EP1119785A2 - Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques - Google Patents

Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques

Info

Publication number
EP1119785A2
EP1119785A2 EP99969589A EP99969589A EP1119785A2 EP 1119785 A2 EP1119785 A2 EP 1119785A2 EP 99969589 A EP99969589 A EP 99969589A EP 99969589 A EP99969589 A EP 99969589A EP 1119785 A2 EP1119785 A2 EP 1119785A2
Authority
EP
European Patent Office
Prior art keywords
fiber
mns
coupled
glass
absorbing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99969589A
Other languages
German (de)
English (en)
Inventor
Shin-Lo Chia
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GC Technologies Ltd
Original Assignee
GC Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GC Technologies Ltd filed Critical GC Technologies Ltd
Publication of EP1119785A2 publication Critical patent/EP1119785A2/fr
Withdrawn legal-status Critical Current

Links

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
    • G02B6/264—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting
    • G02B6/266—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting the optical element being an attenuator
    • 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
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03694—Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress 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
    • G02B6/24—Coupling light guides
    • G02B6/36—Mechanical coupling means
    • G02B6/38—Mechanical coupling means having fibre to fibre mating means
    • G02B6/3807—Dismountable connectors, i.e. comprising plugs
    • G02B6/3833—Details of mounting fibres in ferrules; Assembly methods; Manufacture
    • G02B6/3845—Details of mounting fibres in ferrules; Assembly methods; Manufacture ferrules comprising functional elements, e.g. filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06716—Fibre compositions or doping with active elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06729—Peculiar transverse fibre profile
    • H01S3/06733—Fibre having more than one cladding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06754—Fibre amplifiers

Definitions

  • the present invention relates generally to fiber optic connectors and more specifically to a method and system for suppressing modal noise.
  • Modal noise is generated at mechanical connectors and splices in single mode fiber optic systems, especially when several connectors or splices are in close proximity, i.e. , separated by a few meters or less. This type of noise is troublesome in many systems applications, and increasingly so as higher data rates and wavelength density is achieved in such systems.
  • the modal noise results from a fraction of the signal power in the propagating mode of the system being scattered into higher, " non- propagating" modes at discontinuities, such as connectors or splices.
  • the lowest order of the non-propagating modes are highly attenuated over distances of tens or hundreds of meters, where their energy dissipates into the outer cladding and buffer coating of the fiber.
  • the power of the non- propagating mode in the vicinity of the core can still be considerable, and a fraction of it can be converted back to propagating mode power at a second discontinuity.
  • the converted power then interferes with the directly transmitted propagating mode power, since the propagation velocity of the higher order modes is different from the lowest order mode. Whether the interference is constructive or destructive depends on a variety of factors, such as spacing between the discontinuities, wavelength of the signal, and propagation velocity of the dominant higher order mode.
  • the present invention provides a method and system for modal noise suppression in a fiber optics systems.
  • a single mode optical fiber comprises a strongly absorbing outer cladding glass and a non-absorbing inner cladding glass.
  • the fiber also includes a non-absorbing core glass. Through this combination modal noise is suppressed.
  • an in-line attentuator in a second aspect, includes the above-described single mode optical fiber; an attentuating fiber coupled thereto, and a ferrule member for holding the single mode optical fiber and the attentuating fiber.
  • an isolator in a third aspect, comprises an optics assembly and an input transmission fiber coupled to the optics assembly.
  • the isolator further includes a first modal noise suppression (MNS) fiber coupled in the input transmission fiber and a gradient index lens coupled between the optics assembly and the first MNS fiber.
  • MNS modal noise suppression
  • the isolator further includes a second MNS fiber coupled to the gradient index lens and an output filter coupled to the second MNS fiber.
  • a fiber amplifier comprising first and second wavelength division multiplexers (WDMS) means and first and second fibers which provide pump power into the first and second WDM means.
  • the fiber amplifier further includes an amplifier section and a third fiber for providing signal power through the first WDM means to the amplifier section.
  • the fiber amplifier includes a first modal noise suppression (MNS) fiber coupled between the first WDM and the amplifier section and a second MNS fiber coupled between the second WDM means and the amplifier section.
  • MNS modal noise suppression
  • a field repair patch for a broken optic fiber is provided.
  • the repair patch first and second ferrule sections, each of the ferrule sections including a
  • ferrule sections adapted to retain one end of the broken optic fiber and a transmission fiber coupling the first and second ferrule sections.
  • the present invention includes a special type of single mode fiber which can be fusion spliced into standard single mode fiber with very low backscatter from the splice, and a method for choosing the proper length of special fiber to optimize rejection of non-propagating modes relative to the propagating mode.
  • This rejection is accomplished by noting that the fraction of the power which propagates in the cladding is much higher for the non-propagating modes than for the propagating mode. Therefore, mode discrimination can be accomplished by utilizing a strongly absorbing glass in most or all of the cladding.
  • the design will involve a core and inner cladding material having a structure and structure identical to the standard communications fiber to which the modal noise suppression (MNS) fiber is to be coupled, while all the outer cladding is solution doped highly absorbing high silica glass.
  • MNS modal noise suppression
  • the entire cladding can be solution doped, and some of the doping can be permitted to diffuse into the core during the fiber fabrication process.
  • Figure 1 shows cross sections of a preferred embodiment of this invention.
  • Figure la is a cross section of the tubular preform with chemical vapor deposition (CVD) layers.
  • CVD chemical vapor deposition
  • Figure lb represents the cross section of the modal noise suppression (MNS) fiber after the preform tube has been slumped and drawn into a fiber of the proper diameter.
  • Figure 2 is a schematic representation of the application to a fixed build-out attenuator.
  • MNS modal noise suppression
  • Figure 2a shows two sections of MNS fiber 21 fused to a predetermined length of attenuating fiber 22.
  • Figure 2b shows the ferrule inserted into the connector housing 26, which has a male 27 and female 28 end.
  • Figure 3 indicates the preferred application of MNS fiber in an isolator mode.
  • Figure 4 is a representation of the application of MNS fiber in a fiber amplifier.
  • Figure 5 represents the application of MNS fiber in field repair patching of optical fiber transmission line breaks.
  • the present invention relates to an improvement in fiber optic devices.
  • the following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
  • Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments.
  • the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
  • the present invention includes a special type of single mode fiber which can be fusion spliced into standard single mode fiber with very low backscatter from the splice, and a method for choosing the proper length of special fiber to optimize rejection of non-propagating modes relative to the propagating mode.
  • This rejection is accomplished by noting that the fraction of the power which propagates in the cladding is much higher for the non-propagating modes than for the propagating mode. Therefore, mode discrimination can be accomplished by utilizing a strongly absorbing glass in most or all of the cladding. (It will be shown that the optimum design of the cladding glass doping will depend on the desired application).
  • the design will involve a core and inner cladding material having a structure identical to the standard communications fiber to which the modal noise suppression (MNS) fiber is to be coupled, while all the outer cladding is solution doped highly absorbing high silica glass.
  • MNS modal noise suppression
  • the entire cladding can be solution doped, and some of the doping can be permitted to diffuse into the core during the fiber fabrication process.
  • One critical aspect of the present invention is preform of the fiber.
  • the same broadband absorption characteristics of certain transition metal or rare earth oxide dopings of silicon glass as are used for the core glass of the attenuating fiber used to fabricate in-line attenuators can be used to produce solution doped silicon glass for the outer cladding of the MNS fiber.
  • cobalt oxide doping of silica can provide a broadband absorption with little change in the other properties of the cladding glass.
  • a tube of solution doped silica is used as the starting material for the preform.
  • a predetermined layer of pure silica is then vapor deposited inside the preform tube, followed by a layer of germania doped silica to form the core glass, as in a conventional fiber preform.
  • the resulting rod is then slumped to produce the preform rod from which the fiber can be drawn on standard fiber drawing machinery.
  • the cross section of such a preform is shown in Figure la, while typical dimensions in the cross section of drawn fiber are shown in Figure lb.
  • Figure 1 shows cross sections of a preferred embodiment of this invention.
  • Figure la is a cross section of the tubular preform with chemical vapor deposition
  • the outer tube 11 is extruded from solution doped absorbing silica glass. On its inner wall is deposited a thin layer 12 of pure silica cladding glass, followed by a layer 13 of doped silica (typically germania doping), which will form the core of the single mode fiber.
  • Figure lb represents the cross section of the modal noise suppression (MNS) fiber after the preform tube has been slumped and drawn into a fiber of the proper diameter.
  • the outer cladding 14 is the absorbing silica glass, with a thin (optional) inner cladding layer 15 of undoped silica, and the standard core glass 16 to match a standard communications fiber.
  • a length of MNS fiber fused to attenuating core fiber to produce a low modal noise and application independent fixed in-line attenuator (see Figure 2).
  • the attenuating core fiber is placed at the input end, with the MNS fiber section making up the output segment.
  • This configuration results in an in-line attenuator with the same attenuation for direct coupling to a detector or insertion into a long line, and also partly compensates the lower attentuation of longer wavelengths in the attenuating fiber segment with higher attenuation of longer wavelengths in the MNS segment.
  • Figure 2 is a schematic representation of the application to a fixed build-out attenuator.
  • the fiber assembly of the fixed attenuator is inserted into a ferrule matching the tolerances of standard connector ferrules.
  • Figure 2a shows two sections of MNS fiber 21 fused to a predetermined length of attenuating fiber 22. After insertion into the ferrule, the input end 24 and output end 25 are polished.
  • Figure 2b shows the ferrule inserted into the connector housing 26, which has a male 27 and female 28 end.
  • FIG. 3 indicates the preferred application of MNS fiber in an isolator mode.
  • the most common type of isolator utilizes beam forming gradient index lenses 32 to project the optical signal through a "bulk optics" assembly consisting of polarizing crystals, Faraday rotating crystals and analyzer crystals, which are labeled in Figure 3 as "bulk optics assembly” 33.
  • the input transmission fiber 30 is fusion spliced to a section of MNS fiber 31, which is coupled to the gradient index lens 32.
  • the gradient index lens 34 is coupled to a section of MNS fiber 35, which is fused to the output signal filter 36.
  • MNS fiber is used at the input and output ports of isolators or circulators, the MNS fiber not only serves to reduce modal noise, but also improves isolation by strongly rejecting unwanted polarization components primarily propagating in the cladding, a significant fraction of which normally can scatter back into the propagating mode at the connectors.
  • FIG 4 is a representation of the application of MNS fiber in a fiber amplifier.
  • a dual pump amplifier has two wavelength division multiplexers (WDM) 41, which permit insertion of pump power from fibers 45 and signal power from transmission fiber 42 into the amplifier section 43.
  • WDM wavelength division multiplexers
  • the WDM common fiber 47 is fused to a length of MNS fiber 44, the other end of which is fused to the amplifying fiber 43.
  • MNS fiber 44 is fused to the output end of the amplifying fiber 43, the other end of the MNS fiber being fused to the common fiber 47 of the output WDM, which injects the second pump power into the amplifier from pump fiber 45 and delivers amplified output signal to transmission fiber 46.
  • isolators as discussed with Figure 3, which are used in the transmission fibers to prevent backscattered signal from feeding back into the amplifier.
  • Figure 5 represents the application of MNS fiber in field repair patching of optical fiber transmission line breaks.
  • the ends of the broken fiber 51 are cleaved and inserted into ferrules 52 which have sections of MNS fiber 54 bonded in them.
  • a length of transmission fiber 53 joins the two ferrules and is coiled in the repair junction box.
  • the coupling of the transmission fiber to the MNS fiber in the ferrule can be accomplished with low loss if an photopolymerizing index matching cement is used.
  • the fibers can be fusion spliced to the MNS fiber, if field operating conditions permit. In the latter case, a prepared repair fiber with MNS fiber sections at each end could be used as the patch, minimizing modal noise due to the splices.
  • a low modal noise fixed attenuator can be fabricated by fusing the appropriate length of attenuating core fiber to two lengths of MNS fiber, and inserting the resulting assembly into a standard connector ferrule, as shown in Figure 2a.
  • the ferrule is polished and inserted into a BOA connector housing for use with standard connectorized cables.
  • Such an attenuator has the further advantage of having essentially the same attenuation when inserted into a long line or directly into a detector housing.
  • the increasing attenuation of the MNS fiber with wavelength for the propagating mode can compensate the decreasing attenuation of the attenuating fiber with wavelength, improving the wavelength independence of the fixed attenuator.
  • the MNS fiber not only serves to reduce modal noise, but also improves isolation by strongly rejecting unwanted polarization components primarily propagating in the cladding, a significant fraction of which normally can scatter back into the propagating mode at the connectors.
  • a length of MNS fiber fused between the amplifying fiber and the standard transmission fiber reduces modal noise which can result from the discontinuity due to the mismatch in NA between the fibers, and reduce the effect of non-propagating modes introduced by multiplexing couplers and connectors in the amplifier unit.
  • Field repair of damaged fiber optic cables often involves installing a patch section of fiber between the cleaved ends of the broken fiber.
  • a desirable technique utilizes precision ferrules with pre-installed fiber into which the cleaved end of the broken fiber can be inserted in the presence of photopolymerizable index matching cement. While the cement removes most of the reflection due to index mismatch, such ferrules can permit significant core offset error, resulting in modal noise due to the two closely spaced junctions.
  • Using MNS fiber in the patch coupler can reduce this modal noise without adding significantly to the connector losses for the propagating mode.
  • any other system component where closely spaced discontinuities of the fiber path are required can benefit from the use of MNS fiber inserts. While the discontinuities need to be within a few meters to produce significant modal noise, once the modal noise is generated, it is propagated as part of the signal, and is cumulative along a transmission path. Thus, minimization at each sub-system is particularly important in long and complex transmission paths.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Lasers (AREA)

Abstract

La présente invention concerne un procédé et un système destinés à la suppression de bruit modal dans des systèmes de fibres optiques. Dans une première réalisation, une fibre optique (21) à mode unique comprend un verre de revêtement extérieur fortement absorbant et un verre de revêtement intérieur non-absorbant (12). La fibre comprend aussi un verre de couche de coeur non absorbant (13). A l'aide cette combinaison, on élimine le bruit modal. Une deuxième réalisation concerne un atténuateur en ligne. Cet atténuateur comprend une fibre optique à mode unique, une fibre atténuatrice (22) qui lui est couplée, et un élément ferrule afin d'associer la fibre optique à mode unique à la fibre atténuatrice. Une troisième réalisation concerne un isolateur. L'isolateur comprend un assemblage optique et une fibre de transmission d'entrée couplée à l'assemblage optique. L'isolateur comprend, en outre, une première fibre de suppression de bruit modal (MNS) couplée à la fibre de transmission d'entrée et une lentille à gradient d'indice (34) couplée entre l'assemblage optique et la fibre MNS. L'isolateur comprend, en outre, une seconde fibre MNS couplée à la lentille à gradient d'indice (34) et un filtre de sortie (36) couplé à la seconde fibre MNS. Une quatrième réalisation concerne un amplificateur de fibre. L'amplificateur de fibre comprend des premier et second moyens multiplexeurs de division de longueurs d'ondes (WDMS) (41) ainsi que des première et seconde fibres mettant en oeuvre une puissance de pompage dans les premier et second moyens WDM.
EP99969589A 1998-10-09 1999-10-07 Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques Withdrawn EP1119785A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US16956298A 1998-10-09 1998-10-09
US169562 1998-10-09
PCT/US1999/023578 WO2000025091A2 (fr) 1998-10-09 1999-10-07 Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques

Publications (1)

Publication Number Publication Date
EP1119785A2 true EP1119785A2 (fr) 2001-08-01

Family

ID=22616219

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99969589A Withdrawn EP1119785A2 (fr) 1998-10-09 1999-10-07 Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques

Country Status (4)

Country Link
EP (1) EP1119785A2 (fr)
JP (1) JP2002528757A (fr)
AU (1) AU2957700A (fr)
WO (1) WO2000025091A2 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010078701A (ja) 2008-09-24 2010-04-08 Mitsubishi Cable Ind Ltd 光ファイバの接続構造およびシングルモードファイバ
JP2010102276A (ja) 2008-09-26 2010-05-06 Mitsubishi Cable Ind Ltd 光ファイバ及びその製造方法
CN104694081B (zh) * 2015-03-23 2019-09-20 江苏海迅实业集团股份有限公司 含钴掺杂二氧化硅纳米复合磨粒溶胶、抛光液及其制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5095519A (en) * 1990-11-30 1992-03-10 At&T Bell Laboratories Apparatus and method for producing an in-line optical fiber attenuator
US5572618A (en) * 1994-07-13 1996-11-05 Lucent Technologies Inc. Optical attenuator
US5651085A (en) * 1994-09-27 1997-07-22 Chia; Shin-Lo All fiber attenuator
US5581649A (en) * 1995-04-28 1996-12-03 The Whitaker Corporation Fixed value fiber optic attenuator with index matching material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0025091A2 *

Also Published As

Publication number Publication date
WO2000025091A8 (fr) 2001-07-05
AU2957700A (en) 2000-05-15
WO2000025091A3 (fr) 2000-07-06
JP2002528757A (ja) 2002-09-03
WO2000025091A2 (fr) 2000-05-04
WO2000025091A9 (fr) 2000-09-28

Similar Documents

Publication Publication Date Title
US5241613A (en) Optical fiber coupling/connector element
US5633974A (en) All fiber attenuator
US6278816B1 (en) Noise reduction technique for cladding pumped optical amplifiers
US5216728A (en) Optical fiber amplifier with filter
US20230014659A1 (en) Optical connector assemblies for low latency patchcords
US6424765B1 (en) Optical device and method of making the same
US20090041415A1 (en) Double-core optical fiber
EP1514145B1 (fr) Guide d'ondes optique double bande resistant a la courbure
Jung et al. Compact micro-optic based components for hollow core fibers
US20110317967A1 (en) Spliced connection between two optical fibers and method for producing a spliced connection of this type
AU2014293293B2 (en) Fiber optic cable and connector assembly including integrated enhanced functionality
JP3504823B2 (ja) 光ファイバ通信システム
EP1191372A2 (fr) Dispositif comprenant un coupleur à fibre optique multimode
CN114616500B (zh) 多芯光纤和扇出组件
GB2319355A (en) Expanded core optical fibre coupler using UV curing resin
CA2364437A1 (fr) Couplage de fibres optiques a haute puissance
EP1562059A1 (fr) Structure de couplage à fibre optique et procédé de couplage de fibres optiques
WO2000025091A2 (fr) Procede et systeme de suppression de bruit modal dans des systemes de fibres optiques
JP2005043442A (ja) 光ファイバの接続構造及び光接続部材並びに光コネクタ
US20260029581A1 (en) Low loss connection between hollow-core optical fibers using tube fiber as an optical coupler
US11835766B2 (en) Slope gain equalizer
Jung et al. Multiport micro-optic devices for hollow core fibre applications
Jiang et al. A low-loss specialty fiber designed for 980/1600 WDM coupler used in the L-band EDFA
JPH09311221A (ja) 光減衰性光ファイバ
Nolan Multiply tapered fiber devices

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20010405

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

RIC1 Information provided on ipc code assigned before grant

Free format text: 7G 02B 6/00 A, 7G 02B 6/02 B, 7G 02B 6/10 B, 7G 02B 6/26 B, 7G 02B 6/32 B, 7G 02B 6/36 B

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20020502