WO2002030017A1 - Raman amplification - Google Patents
Raman amplification Download PDFInfo
- Publication number
- WO2002030017A1 WO2002030017A1 PCT/GB2001/004415 GB0104415W WO0230017A1 WO 2002030017 A1 WO2002030017 A1 WO 2002030017A1 GB 0104415 W GB0104415 W GB 0104415W WO 0230017 A1 WO0230017 A1 WO 0230017A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- waveguide
- raman amplification
- optical
- raman
- Prior art date
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
- H04B10/29—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
- H04B10/2916—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 using Raman or Brillouin amplifiers
-
- 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
- H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
- H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre
Definitions
- the present invention relates to Raman amplification, and in particular to a method and apparatus for providing Raman amplification that is suitable for, but not limited to, providing Raman amplification in a telecommunications system.
- Raman amplifiers use a non-linear effect called Raman scattering, whereby a small proportion of light at the pump frequency is scattered by the molecules in a medium (i.e. the optic fibre), and down shifted in frequency by an amount dependant on the vibrational modes of the medium.
- This down shifted light called the Stokes wave
- the Stokes wave may have a fairly broad spectrum, the intensity of which is dependant on the fibre type and geometry.
- Stimulated Raman scattering occurs when light at the same frequency as the Stokes wave is instant in the fibre, and results in the amplification of the incident light.
- Raman amplifiers typically require long lengths of fibre (e.g. greater than 5 kilometres) to achieve satisfactory gain (e.g. greater than 20 dB).
- Distributed Raman amplification can thus be used to extend the reach of long-haul optical transmission systems by amplifying signals whilst they are in the transmission fibre, significantly proving the signal- spontaneous beat noise performance at the receiver.
- MPI multi-path interference
- DRS double Rayleigh scattering
- Figure 1 shows a short length of a fibre 10 in which DRS is occurring.
- the information signal light 12 is Rayleigh scattered 14 by small irregularities in the fibre. This results in a back scattered signal 16 travelling in the opposite direction to the information signal (i.e. it is counter propagating rather than co-propagating). This signal 16 may undergo Raman gain, and may be scattered again 18, resulting in a co- propagating DRS noise signal 20.
- the noise signal 20 has taken a different path than the information signal 12, and thus is likely to be incoherent, it does represent noise and can cause system penaltys. It is therefore desirable to limit the distance over which distributed Raman amplification is applied in a transmission fibre.
- Relatively high power sources are used as Raman pumps. If such a signal is launched into an optical fibre, and the optical fibre broken, the resulting light output from the fibre could be exceptionally dangerous. Consequently, a shutdown mechanism is necessary.
- Conventional systems would rely upon the detection of the Raman pump signal at the end of the span (i.e at the next amplifying stage), with a signal being sent back via a supervisory system to the Raman pump source.
- Such a shutdown system has drawbacks. For instance, it requires the generation and transmission of a separate, supervisory signal. Also, due to the detection location at the end of the span, and the subsequent requirement to signal back to the Raman pump (typically at the start of the span) then the system is relatively slow. If the Raman pump is not located at the start of the span, then this can bring its own implementation problems e.g a separate power source is required for the Raman pump source.
- the present invention provides a system comprising a first optical waveguide suitable for transmitting a first information signal, a second optical waveguide suitable for transmitting a second information signal, and input means for providing an electro magnetic radiation signal into said first waveguide, said signal being suitable for providing Raman amplification of the information signals, the system further comprising an optical coupling between said waveguides, arranged to transmit at least a portion of the Raman amplification signal from the first waveguide to the second whilst substantially blocking the transmission of the information signals between the waveguides.
- the system further comprises a detector means arranged to detect the transmission of the Raman amplification signal along the second waveguide. This allows a positive test that the Raman pump and the transmission fibre are functioning correctly.
- said detector means can comprise an optical power detector, an optical tap coupling the second waveguide to the detector, and filtering means arranged to pass the Raman amplification signal but substantially block the transmission signals.
- the system further comprises control means arranged to prohibit the provision of the Raman amplification signal into said first waveguide when said detector means does not detect the Raman amplification signal.
- control means arranged to prohibit the provision of the Raman amplification signal into said first waveguide when said detector means does not detect the Raman amplification signal.
- the system may further comprise a source suitable for providing said Raman amplification signal.
- said detector means and said source are co-located. This allows the sharing of any of the power supply, control signals and control processor (hardware and/or software).
- said optical coupling comprises at least one of a dielectric coupler, an optical circulator, and a tapered fibre wavelength selective coupler.
- the system further comprises an optical isolator arranged such so as to suppress multi-path interference.
- an optical isolator arranged such so as to suppress multi-path interference.
- This may be provided in the form of an integral part of another component e.g. an optical circulator, or may be a separate component.
- the system is arranged such that the first information signal is substantially transmitted in the opposite direction to the second information signal, and the Raman amplification signal is transmitted along each respective waveguide in the opposite direction to the information signal for that waveguide.
- the Raman amplification signal is counter propagating with respect to the information signals, the noise transfer between the Raman amplification signal and the information signals is less than for co-propagating Raman amplification and information signals.
- the system further comprises at least one erbium amplifier arranged to amplify said first and second information signals, said system being arranged such that one of said information signals undergoes Raman amplification prior to amplification by said erbium amplifier, and the other information signal undergoes Raman amplification after amplification by said erbium amplifier.
- the system can include other discrete amplifiers (as distinct from a distributed amplifier), such as discrete Raman amplifiers, Thulium doped fibre amplifiers, or indeed any rare-earthed doped fibre amplifiers.
- discrete amplifiers need not be present if the distributed Raman amplification is sufficiently large.
- the amplifier and said Raman source are co-located.
- the present invention provides a method of providing Raman amplification to a communications system, the system comprising a first optical waveguide suitable for transmitting a first information signal and a second optical waveguide suitable for transmitting a second information signal, the method comprising the steps of: providing an electro magnetic radiation signal into said first waveguide, said signal being suitable for providing Raman amplification of the information signals; and transferring at least a portion of the Raman amplification signal to said second waveguide.
- system further comprises the step of detecting the presence of the
- the electromagnetic radiation signal is prevented from entering into said first waveguide.
- the present invention provides a computer programme arranged to control a communications system so as to perform the method of providing Raman amplification to a communications system, the system comprising a first optical waveguide suitable for transmitting a first information signal and a second optical waveguide suitable for transmitting a second information signal, the method comprising the steps of: providing an electro magnetic radiation system into said first waveguide, said signal being suitable for providing Raman amplification of the information signals; and transferring at least a portion of the Raman amplification signal to said second waveguide.
- the computer programme can be stored on a machine readable medium.
- Figure 1 shows double Rayleigh back scatter occurring in an optical fibre (PRIOR ART)
- Figure 2 shows a transmission system incorporating loopbacks according to a first embodiment of the present invention
- Figures 3a and 3b show the implementation of a loopback using a 3 port optical circulator and a 4 port optical circulator respectively
- Figure 4 shows examples of power profiles along a 100km fibre for various loopback positions (x) along the length of the fibre (gain equals 20dB, attenuation equals 0.2dB/km), and
- Figures 5a and 5b show respectively examples of effective noise figures and approximate MPI for 80, 100, 120 & 160km spans using loopbacks at fractional distance x.
- FIG. 2 shows a schematic of an optical communication system incorporating a preferred embodiment.
- the system comprises two transmission fibres (214, 200, 312;212, 300, 314) each of length L km, used to transmit information between the respective erbium doped amplifiers (EDFA).
- the fibres are used as unidirectional transmission lines, with the information signals carried by the fibres propagating in the opposite directions.
- the information signal transmitted along the upper fibre shown in the diagram (212,200,312) is shown as being transmitted from left to right, whilst that in the lower fibre (314,300,212) can be seen to be transmitted from right to left.
- Such a configuration is typical in many of today's optical systems, wherein unidirectional optical fibre pairs act to provide a bi-directional function.
- Raman pump units (210,310) provide a source of electro magnetic radiation used to provide Raman amplification within the fibre.
- Each pump unit (210,310) is co-located with a respective EDFA. This allows the sharing of power supplies and control functions.
- Each pump unit is arranged to provide a Raman signal propagating in the respective fibre (212,312) in the opposite direction to the information signal.
- Such a counter-pumping scheme allows for any noise on the Raman pump to be averaged over the amplifier length, with noise transfer from the pump to the signal occurring less readily than if the pump and information signal were co-propagating.
- Each pump unit (210,310) has a respective "loop back" 400 which is used to couple the Raman amplification signal from one transmission fibre to the other.
- the Raman signal is always coupled to the second transmission fibre so that it is once again counter propagating with respect to the information signal.
- each Raman pump unit 210,310
- a respective safety detector Associated with each Raman pump unit (210,310) is a respective safety detector (220, 320).
- Each safety detector is arranged to detect the presence of the Raman amplification signal. If no Raman amplification signal is detected, then the Raman pump unit is shut-off or blocked from entering the fibre, in case a break has occurred in the fibre. This does prevent any of the high power Raman amplification signal being transmitted from the fibre break.
- each safety detector (220,320) is co-located with the respective Raman pump unit (210,310). This allows the sharing of power supplies, and minimises the distance that any control signals from the safety detector to the pump unit must travel.
- the system is arranged such that the Raman signal from unit 210 will propagate along length of (x L)km fibre 212 (where x is a fraction; 0 ⁇ x ⁇ 0.5), around the loop back 400, along length (x L) km of fibre 214 and can be detected by the safety detector 220.
- a filter may be inserted on the transmission line such that all of the Raman signal on the fibre 214 is diverted towards the safety detector 220. This may be exactly the same filter as used in the pump unit 210.
- the Raman signal is transmitted from unit 210 to detector 220 via two lengths of fibre (212, 214).
- the loop back could be implemented at any position desired or for any length of the transmission fibre.
- the fibre lengths 212,214,312 and 314 could all be of different lengths, or any two or more could be of the same length.
- the Raman radiation from unit 310 is transmitted along fibre length 312 through loop back 400 and via fibre length 314 to the safety detector 320.
- Such a scheme provides Raman amplification both pre and post signal amplification by the erbium amplifiers, whilst only utilising counter-pumped methodology. It provides an easy to implement and reliable safety mechanism. It permits efficient use of the Raman pump, allowing a single Raman pump unit to provide Raman amplification along two distinct transmission fibres. Finally, as the Raman signal is only propagated along a fraction of each of the total length of transmission fibre, it reduces multi-path interference compared with allowing the Raman signal to propagate uninterrupted along the whole transmission fibre.
- a loop back could take the form of a dielectric coupler, separating the Raman pump wavelengths from the signal wavelengths, and can include an isolator that further reduces MPI.
- a loop back 410 could be implemented utilising 2 3 port optical circulators 410a, 410b.
- a single 4-port optical circulator 420a could be utilised to provide the loop back 420.
- a tapered fibre wavelength selective coupler could be utilised.
- the present invention can be utilised by placement of the loop back in the form of a few small passive components along the length of the transmission fibre.
- transmission of fibres are laid in lengths of 10 or 15km, with access being provided by man hole covers.
- Figure 4 shows the relative power profile of an information signal as it traverses 100km of fibre for the case where overall the Raman gain is equal to the fibre loss.
- the discontinuities indicate the position of the loop backs. It can be seen that as the loop back position is moved closer to the end of the span, thus reducing x, there is a larger amount of residual pump which causes greater gain closer to the post amplifier.
- Figures 5a and 5b show results for 80, 100, 120 and 160km systems where the span loss is completely compensated for using distributed Raman amplification, corresponding to added Raman gains of 16, 20, 24 and 32db respectfully. In such instances, the erbium pre-amplifier could be removed.
- optical and light should be understood as pertaining not only to the visible part of the electromagnetics spectrum but also to the infra-red and ultra-violet parts that bound the visible part.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001292079A AU2001292079A1 (en) | 2000-10-05 | 2001-10-04 | Raman amplification |
CA002424874A CA2424874A1 (en) | 2000-10-05 | 2001-10-04 | Raman amplification |
EP01972302A EP1327319A1 (en) | 2000-10-05 | 2001-10-04 | Raman amplification |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0024453.3 | 2000-10-05 | ||
GBGB0024453.3A GB0024453D0 (en) | 2000-10-05 | 2000-10-05 | Raman amplification |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2002030017A1 true WO2002030017A1 (en) | 2002-04-11 |
Family
ID=9900762
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2001/004415 WO2002030017A1 (en) | 2000-10-05 | 2001-10-04 | Raman amplification |
Country Status (6)
Country | Link |
---|---|
US (1) | US6674566B2 (en) |
EP (1) | EP1327319A1 (en) |
AU (1) | AU2001292079A1 (en) |
CA (1) | CA2424874A1 (en) |
GB (1) | GB0024453D0 (en) |
WO (1) | WO2002030017A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2400763B (en) * | 2003-03-14 | 2006-06-21 | Fujitsu Ltd | Measurement method by OTDR and terminal station apparatus |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6862132B1 (en) * | 2001-08-13 | 2005-03-01 | Cisco Technology, Inc. | Suppression of double rayleigh backscattering and pump reuse in a raman amplifier |
US6798945B1 (en) | 2001-08-30 | 2004-09-28 | Cisco Technology, Inc. | Lumped raman amplifier for adaptive dispersion compensation |
US6856744B2 (en) * | 2002-02-13 | 2005-02-15 | The Furukawa Electric Co., Ltd. | Optical fiber and optical transmission line and optical communication system including such optical fiber |
US8750702B1 (en) * | 2002-06-21 | 2014-06-10 | Rockstar Consortium Us Lp | Passive optical loopback |
US7260324B2 (en) * | 2002-09-11 | 2007-08-21 | Altera Corporation | Automatic optical power management in optical communications system |
FR2853092A1 (en) * | 2003-03-31 | 2004-10-01 | France Telecom | OPTICAL DEVICE, IN PARTICULAR FOR SUPPRESSING NOISE, known as RAYLEIGH DOUBLE BACK BROADCAST, AND INSTALLATION COMPRISING SUCH A DEVICE |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0779687A2 (en) * | 1995-12-14 | 1997-06-18 | Nec Corporation | Optical fiber amplifying device and method of operation therefor |
WO1998042088A1 (en) * | 1997-03-17 | 1998-09-24 | Sdl, Inc. | Multiple stage optical fiber amplifier |
WO2000049721A2 (en) * | 1999-02-19 | 2000-08-24 | Corvis Corporation | Optical transmission systems including signal varying devices and methods |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5039199A (en) * | 1989-12-29 | 1991-08-13 | At&T Bell Laboratories | Lightwave transmission system having remotely pumped quasi-distributed amplifying fibers |
US5181210A (en) * | 1991-05-28 | 1993-01-19 | At&T Bell Laboratories | Electrically tunable fiber ring laser |
US5343320A (en) * | 1992-08-03 | 1994-08-30 | At&T Bell Laboratories | Pump laser control circuit for an optical transmission system |
JP3379052B2 (en) * | 1994-09-26 | 2003-02-17 | 富士通株式会社 | WDM optical amplifier, WDM transmission system, and WDM transmission method |
EP1291986B1 (en) * | 1995-03-20 | 2008-06-11 | Fujitsu Limited | Apparatus and method for processing an optical signal |
US6122298A (en) * | 1996-11-01 | 2000-09-19 | Tyco Submarine Systems Ltd. | Multi-wavelength optical pump |
DK129396A (en) * | 1996-11-15 | 1998-05-16 | Dsc Communications As | Optical amplifier and method for preventing the emitting of an optical power exceeding a preset |
US6072614A (en) * | 1997-08-21 | 2000-06-06 | Nortel Networks Corporation | Monitoring induced counterpropagating signals in optical communications systems |
US6081366A (en) * | 1997-08-28 | 2000-06-27 | Lucent Technologies Inc. | Optical fiber communication system with a distributed Raman amplifier and a remotely pumped er-doped fiber amplifier |
US6335820B1 (en) * | 1999-12-23 | 2002-01-01 | Xtera Communications, Inc. | Multi-stage optical amplifier and broadband communication system |
WO2000005622A1 (en) * | 1998-07-23 | 2000-02-03 | The Furukawa Electric Co., Ltd. | Raman amplifier, optical repeater, and raman amplification method |
US6151160A (en) * | 1998-10-05 | 2000-11-21 | Tyco Submarine Systems Ltd. | Broadband Raman pre-amplifier for wavelength division multiplexed optical communication systems |
US6304368B1 (en) * | 1999-01-15 | 2001-10-16 | Lucent Technologies, Inc. | Broadband optical amplification system |
US6163636A (en) * | 1999-01-19 | 2000-12-19 | Lucent Technologies Inc. | Optical communication system using multiple-order Raman amplifiers |
-
2000
- 2000-10-05 GB GBGB0024453.3A patent/GB0024453D0/en not_active Ceased
-
2001
- 2001-05-08 US US09/850,760 patent/US6674566B2/en not_active Expired - Fee Related
- 2001-10-04 AU AU2001292079A patent/AU2001292079A1/en not_active Abandoned
- 2001-10-04 WO PCT/GB2001/004415 patent/WO2002030017A1/en not_active Application Discontinuation
- 2001-10-04 CA CA002424874A patent/CA2424874A1/en not_active Abandoned
- 2001-10-04 EP EP01972302A patent/EP1327319A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0779687A2 (en) * | 1995-12-14 | 1997-06-18 | Nec Corporation | Optical fiber amplifying device and method of operation therefor |
WO1998042088A1 (en) * | 1997-03-17 | 1998-09-24 | Sdl, Inc. | Multiple stage optical fiber amplifier |
WO2000049721A2 (en) * | 1999-02-19 | 2000-08-24 | Corvis Corporation | Optical transmission systems including signal varying devices and methods |
Non-Patent Citations (1)
Title |
---|
FLUDGER C R S ET AL: "Inline loopbacks for improved OSNR and reduced double Rayleigh scattering in distributed Raman amplifiers", OFC 2001. OPTICAL FIBER COMMUNICATION CONFERENCE AND EXHIBIT. TECHNICAL DIGEST POSTCONFERENCE EDITION (IEEE CAT. 01CH37171), OFC 2001. OPTICAL FIBER COMMUNICATION CONFERENCE AND EXHIBITION. TECHNICAL DIGEST, ANAHEIM, CA, USA, 17-22 MARCH 2001, 2001, Washington, DC, USA, Opt. Soc. America, USA, pages MI1/1 - 3 vol.1, XP002186141, ISBN: 1-55752-655-9 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2400763B (en) * | 2003-03-14 | 2006-06-21 | Fujitsu Ltd | Measurement method by OTDR and terminal station apparatus |
US7215415B2 (en) | 2003-03-14 | 2007-05-08 | Fujitsu Limited | Measurement method by OTDR and terminal station apparatus |
US7420666B2 (en) | 2003-03-14 | 2008-09-02 | Fujitsu Limited | Measurement method by OTDR and terminal station apparatus |
Also Published As
Publication number | Publication date |
---|---|
GB0024453D0 (en) | 2000-11-22 |
EP1327319A1 (en) | 2003-07-16 |
AU2001292079A1 (en) | 2002-04-15 |
US20020041430A1 (en) | 2002-04-11 |
CA2424874A1 (en) | 2002-04-11 |
US6674566B2 (en) | 2004-01-06 |
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