferably ⁇ /n, with ⁇ the wavelength of the signal and n the refractive index of the substrate in which the waveguide and the nano-holes are formed.
• ⁇ the wavelength of the signal
• n the refractive index of the substrate in which the waveguide and the nano-holes are formed.
• an apodized grating This apodization can be done in two ways: either by controlling the diameter of the nano-holes, or by vertical shift of the position of the nano-holes.
• the period of the nano-holes is 2 to 3 times greater than ⁇ /n, there are several radiated Bragg orders (i.e. several directions of light radiation in addition to the normal direction).
• the invention can thus make it possible to develop a compact optical spectrometer, without any moving parts, the detector being stuck to the waveguide collecting photons to be characterized, with a Bragg grating as the only relay optic.
• the present invention therefore relates to an optical substrate with an integrated waveguide, the optical substrate having a longitudinal direction, a transverse direction and a height direction and being made of a material of refractive index n, the guide d waves being formed in the optical substrate in the longitudinal direction of the optical substrate, at least one antenna being formed in the optical substrate offset from the waveguide in the height direction, the at least one antenna being configured to diffract, in the height direction of the optical substrate, an evanescent wave produced on the surface of the waveguide by a standing wave generated by the injection of an optical signal of wavelength ⁇ into the waveguide, characterized by the fact that the at least one antenna is formed by several nano-holes formed in the transverse direction of the optical substrate, at least one of the nano-holes differing from the other nano-holes by at least one of its diameter, its spacing of the waveguide according to the height direction of the optical substrate and its spacing to an adjacent nano-hole of the same antenna according to the longitudinal direction of the optical substrate.
• the at least one antenna comprises an odd number of nano-holes, preferably between three and five nano-holes, more preferably comprises five nano-holes.
• the width (angular flare) and intensity of the diffracted signal are linked to the number of nano-holes: the more holes there are, the more coherent the signal, with a finer peak and less crosstalk.
• the intensity of the signal is proportional to the number of holes, the diffraction width being inversely proportional to the number of holes. Increasing the number of holes introduces constraints on repeatability.
• the at least one antenna may be formed between the waveguide and the detector, in which case the at least one antenna diffracts the evanescent wave away from the waveguide, or the at least one antenna may be formed opposite the detector relative to the waveguide, in which case the at least one antenna diffracts the evanescent wave towards the waveguide and the detector.
• the standing wave formed in the waveguide by the injection of an optical signal of wavelength ⁇ can be obtained either by reflection at the end of the waveguide using a mirror, or by injection of two sources on either side of the waveguide (therefore injection from the left and right of the waveguide simultaneously), which requires a prior division of the optical flow of the source to make a 50/50 distribution then a separation of the optical paths to inject through the two opposite entrances of the waveguide.
• the nano-holes have diameters decreasing symmetrically from a central nano-hole of the antenna towards the end nano-holes.
• a variable diameter of nano-holes (apodization) within the same antenna makes it possible to adjust the envelope of the diffracted signal.
• a larger hole in the center of the antenna makes it possible to reduce the secondary lobes of the signal diffracted by the antenna to improve the quality of extraction of the signal diffracted towards the outside of the optical substrate, making it possible, for example, to move from a diffracted signal having the shape of a cardinal sine to a Gaussian form.
• the nano-holes are in parallel planes in the height direction of the optical substrate.
• the nano-holes have a V-shaped arrangement, the central nano-hole constituting the tip of the V facing the waveguide and the other nano-holes being arranged symmetrically along each branch of the V in planes perpendicular to the direction of height of the optical substrate moving away from the waveguide depending on whether the nano-holes they contain approach the ends of the branches of the V, the spacing spacing two adjacent nano-holes in projection in a plane perpendicular to the height direction of the optical substrate being equal to ⁇ /n or an integer multiple of ⁇ /n.
• the spacing separating each pair of adjacent nano-holes may be the same, but the invention is not limited in this respect, the spacings within the same antenna may differ accordingly.
• the present invention also relates to a spectrometer comprising a light source, an optical substrate as defined above and a detector, the substrate having two parallel plane faces opposite in the height direction of the optical substrate, the light source being configured to inject light into the waveguide of the optical substrate, the detector being arranged facing the flat face of the substrate towards which the light diffracted by the at least one antenna is directed.
• the injection of light can be done using an optical fiber glued to the substrate, in front of the waveguide, or using microlenses glued to the waveguide, or by focusing the beam from the light source with microscope objectives or any suitable optical lens assembly.
• FIG. 6 is a view similar to Figure 2 of an antenna 230 according to a third embodiment of the invention, in which the nano-holes 241, 242, 243 are arranged in the same plane at a certain distance from the waveguide 2 in the height direction of the substrate.
• the optical signal emitted by the optical source 7 in the waveguide 2 generates, by circulation in the waveguide 2, an evanescent wave directed by the antenna 330 towards the detector 5, and in particular towards the network of pixels schematized by the layer 6 in the upper part of the detector 5 , the resulting signals being sent to the signal processing device 8.
• the signal processing device 8 can be a microprocessor, a microcontroller, a processor, a digital signal processor (DSP), a programmable gate array (FPGA), a specific application component (ASIC), or even a computer with software enabling it to process and analyze the signals emitted by the pixels of layer 6.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Optical Integrated Circuits (AREA)

Applications Claiming Priority (2)

Publications (1)

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Country Status (4)

Family Cites Families (4)

• 2022
  • 2022-10-04 FR FR2210146A patent/FR3140451B1/fr active Active
• 2023
  • 2023-08-16 WO PCT/EP2023/072610 patent/WO2024074241A1/fr not_active Ceased
  • 2023-08-16 CN CN202380070930.1A patent/CN119998702A/zh active Pending
  • 2023-08-16 EP EP23765443.9A patent/EP4599278A1/de active Pending

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