WO2001024431A1 - Signaux de donnees optiques - Google Patents

Signaux de donnees optiques Download PDF

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Publication number
WO2001024431A1
WO2001024431A1 PCT/GB2000/003646 GB0003646W WO0124431A1 WO 2001024431 A1 WO2001024431 A1 WO 2001024431A1 GB 0003646 W GB0003646 W GB 0003646W WO 0124431 A1 WO0124431 A1 WO 0124431A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
control information
data signal
optical data
modulation technique
Prior art date
Application number
PCT/GB2000/003646
Other languages
English (en)
Inventor
Kenneth Guild
Dimitra Simeonidou
Anna Tzanakaki
Michael O'mahony
Original Assignee
Btg International 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 Btg International Limited filed Critical Btg International Limited
Priority to CA002386660A priority Critical patent/CA2386660A1/fr
Priority to EP00960879A priority patent/EP1224761A1/fr
Priority to AU73039/00A priority patent/AU7303900A/en
Priority to JP2001527492A priority patent/JP2003510960A/ja
Publication of WO2001024431A1 publication Critical patent/WO2001024431A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • 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
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/503—Laser transmitters
    • H04B10/505—Laser transmitters using external modulation
    • 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
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/503—Laser transmitters
    • H04B10/505—Laser transmitters using external modulation
    • H04B10/5051—Laser transmitters using external modulation using a series, i.e. cascade, combination of modulators
    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/5161—Combination of different modulation schemes
    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/532—Polarisation modulation
    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/54—Intensity modulation
    • H04B10/541—Digital intensity or amplitude modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0298—Wavelength-division multiplex systems with sub-carrier multiplexing [SCM]

Definitions

  • This invention relates to a method of encoding control information on an optical data signal, to a transmitter configured to encode such information, and to a method of modifying or removing control information carried by an optical data signal.
  • wavelength converters will be an enabling technology for dynamic routing of optical packets through the network and for resolving contention within the switching nodes.
  • the routing control is a critical function; the packets of data have a routing tag or header and the ability dynamically to update or modify the routing tag/header is essential in certain types of network architectures. This functionality must be performed with minimal impact on the optical payload and several techniques for achieving this have been previously proposed.
  • the present invention aims at providing a particularly effective technique permitting the modification of control tags or headers associated with packets transmitted through an optical network, which technique has a minimal effect on the data itself.
  • a method of encoding control information on an optical data signal to be transmitted through an optical network comprising operating an optical source to generate a substantially coherent continuous-wave light beam, amplitude-modulating the light beam with a data stream to produce an optical data signal, and also modulating the data signal with control information, using a substantially constant amplitude modulation technique.
  • an optical data signal transmitter adapted to encode control information on an optical data signal to be transmitted through an optical network, which transmitter comprises an optical source arranged to generate a substantially coherent continuous-wave light beam, an amplitude-modulator which modulates said light beam with a data stream to produce an optical data signal, and a substantially constant amplitude modulator arranged also to modulate the data signal with control information, using a non-amplitude modulation technique.
  • a third aspect of this invention provides a method of modifying control information carried by an optical data signal transmitted through an optical network, comprising the steps of encoding the control information on the optical signal in a non-amplitude varying format so as to be associated with a stream of data, transmitting the optical signal to a traffic processor, reading and decoding the control information and then deciding upon the routing of the stream of data depending upon the decoded information, and passing the optical data signal through a wavelength converter based on a semiconductor optical amplifier thereby simultaneously removing the control information.
  • IM intensity-modulated
  • XGM cross-gain modulation
  • SOA semi-conductor optical amplifier
  • An SOA is therefore opaque to modulation formats that convey information in a non amplitude-varying fashion.
  • a preferred form of the method of this invention employs a subcarrier signaling format and encodes this information on the polarisation of the continuous-wave light preceding the payload of an optical packet.
  • the header information is extracted using direct -detection and the original header is removed without any additional guard bands or timing control .
  • Figure 1 illustrates an example of an optical packet transmitter
  • Figure 2 illustrates a technique for control information decoding and removal
  • Figure 3a shows the header information at the input to the polarisation modulator and Figures 3b and 3c the output of decoder in a switching node;
  • Figure 4 shows the optical spectral output after the A G;
  • Figure 5 shows the AWG output after wavelength conversion.
  • a data packet is l. ⁇ s in duration and consists of a payload containing a pseudo-random bit sequence (PRBS) at 2.5Gbit/s, an 8-bit header and a conservative guard band of 20ns.
  • PRBS pseudo-random bit sequence
  • the header consists of a byte of 78Mbit/s nonreturn-to- zero (NRZ) data: start and stop bits for synchronisation and six data bits that denote the packet destination.
  • the baseband header amplitude modulates a 2.7GHz subcarrier in the microwave mixer.
  • a 5Gbit/s iNb0 3 phase modulator was used for modulating polarisation states.
  • the linearly polarised signal from the Mach-Zehnder interferometer was rotated to be 45° to the principal axis of the phase modulator, and the drive voltage adjusted such that orthogonal polarisation states were assigned for a peak and trough of the subcarrier cosine.
  • An erbium-doped fibre amplifier (EDFA) amplifies the resulting signal.
  • the polarisers are arranged to pass horizontally polarised light through one arm, polarisation states at +45° to the vertical through a second arm, and right hand circular through the third arm. In this way, the incoming polarisation-modulated subcarrier will always result in an amplitude-varying component at 2.7GHz at the output when a "one" is received for all evolutionary states of the signal .
  • the sum of the components is the recovered header.
  • the control electronics process the baseband header information to determine the wavelength to which the payload is to be converted. After passing through an optical delay equal to the electronic processing time
  • the signal is coupled into the wavelength converter using an optical circulator.
  • Cross-gain modulation in a SOA is used to translate the wavelength of the packet to 1552nm.
  • a counter-propagating arrangement is employed, and the input/output wavelengths are chosen to lie in the stop-and pass-bands of the arrayed-waveguide grating (AWG) . In this way, very high rejection of the residual input signal, due to the SOA residual facet reflectivity, is achieved.
  • alternate packets may be encoded with a "10101001" header.
  • a lookup table is updated at the start of the process to direct such packets to output port 1 of the AWG by activating the 1552nm laser at the appropriate time.
  • Figure 3a shows the header signal at the input to the polarisation modulator after up-conversion in the microwave mixer.
  • the output of the optical packet generator is fed directly into the optical switching node arrangement.
  • the polarisation controller at the input of the header receiver allows the state of polarisation of the signal to be adjusted in order to present a variety of polarisation states to the receiver.
  • Figure 4 shows the routed packets at output port 1 of the AWG after wavelength conversion.
  • the residual input signal at 1554.4nm is suppressed to more than 45dB less than the converted signal, and the time-domain plots are illustrated in Figure 5.
  • Owing to the inverting nature of the SOA the header is extinguished and no polarisation to amplitude conversion is visible (lower trace) .
  • Confirmation of suppression of the header can be obtained by feeding the output of the wavelength converter to a header decoder; tests have shown that no residual header could be observed.
  • the header can be transmitted at a higher bit-rate.
  • the header data aggregate can be increased by employing frequency division multiplexing of additional subcarrier signals.
  • the depolarising tone, driving the scrambler may be modulated with the inverse of the header information to impose the header information on to the optical packet.
  • the invention provides a technique for polarisation-encoding subcarrier multiplexed headers on to an optical packet .
  • the XGM functionality of an SOA is used effectively to remove the header without the addition of any timing control, and without the need for a guard band between the header and payload.
  • a simple direct-detection receiver can be used to decode the header information and all -optical wavelength conversion and routing of 2.5Gbit/s payloads is thereby possible .

Landscapes

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

Abstract

Cette invention concerne une technique de codage de l'information de commande sur un signal de donnée optique à transmettre via un réseau optique. Cette technique consiste à : solliciter une source optique pour générer un faisceau de lumière continue sensiblement cohérente ; à moduler en amplitude le faisceau lumineux au moyen d'un train de données pour obtenir un signal de donnée optique ; et moduler par ailleurs le signal de donnée portant l'information de commande au moyen d'une technique de modulation d'amplitude sensiblement constante.
PCT/GB2000/003646 1999-09-25 2000-09-22 Signaux de donnees optiques WO2001024431A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002386660A CA2386660A1 (fr) 1999-09-25 2000-09-22 Signaux de donnees optiques
EP00960879A EP1224761A1 (fr) 1999-09-25 2000-09-22 Signaux de donnees optiques
AU73039/00A AU7303900A (en) 1999-09-25 2000-09-22 Optical data signals
JP2001527492A JP2003510960A (ja) 1999-09-25 2000-09-22 光データ信号

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9922678.9 1999-09-25
GBGB9922678.9A GB9922678D0 (en) 1999-09-25 1999-09-25 Optical data signals

Publications (1)

Publication Number Publication Date
WO2001024431A1 true WO2001024431A1 (fr) 2001-04-05

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/003646 WO2001024431A1 (fr) 1999-09-25 2000-09-22 Signaux de donnees optiques

Country Status (6)

Country Link
EP (1) EP1224761A1 (fr)
JP (1) JP2003510960A (fr)
AU (1) AU7303900A (fr)
CA (1) CA2386660A1 (fr)
GB (1) GB9922678D0 (fr)
WO (1) WO2001024431A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1113695A2 (fr) * 1999-12-29 2001-07-04 Nortel Networks Limited Commutation optique de paquets
DE102004036493A1 (de) * 2004-07-28 2006-03-23 Siemens Ag Verfahren zur Übertragung von Datensignalen und Zusatzsignalen in einem optischen Netz
US7457549B2 (en) 2005-05-13 2008-11-25 Fujitsu Limited Sub signal modulation apparatus, sub signal demodulation apparatus, and sub signal modulation demodulation system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4915605B2 (ja) * 2005-03-09 2012-04-11 独立行政法人情報通信研究機構 光デバイス
JP4996587B2 (ja) * 2008-12-02 2012-08-08 日本電信電話株式会社 光送受信器及びそれを用いた光伝送システム

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0455108A2 (fr) * 1990-04-27 1991-11-06 Hitachi, Ltd. Procédé pour la transmission cohérente, dispositif de brassage et dispositif de commutation
EP0523921A1 (fr) * 1991-07-18 1993-01-20 Nortel Networks Corporation Discriminateur optique insensible pour l'état de polarisation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0455108A2 (fr) * 1990-04-27 1991-11-06 Hitachi, Ltd. Procédé pour la transmission cohérente, dispositif de brassage et dispositif de commutation
EP0523921A1 (fr) * 1991-07-18 1993-01-20 Nortel Networks Corporation Discriminateur optique insensible pour l'état de polarisation

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
KAZOVSKY L G ET AL: "STARNET: A MULTI-GIGABIT-PER-SECOND OPTICAL LAN UTILIZING A PASSIVE WDM STAR", JOURNAL OF LIGHTWAVE TECHNOLOGY, IEEE, vol. 11, no. 5/06, May 1993 (1993-05-01), New York, USA, pages 1009 - 1027, XP000396729, ISSN: 0733-8724 *
SHIEH W ET AL: "A WAVELENGTH-ROUTING NODE USING MULTIFUNCTIONAL SEMICONDUCTOR OPTICAL AMPLIFIERS AND MULTIPLE-PILOT-TONE-CODED SUBCARRIER CONTROL HEADERS", IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 9, no. 9, September 1997 (1997-09-01), New York, USA, pages 1268 - 1270, XP000721230, ISSN: 1041-1135 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1113695A2 (fr) * 1999-12-29 2001-07-04 Nortel Networks Limited Commutation optique de paquets
EP1113695A3 (fr) * 1999-12-29 2005-05-04 Nortel Networks Limited Commutation optique de paquets
DE102004036493A1 (de) * 2004-07-28 2006-03-23 Siemens Ag Verfahren zur Übertragung von Datensignalen und Zusatzsignalen in einem optischen Netz
US7457549B2 (en) 2005-05-13 2008-11-25 Fujitsu Limited Sub signal modulation apparatus, sub signal demodulation apparatus, and sub signal modulation demodulation system

Also Published As

Publication number Publication date
EP1224761A1 (fr) 2002-07-24
GB9922678D0 (en) 1999-11-24
AU7303900A (en) 2001-04-30
CA2386660A1 (fr) 2001-04-05
JP2003510960A (ja) 2003-03-18

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