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WO1992005642A1 - Amplificateur de fibre optique a couplage d'energie de pompage provenant de differentes sources de pompage - Google Patents

Amplificateur de fibre optique a couplage d'energie de pompage provenant de differentes sources de pompage Download PDF

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Publication number
WO1992005642A1
WO1992005642A1 PCT/DK1991/000267 DK9100267W WO9205642A1 WO 1992005642 A1 WO1992005642 A1 WO 1992005642A1 DK 9100267 W DK9100267 W DK 9100267W WO 9205642 A1 WO9205642 A1 WO 9205642A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
pump
signal
energy
fibre
Prior art date
Application number
PCT/DK1991/000267
Other languages
English (en)
Inventor
Peter Johansen Viereck
Peter Wieslander Madsen
Original Assignee
Nkt Elektronik A/S
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 Nkt Elektronik A/S filed Critical Nkt Elektronik A/S
Publication of WO1992005642A1 publication Critical patent/WO1992005642A1/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
    • H01S3/09—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
    • 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
    • H01S3/09408—Pump redundancy

Definitions

  • the invention concerns an optical fibre amplifier, and in particular the part that concerns coupling of pump energy from a plurality of pump sources. '
  • optical fibre amplifiers may e.g. be used in a fibre-optical ringnet accessed by a plurality of transmitter/receiver units, and it may be used for in ⁇ creasing the distance over which a receiver can receive and re-form a signal from a transmitter.
  • it may e.g. be used as an in-line amplifier, it being positioned at a great distance from both transmitter and receiver.
  • an optical amplifier may be used as a pre-ampli- fier of a receiver.
  • it may be used as a booster amplifier, i.e. the fibre amplifier amplifies the optical signal immediately after it is transmitted from the transmitter.
  • Optical fibre amplifiers are usually made by doping an optical fibre with rare earths, such as erbium, d'- ⁇ ng the manufacturing process. Amplification takes place addi ⁇ tion of energy that excites electrons to a higher energy level. When stimulated with light energy from e.g. the arriving signal, the electrons will fall to a lower energy level, transmitting light at the frequency in question. This is analogous to the behaviour of a laser.
  • the active fibre is pumped optically with a plurality of pump lasers to provide the desired amplification.
  • the reliability of these pump lasers is a problem since their life is limited considerably when providing maximum power.
  • the threshold value also depends upon the ion concentration, said threshold value being the pump energy amount to be added to the active fibre for this to contribute with amplification which corresponds precisely to the fibre absorption of signal energy.
  • the threshold value being the pump energy amount to be added to the active fibre for this to contribute with amplification which corresponds precisely to the fibre absorption of signal energy.
  • the object of the invention is to provide a reliable opti- cal fibre amplifier without the prior art sensitivity to drop-out of pump lasers. This object is achieved as stated in the characterizing portion of claim 1.
  • the advantage is that the pump signal from a laser is divided on a plurality of active fibres so that the signal from there just contributes with a frac- tion of the pump power to each fibre, so that even though missing contribution from a laser is still noticeable, the active fibre nevertheless continues to contribute actively to amplification of an optical signal.
  • An optical fibre amplifier may e.g. be pumped with pump energy with a variety of wavelengths, which may e.g. be those stated in claim 4.
  • the advantage of pumping at two different wavelengths is that two pump sources can be coupled into a fibre, so that four pumps may be used for an active fibre.
  • the combination network may consist of a fibre-optical network with fibre couplers, thereby minimizing the coupling losses.
  • fig. 2 schematically shows the structure of a fibre ampli ⁇ bomb according to the prior art
  • fig. 3 schematically shows a preferred embodiment of the structure of an optical fibre amplifier according to the invention
  • fig. 4 schematically shows an alternative embodiment of an optical fibre amplifier according to the invention.
  • fig. 5 schematically shows an embodiment of compensation circuits for use in an optical fibre amplifier according to the invention.
  • Fig. la shows a transmitter 5 which transmits an optical signal to a receiver 9 through an optical transmission line 6.
  • the transmitted signal must be amplified en route. This is done by coupling a fibre end suitably spaced from the transmitter 5 into an optical fibre amplifier 7, which amplifies the signal and passes the signal thus amplified back to the transmission line 6 and further on to the receiver 9.
  • an optical bandpass filter 8 is po ⁇ sitioned before a receiver 9.
  • An optical fibre amplifier used in this manner is usually called an in-line ampli ⁇ fier.
  • lb shows an optical fibre amplifier used as a pre-amplifier, it being used for amplifying the optical signal on the transmission line 6 prior to signal detec ⁇ tion. Since, here too, the noise is amplified by the opti ⁇ cal amplifier, a bandpass filter 8 is positioned before the receiver 9.
  • Fig. lc shows an optical fibre amplifier used as a booster amplifier, said fibre amplifier being thus connected to the output on the transmitter 5.
  • Fig. 2 shows the structure of an optical fibre amplifier according to the prior art, where an optical signal is introduced via an optical transmission line 13 and coupled into an active fibre.
  • an active fibre 12 may e.g. be doped with erbium and have a length of typically 10-100 m.
  • an optical sig ⁇ nal is again passed back to an optical transmission path 14.
  • amplification takes place by exciting electrons in an active medium to a higher energy level, from which the electrons can fall back to a lower energy level at stimulated emission, thereby transmitting light in a given wavelength range.
  • ac- tive pump sources 10 in the form of laser diodes are ordi ⁇ narily used in optical fibre amplifiers. Energy from the pump sources 10 is coupled into the active fibre 3 through respective dichromatic couplers 11.
  • Fig. 3 shows an optical fibre network connecting four pump sources 20, 21, 22, 23 to four active fibres 30, 31, 32, 33, which are coupled in series (cascade coupling) and are adapted to receive an optical signal on an input 34, to amplify this signal and to apply the amplified signal on an output 35.
  • Each of the pump sources 20, 23 emit optical power P, which will usually be the same for the four pump sources. This optical power will be marked by an index A, B, C, D below, so that the origin of the power will be visible from the expressions used.
  • the output signal from the pump source 20 and the pump source 21, respectively, is passed to a fibre coupler 25 (3 dB coupler) designed so that there will be a signal with the power (P + P B )/2 on each of the outputs of the fibre coupler.
  • a fibre coupler 26 divides the optical energy from the pump sources 22, 23, so that there will be an optical sig ⁇ nal with the power (P_ + P_)/2 on each of the outputs of the fibre coupler 26.
  • Each of two additional fibre coup ⁇ lers 27, 28 receives a signal from respective outputs of the fibre couplers 25, 26, whereby the optical energy from each of the pump sources 20-23 is combined so that there will be an optical signal with the power (P + P + P_ + P )/4 on each output of the fibre couplers 27, 28.
  • Each of the four active fibres 30-33 will thus receive an optical signal combined so that the output signal from a pump source 20-23 is passed to several pump inputs. Drop-out of a pump source 20-23 will thus entail that approximately 25% less optical power will be added to each of the active fibres 30-33. This loss may be compensated by increasing the pump power of the other pump sources by 33%, as will be explained in connection with fig. 5.
  • Fig. 4 shows a corresponding configuration, where an opti ⁇ cal signal on an input 52 is amplified in two active fibres 50, 51 and is passed to an output 53.
  • Four pump sources 40, 41, 42, 43 emit optical power P like in the previous example.
  • the pump power from the pump sources 40, 41 is passed to a fibre coupler 45 having a signal with the power (P A + P ⁇ )/2 on each of its outputs.
  • a fibre coupler 46 has an optical signal with the power (P_ + P D )/2 on each of its outputs.
  • the two active fibres 50, 51 are pumped bi-directionally, i.e.
  • each active fibre 50, 51 are pumped from their respective ends with a signal from each of the fibre couplers 45, 46.
  • each fibre receives an optical signal having the power (P ⁇ + P réelle + P + P )/2. It is noted that each active fibre 50, 51 receives a pump signal which is twice as great as in the above-mentioned example.
  • Fig. 5 shows a drive circuit 90 which drives a plurality of laser diodes 102 A-N which are coupled to respective fibre ends 103 A-N. From there, the optical pump energy from respective laser diodes 102 A-N is passed to an opti ⁇ cal combination network, such as the one shown in fig. 3 or 4, through a fibre section 104 A-N.
  • the fibre 103 A-N is moreover coupled to an optical fibre coupler 100 A-N, which may e.g. be designed so that 1% of the energy on the optical fibre is passed through the fibre branch 106 A-N, while the rest of the op- ⁇ ical energy is passed through the fibre branch 104 A-N.
  • the fibre coup ⁇ lers 100 A-N are terminated in respective adaptations 101 A-N.
  • the optical energy on the fibre 106 A-N is passed to respective photodiodes 108 A-N, where the optical signal is converted to an electrical signal passed to respective amplifiers 110 A-N and from there further on to respective detection circuits 112 A-N.
  • These detection circuits 112 A-N apply a signal on the output which is passed through respective wires 114 A-N to respective inputs 116 A-N on the drive circuit.
  • the detection circuit 112 A-N detect whether the photo ⁇ diodes 108 A-N receive an optical signal and thus whether the laser diodes 102 A-N apply a signal. If one of the laser diodes 102 A-N.drops out and thus stops emitting op ⁇ tical energy, this can be detected by the detection cir ⁇ cuit 112 A-N which applies a signal to the drive circuit 90 in response to this, said signal indicating whether the laser diode 102 A-N associated with the individual detec ⁇ tion circuit 112 A-N operates correctly or is faulty.
  • the laser diodes 102 A-N do not emit maximum po ⁇ were, but is driven at a smaller load owing to reliability and life.
  • the drive circuit 90 can increase the output power of the remaining laser dio ⁇ des 102 A-N, thereby fully compensating for the missing power from one or more laser diodes which have dropped out.
  • drop out of a single laser diode may be compensated by increas ⁇ ing the pump power of the other pump sources by 33%.
  • the drive circuit 90 may simultaneously be designed to apply a signal to a central monitoring unit, which will then be informed that there is a faulty laser diode in the optical amplifier, and that this laser diode should be replaced at a later time.
  • the principle of combining an optical pump power in a com ⁇ bination network before the pump signals are applied to a variety of optical fibres can b developed in simple manner. If, e.g. amplification of an optical signal is needed on a not very accessible locality, the number of pump sources may expediently be increased to e.g. 16.
  • the pump signals are combined and passed to a plurality of active fibres, of which there may e.g. be 4. Pump power corresponding to (P 1 + P 2 + ... + P_ 6 )/4 may then be added to the fibres.
  • the output power from each individual pump source is then regulated so that the optical amplifier is dimensioned to be able to still provide an acceptable amplification, even though a number of pump sources drop out en route (e.g. 5).
  • the amplifier may thus be dimen- sioned so that it is attempted to limit the output power of the individual pump sources in the same manner as in the prior art, thereby increasing their life while making the system immune to the possibility that a not insignifi ⁇ cant number of the pump sources eventually become defec- tive.
  • the invention has been explained with reference to a fibre optical network consisting of optical fibres having fibre couplers of the 2:2 type, i.e. couplers with two inputs and two outputs. None prevents the invention from being performed with other coupling configurations, such as 4:4 couplers, or configurations where the number of inputs and outputs is not the same.
  • the active fibres may be pumped to va ⁇ rious atomic energy levels.

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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

Amplificateur de fibre optique possédant une ou plusieurs fibres actives couplées à une ligne de transmission optique afin que chacune des fibres actives ait au moins une entrée de signal de pompage. Les fibres actives sont conçues pour amplifier un signal optique à une première longueur d'onde pour une émission stimulée, quand l'énergie optique est ajoutée sous forme d'un signal de pompage à une deuxième longueur d'onde. Les signaux de pompage sont produits au moyen de lasers de pompage conçus pour émettre de l'énergie à la deuxième longueur d'onde. L'amplificateur de fibre optique possède un réseau optique combiné pourvu d'une pluralité d'entrées couplées aux lasers de pompage respectifs et conçues pour en recevoir de l'énergie. Les sorties du réseau combiné sont couplées aux entrées des signaux de pompage situées sur les fibres actives, ledit réseau étant conçu pour combiner l'énergie optique ajoutée, provenant des lasers de pompage pour que l'énergie optique de chacune des sorties du réseau combiné provienne de plusieurs lasers de pompage. La désexcitation d'un laser de pompage provoquera la diminution du signal optique sur plusieurs sorties du réseau combiné mais la mise au repos complète de l'énergie optique sur une sortie est évitée.
PCT/DK1991/000267 1990-09-14 1991-09-13 Amplificateur de fibre optique a couplage d'energie de pompage provenant de differentes sources de pompage WO1992005642A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK220690A DK220690A (da) 1990-09-14 1990-09-14 Optisk fiberforstaerker med kobling af pumpeenergi fra flere pumpekilder
DK2206/90 1990-09-14

Publications (1)

Publication Number Publication Date
WO1992005642A1 true WO1992005642A1 (fr) 1992-04-02

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PCT/DK1991/000267 WO1992005642A1 (fr) 1990-09-14 1991-09-13 Amplificateur de fibre optique a couplage d'energie de pompage provenant de differentes sources de pompage

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Country Link
AU (1) AU8612991A (fr)
DK (1) DK220690A (fr)
WO (1) WO1992005642A1 (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0585005A1 (fr) * 1992-08-21 1994-03-02 AT&T Corp. Système d'amplificateur optique à tolérance de fautes
EP0588557A1 (fr) * 1992-09-15 1994-03-23 AT&T Corp. Amplificateur optique équilibré
EP0621663A1 (fr) * 1993-04-22 1994-10-26 Sumitomo Electric Industries, Limited Amplificateur à fibre optique
GB2279194A (en) * 1993-05-24 1994-12-21 Northern Telecom Ltd Optical transmission system
EP0652653A1 (fr) * 1993-11-09 1995-05-10 Alcatel N.V. Procédé de télécommunication à fibres optiques, liaison appliquant ce procédé et système de pompage pour mélange à quatre ondes, notamment pour cette liaison
US5506723A (en) * 1993-02-26 1996-04-09 Alcatel N.V. Multistage fiber-optic amplifier
WO1998053564A1 (fr) * 1997-05-24 1998-11-26 N.V. Raychem S.A. Appareil de telecommunication comportant un amplificateur optique
US6008934A (en) * 1997-11-07 1999-12-28 Lucent Technologies Inc. Shared-pump multi-fiber optical amplifier
US6016219A (en) * 1996-12-31 2000-01-18 Lucent Technologies Inc. Optical protection switching system
WO2000049687A1 (fr) * 1999-02-19 2000-08-24 University Of Southampton Emetteur mrl
US6236777B1 (en) 1997-05-13 2001-05-22 Pirelli Cavi E Sistemi S.P.A. Reliability of an optical communication system and of an optical amplifying system, and a method suitable to this aim
EP1535411A4 (fr) * 2002-08-20 2006-02-01 Red Sky Systems Inc Procede et appareil de partage de l'energie de pompage d'un agencement a une seule pompe vers des fibres optiques placees dans differentes paires de fibres

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0215711A2 (fr) * 1985-09-10 1987-03-25 Alcatel N.V. Système de distribution pour la parole et les données comportant un réseau à fibres optiques en étoile à plusieurs noeuds
EP0339840A2 (fr) * 1988-04-25 1989-11-02 AT&T Corp. Système de communication optique comportant des moyens d'amplification à effet Raman
EP0395277A1 (fr) * 1989-04-22 1990-10-31 Nortel Networks Corporation Amplificateur optique avec commande de gain
EP0408394A1 (fr) * 1989-07-13 1991-01-16 BRITISH TELECOMMUNICATIONS public limited company Réseau de communication optique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0215711A2 (fr) * 1985-09-10 1987-03-25 Alcatel N.V. Système de distribution pour la parole et les données comportant un réseau à fibres optiques en étoile à plusieurs noeuds
EP0339840A2 (fr) * 1988-04-25 1989-11-02 AT&T Corp. Système de communication optique comportant des moyens d'amplification à effet Raman
EP0395277A1 (fr) * 1989-04-22 1990-10-31 Nortel Networks Corporation Amplificateur optique avec commande de gain
EP0408394A1 (fr) * 1989-07-13 1991-01-16 BRITISH TELECOMMUNICATIONS public limited company Réseau de communication optique

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0585005A1 (fr) * 1992-08-21 1994-03-02 AT&T Corp. Système d'amplificateur optique à tolérance de fautes
EP0588557A1 (fr) * 1992-09-15 1994-03-23 AT&T Corp. Amplificateur optique équilibré
US5506723A (en) * 1993-02-26 1996-04-09 Alcatel N.V. Multistage fiber-optic amplifier
EP0621663A1 (fr) * 1993-04-22 1994-10-26 Sumitomo Electric Industries, Limited Amplificateur à fibre optique
GB2279194A (en) * 1993-05-24 1994-12-21 Northern Telecom Ltd Optical transmission system
EP0652653A1 (fr) * 1993-11-09 1995-05-10 Alcatel N.V. Procédé de télécommunication à fibres optiques, liaison appliquant ce procédé et système de pompage pour mélange à quatre ondes, notamment pour cette liaison
FR2712445A1 (fr) * 1993-11-09 1995-05-19 Alcatel Nv Procédé de télécommunication à fibres optiques, liaison appliquant ce procédé et système de pompage pour mélange à quatre ondes notamment pour cette liaison.
AU668324B2 (en) * 1993-11-09 1996-04-26 Alcatel N.V. An optical fiber telecommunications method, a link using the method, and a pumping system for four-wave mixing in particular for the link
US6016219A (en) * 1996-12-31 2000-01-18 Lucent Technologies Inc. Optical protection switching system
US6236777B1 (en) 1997-05-13 2001-05-22 Pirelli Cavi E Sistemi S.P.A. Reliability of an optical communication system and of an optical amplifying system, and a method suitable to this aim
WO1998053564A1 (fr) * 1997-05-24 1998-11-26 N.V. Raychem S.A. Appareil de telecommunication comportant un amplificateur optique
AU740988B2 (en) * 1997-05-24 2001-11-22 N.V. Raychem S.A. Communications apparatus comprising optical amplifier
US6008934A (en) * 1997-11-07 1999-12-28 Lucent Technologies Inc. Shared-pump multi-fiber optical amplifier
WO2000049687A1 (fr) * 1999-02-19 2000-08-24 University Of Southampton Emetteur mrl
US6993258B2 (en) 1999-02-19 2006-01-31 University Of Southampton WDM transmitter
EP1535411A4 (fr) * 2002-08-20 2006-02-01 Red Sky Systems Inc Procede et appareil de partage de l'energie de pompage d'un agencement a une seule pompe vers des fibres optiques placees dans differentes paires de fibres

Also Published As

Publication number Publication date
DK220690D0 (da) 1990-09-14
AU8612991A (en) 1992-04-15
DK220690A (da) 1992-03-15

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