EP1264425A1 - Procede et systeme pour la modulation d'amplitude d'un signal optique - Google Patents

Procede et systeme pour la modulation d'amplitude d'un signal optique

Info

Publication number
EP1264425A1
EP1264425A1 EP01915009A EP01915009A EP1264425A1 EP 1264425 A1 EP1264425 A1 EP 1264425A1 EP 01915009 A EP01915009 A EP 01915009A EP 01915009 A EP01915009 A EP 01915009A EP 1264425 A1 EP1264425 A1 EP 1264425A1
Authority
EP
European Patent Office
Prior art keywords
signal
optical
adjustable
output
amplitude modulation
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP01915009A
Other languages
German (de)
English (en)
Inventor
Erich Gottwald
Christoph Glingener
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP1264425A1 publication Critical patent/EP1264425A1/fr
Withdrawn legal-status Critical Current

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
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/503—Laser transmitters
    • H04B10/505—Laser transmitters using external modulation
    • H04B10/5053—Laser transmitters using external modulation using a parallel, i.e. shunt, 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
    • H04B10/501—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
    • H04B10/5057—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output
    • H04B10/50572—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output to control the modulating signal amplitude including amplitude distortion
    • 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
    • H04B10/5057—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output
    • H04B10/50577—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output to control the phase of the modulating 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/5165—Carrier suppressed; Single sideband; Double sideband or vestigial
    • 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

Definitions

  • the invention relates to a method and an arrangement for amplitude modulation of an optical signal with a binary data signal that is fed to a modulator to generate an optical transmission signal.
  • a low extinction ratio in particular in optical long-haul systems with optical amplifiers, contributes significantly to the fact that the optical signal to noise ratio required on the receiving end for the reconstruction of the data OSNR) deteriorates.
  • the extinction ratio results from the power ratio between the logic “0” signal power ”and the logic“ 1 ”signal power, ie an amplitude-modulated signal with a high continuity portion or carrier portion which exceeds half the total power of the optical transmission signal and a low portion Extinction ratio and an almost completely "fully modulated” signal have a very high extinction ratio.
  • the extinction ratio of the amplitude-modulated optical signal is 3 dB in a transmission system with optical amplifiers, an OSNR that is higher by a factor of 10 than for an extinction ratio of 20 dB is required for the error-free reception of the amplitude-modulated optical signal. This results in a considerable shortening of the transmission path that can be bridged without regeneration by about an order of magnitude.
  • MZM modulators In addition to the modulation signal, MZM modulators generally require a high drive voltage or driver voltage of 6 volts to 2 x 6 volts in order to achieve the high extinction ratio required for successful transmission.
  • the driver circuits required to generate such high driver voltages are manufactured, for example, by manufacturers such as SHF-Design, Berlin - see product brochure "SHF 106P" or "SHF 103 CPA".
  • driver amplifiers of this type have a signal quality that is just sufficient and are very cost-intensive.
  • the procurement costs for such a driver amplifier many times exceed the procurement costs for an MZM modulator, which considerably worsens the competitiveness of the optical transmission system.
  • the object on which the invention is based is to improve the amplitude modulation of an optical signal such that the amplitude-modulated optical transmission signal has a reduced carrier component.
  • the object is achieved by the characterizing features thereof.
  • the optical signal is divided into a first and second adjustable optical signal and the first adjustable optical signal is fed to the modulator, which emits the optical transmission signal after amplitude modulation with the binary data signal. Furthermore, a second antiphase optical signal is formed from the second adjustable optical signal and that optical transmission signal and the second antiphase optical signal are combined to form a reduced-carrier optical transmission signal.
  • a lower modulation voltage is required to modulate the first optical signal in order to obtain an almost completely modulated optical transmission signal.
  • Electrical driver amplifiers with a low control voltage can thus be used to control the modulator, which are inexpensive and additionally contribute to an improvement in the signal quality of the transmission signal due to the distortions in the optical transmission signal which are reduced by the lower modulation voltage.
  • the division of the power of the optical signal into a first and second adjustable optical signal can be controlled in a particularly advantageous manner by means of an adjustable fade switch via a first control signal.
  • the power of the optical signal can be controlled into a first and second adjustable optical signal by means of a fixed one Cross-fade switch having a cross-fade switch, the power of the second adjustable optical signal being controllable via an adjustable optical attenuator via the first control signal - claim 3.
  • the carrier portion of the amplitude-modulated optical is Transmission signal adjustable so that the power of the carrier can be reduced to almost half the total power of the amplitude-modulated optical transmission signal, ie the Ge total output of the amplitude modulating
  • the optical transmission signal is " distributed almost uniformly by the method according to the invention on the carrier and on the two sidebands.
  • a relatively low modulation voltage for example the data signal emitted by a multiplexer, is sufficient for the complete modulation of the optical signal in order for the optical carrier-reduced according to the invention Generate transmission signal.
  • the phase position of the antiphase second optical signal can advantageously be controlled by an adjustable phase actuator via a second control signal. This makes it particularly advantageous to regulate the phase position of the antiphase second optical signal in order to generate an exact 180 ° phase shift with respect to the optical transmission signal.
  • the setting of the phase shift is changed by “wobble” and regulation is carried out according to the lock-in principle.
  • FIG. 1 shows the basic structure of the arrangement for amplitude modulation according to the invention
  • FIG. 2 shows a further variant of the arrangement for amplitude modulation according to the invention
  • FIG. 3 shows an amplitude-modulated optical transmission signal with a low extinction ratio, ie an excessively high proportion of carrier
  • FIG. 4 also shows the carrier-reduced optical transmission signal according to the invention a high extinction ratio
  • FIG. 5 shows the arrangement according to the invention for amplitude modulation integrated in a modulator module.
  • FIG. 1 shows, for example, an arrangement for amplitude modulation of an optical signal os with a binary data signal ds, which has an adjustable phase actuator PSG, an adjustable cross-fade switch OCU, a modulator MZM, a data source DQ, an optical coupler OC, and an optical transmitter unit CW and has a control unit Cü.
  • the adjustable cross-fade switch OCU can be implemented, for example, as an optical coupler with an adjustable cross-fade ratio.
  • the input i of the adjustable cross-fade switch OCU is connected to the optical transmission unit CW via an optical connecting fiber.
  • the adjustable crossfader OCU has a first and second output el, e2 and a control input ri, the first output el being connected to the input i of the modulator MZM and the second output e2 being connected to the input i of the adjustable phase actuator PSG is.
  • a Mach-Zehnder modulator can be provided as the modulator MZM, for example, which, in addition to an optical input i, has an electrical data input di and an optical output e, the data input di being connected to a data source DQ and the output e having the first input il of the optical coupler OC is connected.
  • the adjustable phase actuator PSG has an output e and a control input ri, the output e of the adjustable phase element PSG being connected to the second input i2 of the optical coupler OC via an optical connecting fiber.
  • the optical coupler OC has, for example, a first output el and a second output e2, wherein in FIG. 1 the first output el is connected via a TAP coupler TAP to a remote optical receiving unit EU and the second output e2 optionally via one in FIG 1 dashed line is connected to the control unit CU.
  • the optical TAP coupler TAP is connected to the control unit CU.
  • the control unit CU has an optical converter OW, a first and second filter unit FU1, FU2, a phase controller PR and a power controller LR.
  • the optical converter OW is connected to the TAP coupler TAP and to the first and second filter units FU1, FU2, and the first filter unit FU1 is connected to the phase controller PR, which is connected via a first control line RL1 to the control input ri of the adjustable phase actuator PSG ,
  • the second filter unit FU2 is connected to the power regulator LR, which is connected via a second control line R2 to the control input ri of the adjustable crossfader OCU.
  • An optical signal os is generated in the optical transmission unit CW and output via an optical connecting fiber to the input i of the adjustable cross-fade switch OCU.
  • the optical signal os is divided into a first and second optical signal osl, os2 with regard to the set crossfade ratio.
  • the first optical signal osl is fed to the first output el of the adjustable cross-fade switch OCU and fed to the input i of the modulator MZM via an optical connecting fiber or an optical waveguide.
  • the second optical signal os2 is emitted at the second output e2 of the adjustable cross-fade switch OCU and is fed to the input i of the adjustable phase control element PSG via a further optical connecting fiber.
  • the first optical signal os1 is amplitude-modulated in the modulator MZM with the aid of the data signal ds present at the data input di, and an optical transmission signal ts is thus generated.
  • the optical transmission signal ts is emitted at the output e of the modulator MZM via an optical connecting fiber to the first input il of the optical coupler OC.
  • the second optical signal os2 is shifted by the preset phase amount in accordance with the set phase shift amount.
  • inventions dung according to a phase shift of 'loan amount selected in the range of 180 ° anti-phase, particularly to produce at the output e of the adjustable phase control element PSG a one with respect to the carrier portion of the optical transmission signal ts anti-phase, second optical signal gps.
  • This antiphase second optical signal gps is transmitted from the output e of the adjustable phase actuator PSG via an optical connecting fiber to the second input i2 of the optical coupler OC.
  • the optical transmission signal ts and the antiphase second optical signal gps are superimposed or coupled, so that a carrier-reduced optical transmission signal rts arises due to destructive interference.
  • the carrier-reduced optical transmission signal rts is controlled at the first output el of the optical coupler OC and from there via the optical TAP coupler TAP to the distant optical receiver unit EU, which is indicated in FIG. 1 by a dotted transmission fiber OF.
  • an “inverted” optical transmission signal irt is generated, the carrier component of which has increased in comparison to the optical transmission signal.
  • the carrier-reduced optical transmission signal rts has a carrier portion of 50% and an information or data signal portion of the remaining 50% distributed over the sidebands, ie the power of the carrier corresponds to half the total signal power of the carrier-reduced optical transmission signal rts.
  • the carrier-reduced optical transmission signal rts is also referred to in the technical field as a completely modulated transmission signal rts.
  • part, for example 10 percent, of the carrier-reduced optical transmission signal rts' is coupled out and fed to the control unit CU, in particular the optical converter OW, via an optical connecting fiber.
  • the part of the carrier-reduced optical transmission signal rts' which is decoupled is converted into an electrical signal es which is controlled by the first and second filter units FU1, FU2.
  • the first filter unit FU1 is designed, for example, as a bandpass, the pass band of the bandpass having a bandwidth which is approximately half the data transmission rate.
  • the electrical signal is filtered and the result of the filtering is delivered to the phase controller PR.
  • the filtered electrical signal is evaluated with regard to its signal amplitude or signal amplitude position, and a second control signal rs2 for regulating the adjustable phase actuator PSG is determined from the evaluation result with regard to the amount of the phase shift.
  • the second control signal is controlled via the first control line RL1 to the control input ri of the adjustable phase actuator PSG.
  • phase deviation or the sign of the phase deviation of the antiphase second optical signal os2 from the optical transmission signal ts is determined by “wobble” (periodic change of the phase shift by a small amount by wobble voltages) and a phase control according to the
  • the phase position of the second optical signal os2, which is in phase opposition, is set by the adjustable phase actuator PSG in such a way that the measured amplitude of the electrical signal it assumes a maximum, ie the eye diagram of the carrier-reduced optical transmission signal rts has a maximum opening.
  • the second filter unit FU2 is implemented, for example, as a low-pass filter having a low cut-off frequency, with the aid of which the power of the electrical signal is determined.
  • the result of the filtering by the second filter unit FU2 is delivered to the power regulator LR.
  • the power of the filtered electrical signal es is evaluated in the power regulator LR and a first control signal rsl for regulating the adjustable cross-fade switch OCU is obtained on the basis of the evaluation result.
  • the first control signal rsl is transmitted via the second control line RL2 to the control input ri of the adjustable optical crossover switch OCU.
  • the measured signal power of the electrical signal es is regulated to a minimum, as a result of which the carrier power component in the carrier-reduced optical transmission signal rts is reduced to half the total signal power of the carrier-reduced optical transmission signal rts.
  • FIG. 2 shows a further embodiment of the arrangement for amplitude modulation according to the invention, in which the adjustable optical cross-switch OCU shown in FIG. 1 is replaced by an optical cross-switch C having a preset cross-fade ratio, for example 50:50.
  • the optical cross-fade switch C has an input e and a first and second output el, e2, the input e being connected to the optical transmitter unit CW and the first output el being connected to the input i of the modulator MZM.
  • an adjustable optical attenuator A is provided, which has an input i, a control input ri and an output e.
  • the input i of the adjustable optical attenuator A is connected to the second output e2 of the optical cross-fader switch C. connected and the output e of the adjustable optical attenuator A is connected to the input i of the adjustable phase actuator PSG. Furthermore, the control input ri of the adjustable optical attenuator A is connected to the power controller LR of the control unit CU via the second control line RL2.
  • the mode of operation of the arrangement for amplitude modulation shown in FIG. 2 differs in principle from the embodiment shown in FIG. 1 in that the optical fade switch C divides the power of the optical signal os into a first and a second optical signal by means of the fixed fade ratio osl, os2 takes place.
  • the regulation of the power distribution between the carrier and signal components of the carrier-reduced optical transmission signal rts is carried out with the aid of the adjustable optical attenuator A connected to the power controller LR.
  • the attenuation amount of the adjustable optical attenuator A is regulated, for example, on the basis of the first control signal rsl.
  • FIG. 3 the amplitude-modulated optical transmission signal ts, which has a low extinction ratio
  • FIG. 4 the optical transmission signal rts, reduced according to the invention, with a high extinction ratio
  • optical transmission signals ts, rts were shown in FIGS. 3 and 4 in FIGS - (No-Return-To-Zero) transmission signals selected.
  • the diagram shown in Figure 3 and Figure 4 each have a horizontal and a vertical axis T, OSA, with the horizontal axis, the time course T and the vertical axis OSA, the amplitude OSA of the amplitude-modulated optical transmission signal ts and the slow - 00 ⁇ IV) M t- 1 ⁇ o (_ ⁇ o C ⁇ o c ⁇

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optics & Photonics (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Optical Communication System (AREA)

Abstract

L'invention concerne un procédé et un système pour la modulation d'amplitude d'un signal optique (os) avec un signal de données binaire (ds). Selon l'invention, le signal optique (os) est d'abord subdivisé en un premier et en un deuxième signal optique ajustable (os1, os2). Le premier signal optique (os1) est transmis à un modulateur (MZM) qui délivre un signal de transmission optique (ts) après la modulation d'amplitude avec un signal de données binaire (ds). Un deuxième signal optique (gps) en opposition de phase est formé à partir du deuxième signal optique ajustable (os2), puis le signal de transmission optique (ts) et le deuxième signal optique (gps) en opposition de phase sont combinés en un signal de transmission optique (rts) à porteuse réduite.
EP01915009A 2000-03-17 2001-02-15 Procede et systeme pour la modulation d'amplitude d'un signal optique Withdrawn EP1264425A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10013197 2000-03-17
DE10013197A DE10013197A1 (de) 2000-03-17 2000-03-17 Verfahren und Anordnung zur Amplitudenmodulation eines optischen Signals
PCT/DE2001/000580 WO2001069819A1 (fr) 2000-03-17 2001-02-15 Procede et systeme pour la modulation d'amplitude d'un signal optique

Publications (1)

Publication Number Publication Date
EP1264425A1 true EP1264425A1 (fr) 2002-12-11

Family

ID=7635229

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01915009A Withdrawn EP1264425A1 (fr) 2000-03-17 2001-02-15 Procede et systeme pour la modulation d'amplitude d'un signal optique

Country Status (4)

Country Link
US (1) US20030030874A1 (fr)
EP (1) EP1264425A1 (fr)
DE (1) DE10013197A1 (fr)
WO (1) WO2001069819A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7330666B1 (en) * 2003-01-31 2008-02-12 Ciena Corporation Method and apparatus for controlling modulator phase alignment in a transmitter of an optical communications system
CA2523298C (fr) * 2003-05-08 2013-10-01 Sioptical, Inc. Modulateur electro-optique tres rapide a base de silicium
EP2058690A4 (fr) * 2006-08-30 2010-10-20 Hitachi Ltd Modulateur optique
JP5233115B2 (ja) * 2006-12-22 2013-07-10 日本電気株式会社 Ｄｑｐｓｋ復調方法を用いた光受信装置およびｄｑｐｓｋ復調方法
DE102011111114A1 (de) 2011-08-19 2013-02-21 Deutsches Elektronen-Synchrotron Desy System und Verfahren zum Erzeugen eines Synchronisationssteuersignals
US9838239B2 (en) * 2015-01-22 2017-12-05 Futurewei Technologies, Inc. Digital generation of multi-level phase shifting with a Mach-Zehnder modulator (MZM)
CN112578379A (zh) * 2020-11-27 2021-03-30 南京航空航天大学 光子辅助的脉冲体制微波雷达探测方法及装置

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Publication number Priority date Publication date Assignee Title
US3852519A (en) * 1972-10-20 1974-12-03 Optical Systems Corp Video and audio encoding/decoding system employing suppressed carrier modulation
US5424863A (en) * 1993-09-23 1995-06-13 Ael Industries, Inc. Dual-polarization fiber optic communications link
US5532857A (en) * 1994-09-07 1996-07-02 Ael Industries, Inc. Wide dynamic range optical link using DSSC linearizer
EP0928080A1 (fr) * 1997-12-31 1999-07-07 PIRELLI CAVI E SISTEMI S.p.A. Suppression du brûlage de trous dépendant de la polarisation avec un modulateur acousto-optique
US6292598B1 (en) * 1998-11-04 2001-09-18 Corvis Corporation Optical transmission apparatuses, methods, and systems

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Also Published As

Publication number Publication date
US20030030874A1 (en) 2003-02-13
WO2001069819A1 (fr) 2001-09-20
DE10013197A1 (de) 2001-09-27

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