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WO1997010658A1 - Procede permettant de commander separement les puissances des composantes de longueur d'onde dans un systeme de transmission optique a multiplexage par repartition en longueur d'onde - Google Patents

Procede permettant de commander separement les puissances des composantes de longueur d'onde dans un systeme de transmission optique a multiplexage par repartition en longueur d'onde Download PDF

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Publication number
WO1997010658A1
WO1997010658A1 PCT/GB1996/002278 GB9602278W WO9710658A1 WO 1997010658 A1 WO1997010658 A1 WO 1997010658A1 GB 9602278 W GB9602278 W GB 9602278W WO 9710658 A1 WO9710658 A1 WO 9710658A1
Authority
WO
WIPO (PCT)
Prior art keywords
wavelength
optical signal
optical
filter
component
Prior art date
Application number
PCT/GB1996/002278
Other languages
English (en)
Inventor
Adrian Charles O'donnell
Original Assignee
Integrated Optical Components 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 Integrated Optical Components Limited filed Critical Integrated Optical Components Limited
Priority to JP9511775A priority Critical patent/JPH11511619A/ja
Priority to EP96930285A priority patent/EP0850520A1/fr
Publication of WO1997010658A1 publication Critical patent/WO1997010658A1/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
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/25073—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion using spectral equalisation, e.g. spectral filtering
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0221—Power control, e.g. to keep the total optical power constant
    • 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
    • H04B10/07—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
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • H04B10/07955—Monitoring or measuring power

Definitions

  • This invention relates to a method of and apparatus for controlling the relative amplitudes of the individual wavelength components of a wavelength division multiplexed optical signal.
  • the use of wavelength division multiplexing on optical communications systems is rapidly expanding in order to increase the information carrying capacity of a system.
  • multiplexing also allows the provision of network switching and protection functions in an effective and economic manner.
  • a wavelength division multiplexed optical signal propagated along optical fibre carries several channels at different wavelengths. At transmission, the wavelength component for any one channel normally has the same amplitude as that of the other channels, but as these wavelength components are processed through a network, the relative amplitudes of the channels become unbalanced.
  • optical power per channel at key points in a network will vary depending upon the path taken to reach a given key point. Moreover, the optical power will vary dynamically should network reconfiguration or re-routing take place. Any initial wavelength imbalance in a transmitter will exacerbate the variation in channel optical power following processing of the optical signal through the network.
  • a further problem is that a typical optical amplifier has a non linear transfer function, in that the gain varies dependent upon the wavelength being amplified. If a wavelength division multiplexed optical signal is passed through such a non linear amplifier, any imbalance in the input signal will be worsened, so degrading the network performance.
  • the present invention aims at providing both a method of and apparatus for addressing the difficulties arising from optical power variation across the channels of a wavelength division multiplexed optical signal consequent upon the propagation of the wavelength components of that signal through a network.
  • a method of controlling the relative amplitudes of the individual wavelength components of a wavelength division multiplexed optical signal in which method the wavelength division multiplexed optical signal is processed through an adaptive optical wavelength filter, the relative powers of each wavelength component of the optical signal are determined, and a complex control signal is supplied to the adaptive optical wavelength filter which control signal includes a control component for each wavelength component of the multiplexed optical signal, the magnitude of each control component being adjusted dependent upon the determined power of the respective optical signal wavelength component.
  • the present invention makes use of the transfer characteristics of an adaptive optical wavelength filter, known per se.
  • Embodiments of such filters include acousto-optic and electro-optic tunable filters.
  • the interaction between the optical signal and the stressed waveguide results in a polarisation conversion of the optical signal.
  • polarisation selective elements are added before and/or after the interactive section of the filter, the passband on the (or each) output port of the filter will be governed by whether polarisation conversion has occurred.
  • the stress-induced birefringence is defined by injecting into the filter a lower frequency waveform, i.e. electromagnetic energy typically in the range of a few hundred MHz.
  • the birefrigence is induced by an electrode structure arranged along the wave guide.
  • An adaptive optical wavelength filter as described above allows for the selective addition or subtraction of a wavelength division multiplexed channel from an optical communication network.
  • the simultaneous addition or subtraction of multiple channels can be achieved by the use of an appropriately configured filter of this kind.
  • the two types of adaptive optical wavelength filter usually employed m optical networks are known as acousto-optic and electro-optic tunable filters.
  • a relatively low frequency control signal is applied to the filter
  • a d.c. control signal is applied to the filter electrode structure, there being a separate electrode structure for each channel.
  • Either kind of filter may be used in the present invention.
  • Both kinds of filter may be configured to have more than one output port and it is preferred to use such a filter, with the channel power determination being performed on the output from one port, and the principal optical signal being propagated from the other output port.
  • the output at said one port is the inverse of the output at said other port.
  • the filter may have a single output port and the channel power determination is performed on the optical signal obtained from a passive tapping on the output from that port.
  • a 'window' could be set, which would be a fraction
  • optical signals transmitted may therefore be anywhere within this 'window' for each channel, and so both the optical filter and the network will need fairly broad responses to these 'windows' .
  • the filter and channel power determining elements will need to be locked tightly only if the responses are well matched.
  • a more relaxed locking requirement would be possible if the analyser has slightly wider 'windows' than the filter.
  • the analyser takes the form of a passive demultiplexer, this may be achieved by changing the specification of the filters and other components within the demultiplexer.
  • the analyser comprises a second active filter, a small design change to widen the filter response may be all that is required to achieve a relaxed locking regime, as both filters would, in such an arrangement, be locked to the same driver circuit.
  • the transmission standards for an optical communication network define specific centre wavelengths for the network. Consequently, no locking of the adaptive filters to each other, across the network, should be required.
  • apparatus for controlling the relative amplitudes of the individual wavelength components of a wavelength division multiplexed optical signal
  • apparatus comprises an adaptive optical wavelength filter through which the optical signal is passed for processing therein, means to determine the relative powers of the wavelength components of the processed optical signal, control means responsive to the determined powers of each wavelength component and providing a complex control signal to the adaptive optical wavelength filter which complex control signal includes a control component for each wavelength component of the multiplexed optical signal, the control means controlling the magnitude of each control component dependent upon the determined power of the respective optical signal wavelength component.
  • the complex control signal has a control component for each wavelength channel of the optical signal, the energy or magnitude of each such component being controlled dependent upon the detected power of each wavelength component of the optical signal.
  • the relative powers of the individual wavelength components of the optical signal should be determined following the processing of that signal in the adaptive optical wavelength filter.
  • the control signal When an acousto-optic tunable filter is employed, the control signal will have a frequency component for each channel of the optical signal, the energy of each such frequency component being adjusted in order to control the power of the respective wavelength component of the optical signal. If an electro-optic tunable filter is employed, the control signal will have a d.c. component for each channel of the optical signal, each d.c. component being applied to the respective electrode structure of the filter to control the power of the respective channel of the optical signal, dependent upon the voltage of the applied d.c. control component.
  • the determination of the power of each channel of a wavelength division multiplexed optical signal may be performed by any suitable manner known in the art.
  • in-line optical filters may be employed to separate a portion of the optical signal into its individual wavelength components, the amplitude of each of which then being determined for instance by an individual photo-detector for each channel.
  • a wavelength division demultiplexer may be employed to separate a portion of the optical signal into individual wavelength components .
  • the determination of the power of each channel of the optical signal may instead be determined by a further adaptive optical wavelength filter similar to that employed to control the magnitude of each wavelength component of the optical signal.
  • a further filter may sample each channel of the optical signal, in sequence, the output of the further filter sequentially corresponding to the power of each channel of the optical signal.
  • each control component of the control signal may be adjusted such that the relative powers of each wavelength component of the optical signal are, after processing in the filter, substantially the same.
  • each control component of the control signal may be adjusted having regard to the transfer function of the subsequent non-linear component. In this way, the power of all wavelength channels of the optical signal may be controlled so as to be essentially the same, following processing through the non-linear component.
  • Figure 1 schematically shows a network for the processing of wavelength division multiplexed optical signals
  • Figure 2 diagrammatically illustrates a first example cf a method of this invention
  • FIG. 3 diagrammatically illustrates a second example cf a method of this invention, similar to that of Figure 2;
  • Figure 4 diagrammatically illustrates a third example, using a filter to analyse the channel wavelengths
  • Figure 5 illustrates yet another example, similar to that of Figure 4;
  • Figure 6 shows the transfer function of an adaptive filter, showing the slewing of power between the secondary and main outputs of the filter, as used in the embodiment of Figure 2;
  • Figures 7A and 7B compare the output signals from a non-linear optical amplifier, respectively without and ith adaptive balancing according to this invention.
  • Figure 1 diagrammatically illustrates a network including a plurality of switching nodes 10 for optical signals propagated along optical fibres 11.
  • the signals may be multi-channel wavelength division multiplexed signals and so there may be a plurality of wavelengths appearing at any one or more of the nodes 10.
  • fibre 12 may be carrying a channel of wavelength ⁇ (_ 1 and of amplitude ⁇ 1
  • fibre 13 a channel of wavelength ⁇ 2 and amplitude ⁇ 2.
  • FIG 2 shows the processing of a wavelength division multiplexed signal with channel amplitudes out of balance, such as the signal on fibre 14 of Figure 1.
  • An electro-optic or acousto-optic adaptive filter 20 has an input port 21 and main and secondary output ports 22 and 23 respectively. The filter further has a control port 24. Such a filter is known per se in the art and will not be described in further detail here.
  • Optical fibre 14 carrying a wavelength division multiplexed signal is connected to the input port 21 and a further fibre to the main output port 22. All of the input channels appear at both the main and secondary ports, but the signal from the secondary port 23 is supplied to a wavelength demultiplexer (not shown, but known per se in the art) in order to provide individual channel components to a group of photo ⁇ detectors 25, with one channel component supplied to each photo-detector respectively.
  • the photo-detectors each determine the power of the channel component supplied thereto and in turn provide an output to a control circuit 26. That circuit 26 controls the operation of a plurality of oscillators 27, one oscillator for each wavelength channel of the input signal; the outputs of the oscillators 27 are combined at 28 and supplied to the control port 24 of the filter.
  • Figure 3 shows an arrangement similar to that of Figure 2, but the adaptive filter 20 has only a main output port 22.
  • the input to the channel power analyser section of the arrangement is taken from a passive tapping 29 on the main output from the filter.
  • this arrangement corresponds to that of Figure 2 and will not be described in further detail here.
  • the third embodiment shown in Figure 4 employs a channel power analyser section utilising a second adaptive wavelength filter 30 the input port 31 of which is connected to the secondary output port 23 of the principal adaptive filter 20.
  • a single control circuit 32 controls the operation of two separate sets 33 and 34 of oscillators, the two sets of oscillators being associated with the two adaptive filters 20 and 30 respectively.
  • the outputs of the oscillators of each set are combined at 35 and 36 respectively and the resultant control signals are supplied to the control ports 24 and 37 respectively, of the two adaptive filters 20 and 30.
  • the output of the adaptive filter 30 is supplied to a single photo-detector 38 and the signal indicative of the power of the channel component instantaneously supplied to the photo-detector 38 is fed to the control circuit 32, in order to control the appropriate oscillator of the set 33 associated with the filter 20.
  • the powers of the various wavelengths in the signal leaving the main output port of the filter 20 may be balanced as required, with the analysis of the powers of the channels being performed using the further adaptive filter 30 for sampling the channels one at a time, in sequence, under the control of circuit 32.
  • the operation of the embodiment may properly be synchronised to ensure that the transfer function of the filter 20 for each channel is properly matched to the detected power of that channel.
  • FIG. 5 illustrates a further embodiment similar to that of Figure 4 in that a second adaptive filter 30 is employed to perform the analysis of the multi ⁇ channel signal passing through the filter 20.
  • a single set 40 is arranged to control both filters 20 and 30.
  • the outputs from the oscillators are passed through elements 41 the effective resistance of which can be varied by the control circuit 32, before the outputs are combined and supplied to the control port 24 of filter 20.
  • An output is also taken from each oscillator to a switch circuit 43, the operation of the switch being performed by the control circuit 32 so that the appropriate oscillator output is supplied to the control port of filter 30 in a timed relationship to the operation of the oscillators.
  • the transfer function of the filter for the channel associated with the frequency of the control signal can be varied.
  • the power of the output signal at the secondary port 23 is the inverse of the power of the signal at the main output port 22.
  • the power of the optical signal at the main output port 22 may be controlled to have a desired value. Such control is performed dependent upon the determined power of the signal from the secondary output port 23.
  • the control circuit may thus be configured to define a closed loop system to ensure the power of the optical system at the main output port is maintained constant at a desired value, irrespective of variations in the power of the optical signal at the input port 21.
  • Figure 7A shows the effect of a typical non-linear optical amplifier 45 on a wavelength division multiplexed optical signal the relative powers of the individual channels of which are as shown at 46. As can be seen at 47, following processing by the amplifier 45, the relative imbalance in the channel powers is increased. However, by subjecting the input signal to the amplifier 45 to adaptive balancing by the method and apparatus of this invention as described above, the relative powers of the channels of the output signal from the amplifier 45 may all be substantially the same, as shown in Figure 7B at 48.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Optical Communication System (AREA)

Abstract

Cette invention concerne un procédé et un dispositif permettant de commander les amplitudes relatives des différentes composantes de longueur d'onde d'un signal optique (14) multiplexé par répartition en longueur d'onde et fait appel à un filtre de longueur d'onde optique adaptatif (20) au travers duquel est transféré le signal optique (14). Le filtre (20) est commandé en fonction de l'analyse des puissances des différentes composantes de longueur d'onde (μ1, μ2...) du signal optique, de sorte que les puissances de sortie peuvent être équilibrées pour donner une relation prédéfinie. On peut utiliser un filtre parmi plusieurs filtres optiques en ligne, un démultiplexeur et un autre filtre de longueur d'onde optique adaptatif pour analyser les puissances des composantes de longueur d'onde du signal optique.
PCT/GB1996/002278 1995-09-15 1996-09-13 Procede permettant de commander separement les puissances des composantes de longueur d'onde dans un systeme de transmission optique a multiplexage par repartition en longueur d'onde WO1997010658A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP9511775A JPH11511619A (ja) 1995-09-15 1996-09-13 光学的波長分割多重伝送システムにおける波長要素強度を独立して制御する方法
EP96930285A EP0850520A1 (fr) 1995-09-15 1996-09-13 Procede permettant de commander separement les puissances des composantes de longueur d'onde dans un systeme de transmission optique a multiplexage par repartition en longueur d'onde

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9518922.1 1995-09-15
GBGB9518922.1A GB9518922D0 (en) 1995-09-15 1995-09-15 Controlling optical signals

Publications (1)

Publication Number Publication Date
WO1997010658A1 true WO1997010658A1 (fr) 1997-03-20

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EP (1) EP0850520A1 (fr)
JP (1) JPH11511619A (fr)
CN (1) CN1202285A (fr)
CA (1) CA2232159A1 (fr)
GB (1) GB9518922D0 (fr)
WO (1) WO1997010658A1 (fr)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999000924A1 (fr) * 1997-06-30 1999-01-07 Uniphase Telecommunications Products, Inc. Amplificateur optique dynamique
WO1999000919A1 (fr) * 1997-06-30 1999-01-07 Uniphase Telecommunications Products, Inc. Moniteur d'etat de boucle servant a determiner l'amplitude des composantes de signal d'un faisceau optique a multiples longueurs d'ondes
US6151157A (en) * 1997-06-30 2000-11-21 Uniphase Telecommunications Products, Inc. Dynamic optical amplifier
US6351323B1 (en) 1998-04-02 2002-02-26 Fujitsu Limited Optical transmission apparatus, optical transmission system, and optical terminal station
FR2820837A1 (fr) * 2001-02-12 2002-08-16 Fastlite Perfectionnement aux dispositif acousto-optiques programmables pour systemes de communication optiques
US6542287B1 (en) * 2000-12-12 2003-04-01 Onetta, Inc. Optical amplifier systems with transient control
WO2003036826A1 (fr) * 2001-10-23 2003-05-01 Pro Forma Alfa Spectrometre
EP1306987A1 (fr) * 2001-10-23 2003-05-02 Pro Forma Alfa Spectromètre
WO2003077449A1 (fr) * 2002-03-14 2003-09-18 Aelis Photonics (Israel) Ltd. Egaliseur optique dynamique a bande large
EP1324526A3 (fr) * 2001-12-28 2005-12-14 Fujitsu Limited Procédé et dispositif de commande de filtres optiques
US7116907B1 (en) 1998-02-20 2006-10-03 Fujitsu Limited Acousto-optical tunable filters cascaded together
US7142785B2 (en) 1998-02-02 2006-11-28 Fujitsu Limited Light branching/inserting apparatus and light branching apparatus using wavelength selection filter
RU2487469C1 (ru) * 2009-06-05 2013-07-10 ЗетТиИ Корпорейшн Схема и способ управления мощностью в множестве каналов
US11626937B2 (en) 2016-03-18 2023-04-11 Nec Corporation Optical transmission apparatus and control method of optical transmission apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4665344B2 (ja) 2001-06-04 2011-04-06 株式会社日立製作所 波長間レベル偏差や光ｓｎ偏差を補償する光伝送装置
CN118041454B (zh) * 2024-04-15 2024-06-11 四川省光为通信有限公司 基于自适应波长分割多路复用的高速多模光模块系统

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EP0467396A2 (fr) * 1990-07-20 1992-01-22 Canon Kabushiki Kaisha Système de communication optique par multiplexage à longueur d'onde et un amplificateur optique utilisé dans ce système
EP0475016A2 (fr) * 1990-08-24 1992-03-18 Hitachi, Ltd. Réseau pour signaux optiques multiplexés en l'ongueur d'onde
EP0637148A1 (fr) * 1993-07-31 1995-02-01 Nortel Networks Corporation Système de transmission optique par multiplexage à longueur d'onde utilisant l'amplification optique

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
EP0467396A2 (fr) * 1990-07-20 1992-01-22 Canon Kabushiki Kaisha Système de communication optique par multiplexage à longueur d'onde et un amplificateur optique utilisé dans ce système
EP0475016A2 (fr) * 1990-08-24 1992-03-18 Hitachi, Ltd. Réseau pour signaux optiques multiplexés en l'ongueur d'onde
EP0637148A1 (fr) * 1993-07-31 1995-02-01 Nortel Networks Corporation Système de transmission optique par multiplexage à longueur d'onde utilisant l'amplification optique

Non-Patent Citations (1)

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Title
WEBER J -P: "SPECTRAL CHARACTERISTICS BRAGG-REFLECTION TUNABLE OPTICAL FILTER", IEE PROCEEDINGS J. OPTOELECTRONICS, vol. 140, no. 5, PART J, 1 October 1993 (1993-10-01), pages 275 - 284, XP000412788 *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999000919A1 (fr) * 1997-06-30 1999-01-07 Uniphase Telecommunications Products, Inc. Moniteur d'etat de boucle servant a determiner l'amplitude des composantes de signal d'un faisceau optique a multiples longueurs d'ondes
US6151157A (en) * 1997-06-30 2000-11-21 Uniphase Telecommunications Products, Inc. Dynamic optical amplifier
WO1999000924A1 (fr) * 1997-06-30 1999-01-07 Uniphase Telecommunications Products, Inc. Amplificateur optique dynamique
US7142785B2 (en) 1998-02-02 2006-11-28 Fujitsu Limited Light branching/inserting apparatus and light branching apparatus using wavelength selection filter
US7116907B1 (en) 1998-02-20 2006-10-03 Fujitsu Limited Acousto-optical tunable filters cascaded together
US6583900B2 (en) 1998-04-02 2003-06-24 Fujitsu Limited Optical transmission apparatus, optical transmission system, and optical terminal station
US6351323B1 (en) 1998-04-02 2002-02-26 Fujitsu Limited Optical transmission apparatus, optical transmission system, and optical terminal station
US6542287B1 (en) * 2000-12-12 2003-04-01 Onetta, Inc. Optical amplifier systems with transient control
FR2820837A1 (fr) * 2001-02-12 2002-08-16 Fastlite Perfectionnement aux dispositif acousto-optiques programmables pour systemes de communication optiques
WO2002065202A1 (fr) * 2001-02-12 2002-08-22 Fastlite Dispositifs acousto-optiques programmables
EP1306987A1 (fr) * 2001-10-23 2003-05-02 Pro Forma Alfa Spectromètre
WO2003036826A1 (fr) * 2001-10-23 2003-05-01 Pro Forma Alfa Spectrometre
EP1324526A3 (fr) * 2001-12-28 2005-12-14 Fujitsu Limited Procédé et dispositif de commande de filtres optiques
WO2003077449A1 (fr) * 2002-03-14 2003-09-18 Aelis Photonics (Israel) Ltd. Egaliseur optique dynamique a bande large
RU2487469C1 (ru) * 2009-06-05 2013-07-10 ЗетТиИ Корпорейшн Схема и способ управления мощностью в множестве каналов
US11626937B2 (en) 2016-03-18 2023-04-11 Nec Corporation Optical transmission apparatus and control method of optical transmission apparatus

Also Published As

Publication number Publication date
JPH11511619A (ja) 1999-10-05
CA2232159A1 (fr) 1997-03-20
CN1202285A (zh) 1998-12-16
EP0850520A1 (fr) 1998-07-01
GB9518922D0 (en) 1995-11-15

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