WO1997004539A1 - Systeme de telecommunications optique - Google Patents

Systeme de telecommunications optique Download PDF

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Publication number
WO1997004539A1
WO1997004539A1 PCT/GB1996/001727 GB9601727W WO9704539A1 WO 1997004539 A1 WO1997004539 A1 WO 1997004539A1 GB 9601727 W GB9601727 W GB 9601727W WO 9704539 A1 WO9704539 A1 WO 9704539A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
supervisory
supervisory signal
waveguide
amplifier
Prior art date
Application number
PCT/GB1996/001727
Other languages
English (en)
Inventor
Jennifer Frances Massicott
Robert John Campbell
Richard Wyatt
Original Assignee
British Telecommunications Public Limited Company
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
Priority claimed from GBGB9600375.1A external-priority patent/GB9600375D0/en
Application filed by British Telecommunications Public Limited Company filed Critical British Telecommunications Public Limited Company
Priority to EP96924994A priority Critical patent/EP0839414A1/fr
Priority to AU65257/96A priority patent/AU6525796A/en
Publication of WO1997004539A1 publication Critical patent/WO1997004539A1/fr

Links

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
    • 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
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • 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
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2210/00—Indexing scheme relating to optical transmission systems
    • H04B2210/07—Monitoring an optical transmission system using a supervisory signal
    • H04B2210/078—Monitoring an optical transmission system using a supervisory signal using a separate wavelength

Definitions

  • the present invention relates to an optical communications system including an optically pumped waveguide amplifier for amplifying message signals and an optical supervisory signalling system.
  • optical communications networks for instance telephone networks
  • optical supervisory signal whose wavelength is outside of the band used for message signals.
  • the supervisory signal is coupled into the transmission medium and then back out at certain points in the network.
  • the signals coupled back out can be processed to derive information about the state of the network.
  • the supervisory signal may comprise, for example, data reporting the performance of repeaters or other network components.
  • an optical communications system including at least one optically pumped waveguide amplifier for amplifying message signals and an optical supervisory signalling system, wherein the supervisory signalling system uses a wavelength approximately equal to a pump wavelength of the amplifier for signalling and the supervisory signal is produced by a source other than the pump of a waveguide amplifier.
  • the system further comprises optical message signalling means for generating optical message signals in a predetermined wavelength band, wherein the supervisory signal has a wavelength outside said predetermined band.
  • supervisory signals have not been provided by a source independent of the amplifier's pump (or indeed independent of all of an amplifier's pumps where, for example, the amplifier is pumped at a plurality of wavelengths by more than one pump source). It is believed that one of the reasons for this is that significant levels of light at these wavelengths are present in networks, as a side-effect of the use of optically pumped waveguide amplifiers, such as erbium-doped fibre amplifiers (EDFA), to amplify message signals, leading to the assumption that there would be beating with a supervisory signal, producing undesirable results.
  • EDFA erbium-doped fibre amplifiers
  • the present inventors have discovered that these fears were unfounded and, in particular, that the use of a pump wavelength of amplifiers in the system for a supervisory signal is practical.
  • the use of approximately 1480nm as the wavelength of the supervisory signal for an EDFA is advantageous because it makes use of readily available technology, including standard pump laser diodes and standard 1480nm/1 550nm wavelength division multiplexer (WDM) couplers. Conveniently, substandard pump laser diodes may be used.
  • WDM wavelength division multiplexer
  • the optical output power of the supervisory signal source is in the range -30dBm to 20dBm.
  • a system includes first and second optically pumped waveguide amplifiers connected by an optical waveguide, wherein the waveguide is at least 30km long. More preferably, the waveguide is at least 80km long. In a preferred embodiment, the waveguide is at least 1 20km long.
  • Substandard pump diodes that is diodes manufactured to be used to pump fibre amplifiers but generating insufficient output power for that purpose, may be used to generate the supervisory signal. Surprisingly, it has been found that such diodes may be easily modulated at the rate required for supervisory signals (e.g. of the order of 2Mb ⁇ ts/s) and the signals produced transmitted over lengths of optical fibre corresponding to typical amplifier separations (e.g. 40km).
  • a system comprises a repeater including said waveguide amplifier, said optical supervisory signalling means, an optical receiver, a first wavelength division multiplexer for coupling a supervisory signal from the transmission medium and applying it to the optical receiver, processing means for processing supervisory signal data received by the receiving means and controlling the optical supervisory signalling means to generate a further supervisory signal, and a second wavelength division multiplexer for coupling the further supervisory signal into the transmission medium, wherein the first and second wavelength division multiplexers are arranged one on either side of the waveguide amplifier. More preferably, there will be a plurality of such repeaters.
  • the present invention also provides an optical repeater station comprising an optically pumped waveguide amplifier and an optical supervisory signalling means other than the amplifier pump, wherein the wavelength of the supervisory signal produced by the signalling means is approximately equal to that of the waveguide amplifier's pump.
  • the optical supervisory signalling means is included in a bypass route comprising also an optical receiver, a first wavelength division multiplexer for coupling a supervisory signal from a transmission medium and applying it to the optical receiver, processing means for processing supervisory signal data received by the receiving means and controlling the optical supervisory signalling means to generate a further supervisory signal, and a second wavelength division multiplexer for coupling the further supervisory signal into the transmission medium, wherein the first and second wavelength division multiplexers are arranged one on either side of the waveguide amplifier
  • Figure 2 is a graph of bit error rates for the arrangement of Figure 1 under different conditions
  • Figure 3 is a graph illustrating typical receiver sensitivities against bit rate
  • Figure 4 is a simplified block diagram of a portion of an illustrative example of a network according to the present invention.
  • Figure 5 is a simplified block diagram of another illustrative example of a network according to the present invention.
  • an experimental arrangement comprises a first pump laser diode 1 arranged to output a continuous wave (CW) signal for simulating the remnant pump light from EDFAs in a network.
  • the output of the first laser diode 1 is applied via an optical fibre to a first isolator 2 and then to a first variable attenuator 3.
  • the output of the first attenuator 3 is applied to a polarisation controller 4.
  • a second pump laser diode 5 is modulated to produce a light signal simulating a supervisory signal.
  • the output of the second laser diode 5 is applied to a second isolator 6.
  • the laser diodes 1 and 5 are substandard pump diodes, operating in the region of 1480nm.
  • the outputs of the polarisation controller 4 and the second isolator 6 are fed to a coupler 7 which combines them and supplies them to a 40km length of optical fibre 8, representing a portion of a network.
  • a second attenuator 9 is arranged to receive light from the optical fibre 8. The output of the second attenuator 9 is applied to a splitter 10, the outputs of which are coupled respectively to a receiver 1 1 and a power monitor (not shown).
  • the first laser diode 1 was supplied with a bias current of 196mA and the second laser diode 5 was supplied with a 55mA bias current.
  • Both lasers diodes 1 ,5 were temperature tuned so that their peak outputs coincided at 1470nm and so that the longitudinal cavity modes were aligned in order to maximise any detrimental mode beating effects.
  • the polarisation controller 4 was adjusted so that both signals applied to the coupler 7 had the same polarisation.
  • a 3V modulation at 100Mbits/s was imposed on the second laser diode 5 and the first attenuator 3 was set so that the average powers from the two laser diodes 1 , 5 were equal after the coupler 7.
  • Bit error rate (BER) measurements using a 2 23 - 1 pseudo random binary sequence bit pattern, were made with and without the output of the first laser diode and with and without the 40km length of optical fibre 8. The results of these measurements are shown in Figure 2.
  • SMF Single-Mode Fibre
  • bit rates of up to 50Mb/s are practical.
  • Mode partition noise is not a major factor below bit rates of approximately 70Mb/s.
  • DSF Dispersion Shifted Fibre
  • a first node of a network 20 is connected to a second node 21 by a fibre optic transmission path 22.
  • the transmission path contains repeaters (only one shown) comprising EDFAs 23.
  • Each EDFA 23 comprises a length of erbium-doped optical fibre 24, a pump laser diode 25 producing light at 1480nm wavelength to pump the erbium-doped fibre and a WDM 26 for coupling the pumping light into the transmission path.
  • WDMs 27, 28 are located on either side of the EDFA 23.
  • the WDM 27 is coupled by an optical fibre to an optical receiver 29.
  • the output of the optical receiver 29 is fed to a supervisory signal control unit 30.
  • An output of the control unit 30 is connected to an optical transmitter 31 .
  • the control unit 30 is also coupled to the EDFA 23 for controlling and monito ⁇ ng the performance of the EDFA 23.
  • Light generated by the optical transmitter 31 is coupled into the transmission path 22 by WDM 28.
  • WDM 28 will also have the effect providing some isolation at the pumping wavelength between the EDFA 23 and the waveguide to the second node 21 . This isolation is >10dB and a figure of 20dB would be reasonable.
  • Supervisory signals at 1480nm are coupled out of the transmission path 22 by WDM 27 and are detected by the receiver 29
  • the receiver 29 outputs an electronic signal, dependent on the received 1480nm optical signal, to the control unit 30 for analysis.
  • a new supervisory signal is generated by the transmitter 31 under the control of the control unit 30 and introduced into the transmission path 22.
  • each repeater is provided with a bypass for supervisory signals, comprising a WDM 27, a receiver 29, a control unit 30, a transmitter 31 and another WDM 28.
  • the supervisory signal generated by one transmitter 31 will be processed by the control unit 30 at the next repeater.
  • no separate WDM 26 is provided for injecting pump light into the erbium-doped optical fibre 24
  • two pump laser diodes 25a, 25b are provided.
  • the outputs of the laser diodes 25a, 25b are coupled into the erbium- doped optical fibre 24 by the four port WDMs 27, 28 that are used for extracting and inserting supervisory signals.
  • One of the laser diodes 25a, 25b may be omitted if sufficient light intensity can be generated by one alone.
  • the WDMs 27, 28 may be packaged bulk devices such as fused fibre devices L2SWM1480/1 550B from Sifam Ltd, Torquay, Devon, UK or fibre pigtailed devices from the WD141 5 Series from JDS Fitel, Nepean, Ontario, Canada.
  • supervisory signals may be transmitted in either direction along the optical fibre transmission line or in both directions.
  • supervisory signalling principle will apply to other types of amplifier, for example praseodymium-doped fibre amplifiers operating at 1 300nm and pumped at between about 950nm to 1070nm or thulium-doped amplifiers operating at about 1500nm, with the supervisory signal being arranged substantially at the, or at least one of the, pump wavelength(s).

Abstract

Réseau optique comprenant des amplificateurs (23) de guide d'onde à pompage optique. Un signal de surveillance utilise la longueur d'onde de pompage (23) des amplificateurs, par exemple ≈ 1480 nm si des amplificateurs à fibres optiques dopées à l'erbium (EDFA) sont utilisés. Des diodes de pompage sous-normées peuvent être utilisées pour générer le signal de surveillance. Une station de répéteur du réseau comprend un amplificateur (23) de guide d'onde à pompage optique et une voie de dérivation (27, 28, 29, 30, 31) destinées aux signaux de surveillance. Dans un exemple décrit dans la demande, la voie de dérivation comprend un dispositif optique (31) émettant des signaux de surveillance, un récepteur optique (29), un premier multiplexeur en longueur d'onde (27) permettant de coupler un signal de surveillance provenant d'un support de transmission et de l'envoyer au récepteur optique, un dispositif de traitement (30) destiné à traiter les données du signal de surveillance reçues par le récepteur et à commander le dispositif optique émettant des signaux de surveillance afin de générer un autre signal de surveillance, et un second multiplexeur en longueur d'onde (28) destiné à coupler cet autre signal de surveillance au support de transmission, ces premier et second multiplexeurs en longueur d'onde étant placés de chaque côté de l'amplificateur de longueur d'onde.
PCT/GB1996/001727 1995-07-18 1996-07-18 Systeme de telecommunications optique WO1997004539A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP96924994A EP0839414A1 (fr) 1995-07-18 1996-07-18 Systeme de telecommunications optique
AU65257/96A AU6525796A (en) 1995-07-18 1996-07-18 Optical communications system

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP95304992.1 1995-07-18
EP95304992 1995-07-18
GBGB9600375.1A GB9600375D0 (en) 1996-01-09 1996-01-09 Optical telecommunications system
GB9600375.1 1996-01-09

Publications (1)

Publication Number Publication Date
WO1997004539A1 true WO1997004539A1 (fr) 1997-02-06

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/001727 WO1997004539A1 (fr) 1995-07-18 1996-07-18 Systeme de telecommunications optique

Country Status (3)

Country Link
EP (1) EP0839414A1 (fr)
AU (1) AU6525796A (fr)
WO (1) WO1997004539A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998054863A1 (fr) * 1997-05-27 1998-12-03 Ciena Corporation Systeme de gestion d'une liaison destine a un reseau multiplexe en longueur d'onde
EP0964487A1 (fr) * 1997-02-25 1999-12-15 Hitachi, Ltd. Emetteur optique, repeteur optique et dispositif d'interconnexion optique
EP1065811A2 (fr) * 1999-06-30 2001-01-03 Nortel Networks Limited Amplificateurs optiques

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0449475A2 (fr) * 1990-03-26 1991-10-02 AT&T Corp. Télémétrie pour répéteur à fibre optique

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0449475A2 (fr) * 1990-03-26 1991-10-02 AT&T Corp. Télémétrie pour répéteur à fibre optique

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
HIRST ET AL: "Performance monitoring of long chains of optical amplifiers", ELECTRONICS LETTERS, vol. 29, no. 3, 4 February 1993 (1993-02-04), STEVENAGE GB, pages 255 - 256, XP000336779 *
INSPEC database, IEE, London, GB INSPEC No. 5058397 Asonen et al: "400 mW single mode Al-free pump laser for 980 nm" *
MATSUOKA ET AL: "Supervisory signal transmission methods for optical amplifier repeater systems", IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE AND EXHIBITION (GLOBECOM '90), vol. 3, 2 December 1990 (1990-12-02) - 5 December 1990 (1990-12-05), SAN DIEGO, pages 1846 - 1850, XP000218888 *
PROCEEDINGS OF ECOC'94, 25 September 1994 (1994-09-25) - 29 September 1994 (1994-09-29), GENOVA, IT, pages 955 - 958 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0964487A1 (fr) * 1997-02-25 1999-12-15 Hitachi, Ltd. Emetteur optique, repeteur optique et dispositif d'interconnexion optique
EP0964487A4 (fr) * 1997-02-25 2005-10-19 Hitachi Ltd Emetteur optique, repeteur optique et dispositif d'interconnexion optique
WO1998054863A1 (fr) * 1997-05-27 1998-12-03 Ciena Corporation Systeme de gestion d'une liaison destine a un reseau multiplexe en longueur d'onde
US5978115A (en) * 1997-05-27 1999-11-02 Ciena Corporation Span management system for wavelength division multiplexed network
EP1065811A2 (fr) * 1999-06-30 2001-01-03 Nortel Networks Limited Amplificateurs optiques
EP1065811A3 (fr) * 1999-06-30 2001-02-21 Nortel Networks Limited Amplificateurs optiques
JP2001053366A (ja) * 1999-06-30 2001-02-23 Nortel Networks Ltd 光学増幅器
US6275331B1 (en) 1999-06-30 2001-08-14 Nortel Networks Limited Optical amplifiers

Also Published As

Publication number Publication date
EP0839414A1 (fr) 1998-05-06
AU6525796A (en) 1997-02-18

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