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WO1997032372A1 - Unite de branchement destinee au multiplexage par repartition en longueur d'onde - Google Patents

Unite de branchement destinee au multiplexage par repartition en longueur d'onde Download PDF

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Publication number
WO1997032372A1
WO1997032372A1 PCT/GB1997/000565 GB9700565W WO9732372A1 WO 1997032372 A1 WO1997032372 A1 WO 1997032372A1 GB 9700565 W GB9700565 W GB 9700565W WO 9732372 A1 WO9732372 A1 WO 9732372A1
Authority
WO
WIPO (PCT)
Prior art keywords
branching unit
fibre
output
input
port
Prior art date
Application number
PCT/GB1997/000565
Other languages
English (en)
Inventor
Surinder Singh Sian
Original Assignee
Stc Submarine Systems Limited
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 Stc Submarine Systems Limited filed Critical Stc Submarine Systems Limited
Publication of WO1997032372A1 publication Critical patent/WO1997032372A1/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
    • H04B10/2912—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
    • 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
    • H01S3/06758—Tandem amplifiers
    • 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
    • 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
    • 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
    • H01S3/09408—Pump redundancy
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2210/00—Indexing scheme relating to optical transmission systems
    • H04B2210/003—Devices including multiple stages, e.g., multi-stage optical amplifiers or dispersion compensators

Definitions

  • the invention relates to a branching unit for a wavelength division multiplexed optical communication system.
  • the invention relates particularly to branching units which employ doped fibre amplifiers to amplify the traffic signals.
  • Several factors compete in the optimisation of the amplifier structure for such a branching unit. It is desirable to reduce the number of pump lasers required in order to minimise the expense of the unit and also to minimise the amount of power required by the branching unit. It is, however, also desirable to provide redundancy for pump lasers, so that the failure of an individual pump laser does not render the branching unit inoperative. It is also desirable to adjust d e amplification provided to provide optimised gain and noise characteristics for the system. This may render it desirable to amplify at a branching unit not only signals passing directly along the main trunk, but also signals added from the branch or dropped to the branch.
  • the output of two pump lasers is coupled and split to provide two separate outputs of pump laser light such that if either of the pump lasers fails, light will still be available from the other pump laser for pumping of doped fibre amplifiers on both the two outputs.
  • the first output from such an arrangement has been used to pump an amplifier situated on a first trunk fibre and the other output used to pump an amplifier situated on a second trunk fibre carrying signals in the opposite direction to those carried on the first trunk fibre.
  • This does reduce the number of pump lasers required and achieve redundancy, but is disadvantageous in that a total failure of these pump lasers, or in the pump laser system up until the separate outputs are provided, will result in failure of traffic in both directions through the branching unit.
  • this arrangement will not provide for amplification of all add or drop channels.
  • the invention provides a branching unit for a wavelength division multiplexed optical communication system, comprising: a first input for a trunk input fibre; a first output for a trunk output fibre; one or more branch inputs or outputs, each for connection to a branch fibre; two or more doped fibre optical amplifiers; a pump laser section comprising at least one pump laser for pumping the two or more optical amplifiers; and means for splitting the output of the pump laser section and for routing a first part of the output of the pump laser section to a first one of said two or more optical amplifiers and a second part of the output of the pump laser section to a second one of said two or more optical amplifiers, wherein the first optical amplifier is adapted to amplify signals selected to enter the branching unit at the first input and to leave the branching unit at the first output, wherein the second optical amplifier is adapted to amplify signals selected either to enter the branching unit at the first input and to leave the branching unit on one of said one or more branch outputs or to enter the branching
  • An advantage of this arrangement is that complete failure of the pump laser section will only affect one fibre of the trunk.
  • the structure has the result that the relevant path between branch and trunk will fail if the path on the main trunk fibre fails through failure of the pump laser section, but this is less critical as there is no particular advantage in the trunk to branch path being viable when the path on the main trunk fibre has failed.
  • the arrangement has the benefits of minimising the number of pump lasers required yet retaining redundancy when two lasers are used in the pumping section.
  • one of the two amplifiers pumped by the pump laser section is a two-stage amplifier.
  • the relevant output from the pump laser section is split onto two fibres, such that each fibre is routed to pump one of the parts of the two-part amplifier.
  • the branching unit comprises a three port circulator, such that one of the inputs of the branching unit is connected through one of die first and second optical amplifiers to the first port of die three port circulator, the second port of the three port circulator is connected to a further routing section of the branching unit, and the third port of the three port circulator is connected through the other of the first and second amplifiers to an output of the branching unit.
  • the branching unit may comprise two three port circulators with in each case an input connected to the first port of the circulator, an output connected to die third port of die circulator, and e second ports of me circulators being connected to each other through notch reflection filters.
  • the circulator to which the optical amplifiers are connected may be either the first or the second circulator in such an arrangement.
  • the first input may be connected to the first port of the first circulator and a branch add input connected to me first port of me second circulator.
  • the first output and a branched drop output may be connected, respectively, to one and the other respectively of the third port of the first circulator and the third port of the second circulator.
  • the invention provides an add/drop multiplexer for use in wavelength division multiplexing, comprising: an input; an output; an input/output; a three port optical circulator, wherein the input is connected to the first port, d e input/output is connected to the second port, and the output is connected to d e third port; two doped fibre optical amplifiers comprising a first optical amplifier between the input and die tiiree port circulator and a second optical amplifier between die three port circulator and the output; and a pump laser section comprising at least one pump laser for pumping die two optical amplifiers, and means for splitting me output of the pump laser section for provision to d e first optical amplifier and the second optical amplifier respectively.
  • FIG 1 shows an amplified part of a branching unit according to an embodiment of me invention
  • FIG 2 shows a first branching unit structure
  • FIG 3 shows a second branching unit structure.
  • FIG 1 illustrates relevant parts of a branching unit for a wavelengtii division multiplexed optical communication system.
  • the relevant ports provide essentially an amplified add/drop multiplexer.
  • the branching unit contains a first input for a trunk input fibre and a first output for a trunk output fibre.
  • d e first input may be provided eitiier on fibre 11 or (indirectly) on fibre 15, and likewise the first output may be provided (indirectly) on fibre 15 or on fibre 12.
  • the branching unit further comprises one or more branch inputs or outputs, each for connection to a branch fibre. In the arrangement shown, as discussed further below, such branch inputs or outputs may be present directly, at fibres 11 or 12, or indirectly, at fibre 15.
  • the branching unit further comprises two or more doped fibre optical amplifiers 21,22,23.
  • the branching unit also contains a pump laser section comprising at least one pump laser 31,32 for pumping the two or more optical amplifiers 21,22,23.
  • a fibre optic coupler 33 which serves as a means for splitting the output of d e pump laser section.
  • the output of the pump laser section is therefore divided into two parts. A first part of me output of the pump laser section is routed along fibre 34 to a first one 21,22 of die optical amplifiers. The second part of me output of the pump laser section is routed along to fibre 35 to the second one 23 of the optical amplifiers.
  • a waveleng division multiplexer 42 is provided on fibre 12.
  • the multiplexer has the property that signals at the pump laser wavelength transfer across from fibre 35 through to doped fibre amplifier 23, but traffic signals approaching the multiplexer from doped fibre amplifier 23 do not transfer across to fibre 35 but instead pass through to fibre 12 and to an output of the branching unit.
  • the first amplifier is a two-stage doped fibre amplifier with a first doped fibre stage 21 and a second doped fibre stage 22.
  • light from the pump laser section on fibre 34 is split at optical coupler 43 onto fibres 44, 45.
  • Fibres 44,45 are provided as inputs at opposite ends of wavelength division multiplexer 41, with an input at one end of wavelength division multiplexer 41 being connected to doped fibre amplifier part 21 and the other end of wavelength division multiplexer 41 being connected to doped fibre amplifier part 22.
  • Wavelength division multiplexer 41 has essentially the same properties as wavelength division multiplexer 42.
  • fibre 44 will be able to transfer across to reach doped fibre amplifier part 22, and likewise light from fibre 45 will be able to transfer across the multiplexer to reach doped fibre part 21.
  • Traffic signals will pass through the first doped fibre amplifier part 21, the multiplexer 41, and the second doped fibre amplifier part 22 without transferring onto either of fibres 44 or 45.
  • the combination of a first, two-stage, amplifier and second, one-stage, amplifier is advantageous as it enables particularly effective control of gain and noise characteristics.
  • an appropriately functioning device can be devised if either the two-stage amplifier is replaced by a one-stage amplifier, or the one-stage amplifier is replaced by a two-stage amplifier, or both.
  • this part of the branching unit contains an isolator to prevent reflection of unwanted signals back to the trunk fibre input: such signals can result from doped fibre amplification.
  • This isolator may be placed, for example, in wavelength division multiplexer 41.
  • the branching unit of this embodiment comprises a first three port circulator 51.
  • an input of the branching unit is connected to the first port of the first tiiree port circulator 51, here through two-stage amplifier 21, 22.
  • the second port of d e three port circulator 51 is connected through fibre 15 to a further routing section of the branching unit.
  • the third port of the three port circulator 12 is connected through the second doped fibre amplifier 42 to an output of the branching unit.
  • Fig. 1 The arrangement shown in Fig. 1 can readily be employed in a basic wavelength division multiplexing unit design of the type shown in Fig. 2.
  • the branching unit comprises two three port circulators 7,8 and one or more notch reflection filters 5.
  • a trunk input fibre 1 is connected to the first port of the first circulator 7 and a trunk output fibre 2 is connected to the third port of the second circulator 8.
  • a branch add input fibre 4 is connected to the first port of the second circulator 8 and a branch drop output fibre 3 is connected to the third port of the first circulator 7.
  • the second ports of first circulator 7 and second circulator 8 are connected to each other through one or more notch reflection filters 5.
  • Fig. 1 the branch input fibre 1 is connected to the first port of the first circulator 7 and a trunk output fibre 2 is connected to the third port of the second circulator 8.
  • a branch add input fibre 4 is connected to the first port of the second circulator 8 and a branch drop output fibre 3 is connected to the third port of the first circulator 7.
  • notch reflection filter 5 reflects signals at the wavelength to be added or dropped (X ADD D Q P ). Signals to pass straight through the branching unit along the trunk thus enter the first input 1, pass through first circulator 7 to the second port thereof, pass through notch reflection filters 5, enter the second port of second circulator 8, and pass out through first output 2. Signals to be added from branch add input 4 enter the first port of second circulator 8, pass out of the second port of first circulator 8 and are reflected by notch reflection filters 5 back to the second port of second circulator 8. The signals then pass out through the third port of second circulator 8 to the first output 2. Similarly, signals to be dropped from the trunk pass into the first input 1 , through the first circulator 7 from first port to second port and into notch reflection filters 5.
  • circulator 51 of Fig. 1 can take the place of either circulator 7 or second circulator 8 of Fig. 2. If circulator 51 takes the place of first circulator 7, the first input 1 is provided at fibre 11, the branch drop output 3 provided at second fibre 12, and fibre 15 leads towards notch reflection filters 5 and the second circulator 8. If circulator 51 takes the place of second circulator 8, the branch add input 4 is provided at fibre 11, the first output 2 is provided at fibre 12, and fibre 15 again leads towards notch reflection filters 5 and in this case the first optical circulator 7.
  • the first amplifier comprising doped fibre amplifier parts 21 and 22 amplifies the signal input along the trunk fibre
  • the second amplifier 23 amplifies the signal dropped at the branch drop output 3.
  • the first amplifier comprising the two amplifier parts 21 and 22 amplifies the branch add input 4 signal
  • the second amplifier 23 amplifies the signal output at the first output 2. Accordingly, one of the two amplifiers amplifies signals which pass directly along the trunk fibre, whereas the other of the two amplifiers amplifies signals which pass between either the first input or first output and one of the branch inputs or outputs.
  • Fig. 3 An alternative form of basic wavelength division multiplexing unit is shown in Fig. 3.
  • the first output 2 is provided at the third port of the first circulator 7, whereas the branch drop output 3 is provided at the third port of the second circulator 8.
  • the notch reflection filter 5' reflects all the traffic signal wavelengths which remain on the trunk in progress through the unit, and allows passage of the wavelengths of the traffic signals which are to be added and/or dropped.
  • circulator 51 replaces first circulator 7, then fibre 11 is connected to first input 1 and fibre 12 is connected to first output 2.
  • signals to be dropped will be amplified by a two-stage amplifier 21, 22, whereas signals which are added will subsequently be amplified by second amplifier 23.
  • Fig. 1 is not limited to the multiplexer unit of Figures 2 and 3. Quite different arrangements for signal routing can be provided at fibre 15 and it is possible that, for example, a plurality of inputs and outputs may be provided in the further routing section.
  • embodiments of the present invention provide for optimised use of pump lasers in a doped fibre amplifier branching unit for a wavelength division multiplexed optical communication system.
  • the arrangement allows for redundancy of pump lasers and for use of a minimum number of pump lasers.
  • the construction may be adapted to optimise gain and noise characteristics.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Optical Communication System (AREA)

Abstract

L'invention concerne une unité de branchement destinée à un système de communication optique par multiplexage en longueur d'onde. Cette unité comprend au moins une entrée pour fibre d'entrée de réseau, une sortie pour fibre de sortie de réseau, ainsi qu'une ou plusieurs entrées ou sorties de dérivation destinées chacune à être connectée à une fibre de dérivation, et elle comprend également un multiplexeur amplifié d'insertion/extraction, lequel présente deux amplificateurs optiques à fibre dopée (21, 22, 23) ou davantage, ainsi qu'une section de laser de pompage comprenant deux lasers de pompage (31, 32) servant à pomper les amplificateurs optiques. Un coupleur (33) pour fibres optiques est monté afin de diviser la sortie de la section des lasers de pompage et acheminer une première partie de cette sortie le long de la fibre (35) vers le premier amplificateur (21, 22) à fibre dopée, et la seconde partie le long de la fibre (35) vers le second amplificateur (23) à fibre dopée. Cet agencement est conçu de manière à amplifier les signaux passant directement à travers l'unité de branchement le long de la fibre réseau, et à amplifier également les signaux passant entre l'entrée ou la sortie de fibre réseau et l'une des entrées ou sorties de dérivation, le pompage de l'amplificateur étant, dans les deux cas d'amplification, effectué par les lasers de pompage (31, 32) de la section correspondante. Cet agencement permet d'utiliser un nombre minimum de lasers de pompage, et donc de supprimer les lasers superflus, et il permet également une optimisation des caractéristiques de gain et de bruit.
PCT/GB1997/000565 1996-02-29 1997-02-27 Unite de branchement destinee au multiplexage par repartition en longueur d'onde WO1997032372A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9604336.9 1996-02-29
GB9604336A GB9604336D0 (en) 1996-02-29 1996-02-29 Amplifier

Publications (1)

Publication Number Publication Date
WO1997032372A1 true WO1997032372A1 (fr) 1997-09-04

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WO (1) WO1997032372A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2337357A (en) * 1998-05-13 1999-11-17 Alsthom Cge Alcatel Optical amplifier
EP0914015A3 (fr) * 1997-10-28 2003-03-12 Nec Corporation Commutateur optique, amplificateur optique et commande de puissance optique ainsi que multiplexeur optique a insertion-extraction
EP1585997A4 (fr) * 2001-07-27 2009-06-03 Xtera Communications Inc Systeme et procede permettant de reguler un facteur de bruit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112152058B (zh) * 2020-10-22 2024-10-22 中国电子科技集团公司第三十四研究所 一种多输入多输出光纤放大器

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5253104A (en) * 1992-09-15 1993-10-12 At&T Bell Laboratories Balanced optical amplifier
US5394265A (en) * 1993-10-25 1995-02-28 At&T Corp. In-line two-stage erbium doped fiber amplifier system with in-band telemetry channel
EP0695002A2 (fr) * 1994-07-29 1996-01-31 Corning Incorporated Amplificateur hybride à fibre

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5253104A (en) * 1992-09-15 1993-10-12 At&T Bell Laboratories Balanced optical amplifier
US5394265A (en) * 1993-10-25 1995-02-28 At&T Corp. In-line two-stage erbium doped fiber amplifier system with in-band telemetry channel
EP0695002A2 (fr) * 1994-07-29 1996-01-31 Corning Incorporated Amplificateur hybride à fibre

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JONES K P ET AL: "OPTICAL WAVELENGTH ADD-DROP MULTIPLEXER IN INSTALLED SUBMARINE WDM NETWORK", ELECTRONICS LETTERS, vol. 31, no. 24, 23 November 1995 (1995-11-23), pages 2117/2118, XP000548194 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0914015A3 (fr) * 1997-10-28 2003-03-12 Nec Corporation Commutateur optique, amplificateur optique et commande de puissance optique ainsi que multiplexeur optique a insertion-extraction
US7197246B2 (en) 1997-10-28 2007-03-27 Nec Corporation Optical switch, optical amplifier and optical power controller as well as optical add-drop multiplexer
GB2337357A (en) * 1998-05-13 1999-11-17 Alsthom Cge Alcatel Optical amplifier
EP1585997A4 (fr) * 2001-07-27 2009-06-03 Xtera Communications Inc Systeme et procede permettant de reguler un facteur de bruit

Also Published As

Publication number Publication date
GB9604336D0 (en) 1996-05-01

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