WO1990015980A1 - Optical time domain reflectometry - Google Patents
Optical time domain reflectometry Download PDFInfo
- Publication number
- WO1990015980A1 WO1990015980A1 PCT/GB1990/000962 GB9000962W WO9015980A1 WO 1990015980 A1 WO1990015980 A1 WO 1990015980A1 GB 9000962 W GB9000962 W GB 9000962W WO 9015980 A1 WO9015980 A1 WO 9015980A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- optical
- time domain
- waveguide
- domain reflectometer
- optical time
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
- G01M11/319—Reflectometers using stimulated back-scatter, e.g. Raman or fibre amplifiers
Definitions
- This invention relates to Optical Time Domain Reflectometry (OTDR), and especially to enhancing the dynamic range of OTDR equipment.
- an optical pulse is launched into an optical fibre (or more generally into a waveguide; in this specification the expression 'fibre 1 is used to include the more general case of a waveguide as well as optical fibres) and backscattered signal returning to the launch end is monitored.
- the amount of backscattering generally increases and this change is detected in the monitored return signal.
- Backscattering and reflection also occur from elements such as couplers and so the monitored signal is usually compared with a reference record, new peaks and other cnanges in the monitored signal level or plot being indicative of changes in the fibre path, normally indicating a fault.
- OTDR time between pulse launch and receipt of the backscattered pulse is proportional to the distance along the fibre to the source of the backscattering, and so OTDR is a useful technique for fault location.
- One of the limitations is the dynamic range of the OTDR receiver which has to be sufficiently sensitive to detect the low level of backscattered light returning from the more distant part of the fibre, but also capable of receiving, without damage, much greater intensity reflection and backscattering from fibre locations close to the launch end.
- OTDR receivers have about a 30dB optical one-way measurement range, that is a 60dB optical dynamic range, and this requires the electronics to have a twofold dynamic range of 120dB resulting from the optical to electrical conversion.
- optical sources chosen for use in such equipment are almost invariably semiconductor laser diodes.
- the optical source in an OTDR needs to be capable of providing short-duration, well-defined optical pulses if the OTDR is to provide satisfactory resolution.
- satisfactory resolution requires the use of a narrow linewidth source, since the dispersion properties of commonly used optical fibres result in pulse spreading if other than narrow linewidth sources are used.
- narrow linewidth semiconductor diode lasers naturally have very limited power outputs.
- Increases in OTDR range have in general come about from continual and gradual improvements to the signal processing, software, electronics, and the laser diodes.
- the present invention provides an optical time domain reflectometer comprising a source of optical pulses, means for launching the optical pulses into a waveguide and means for optically pumping the waveguide to produce gain at the optical pulse wavelength prior to launching the amplified pulses into a waveguide to be tested.
- a further aspect of the invention provides a method of increasing the measurement range of an optical time domain reflectometer, the method comprising launching an optical pulse into a waveguide and optically pumping the waveguide to induce gam of ne pulse prior to launching the amplified pulses into a waveguide to be tested.
- Figure I is a schematic diagram of an embodiment of the invention.
- Figures 2a and 2b show OTDR traces respectively without and with the invention.
- Figure 3 is a plot cf forward spontaneous emission spectrum of an erbium doped fibre amplifier.
- a modified Hewlett Packard HP8145A OTDR 1 was connected to one input arm 2 of a wavelength division multiplexer (WDM) coupler 3, which was in turn connected to a single-mode fibre under test 4.
- WDM wavelength division multiplexer
- the bandwidth was chosen to be narrow enough to reduce the amount of spontaneous amplifier noise reaching the OTDR receiver but sufficiently broad to easily allow the laser emission, which occurs over a few hundred MHz, to pass with low loss.
- the second input arm 5 of the WDM coupler was connected to a 1485nm pump laser 6, which could be any suitable laser such as a 1.485 micron semiconductor laser module, for example a GRINSCH M W laser.
- a semiconductor diode laser is preferred.
- Suitable pump lasers are available from OKI of Tokyo, Japan, these particular type are of VIF3 structure and are supplied in.a module with an integral WDM coupling arrangement.
- the OKI integral coupler serves as coupler 3. Initially the pump power was 65mW.
- Figure 3 shows the amplifier forward spontaneous emission spectrum, including the residual pump power at the amplifier output, when pumped with about 65mW at 1.485 ⁇ m. At a signal wavelength of 1.53 a peak gain of 24dB was obtained, while at the OTDR wavelength of 1.536 «m the amplifier gam was 20dB.
- amplification of both outbound OTDR pulse and returning backscattered signals occurs in the fibre laser amplifier. Less preferably, there is only amplification of the optical pulses to be launched into the fibre under test, and not of the backscattered signals. Pulsed pump power could be employed, in conjunction with suitable - ⁇ -
- HP8145A OTDR single-pulse OTDR equipment instead of the HP8145A.
- HP8145A OTDR was selected for the embodiment because it automatically subtracts the mean received light level from the measurements, and thus it is able to cope with residual pump and spontaneous amplifier noise signals that reach the OTDR.
- Other types of OTDRs may be employed if the filtering is adequate.
- Figure 2a is a typical OTDR trace on a 12.4Km high attenuation test fibre 1.3dB/Km) with the power falling to a substantially steady background level given by the OTDR receiver noise floor after about 7Km.
- the pump is turned on the trace modifies to that shown in Figure 2b so that instead of the trace falling to the noise floor after 7Km one is able to 'see' the entire fibre length.
- test fibre was measured in two stages, allowing the use of reduced optical amplifier gam on the initial fibre span, to avoid saturating the OTDR receiver.lt should be noted that both the outbound and returning signals are amplified rather than ]ust outbound signals, and thus the signals reach and can be detected from further along the fibre than would otherwise be the case.
- Figure 2a and the second measurement of Figure 2b were obtained with identical settings on the vertical offsets.
- the measurement noise floor is approximately the same in both cases, thus it can be expected that the erbium fibre gain of 18dB (20dB minus ldB for each of two fusion splices) should lead to an OTDR range increase of l8dB one way.
- the benefits of the invention may be utilised to aid fault detection in branched networks, where the total span length is less but division of the signal occurs.
- Branch line identification signals may be superimposed on the returning signals.
- higher OTDR resolution is required and so the OTDR pulses used are narrower and the lower power injection means that a range of 20dB is the present upper limit. Increasing this to 30dB utilising fibre amplification is thus of benefit and is within the ability of available electrical dynamic range.
- the system is preferably not merely used as a power amplifier, the returning signals preferably also pass through the amplifying fibre.
- a particular advantage of using a fibre amplifier is that pulses of any duration can be amplified, for example from microsecond to picosecond lengths, which is more versatile than amplification provided by semiconductor laser amplifiers which at present cannot provide sufficient power amplification for pulses over IOC picoseconds.
- pump powers of 65mW have been used here, lower pump powers of approximately lOmW can give the same level of amplification, as shown by R. S. Vodhanel et al m Electronic Letters, 1989, Volume 25, page 1386.
- erbium is the preferred dopant for the fibre amplifier.
- High power semiconductor laser pumps are available with wavelengths in the range 1460-1480nm, for example the previously mentioned GRINSCH MQW lasers. It has been shown by Atkins et al that erbium fibre amplifiers can usefully be operated at wavelengths out to 1580nm.
- neodymium can be used as the dopant for the fibre amplifier with an appropriate pump.
- fron Nd fibre amplifiers is much lower than that available from erbium fibre amplifiers, but nevertheless it is feasible to obtain usefully increased launched pulse power. Further details on neodymium doped fibre amplifiers can be found in Y. Miyajima et al's paper published in the proceedings of the Optical Fiber Communications (OFC 90) conference held in San Francisco in January 1990.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT90909768T ATE97237T1 (en) | 1989-06-22 | 1990-06-22 | OPTICAL REFLECTION MEASUREMENT IN THE TIME DOMAIN. |
CA002058957A CA2058957C (en) | 1989-06-22 | 1990-06-22 | Optical time domain reflectometry |
GB9126780A GB2250654B (en) | 1989-06-22 | 1991-12-17 | Optical time domain reflectometry |
FI916037A FI101746B1 (en) | 1989-06-22 | 1991-12-20 | Optical time-circuit reflectometer |
HK135696A HK135696A (en) | 1989-06-22 | 1996-07-25 | Optical time domain reflectometry |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8914364.8 | 1989-06-22 | ||
GB898914364A GB8914364D0 (en) | 1989-06-22 | 1989-06-22 | Optical time domain reflectometry |
GB898915165A GB8915165D0 (en) | 1989-07-01 | 1989-07-01 | Optical time domain reflectometry |
GB8915165.8 | 1989-07-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1990015980A1 true WO1990015980A1 (en) | 1990-12-27 |
Family
ID=26295522
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1990/000962 WO1990015980A1 (en) | 1989-06-22 | 1990-06-22 | Optical time domain reflectometry |
PCT/GB1990/000961 WO1990015979A1 (en) | 1989-06-22 | 1990-06-22 | Optical time domain reflectometry |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1990/000961 WO1990015979A1 (en) | 1989-06-22 | 1990-06-22 | Optical time domain reflectometry |
Country Status (13)
Country | Link |
---|---|
US (2) | US5298965A (en) |
EP (1) | EP0478654B1 (en) |
JP (1) | JP2957696B2 (en) |
AT (1) | ATE97237T1 (en) |
AU (2) | AU5839290A (en) |
CA (1) | CA2058957C (en) |
DE (1) | DE69004571T2 (en) |
DK (1) | DK0478654T3 (en) |
ES (1) | ES2045933T3 (en) |
FI (1) | FI101746B1 (en) |
GB (1) | GB2250654B (en) |
HK (1) | HK135696A (en) |
WO (2) | WO1990015980A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2252154A (en) * | 1991-01-26 | 1992-07-29 | Stc Plc | Testing erbium doped optical fibres. |
USH1436H (en) * | 1992-10-13 | 1995-05-02 | Kersey Alan D | Interferometric fiber optic sensor configuration with pump-induced phase carrier |
WO1996035935A1 (en) * | 1995-05-10 | 1996-11-14 | Dsc Communications A/S | A method of measuring on an optical fibre |
Families Citing this family (21)
Publication number | Priority date | Publication date | Assignee | Title |
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ES2073161T3 (en) * | 1990-02-15 | 1995-08-01 | British Telecomm | OPTICAL CHECKING DEVICE COMPRISING AN OPTICAL REFLECTOMETER BY TIME DOMAIN. |
GB9115453D0 (en) * | 1991-07-18 | 1991-09-04 | British Telecomm | Fault location in optical systems |
GB9715289D0 (en) * | 1997-07-22 | 1997-09-24 | King S College London | Wavelength measuring system |
US6552290B1 (en) * | 1999-02-08 | 2003-04-22 | Spectra Systems Corporation | Optically-based methods and apparatus for performing sorting coding and authentication using a gain medium that provides a narrowband emission |
WO2002005461A2 (en) | 2000-07-10 | 2002-01-17 | Mpb Technologies Inc. | Cascaded pumping system for distributed raman amplification in optical fiber telecommunication systems |
JP3904835B2 (en) * | 2001-01-29 | 2007-04-11 | 株式会社日立製作所 | Optical amplifier, optical fiber Raman optical amplifier, and optical system |
US6433922B1 (en) | 2001-02-26 | 2002-08-13 | Redc Optical Networks Ltd. | Apparatus and method for a self adjusting Raman amplifier |
US6850360B1 (en) * | 2001-04-16 | 2005-02-01 | Bookham, Inc. | Raman amplifier systems with diagnostic capabilities |
US6526189B1 (en) | 2001-06-13 | 2003-02-25 | The United States Of America As Represented By The Secretary Of The Army | Scour sensor assembly |
US20040208503A1 (en) * | 2001-12-06 | 2004-10-21 | William Shieh | Systems and methods for detecting faults in optical communication systems |
KR100488195B1 (en) * | 2002-01-31 | 2005-05-10 | 주식회사 럭스퍼트 | Fiber Raman amplifier |
JP3961973B2 (en) * | 2003-03-14 | 2007-08-22 | 富士通株式会社 | OTDR measurement method and terminal device |
GB201207881D0 (en) * | 2012-05-04 | 2012-06-20 | Isis Innovation | Active chemical sensing using optical microcavity |
US9140624B2 (en) | 2012-07-03 | 2015-09-22 | Ciena Corporation | Systems and methods reducing coherence effect in narrow line-width light sources |
US9752955B2 (en) | 2014-07-31 | 2017-09-05 | Ii-Vi Incorporated | Edge propagating optical time domain reflectometer and method of using the same |
US9503181B2 (en) | 2015-01-06 | 2016-11-22 | Ii-Vi Incorporated | Rare earth-doped fiber amplifier with integral optical metrology functionality |
US10763962B2 (en) | 2016-02-18 | 2020-09-01 | Apriori Network Systems, Llc. | Secured fiber link system |
US10284288B2 (en) | 2016-02-18 | 2019-05-07 | Apriori Network Systems, Llc | Secured fiber link system |
US10784969B2 (en) * | 2016-02-18 | 2020-09-22 | Apriori Network Systems, Llc. | Secured fiber link system |
EP3324169A1 (en) * | 2016-11-22 | 2018-05-23 | Xieon Networks S.à r.l. | Detection of gainers and exaggerated losses in unidirectional otdr traces |
US11671172B1 (en) * | 2022-02-25 | 2023-06-06 | Huawei Technologies Co., Ltd. | Systems and methods for characterizing an optical fiber in a dense wavelength division multiplexing optical link |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2175766A (en) * | 1985-05-22 | 1986-12-03 | Pa Consulting Services | Fibre optic communication systems |
GB2182222A (en) * | 1985-10-18 | 1987-05-07 | Stc Plc | Optical fibre testing |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE52143T1 (en) * | 1984-12-13 | 1990-05-15 | Stc Plc | OPTICAL AMPLIFIER. |
JPH01142435A (en) * | 1987-11-28 | 1989-06-05 | Nippon Telegr & Teleph Corp <Ntt> | Apparatus for measuring back scattering light |
US5013907A (en) * | 1990-03-27 | 1991-05-07 | Tektronix, Inc. | Optical time domain testing instrument |
-
1990
- 1990-06-22 US US07/834,293 patent/US5298965A/en not_active Expired - Lifetime
- 1990-06-22 EP EP90909768A patent/EP0478654B1/en not_active Expired - Lifetime
- 1990-06-22 ES ES90909768T patent/ES2045933T3/en not_active Expired - Lifetime
- 1990-06-22 DE DE90909768T patent/DE69004571T2/en not_active Expired - Lifetime
- 1990-06-22 JP JP2509750A patent/JP2957696B2/en not_active Expired - Lifetime
- 1990-06-22 WO PCT/GB1990/000962 patent/WO1990015980A1/en active IP Right Grant
- 1990-06-22 CA CA002058957A patent/CA2058957C/en not_active Expired - Lifetime
- 1990-06-22 DK DK90909768.5T patent/DK0478654T3/en active
- 1990-06-22 AU AU58392/90A patent/AU5839290A/en not_active Abandoned
- 1990-06-22 AT AT90909768T patent/ATE97237T1/en not_active IP Right Cessation
- 1990-06-22 WO PCT/GB1990/000961 patent/WO1990015979A1/en unknown
- 1990-06-22 AU AU59241/90A patent/AU632597B2/en not_active Ceased
- 1990-06-22 US US07/541,973 patent/US5448059A/en not_active Expired - Lifetime
-
1991
- 1991-12-17 GB GB9126780A patent/GB2250654B/en not_active Revoked
- 1991-12-20 FI FI916037A patent/FI101746B1/en active
-
1996
- 1996-07-25 HK HK135696A patent/HK135696A/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2175766A (en) * | 1985-05-22 | 1986-12-03 | Pa Consulting Services | Fibre optic communication systems |
GB2182222A (en) * | 1985-10-18 | 1987-05-07 | Stc Plc | Optical fibre testing |
Non-Patent Citations (1)
Title |
---|
ECOC 87, Technical Digest, Volume 1, 1987, Y. TAMURA et al.: "Fiber Raman Amplifier Module with Semiconductor Laser Pump Source", pages 62-65 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2252154A (en) * | 1991-01-26 | 1992-07-29 | Stc Plc | Testing erbium doped optical fibres. |
USH1436H (en) * | 1992-10-13 | 1995-05-02 | Kersey Alan D | Interferometric fiber optic sensor configuration with pump-induced phase carrier |
WO1996035935A1 (en) * | 1995-05-10 | 1996-11-14 | Dsc Communications A/S | A method of measuring on an optical fibre |
US5870183A (en) * | 1995-05-10 | 1999-02-09 | Dsc Communications A/S | Method of measuring on an optical fibre |
Also Published As
Publication number | Publication date |
---|---|
EP0478654A1 (en) | 1992-04-08 |
HK135696A (en) | 1996-08-02 |
US5448059A (en) | 1995-09-05 |
ES2045933T3 (en) | 1994-01-16 |
DE69004571T2 (en) | 1994-03-10 |
FI916037A0 (en) | 1991-12-20 |
DK0478654T3 (en) | 1994-03-14 |
JP2957696B2 (en) | 1999-10-06 |
DE69004571D1 (en) | 1993-12-16 |
GB2250654B (en) | 1994-04-20 |
US5298965A (en) | 1994-03-29 |
ATE97237T1 (en) | 1993-11-15 |
CA2058957C (en) | 1999-05-04 |
EP0478654B1 (en) | 1993-11-10 |
AU5839290A (en) | 1991-01-08 |
JPH04506405A (en) | 1992-11-05 |
WO1990015979A1 (en) | 1990-12-27 |
FI101746B (en) | 1998-08-14 |
AU5924190A (en) | 1991-01-08 |
GB2250654A (en) | 1992-06-10 |
CA2058957A1 (en) | 1990-12-23 |
AU632597B2 (en) | 1993-01-07 |
FI101746B1 (en) | 1998-08-14 |
GB9126780D0 (en) | 1992-03-11 |
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