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WO2002007270A2 - Procede et appareil d'amplification optique hybride - Google Patents

Procede et appareil d'amplification optique hybride Download PDF

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Publication number
WO2002007270A2
WO2002007270A2 PCT/US2001/022230 US0122230W WO0207270A2 WO 2002007270 A2 WO2002007270 A2 WO 2002007270A2 US 0122230 W US0122230 W US 0122230W WO 0207270 A2 WO0207270 A2 WO 0207270A2
Authority
WO
WIPO (PCT)
Prior art keywords
amplifier
optical
amplified
filter
edfa
Prior art date
Application number
PCT/US2001/022230
Other languages
English (en)
Other versions
WO2002007270A3 (fr
Inventor
Dmitri Foursa
Original Assignee
Tycom (Us) Inc.
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 Tycom (Us) Inc. filed Critical Tycom (Us) Inc.
Priority to CA002385046A priority Critical patent/CA2385046A1/fr
Priority to AU2001280556A priority patent/AU2001280556A1/en
Publication of WO2002007270A2 publication Critical patent/WO2002007270A2/fr
Publication of WO2002007270A3 publication Critical patent/WO2002007270A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
    • H04B10/293—Signal power control
    • H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
    • H04B10/2941—Signal power control in a multiwavelength system, e.g. gain equalisation using an equalising unit, e.g. a filter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
    • H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing
    • H04B10/2916—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing using Raman or Brillouin amplifiers
    • 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
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1608—Solid materials characterised by an active (lasing) ion rare earth erbium
    • 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
    • H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • H01S3/2375—Hybrid lasers
    • 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
    • H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • H01S3/2383—Parallel arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2210/00—Indexing scheme relating to optical transmission systems
    • H04B2210/25—Distortion or dispersion compensation
    • H04B2210/258—Distortion or dispersion compensation treating each wavelength or wavelength band separately

Definitions

  • the invention relates to communications. More particularly, the invention relates to a method and apparatus to improve bandwidth of an optical amplifier by combining a distributed and lumped amplifier to form a hybrid optical amplifier for use with an optical communications system.
  • Optical fiber amplifiers are fundamentally important to long-haul optical communications systems. Optical signals begin to attenuate as they travel over an optical fiber transmission medium due to a variety of factors such as fiber loss and dispersion. Optical amplifiers help compensate for such attenuation by providing additional power to the optical signal as it moves through the system. Because long-haul optical communications system typically carry signals over great distances (e.g., 600-10,000 kilometers or more), the system requires a relatively large number of optical amplifiers. Moreover, optical communications technology continues to move towards increasing the number of communications channels for a given set of wavelengths,- thereby increasing the requisite bandwidth of these amplifiers. Consequently, there is an ever-present need to increase the bandwidth of optical amplifiers, in order to decrease the number of amplifiers required by a given system or increase the overall capacity of the system.
  • the first class of optical amplifiers is referred to as lumped amplifiers.
  • Lumped amplifiers linearly increase optical signal power of a supplied input signal via stimulated emission of fiber dopants such as erbium that is subject to an optical pump source.
  • An example of a lumped amplifier would be an Erbium Doped Fiber Amplifier (EDFA).
  • EDFA Erbium Doped Fiber Amplifier
  • the second class of optical amplifiers is referred to as distributed amplifiers. Distributed amplifiers increase optical signal power along the signal transmission path.
  • An example of a distributed amplifier may be a Raman amplifier.
  • EDFAs are particular well-suited for providing optical gain in the medium to long wavelength ranges of the desired spectrum used by many optical communication systems.
  • EDFAs are used to provide optical gains between 1570 and 1610 nanometers (nm) (also referred to as the "L band”). They are also used to provide optical gain in the conventional wavelength range between 1525 nm and 1565 nm (also referred to as the "C band”). C band EDFAs and L band EDFAs, however, are limited in terms of their respective bandwidths. To overcome this limitation, a new type of lumped amplifier referred to as an "ultra wide band” EDFA was developed that combined the gain of the C band with the gain of the L band. Ultra wide band EDFAs provide a bandwidth of approximately 80 nm by essentially combining L band and C band amplifiers.
  • Ultra wide band EDFAs use a circulator or filter to split (de-multiplex) the incoming optical channels into separate parallel sets of channels for amplification.
  • the first set of channels comprises the L band wavelengths that are amplified by an L band amplifier.
  • the second set of channels comprises the C band wavelengths that are amplified by a C band amplifier.
  • a circulator and Bragg grating combine (re-multiplex) the amplified signals to form the outgoing channels.
  • Raman amplifiers are well-suited for providing optical gain across the desired spectrum used by many optical communications systems, and in particular the short to medium wavelength ranges of such spectrum.
  • Raman amplification is accomplished by introducing the signal and pump energies along the same optical fiber.
  • the pump and signal may be copropagating or counterpropagating with respect to one another.
  • a Raman amplifier uses Stimulated Raman Scattering (SRS), which occurs in silica fibers when an intense pump beam propagates through it.
  • SRS is an inelastic scattering process in which an incident pump photon loses its energy to create another photon of reduced energy at a lower frequency. The remaining energy is absorbed by the fiber medium in the form of molecular vibrations (i.e., optical phonons).
  • Embodiments of the present invention include a method and apparatus to perform optical amplification.
  • an optical amplifier comprises both a lumped and distributed amplifier.
  • the distributed amplifier amplifies a first part of an optical signal, while the lumped amplifier amplifies a second part of the optical signal.
  • FIG. 1 is a block diagram of an optical system in accordance with one embodiment of the present invention.
  • FIG. 2 is a block diagram of an optical amplifier in accordance with one embodiment of the present invention.
  • FIG. 3 is a block diagram of a Raman amplifier in accordance with one embodiment of the present invention.
  • FIG. 4 is a block diagram of a pump source for a Raman amplifier in accordance with one embodiment of the present invention.
  • FIG. 5 is a block diagram of an ultra wide band EDFA amplifier in accordance with one embodiment of the present invention.
  • the embodiments of the present invention comprise a method and apparatus to amplify an optical signal over a greater bandwidth than conventional amplifiers.
  • the greater bandwidth is achieved through the use of a hybrid optical amplifier.
  • the hybrid optical amplifier comprises both a lumped amplifier and a distributed amplifier.
  • the gain of the lumped amplifier is combined with the gain of the distributed amplifier.
  • one embodiment of the present invention utilizes an ultra wide band EDFA amplifier having a bandwidth of approximately 80 nm, and a multi-pump Raman amplifier having a bandwidth of approximately 100 nm.
  • the overall bandwidth of the hybrid optical amplifier is the combination of both bandwidths, or approximately 180 nm minus some insertion loss associated with some of the additional components used to combine both amplifiers (e.g., band splitting filters, combiners and/or circulators).
  • the bandwidth of the hybrid optical amplifier directly correlates to the bandwidth of the respective lumped and distributed amplifiers used in any one embodiment of the present invention. As the bandwidth of each respective type of amplifier increases, the overall bandwidth of the hybrid optical amplifier increases a given amount accordingly.
  • the combination of a lumped and distributed amplifier works well for a number of reasons.
  • the lumped amplifier can be used to amplify longer wavelengths while the distributed amplifier can be used to amplify shorter wavelengths. Therefore the distributed amplifier can still use the transmission media as the gain medium for amplification without interfering with those wavelengths to be amplified by the lumped amplifier.
  • the lumped amplifier can be configured to pass the distributed amplified signals without significantly degrading those signals, Alternatively, a separate path could be set up if higher performance is desired.
  • any reference in the specification to "one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention.
  • the appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
  • fiber paths 110 and 112 are shown in FIG. 1 with only one optical amplifier each. It can be appreciated, however, that any number of optical amplifiers may be employed in each path and still fall within the scope of the present invention.
  • such well-known parts of a communications system as drive electronics, detector electronics, splices, attenuators, couplers and so forth, are considered to be conventional and have been omitted in this and other figures.
  • FIG. 2 is a block diagram of an optical amplifier in accordance with one embodiment of the present invention.
  • FIG. 2 illustrates a hybrid optical amplifier 200 that is representative of amplifiers 106 and 108, of FIG. 1.
  • Amplifier 200 comprises a first amplifier 202, a bandsplitting filter 204, a first amplification path 214, a second amplification path 206, and an optical combiner 226.
  • First amplification path 214 further comprises an optical isolator 216, a bandpass filter 218, a dispersion slope compensator 220, a coupler 222 and a power control line 224.
  • An example of coupler 222 is a wavelength division multiplexer (WDM) coupler or a tap coupler.
  • Second amplification path 206 further comprises an optical isolator 208, a lumped amplifier 210 and a bandpass filter 212.
  • WDM wavelength division multiplexer
  • Amplifier 200 operates to amplify one or more channels of an optical signal.
  • Amplifier 200 receives an incoming optical signal.
  • the incoming optical signal comprises a first part and a second part, with the first part representing those communication channels to be amplified using a distributed amplification scheme, and the second part representing those communication channels to be amplified using a lumped amplification scheme.
  • the wavelengths used by the communications channels of the first part are shorter than the wavelengths used by the communications channels of the second part.
  • Amplifier 202 receives both the first and second parts of the optical signals.
  • amplifier 202 is a Raman amplifier designed to amplify the shorter wavelengths of the first part. More particularly, the longer wavelengths of the second part are outside of the Raman gain region. Consequently, amplifier 202 amplifies the communications channels of the first part but does not substantially affect the communications channels of the second part.
  • Bandsplitting filter 204 receives the amplified first part and the unamplified second part. Bandsplitting filter 204 operates to split (de-multiplex) the amplified first part from the second part.
  • First amplification path 214 receives the amplified first part and passes the signals through to combiner 226.
  • Second amplification path 206 receives the unamplified second part and amplifies the same.
  • First amplification path 214 passes the signals through to combiner 222.
  • Optical isolator 216 receives the amplified first part.
  • Optical isolator 216 operates to prevent transmission of back reflections from other elements and Raleigh back- scattered signals.
  • Bandpass filter 218 receives the amplified first part and ensures that only those wavelengths used for the communications channels of the first part are passed through.
  • Dispersion slope compensator 220 receives the amplified first part and is designed to ensure that the accumulated dispersion of the amplified first part is as close as possible for a desired number (e.g., zero).
  • Coupler 222 receives the amplified first part and sends a power control signal via power control line 224 to amplifier 202.
  • a gain flattening filter (GFF) 223 receives the amplified first part and flattens or equalizes the gain for the amplified first part as desired.
  • Combiner 226 receives the amplified first part and combines the amplified first part with the amplified second part as described below.
  • Second amplification path 206 amplifies the second part of the incoming optical signal.
  • Optical isolator 208 receives the second part of the optical signal.
  • Optical isolator operates to prevent transmission of back reflections from amplifier 210.
  • Amplifier 210 receives the second part of the optical signal.
  • amplifier 210 is a lumped amplifier designed to amplify the longer wavelengths of the communications channels of the second part.
  • Bandpass filter 212 receives the amplified second part and ensures that only those wavelengths used for the communications channels of the second part are passed through.
  • a dispersion slope compensator (not shown) may also be utilized in this path as necessary for the amplified second part.
  • FIG. 3 is a block diagram of a Raman amplifier in accordance with one embodiment of the present invention.
  • FIG. 3 illustrates a Raman amplifier 300 that is representative of amplifier 202, as discussed with reference to FIG. 2.
  • Raman amplifier 300 includes a gain medium referred to as optical fiber portion 306 of the transmission path in which Raman gain is to be generated. This portion 306 of fiber may vary in size and may be limited, for example, to a small section of the transmission path. Alternatively, fiber portion 306 in which Raman gain is generated may have a length encompassing the entire transmission path.
  • Fiber portion 306 is coupled to a source of optical pump energy 302 via a coupler 304 such as a WDM coupler.
  • Pump source 302 receives the power control signal from coupler 222 discussed with reference to FIG. 2.
  • dispersion slope compensator 220 should be configured to provide an average dispersion as close to zero as possible. This can be accomplished by, for example, combining positive and negative dispersion fibers resulting in an accumulated dispersion as close to a desired number as possible for a desired application (e.g., near zero dispersion slope).
  • the dispersion compensation function performed by amplifiers discussed herein obviates the need to use individual dispersion compensators for the system.
  • FIG. 4 is a block diagram of a pump source for a Raman amplifier in accordance with one embodiment of the present invention.
  • FIG. 4 illustrates a pump source 400 that is representative of pump source 302, as discussed with reference to FIG. 3.
  • Pump source 400 comprises a first optical pump 404 and a second optical pump 406.
  • An optical coupler 408 combines the energy from pumps 404 and 406 and directs the resulting beam to WDM coupler 304.
  • Pumps 404 and 406 generate pump energy at different wavelengths selected to maximize the amplifier bandwidth.
  • pump 404 may provide pump energy at 1455 nm and pump 406 may provide pump energy at 1495 nm to amplify a WDM signal ranging from 1530-1610 nm.
  • pump source 400 may provide pump energy at 1455 nm and pump 406 may provide pump energy at 1495 nm to amplify a WDM signal ranging from 1530-1610 nm.
  • a power control unit 410 is connected to pumps 404 and 406. Power control unit 410 operates to actively control the power evolution of amplifier 202. Power control unit 410 receives a power control signal from coupler 222 via power control line 224. Power control unit 410 compensates the gain provided by pump source 302 to the first part of the optical signal in accordance with the power control signal so that the desired signal level power level is maintained.
  • FIG. 5 is a block diagram of an ultra wide band EDFA amplifier in accordance with one embodiment of the present invention.
  • FIG. 5 illustrates an ultra wide band EDFA 500 that is representative of a lumped amplifier 210, as discussed with reference to FIG. 2.
  • Ultra wide band EDFA 500 comprises a bandsplitting filter 502.
  • Bandsplitting filter 502 receives the second part and separates the second part into C band and L band signals.
  • the C band extends between approximately about 1525 nm to 1565 nm while the L band covers between about 1570 and 1610 nm.
  • the C band signals pass through a dispersion slope compensator 504.
  • a C band EDFA amplifier 506 receives and amplifies the C band signals.
  • the L band signals pass through a dispersion slope compensator 508.
  • An L band EDFA amplifier 510 receives and amplifies the L band signals.
  • Combiner 512 receives and combines the amplified C and L band signals into a single amplified second part. It is worthy to note that a skilled person would understand the need to add other components in ultra wide band EDFA 500, such as isolators to prevent transmission of back reflections from amplifier 506 or amplifier 510, as necessary for a particular system.
  • FIG. 6 is a block diagram of an optical amplifier in accordance with another embodiment of the present invention.
  • FIG. 6 illustrates an optical amplifier 600.
  • Optical amplifier 600 comprises a distributed amplifier 602 and a lumped amplifier 604.
  • An example of distributed amplifier 602 is a multi-pump Raman amplifier, such as amplifier 300 as described with FIG. 3.
  • An example of lumped amplifier 604 is an ultra wide band EDFA amplifier, such as amplifier 500 as described with FIG. 5.
  • Optical amplifier 600 operates to amplify optical signals for an optical communications system.
  • Optical amplifier 600 receives an incoming optical signal.
  • the incoming optical signal comprises a first part and a second part, with the first part representing those communication channels to be amplified using a distributed amplification scheme, and the second part representing those communication channels to be amplified using a lumped amplification scheme.
  • the wavelengths used by the communications channels of the first part are shorter than the wavelengths used by the communications channels of the second part.
  • Amplifier 602 receives both the first and second parts of the optical signals.
  • amplifier 602 is a Raman amplifier designed to amplify the shorter wavelengths of the first part. More particularly, the longer wavelengths of the second part are outside the Raman gain region. Consequently, amplifier 602 amplifies the communications channels of the first part but does not substantially affect the communications channels of the second part.
  • Amplifier 604 receives the amplified first part and the unamplified second part.
  • amplifier 604 is an ultra wide band EDFA designed to amplify the longer wavelengths of the second part. More particularly, the shorter wavelengths of the first part are outside of the EDFA gain region. Consequently, amplifier 604 amplifies the communications channels of the second part but does not substantially affect the communications channels of the first part. This can be accomplished by selecting a combination of doping levels and host material that minimizes the absorption of EDFA in the Raman amplifier spectral region.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Lasers (AREA)
  • Optical Communication System (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

L'invention concerne un procédé et un appareil permettant d'amplifier un signal optique. Un premier filtre sépare un signal optique en une première et une deuxième partie. Un premier amplificateur Raman amplifie la première partie. Un deuxième amplificateur à constantes localisées amplifie la deuxième partie. Un combinateur combine les première et deuxième parties amplifiées.
PCT/US2001/022230 2000-07-14 2001-07-13 Procede et appareil d'amplification optique hybride WO2002007270A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CA002385046A CA2385046A1 (fr) 2000-07-14 2001-07-13 Procede et appareil d'amplification optique hybride
AU2001280556A AU2001280556A1 (en) 2000-07-14 2001-07-13 Method and apparatus to perform hybrid optical amplification

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US61645100A 2000-07-14 2000-07-14
US09/616,451 2000-07-14

Publications (2)

Publication Number Publication Date
WO2002007270A2 true WO2002007270A2 (fr) 2002-01-24
WO2002007270A3 WO2002007270A3 (fr) 2002-04-18

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ID=24469520

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/022230 WO2002007270A2 (fr) 2000-07-14 2001-07-13 Procede et appareil d'amplification optique hybride

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AU (1) AU2001280556A1 (fr)
CA (1) CA2385046A1 (fr)
WO (1) WO2002007270A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1744755A4 (fr) * 2004-04-30 2009-07-15 Irm Llc Composes et compositions utilises en tant qu'inhibiteurs de la cathepsine
CN104821481A (zh) * 2015-05-15 2015-08-05 中国电子科技集团公司第八研究所 一种基于双反馈结构的混合分立式高非线性光纤放大器

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5905838A (en) * 1998-02-18 1999-05-18 Lucent Technologies Inc. Dual window WDM optical fiber communication
US6356384B1 (en) * 1998-03-24 2002-03-12 Xtera Communications Inc. Broadband amplifier and communication system
US6985283B1 (en) * 1998-06-16 2006-01-10 Xtera Communications, Inc. Fiber-optic compensation for dispersion, gain tilt, and band pump nonlinearity

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1744755A4 (fr) * 2004-04-30 2009-07-15 Irm Llc Composes et compositions utilises en tant qu'inhibiteurs de la cathepsine
US7985749B2 (en) 2004-04-30 2011-07-26 Novartis Ag Compounds and compositions as cathepsin S inhibitors
US8268996B2 (en) 2004-04-30 2012-09-18 Irm Llc Compounds and compositions as cathepsin S inhibitors
CN104821481A (zh) * 2015-05-15 2015-08-05 中国电子科技集团公司第八研究所 一种基于双反馈结构的混合分立式高非线性光纤放大器

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Publication number Publication date
CA2385046A1 (fr) 2002-01-24
AU2001280556A1 (en) 2002-01-30
WO2002007270A3 (fr) 2002-04-18

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