USRE36715E - Optically amplified transmission systems - Google Patents
Optically amplified transmission systems Download PDFInfo
- Publication number
- USRE36715E USRE36715E US08/856,600 US85660097A USRE36715E US RE36715 E USRE36715 E US RE36715E US 85660097 A US85660097 A US 85660097A US RE36715 E USRE36715 E US RE36715E
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- United States
- Prior art keywords
- modulator
- modulation
- transmitter
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- 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
Definitions
- the optical transmission path between an optical transmitter and a receiver at some remote location includes a concatenation of optical amplifiers distributed at spaced intervals along that transmission path.
- Each of the optical amplifiers has a gain medium which has a population inversion.
- a low power input to such an amplifier is amplified to a higher power as it propagates through the gain medium.
- the signal input to the amplifier interacts with the population inversion to produce stimulated emission, thereby resulting in signal amplification.
- the population inversion will produce some spontaneous emission which is broad-band in comparison with the signal, and this spontaneous emission will also be amplified both in this, and in succeeding amplifies.
- amplified spontaneous emission arrives at the receiver together with the signal. It has been shown, for instance in a paper by N. A. Olsson entitled ⁇ Lightwave Systems with Optical Amplifiers ⁇ , Journal of Lightwave Technology, Vol. 7, No. 7, Jul. 1989, pp 1071-1082, that when the incoming signal is detected at the receiver, the ASE contributes a noise input as the result of signal-spontaneous beat interactions and a further noise input as the result of spontaneous-spontaneous beat interactions.
- the present invention is directed to achieving reduced ASE and a consequent improvement on the signal-to-noise ratio of the signal detected at the receiver.
- an optical data transmission system employing non-coherent detection, the system including an optical transmitter optically coupled with a non-coherent optical receiver by an optical transmission path that includes a concatenation of optical amplifiers, wherein the transmitter includes a data modulator adapted to impress data modulation upon an optical signal transmitted by the transmitter to the receiver, and wherein the transmitter additionally includes a second modulator, which second modulator is adapted to modulate between a pair of substantially orthogonally polarised states the state of polarisation of the optical signal transmitted by the transmitter.
- a second modulator adapted to modulate between substantially orthogonally polarised states the state of polarisation of a data modulated optical signal transmitted by a transmitter has been previously described in U.S. Pat Nos. 4,965,857 and 5,023,494, but that disclosure is in the context of a system employing coherent (superheterodyne) detection.
- the coherent detection system described therein does not use optical amplifiers, and so is in no way concerned with any problems of ASE noise.
- the second modulator is specifically included to enable coherent detection, and so on the face of the document has no apparent relevance to systems employing non-coherent detection.
- FIGS. 1 and 2 are block diagrams of optical transmission systems embodying the invention in alternative preferred forms.
- the optical transmitter system of FIG. 1 has a transmitter 10, at a remote location a non-coherent receiver 11 and, between the two, an optical fibre transmission part 12 that includes a concatenation of optical amplifiers 13, typically of the order of a hundred amplifiers.
- a preferred form of amplifier is an optical fibre amplifier incorporating a rare-earth dopant such as erbium.
- a preferred form of transmitter 10 incorporates an injection laser source 10a, a first modulator 10b supplied with data from a data input 14, and a second modulator 10c fed from an oscillator 15.
- the fist modulator 10b is an intensity modulator.
- the functions of laser source and intensity modulator may be combined in the same integer comprising an injection laser driven with both laser bias current and with data modulation current.
- the second modulator 10c is an optical state of polarisation modulator, and the amplitude of the output of the oscillator is sufficient to drive the second modulator so as to sweep its output between a pair of substantially orthogonally polarised polarisation states.
- a convenient form for such a polarisation modulator 10c is that of a lithium niobate phase shifter for which the state of polarisation of its optical input is arranged so that the input is divided substantially equally between its TE and its TM modes.
- the modulator could, for instance operate by dividing the signal into two equal parts, frequency shifting one part by acoustic-optic modulation, and then arranging to recombine the two parts with orthogonal polarisation states.
- the signal-to-ASE ratio, and hence also the received signal-to-noise ratio, is thereby improved.
- the modulation should be at a rate that is much faster than the response time of the population inversion in the amplifiers. If the polarisation modulation is at a rate short compared with the time constant of the population inversion then, at a single amplifier, the shortfall from total elimination of the gain discrepancy between the two polarisation states at this amplifier is correspondingly small.
- account must also be taken of the number of amplifiers in the system because there is a corresponding shortfall at each of the other amplifiers, with consequent cumulative effect.
- the polarisation modulation frequency for a hundred amplifier system should preferably be in excess of 100 Khz.
- the polarisation modulation does not have to be periodic.
- the polarisation modulator 10c has been represented as being located at, and forming part of, the transmitter 10, but it will be evident that it could in principle equally well be located immediately before the first amplifier of the concatenation. However to locate it after the first amplifier, or even further downstream the concatenation would involve the penalty that it would exercise no effect upon the ASE generated by the amplifier upstream of it.
- the system is liable to have some net polarisation dependent loss (PDL), and hence, if the polarisation modulator 10c is allowed to operate to modulate the signal down the transmission path 12 between any random pair of substantially orthogonally polarised states, there is a risk that this polarisation modulation may be detected at the receiver as amplitude modulation.
- PDL polarisation dependent loss
- This transmission system of FIG. 2 has the same arrangement of receiver 11, transmission path 12, and amplifiers 13 as the system of FIG. 1.
- its transmitter 20 includes the same three elements of laser source 10a and first and second modulators 10b and 10c as the transmitter 10 of the system of FIG. 1.
- the transmitter 20 of FIG. 2 includes a polarisation state adjuster 20d powered from a driver 26 that forms part of a feedback control loop.
- the polarisation adjuster is driven by the feedback loop to minimise the amplitude modulation appearing at the receiver's detector that has the same frequency as that of the modulation applied to the polarisation modulator 10c. If the polarisation modulator takes the form of a lithium niobate phase shifter, the polarisation adjuster may conveniently take the same form.
- an alternative solution to the potential problem of the polarisation dependent loss is to dispense with the adjuster and feedback control loop and instead to modulate the polarisation at a rate faster than the bit rate, preferably at twice, or greater integral multiple of, the bit rate.
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Abstract
Description
Claims (13)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/856,600 USRE36715E (en) | 1993-02-02 | 1997-05-15 | Optically amplified transmission systems |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9302022 | 1993-02-02 | ||
GB939302022A GB9302022D0 (en) | 1993-02-02 | 1993-02-02 | Optically amplified transmission systems |
US08/189,049 US5416626A (en) | 1993-02-02 | 1994-01-31 | Optically amplified transmission systems |
US08/856,600 USRE36715E (en) | 1993-02-02 | 1997-05-15 | Optically amplified transmission systems |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/189,049 Reissue US5416626A (en) | 1993-02-02 | 1994-01-31 | Optically amplified transmission systems |
Publications (1)
Publication Number | Publication Date |
---|---|
USRE36715E true USRE36715E (en) | 2000-05-30 |
Family
ID=10729710
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/189,049 Expired - Lifetime US5416626A (en) | 1993-02-02 | 1994-01-31 | Optically amplified transmission systems |
US08/856,600 Expired - Fee Related USRE36715E (en) | 1993-02-02 | 1997-05-15 | Optically amplified transmission systems |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/189,049 Expired - Lifetime US5416626A (en) | 1993-02-02 | 1994-01-31 | Optically amplified transmission systems |
Country Status (6)
Country | Link |
---|---|
US (2) | US5416626A (en) |
JP (1) | JP3488502B2 (en) |
CA (1) | CA2114471C (en) |
DE (1) | DE4402428C2 (en) |
FR (1) | FR2701179B1 (en) |
GB (1) | GB9302022D0 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6366373B1 (en) * | 1999-11-24 | 2002-04-02 | Luxn, Inc. | Method of intrinsic continuous management data transmission in fiber optic communications |
US20020176144A1 (en) * | 2001-05-07 | 2002-11-28 | Bergano Neal S. | Optical transmission system using optical signal processing in terminals for improved system performance |
US7120364B2 (en) * | 2000-07-07 | 2006-10-10 | Jds Uniphase Corporation | Optical modulator and method for polarization bit interleaving |
US20120148260A1 (en) * | 2010-12-13 | 2012-06-14 | Fujitsu Limited | Optical transmitter and optical transmission method |
Families Citing this family (24)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3846918B2 (en) * | 1994-08-02 | 2006-11-15 | 富士通株式会社 | Optical transmission system, optical multiplex transmission system and related technologies |
US5526162A (en) * | 1994-09-27 | 1996-06-11 | At&T Corp. | Synchronous polarization and phase modulation for improved performance of optical transmission systems |
US5760939A (en) * | 1995-10-23 | 1998-06-02 | Sdl, Inc. | Optical transmission link capable of high temperature operation without cooling with an optical receiver module having temperature independent sensitivity performance and optical transmitter module with laser diode source |
JPH1093164A (en) | 1996-09-17 | 1998-04-10 | Kokusai Denshin Denwa Co Ltd <Kdd> | Multi pre-wavelength light source and variable discrete wavelength light source |
WO1998051025A1 (en) * | 1997-05-02 | 1998-11-12 | Seiko Epson Corporation | Polarized light communication device, transmitter, laser, polarized light communication device for organism, reflected light detector and pulse wave detector |
US6285477B1 (en) * | 1997-09-17 | 2001-09-04 | Kokusai Denshin Denwa Kabushiki Kaisha | Multi-wavelength light source and discrete-wavelength-variable light source |
JP3116348B2 (en) * | 1998-02-24 | 2000-12-11 | 日本電気株式会社 | Control signal transmission method and apparatus for optical transmission system |
EP1248393A3 (en) * | 2001-04-06 | 2004-12-08 | Tyco Telecommunications (US) Inc. | Method and apparatus for detecting localized polarisation dependent anomalies on optical transmission lines |
US6660990B2 (en) * | 2001-06-01 | 2003-12-09 | Nortel Networks Limited | Optical amplification and receiving system and method |
US7305183B2 (en) * | 2001-08-27 | 2007-12-04 | Nortel Networks Limited | Measurement of polarization dependent loss in an optical transmission system |
US7382984B2 (en) * | 2002-10-03 | 2008-06-03 | Nortel Networks Limited | Electrical domain compensation of optical dispersion in an optical communications system |
US7756421B2 (en) * | 2002-10-03 | 2010-07-13 | Ciena Corporation | Electrical domain compensation of non-linear effects in an optical communications system |
US7382985B2 (en) * | 2002-12-02 | 2008-06-03 | Nortel Networks Limited | Electrical domain mitigation of polarization dependent effects in an optical communications system |
US7023601B2 (en) * | 2002-12-02 | 2006-04-04 | Nortel Networks Limited | Optical E-field modulation using a Mach-Zehnder interferometer |
US6781537B1 (en) | 2003-06-10 | 2004-08-24 | Nortel Networks Limited | High speed digital to analog converter |
US7680420B1 (en) | 2003-10-03 | 2010-03-16 | Nortel Networks Limited | Optical E-field modulation using a directly driven laser |
US7266306B1 (en) | 2003-10-03 | 2007-09-04 | Nortel Networks Limited | Method for optical carrier suppression and quadrature control |
US7672595B1 (en) | 2003-12-23 | 2010-03-02 | Nortel Networks Limited | Optical transmission system architecture supporting migration to electronic compensation of link impairments |
US7317845B2 (en) * | 2004-06-23 | 2008-01-08 | Lucent Technologies Inc. | Optical modulator having reduced bandwidth requirements and method of operation thereof |
US7321734B2 (en) | 2004-07-29 | 2008-01-22 | Nortel Networks Limited | Digital synthesis of readily compensated optical signals |
US7676161B2 (en) * | 2004-12-10 | 2010-03-09 | Nortel Networks Limited | Modulation E-field based control of a non-linear transmitter |
US7787778B2 (en) | 2004-12-10 | 2010-08-31 | Ciena Corporation | Control system for a polar optical transmitter |
WO2009007973A1 (en) * | 2007-07-11 | 2009-01-15 | Technion - Research & Development Foundation Ltd | Enhanced smf passive optical networks using polarization beamforming |
JP7190706B2 (en) | 2020-03-12 | 2022-12-16 | 深▲せん▼奥郎格環保有限公司 | Hair Dryer |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4947134A (en) * | 1987-10-30 | 1990-08-07 | American Telephone And Telegraph Company | Lightwave systems using optical amplifiers |
US4965857A (en) * | 1988-09-30 | 1990-10-23 | Siemens Aktiegesellschaft | Method for synchronized polarization switching of an optical transmission signal of an optical transmission system having superheterodyne reception and an apparatus for the implementation of said method |
US5023949A (en) * | 1988-09-30 | 1991-06-11 | Siemens Aktiengesellschaft | Apparatus for generating an FSK-modulated optical signal having two different polarization conditions for an optical transmission system having an optical two-filter FSK super-heterodyne receiver |
WO1991018455A1 (en) * | 1990-05-11 | 1991-11-28 | Fondazione Ugo Bordoni | A multilevel coherent optical system |
US5227908A (en) * | 1990-07-13 | 1993-07-13 | Nec Corporation | Optical communication apparatus using intensity modulation |
US5295013A (en) * | 1992-03-23 | 1994-03-15 | Nec Corporation | Optical receiver of direct detection type |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3272988A (en) * | 1963-03-25 | 1966-09-13 | Gen Telephone & Elect | Polarization modulation system for transmitting and receiving two independent signals over a single electromagnetic carrier |
US3752992A (en) * | 1969-05-28 | 1973-08-14 | Us Navy | Optical communication system |
US4301543A (en) * | 1980-02-20 | 1981-11-17 | General Dynamics Corporation, Pomona Division | Fiber optic transceiver and full duplex point-to-point data link |
JPS58182518A (en) * | 1982-04-12 | 1983-10-25 | インタ−ナショナル ビジネス マシ−ンズ コ−ポレ−ション | Ellipsometer |
JPS59104847A (en) * | 1982-12-07 | 1984-06-16 | Fujitsu Ltd | Radio communicating system |
JPH03144614A (en) * | 1989-10-31 | 1991-06-20 | Nec Corp | Optical transmitter |
US5117303A (en) * | 1990-08-23 | 1992-05-26 | At&T Bell Laboratories | Method of operating concatenated optical amplifiers |
-
1993
- 1993-02-02 GB GB939302022A patent/GB9302022D0/en active Pending
-
1994
- 1994-01-27 DE DE4402428A patent/DE4402428C2/en not_active Expired - Lifetime
- 1994-01-28 CA CA002114471A patent/CA2114471C/en not_active Expired - Lifetime
- 1994-01-31 FR FR9401026A patent/FR2701179B1/en not_active Expired - Lifetime
- 1994-01-31 US US08/189,049 patent/US5416626A/en not_active Expired - Lifetime
- 1994-01-31 JP JP02881594A patent/JP3488502B2/en not_active Expired - Lifetime
-
1997
- 1997-05-15 US US08/856,600 patent/USRE36715E/en not_active Expired - Fee Related
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4947134A (en) * | 1987-10-30 | 1990-08-07 | American Telephone And Telegraph Company | Lightwave systems using optical amplifiers |
US4965857A (en) * | 1988-09-30 | 1990-10-23 | Siemens Aktiegesellschaft | Method for synchronized polarization switching of an optical transmission signal of an optical transmission system having superheterodyne reception and an apparatus for the implementation of said method |
US5023949A (en) * | 1988-09-30 | 1991-06-11 | Siemens Aktiengesellschaft | Apparatus for generating an FSK-modulated optical signal having two different polarization conditions for an optical transmission system having an optical two-filter FSK super-heterodyne receiver |
WO1991018455A1 (en) * | 1990-05-11 | 1991-11-28 | Fondazione Ugo Bordoni | A multilevel coherent optical system |
US5227908A (en) * | 1990-07-13 | 1993-07-13 | Nec Corporation | Optical communication apparatus using intensity modulation |
US5295013A (en) * | 1992-03-23 | 1994-03-15 | Nec Corporation | Optical receiver of direct detection type |
Non-Patent Citations (2)
Title |
---|
Olsson, "Lightwave Systems With Optical Amplifiers", Journal of Lightwave Technology, vol. 7, No. 7. pp. 1071-1082, Jul. 1989. |
Olsson, Lightwave Systems With Optical Amplifiers , Journal of Lightwave Technology, vol. 7, No. 7. pp. 1071 1082, Jul. 1989. * |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6366373B1 (en) * | 1999-11-24 | 2002-04-02 | Luxn, Inc. | Method of intrinsic continuous management data transmission in fiber optic communications |
US7120364B2 (en) * | 2000-07-07 | 2006-10-10 | Jds Uniphase Corporation | Optical modulator and method for polarization bit interleaving |
US20020176144A1 (en) * | 2001-05-07 | 2002-11-28 | Bergano Neal S. | Optical transmission system using optical signal processing in terminals for improved system performance |
US20070009265A1 (en) * | 2001-05-07 | 2007-01-11 | Bergano Neal S | Optical Transmission System Using Optical Signal Processing in Terminals for Improved System Performance |
US7203429B2 (en) * | 2001-05-07 | 2007-04-10 | Tyco Telecommunications (Us) Inc. | Optical transmission system using optical signal processing in terminals for improved system performance |
US7336908B2 (en) * | 2001-05-07 | 2008-02-26 | Tyco Telecommunications (Us) Inc. | Optical transmission system using optical signal processing in terminals for improved system performance |
US20120148260A1 (en) * | 2010-12-13 | 2012-06-14 | Fujitsu Limited | Optical transmitter and optical transmission method |
US8879925B2 (en) * | 2010-12-13 | 2014-11-04 | Fujitsu Limited | Optical transmitter and optical transmission method |
Also Published As
Publication number | Publication date |
---|---|
DE4402428C2 (en) | 2003-06-18 |
CA2114471A1 (en) | 1994-08-03 |
DE4402428A1 (en) | 1994-08-04 |
JP3488502B2 (en) | 2004-01-19 |
US5416626A (en) | 1995-05-16 |
GB9302022D0 (en) | 1993-03-17 |
CA2114471C (en) | 2004-01-27 |
FR2701179A1 (en) | 1994-08-05 |
FR2701179B1 (en) | 1995-11-24 |
JPH077471A (en) | 1995-01-10 |
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