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WO1997039503A1 - Faisceau de fibres optiques a fibre optique monomode entouree de fibres optiques multimode et procede de fabrication - Google Patents

Faisceau de fibres optiques a fibre optique monomode entouree de fibres optiques multimode et procede de fabrication Download PDF

Info

Publication number
WO1997039503A1
WO1997039503A1 PCT/US1997/005579 US9705579W WO9739503A1 WO 1997039503 A1 WO1997039503 A1 WO 1997039503A1 US 9705579 W US9705579 W US 9705579W WO 9739503 A1 WO9739503 A1 WO 9739503A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
single mode
fiber
multimode
radiation
Prior art date
Application number
PCT/US1997/005579
Other languages
English (en)
Inventor
Jeffrey C. Livas
Original Assignee
Massachusetts Institute Of Technology
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 Massachusetts Institute Of Technology filed Critical Massachusetts Institute Of Technology
Publication of WO1997039503A1 publication Critical patent/WO1997039503A1/fr

Links

Classifications

    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • 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
    • 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
    • H01S3/06754—Fibre amplifiers

Definitions

  • This invention relates to an optical fiber coupler, more particularly, a wavelength division multiplexer coupler forming a fiber bundle
  • Optical couplers may be constructed as bulk optical couplers or fiber optic couplers
  • a conventional "bulk optic" optical coupler known to the prior art, for example for combining signal radiation and pump radiation in an optical amplifier, is shown Fig 1
  • a dichroic mirror 1 which is transmissive to the signal radiation wavelength and reflective to the pump radiation wavelength, receives an input optical data signal from signal radiation source 2 and an input pump laser beam from pump laser source 3
  • the data signal is transmitted through the mirror 1 and the pump beam is reflected by the mirror 1
  • the data signal and the pump beam are thus simultaneously combined in the gain medium 4 which amplifies the signal radiation
  • This amplified data signal is, for example, then transmitted into an optical fiber which is a part of an optical fiber network
  • this bulk optic optical coupler effectively combines the data signal and the pump beam, it is difficult to fabricate such a coupler so that it is compact, robust, and available at a low cost
  • the present invention relates to a high efficiency optical coupler suitable for applications requiring amplified optical radiation
  • the WDM coupler of the present invention forms a fiber bundle comprising a plurahty of multimode optical fibers in parallel juxtaposition and a single mode optical fiber in substantially parallel juxtaposition with and substantially surrounded by the plurality of multimode optical fibers
  • the single mode optical fiber is coupled to a first optical radiation source transmitting optical radiation at a first wavelength
  • the multimode optical fibers are coupled to a plurahty of second optical radiation sources transmitting optical radiation at a second wavelength
  • the first and second wavelengths are the same
  • the first and second wavelengths are different
  • the WDM coupler acts as a preamplifier to an optical amplifier
  • a cladless single mode fiber ofthe WDM coupler is doped with an optically active material such that when signal radiation is transmitted therethrough it is combined with pump radiation absorbed from the surrounding cladless multimode optical fibers. In this way energy from the pump laser radiation is transferred to the signal radiation in the single mode doped fiber, resulting in the amplification thereof.
  • the WDM coupler in another embodiment, acts as a coupler to a double clad fiber amplifier.
  • a double clad fiber is coupled to an output end ofthe WDM coupler through an optical system.
  • the double clad fiber comprises a single mode optical fiber core surrounded by a multimode optical material.
  • the single mode optical fiber core of the double clad optical fiber receives signal radiation from the single mode optical fiber ofthe WDM coupler.
  • the multimode optical material ofthe double clad optical fiber receives pump radiation from the plurality of multimode optical fibers ofthe WDM coupler
  • a method of transmitting optical radiation through an optical coupler comprises providing a plurality of multimode optical fibers in parallel juxtaposition, providing a single mode optical fiber in substantially parallel juxtaposition with and substantially surrounded by said plurality of multimode optical fibers, the single mode optical fiber and the multimode optical fibers forming a fiber bundle; transmitting optical radiation at a first wavelength through said single mode optical fiber; and transmitting optical radiation at a second wavelength through the plurality of multimode optical fibers.
  • the first wavelength and the second wavelength are the same In another embodiment the first wavelength and the second wavelength are different.
  • the method can include providing a doped cladless single mode optical fiber, transferring high power optical radiation from cladless multimode optical fibers to the cladless doped single mode optical fiber, and amplifying the signal radiation in the cladless doped single mode optical fiber.
  • the method can include coupling an optical fiber amplifier to the fiber bundle.
  • FIG. 1 shows a prior art bulk optic wave division multiplexer
  • Fig 2 shows a prior art fiber coupler
  • Fig 3 shows an embodiment of the WDM coupler device ofthe present invention including a plurality of multimode fibers encircling a single mode fiber
  • Fig 4 shows another embodiment ofthe fiber WDM coupler device ofthe present invention coupled to a double clad fiber through an optical system
  • Fig 4a shows yet another embodiment ofthe fiber WDM coupler device ofthe present invention coupled to a single mode optical amplifier through an optical system
  • Fig 4b shows an embodiment of a communication system using the WDM couplers ofthe invention with optical amplifiers
  • Fig 5 shows another embodiment ofthe present invention, particularly the WDM coupler device ofthe present invention used as a preamplifier
  • a cladded single mode optical fiber 20 is substantially surrounded by a plurality of cladded multimode optical fibers 22
  • the fibers 20, 22 are close packed such that the centers ofthe fibers 20, 22 in alternating layers are alligned
  • the single mode optical fiber 20 ofthe WDM coupler 10 ofthe present invention receives laser radiation from a signal radiation source 12 through an intermediate optical fiber 13 Similarly each of the plurality of multimode optical fibers 22 receives pump radiation from a respective one of a plurality of pump laser radiation sources 14 (only one shown for clarity) through an intermediate fiber 15
  • the signal radiation source 12 emits laser radiation at a different wavelength and power than the pump laser radiation sources 14
  • the signal radiation source 12 emits laser radiation at the same wavelength as the pump radiation sources 14
  • the signal radiation source 12 is a diode laser with an attached intermediate optical fiber 13
  • the signal radiation source emits signal radiation of a narrow spectral width
  • Each pump laser source 14 is preferably a semiconductor pump laser with an attached intermediate optical fiber 15
  • the pump radiation source 13 em ⁇ ts_opt ⁇ cal radiation of a broad spectral width
  • the signal radiation in one embodiment has a wavelength of about 1550 nm, and low power, typically within the range of 1 mW-JO mW
  • the signal radiation source 12 typically transmits optical radiation which has been modulated to carry data
  • the pump laser radiation in one embodiment has a wavelength within the range of 800 nm to 1480 nm, and high output power, for example 0 1 W - 5 W
  • the signal radiation source 12 and the pump laser radiation sources 13 emit the same wavelength
  • the double clad fiber 40 to which the coupler ofthe invention is optically joined is an optical amplifier 16 comprising a single-mode rare-earth doped optical fiber 42'
  • the rare earth doped single mode optical fiber 42' may be doped with any appropriate rare earth including but not limited to Erbium, Ytterbium, Thulium, and Praseodymium
  • Such single mode optical fibers are inherently diffraction-limited As a result, such an optical amplifier is frequently used to amplify the signals injected into it by the coupler 10
  • the output end 46 of the single mode fiber amplifier 16 is typically connected to an optical commumcation system such as a telecommunications network (not shown)
  • a series of optical amplifiers 16 and couplers 10 may be connected in tandem in a communications network to provide sequential amplification of a data signal
  • the optical system 30 is constructed to image the single mode optical fiber 20 ofthe WDM coupler 10 to the single mode optical fiber 42 or 42' ofthe double clad optical fiber 40 or 16, respectively Similarly, the multimode optical fibers 22 ofthe optical coupler 10 are imaged to simultaneously the multimode portion 44 or 44' ofthe dual clad optical fiber 40 or 16, respectively In this way, the single and multimode light from the signal 12 and pump 14 lasers, respectively, are channeled to the correct portions ofthe double clad optical fiber 40
  • the single mode optical fiber 20 ofthe WDM coupler has a diameter within the range of 3 um - 10 um and a numerical aperture (hereinafter 'NA') of about 0.1.
  • each of the multimode optical fibers 22 has a diameter preferably within the range of 100 um - 1 10 um and a NA of about 0.12.
  • the single mode optical fiber 20 is coupled to the signal radiation source 12, and each ofthe multimode optical fibers 22 is coupled to a pump laser optical source 14.
  • the purpose ofthe optical system 30 is generally to match the exit windows of the single mode 20 and multimode fibers 22 in the coupler 10 to the entrance windows of the single mode 42 and multimode 44 portions of the double clad optical fiber 40. With this arrangement, the WDM coupler 10 of the present invention reduces losses attendant with the coupling ofthe pump laser source 14 to a single mode fiber amplifier 16.
  • a lossless optical system preserves the space-angle bandwidth product, known as the etendue ofthe source.
  • the etendue is one measure ofthe number of spatial modes in an optical source.
  • the product ofthe area ofthe emission aperture, A, and the solid angle subtended by the beam ⁇ is equal to the square ofthe product of the number of modes, M, and the wavelength, ⁇ .
  • the solid angle is well approximated by the square ofthe numerical aperture (NA) ofthe source, which is the trigonometric sine of the half angle ofthe beam emitted from the aperture.
  • NA numerical aperture
  • M is approximately 1.
  • M is typically larger, in one embodiment 5-10.
  • the WDM coupler 10 and optical system 30 of the present invention accomplishes the requisite etendue matching ofthe laser sources 12, 14 to the respective portions 42, 44 single mode fiber amplifier 16.
  • WDM coupler 10 and the double clad fiber 40 are of substantially the same shape and aspect ratio. This occurs because the number of multimode optical fibers 22 is preferably of an amount and arrangement such that the etendue of the double clad fiber 40 is completely filled within the limits imposed by the close packed geometrical stacking of the individual multimode fibers 22. That is, the stacking geometry is set to match that ofthe double clad fiber 40 to within an overall magnification factor
  • the optical system 30 may comprise a simple two lens system for magnifying or demagnifying the image ofthe fibers 20, 22 ofthe WDM coupler 10 to overlap the relevant portions 42, 44 ofthe double clad fiber 40 Because the shape and aspect ratio is the same for both the WDM coupler 10 and the double clad fiber 40, in this embodiment, the lens system need not be astigmatic
  • the coupling ofthe WDM coupler 10 with the optical amplifier 16 is such that the match ofthe single mode optical fibers 20 ofthe WDM coupler 40 and the single mode fiber 42 ofthe optical amplifier 16 need not be exact In fact, the single mode optical fibers 20 and 42 may be mismatched as long as a portion ofthe signal radiation is transmitted from the single mode optical fiber 20 ofthe coupler 10 to the single mode optical fiber 42
  • the multimode optical fibers 22 should be matched with the multimode portion 44 ofthe optical amplifier 16, as closely as possible In this way, whatever amount of signal radiation is injected into in the single mode fiber 42 portion ofthe optical amplifier 16 can be amplified by the pump radiation injected in the multimode portion 44 ofthe optical amplifier 16
  • another embodiment ofthe invention permits butt-coupling the WDM coupler 10 with the double clad fiber 40 (not shown) directly without an mtervemng optical system 30
  • Fig 5 shows an alternative embodiment of the fiber WDM coupler 1 10 ofthe present invention
  • the WDM optical coupler 1 10 acts as a preamplifier to the optical amplifier 16
  • the WDM coupler 1 10 comprises a plurality of_cladless multimode 22 optical fibers encircling a cladless single mode fiber 120 which is rare earth doped to act as an amplifier
  • Pump and signal radiation are transmitted from the signal radiation source 12 and the plurality of pump laser sources 14, (only one shown for clanty) respectively, by the cladless multimode optical fibers 22 and the cladless single mode optical fiber 120, respectively
  • Some ofthe pump radiation propagating through each ofthe multimode fibers 22, passes through the doped single mode fiber core 120 where energy conversion to the signal radiation takes place, leading to an increase in the output signal power in the single mode optical fiber 120
  • This WDM coupler 1 10 is optically coupled to the optical amplifier 16, such that the signal radiation transmitted through the single mode optical fiber 120 ofthe fiber bundle is optically coupled to the single mode fiber ofthe optical amplifier Similarly, all the multimode optical fibers 22 ofthe coupler are optically coupled to the multimode portion ofthe optical amplifier 16 The signal radiation is thus transmitted into the optical amplifier 16 having a greater amplitude than the original signal due to the preamplification ofthe original signal by the WDM coupler 1 10

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Lasers (AREA)

Abstract

La présente invention concerne un coupleur de fibres optiques WDM à multiplexage en longueur d'onde (Wavelength Division Multiplexer) réalisant un couplage efficace du rayonnement optique à l'intérieur d'une fibre optique monomode. L'invention concerne également un procédé d'émission de rayonnement optique via un coupleur de fibres optiques WDM. Le coupleur de fibres optiques WDM vient former un faisceau de fibres optiques constitué, d'une part de plusieurs fibres optiques multimode juxtaposées sensiblement parallèlement les unes par rapport aux autres, et d'autre part d'une fibre optique monomode juxtaposée sensiblement parallèlement aux fibres optiques multimode qui l'entourent. La fibre optique monomode est couplée à une première source de rayonnement émettant un rayonnement laser véhiculant des données. Les fibres optiques multimode sont couplées à plusieurs secondes sources de rayonnement optique émettant le rayonnement d'un laser à pompe. Selon une réalisation, la fibre optique monomode est dopée de façon que, lors de l'émission du rayonnement laser de signalisation via la fibre optique monomode, il y ait transfert de l'énergie de rayonnement du laser à pompe vers cette fibre optique monomode de façon à amplifier le rayonnement laser de signalisation.
PCT/US1997/005579 1996-04-16 1997-04-03 Faisceau de fibres optiques a fibre optique monomode entouree de fibres optiques multimode et procede de fabrication WO1997039503A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US63308096A 1996-04-16 1996-04-16
US08/633,080 1996-04-16

Publications (1)

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WO1997039503A1 true WO1997039503A1 (fr) 1997-10-23

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0893862A3 (fr) * 1997-07-21 2000-04-05 Lucent Technologies Inc. Faisceaux de fibres coniques pour coupler la lumière à l'entrée et à la sortie de dispositifs à fibre pompée à travers le gainage
WO2000067350A1 (fr) * 1999-04-30 2000-11-09 University Of Southampton Dispositif a fibre optique
US7161966B2 (en) 2003-01-24 2007-01-09 Trumpf, Inc. Side-pumped fiber laser
US7542488B2 (en) 2003-01-24 2009-06-02 Trumpf, Inc. Fiber laser
EP1873874A3 (fr) * 1999-04-30 2010-07-21 SPI Lasers UK Limited Agencement de fibre optique
EP0930278B1 (fr) * 1997-12-29 2010-08-11 Lucent Technologies Inc. Procédé pour la fabrication de faisceaux de fibres

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4136929A (en) * 1974-11-29 1979-01-30 Hitachi, Ltd. Apparatus for generating light pulse train
EP0435217A2 (fr) * 1989-12-26 1991-07-03 United Technologies Corporation Lasers à pompage à réseau de Bragg enterré
US5050173A (en) * 1988-05-03 1991-09-17 Phased Array Lasers Pty Ltd. Looped, phased array laser oscillator
EP0497243A2 (fr) * 1991-01-30 1992-08-05 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Système de pompage pour laser ou amplificateurs à guide d'onde
WO1994004365A1 (fr) * 1992-08-20 1994-03-03 Imperial Chemical Industries Plc Enregistrement de donnees a l'aide de rayons laser
WO1996020519A1 (fr) * 1994-12-28 1996-07-04 Italtel Societa' Italiana Telecomunicazioni S.P.A. Agencement d'accouplement entre une source de lumiere multimode et une fibre optique au moyen d'une longueur intermediaire de fibre optique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4136929A (en) * 1974-11-29 1979-01-30 Hitachi, Ltd. Apparatus for generating light pulse train
US5050173A (en) * 1988-05-03 1991-09-17 Phased Array Lasers Pty Ltd. Looped, phased array laser oscillator
EP0435217A2 (fr) * 1989-12-26 1991-07-03 United Technologies Corporation Lasers à pompage à réseau de Bragg enterré
EP0497243A2 (fr) * 1991-01-30 1992-08-05 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Système de pompage pour laser ou amplificateurs à guide d'onde
WO1994004365A1 (fr) * 1992-08-20 1994-03-03 Imperial Chemical Industries Plc Enregistrement de donnees a l'aide de rayons laser
WO1996020519A1 (fr) * 1994-12-28 1996-07-04 Italtel Societa' Italiana Telecomunicazioni S.P.A. Agencement d'accouplement entre une source de lumiere multimode et une fibre optique au moyen d'une longueur intermediaire de fibre optique

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6826335B1 (en) 1909-04-30 2004-11-30 The University Of Southampton Multi-fibre arrangements for high power fibre lasers and amplifiers
EP0893862A3 (fr) * 1997-07-21 2000-04-05 Lucent Technologies Inc. Faisceaux de fibres coniques pour coupler la lumière à l'entrée et à la sortie de dispositifs à fibre pompée à travers le gainage
EP0930278B1 (fr) * 1997-12-29 2010-08-11 Lucent Technologies Inc. Procédé pour la fabrication de faisceaux de fibres
WO2000067350A1 (fr) * 1999-04-30 2000-11-09 University Of Southampton Dispositif a fibre optique
EP1873874A3 (fr) * 1999-04-30 2010-07-21 SPI Lasers UK Limited Agencement de fibre optique
US7161966B2 (en) 2003-01-24 2007-01-09 Trumpf, Inc. Side-pumped fiber laser
US7542488B2 (en) 2003-01-24 2009-06-02 Trumpf, Inc. Fiber laser

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