CN109039442B - Calibrating device and calibrating method for optical return loss - Google Patents
Calibrating device and calibrating method for optical return loss Download PDFInfo
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- CN109039442B CN109039442B CN201810953479.9A CN201810953479A CN109039442B CN 109039442 B CN109039442 B CN 109039442B CN 201810953479 A CN201810953479 A CN 201810953479A CN 109039442 B CN109039442 B CN 109039442B
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- 230000003287 optical effect Effects 0.000 title claims abstract description 117
- 238000000034 method Methods 0.000 title claims abstract description 13
- 239000013307 optical fiber Substances 0.000 claims abstract description 25
- 238000012795 verification Methods 0.000 claims abstract description 15
- 238000005259 measurement Methods 0.000 claims abstract description 14
- 230000003595 spectral effect Effects 0.000 claims abstract description 4
- 238000003780 insertion Methods 0.000 claims description 12
- 230000037431 insertion Effects 0.000 claims description 12
- 238000003556 assay Methods 0.000 claims description 4
- 238000000253 optical time-domain reflectometry Methods 0.000 description 21
- 239000000835 fiber Substances 0.000 description 4
- 238000004891 communication Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
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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
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional 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
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/071—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
-
- 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
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
- H04B10/0775—Performance monitoring and measurement of transmission parameters
-
- 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
- H04B10/25—Arrangements specific to fibre transmission
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Testing Of Optical Devices Or Fibers (AREA)
Abstract
The invention provides an optical return loss verification device and a verification method, wherein the verification device comprises a coupler (11), an isolator (12), a variable optical attenuator (13) and an optical fiber (14) with a preset length; the coupler (11) comprises a trunk port (110), a first branch port (111) and a second branch port (112), wherein the first branch port (111) is connected with the input end of the isolator (12), the output end of the isolator (12) is connected with one end of the variable optical attenuator (13), and the other end of the variable optical attenuator (13) is connected with the second branch port (112) through an optical fiber (14) with a preset length; the spectral ratio of the first branch and the second branch is 1: n. The optical return loss calibrating device is simple in structure, the optical return loss value of the calibrating device is easy to measure based on the light source and the optical power meter, the variable optical return loss value suitable for optical time domain reflectometer measurement can be simulated, and the optical return loss parameter of the optical time domain reflectometer can be calibrated.
Description
Technical Field
The invention relates to the technical field of communication, in particular to an optical return loss calibrating device and an optical return loss calibrating method.
Background
As optical fiber communication networks become more and more complex, there are more and more events such as reflection and loss on optical fiber links, and the requirements for the ability of optical time domain reflectometers (Optical Time Domain Reflectometer, OTDR) to identify events are also more stringent, requiring that optical time domain reflectometers be able to accurately measure the optical return loss of a reflected event.
However, the existing JJG 959-2001 "optical time domain reflectometer verification procedure" does not provide a method and a device for verifying optical return loss, and through the examination and reading of documents, no verification device for optical return loss of an optical time domain reflectometer exists at present, and the existing optical return loss verification device is only aimed at an optical return loss tester and is not applicable to an optical time domain reflectometer.
Aiming at the optical return loss parameters of the optical time domain reflectometer, a reliable metering verification device is lacking at present to verify the optical return loss measurement capability and measurement precision of the optical time domain reflectometer, so that effective magnitude tracing cannot be performed.
Disclosure of Invention
In view of this, the present invention provides an optical return loss calibrating apparatus to solve the problem that the optical return loss parameter of the optical time domain reflectometer cannot be measured and calibrated.
The invention provides an optical return loss verification device, which comprises a coupler (11), an isolator (12), a variable optical attenuator (13) and an optical fiber (14) with a preset length, wherein the coupler is arranged on the coupler;
the coupler (11) comprises a trunk port (110) for receiving light input, a first branch port (111) and a second branch port (112), wherein the first branch port (111) is connected with the input end of the isolator (12), the output end of the isolator (12) is connected with one end of the variable optical attenuator (13), and the other end of the variable optical attenuator (13) is connected with the second branch port (112) through an optical fiber (14) with a preset length;
the spectral ratio of the first branch and the second branch is 1: n.
The invention also includes a method for detecting the optical return loss, which comprises the following steps;
inputting incident light to be measured from equipment to be calibrated to a trunk port of a coupler (11) in the optical return loss verification device, and receiving return light of the incident light to be measured from the trunk port of the coupler (11);
obtaining an optical return loss measurement value of the calibrated equipment based on the power of the incident light and the return light to be measured;
and calibrating the optical return loss measured value by using the optical return loss R with the magnitude traceability of the calibrating device.
The optical return loss calibrating device is simple in structure, can easily measure the optical return loss R value of the calibrating device based on the light source and the optical power meter, can simulate any variable optical return loss value suitable for measuring an optical time domain reflectometer or other instruments in a certain range, and can meet the metering calibration and calibration of the optical return loss parameters of the optical time domain reflectometer or other instruments. The uncertainty of the optical return loss reaches 0.7dB (including the factor k=2) as tested.
Drawings
FIG. 1 shows an optical return loss verification device and a corrected OTDR according to the present invention;
fig. 2 is an optical return loss measurement trace plot.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, the present invention provides an optical return loss verification device, which includes a coupler (11), an isolator (12), a variable optical attenuator (13) and an optical fiber (14) with a preset length;
the coupler (11) comprises a trunk port (110) for receiving light input, a first branch port (111) and a second branch port (112), wherein the first branch port (111) is connected with the input end of the isolator (12), the output end of the isolator (12) is connected with one end of the variable optical attenuator (13), and the other end of the variable optical attenuator (13) is connected with the second branch port (112) through an optical fiber (14) with a preset length;
the spectral ratio of the first branch and the second branch is 1: n.
In order to clearly show the trace of the optical fiber back Rayleigh scattering signal on the calibrated OTDR (2), and simultaneously simulate a larger range of optical return loss value, N is preferably more than or equal to 7 and less than or equal to 9.
Further, in order to completely display the trace of the optical fiber back-to-Rayleigh scattering signal except the initial saturation region on the calibrated OTDR, and reduce the attenuation introduced by the optical fiber link, the preset length is preferably more than or equal to 2km and less than or equal to 4km.
In fig. 1, the main path port (110) of the emission light input coupler (11) of the calibrated OTDR (2) is divided into two paths through the coupler (11), and the upper path is blocked at the isolator (12) after passing through the optical fiber (14) and the variable optical attenuator (13) and cannot return to the calibrated OTDR (1). The lower branch passes through an isolator (12), a variable optical attenuator (13) and an optical fiber (14), and then returns to the calibrated OTDR (2) through a coupler (11) to form an optical echo.
It should be noted that "2" in fig. 1 may be an OTDR to be calibrated, or may be another instrument capable of measuring an optical return loss parameter, which is not limited in the present invention.
The optical return loss measurement trace monitored by the OTDR is shown in fig. 2, and the flat part on the trace is the received light returned to the OTDR by the optical fiber back rayleigh scattering, and the part of the light undergoes a round trip, which is twice the length of the optical fiber, so that the OTDR, when calculating and drawing the trace, divides the total trip by 2 and displays the divided trace on the trace. Thus, when the coupler (11) down-branch light returns to the OTDR via the isolator (12), the variable optical attenuator (13) and the optical fiber (14, e.g., 3 km) to form an optical echo, a reflection peak is formed at the middle position (about 1.5 km) of the trace, and the OTDR automatically measures the optical return loss measurement value R of the reflection peak OTDR 。
Let the insertion loss of the first branch be IL 1 The insertion loss of the isolator is L s The attenuation of the variable optical attenuator is L a The insertion loss of the second branch is IL 2 The attenuation of the optical fiber link with preset length is L f ；
The optical return loss value r=il of the assay device 1 +L s +L a -IL 2 -L f 。
IL 1 、L s 、L a 、IL 2 、L f Both of which can be measured by a light source and an optical power meter. The R value of the verification device according to the invention can be used for calibrating the optical return loss parameter R of the optical time domain reflectometer OTDR 。
Specific description is given below:
in calculating the optical return loss R value of the present application using insertion loss and attenuation, consider first that the losses experienced by the optical transmission of the upper arm of the coupler to the end of the fiber include: second branch on couplerInsertion loss IL 2 Fiber link attenuation L f ，IL 2 And L f The light source and the optical power meter can be used for measurement, and the magnitude can be traced to the national standard of optical power. So that the optical power of the injected light when the upper branch light of the coupler is transmitted to the tail end of the optical fiber is
P in ＝P OTDR –IL 2 -L f (1)
Wherein: p (P) in The unit is dBm for the injection optical power when the light of the upper branch of the coupler is transmitted to the tail end of the optical fiber; p (P) OTDR The initial power of the light emitted by the OTDR is dBm; IL (IL) 2 The unit is dB for the insertion loss of the second branch on the coupler; l (L) f Is the fiber link attenuation in dB.
In addition, the losses experienced by the coupler down-leg light as it propagates to the end of the fiber include: first leg insertion loss IL on coupler 1 Insertion loss L of optical isolator s Attenuation L introduced by variable optical attenuator a ，IL 1 、L s And L a The light source and the optical power meter can be used for measurement, and the magnitude can be traced to the national standard of optical power. So that the power of the echo light when the light of the lower branch of the coupler is transmitted to the tail end of the optical fiber is
P R ＝P OTDR –IL 1 -L s -L a (2)
Wherein: p (P) R The unit is dBm for the echo optical power when the coupler down-branch light is transmitted to the tail end of the optical fiber; IL (IL) 1 The unit is dB of the insertion loss of the first branch on the coupler; l (L) s The insertion loss of the optical isolator is expressed in dB; l (L) a Attenuation introduced for a variable optical attenuator is in dB.
Finally, subtracting the echo optical power from the injection optical power at the tail end of the optical fiber to obtain an optical return loss R value of the calibrating device, wherein the R value is expressed by a formula (3):
R＝IL 1 +L s +L a -IL 2 -L f (3)
when in calibration, the optical return loss measured value R obtained by the measurement of the calibrated OTDR (2) OTDR Reducing the R value to obtain lightReturn loss indication error. From equation (3), the dynamic range of R and L a The dynamic change ranges of the variable optical attenuator are the same, different optical return loss reference values can be obtained by adjusting the attenuation value of the variable optical attenuator, namely, the calibration of the optical return loss indication value errors of different gears is realized, and the height of the reflection peak in fig. 2 also shows the situation when different optical return loss reference values are obtained by adjusting the attenuation value of the variable optical attenuator.
The invention also includes a method for detecting the optical return loss, which comprises the following steps;
inputting incident light to be measured from equipment (2) to be calibrated to a trunk port of a coupler (11) in the optical return loss verification device, and receiving return light of the incident light to be measured from the trunk port of the coupler (11);
obtaining an optical return loss measurement value of the calibrated equipment based on the power of the incident light and the return light to be measured;
and calibrating the optical return loss measured value by using the optical return loss R with the magnitude traceability of the calibrating device.
The calibrating device and the calibrating method can simulate any variable optical return loss value suitable for optical time domain reflectometer measurement in a certain range, and can meet the metering calibration and calibration of optical return loss parameters of the optical time domain reflectometer. The uncertainty of the optical return loss reaches 0.7dB (including the factor k=2) as tested.
The technical advantages of the verification device of the invention are as follows: the simulated reflection peak of the optical return loss is only displayed on the measuring trace of the optical time domain reflectometer, and the repeatability and the stability are good.
The foregoing description of the preferred embodiments of the present invention should not be construed as limiting the scope of the invention, but rather as covering any modification, equivalent replacement, improvement or the like which comes within the spirit and principles of the technical solution of the present invention.
Claims (3)
1. A method of calibrating optical return loss, the method comprising;
inputting incident light to be detected from equipment (2) to be detected into a trunk port of a coupler (11) in an optical return loss verification device, and receiving return light of the incident light to be detected from the trunk port of the coupler (11);
obtaining an optical return loss measurement value of the calibrated equipment based on the power of the incident light to be measured and the power of the return light;
calibrating the optical return loss measurement value by using the optical return loss R with magnitude tracing of the calibrating device;
the calibrating device for the optical return loss comprises a coupler (11), an isolator (12), a variable optical attenuator (13) and an optical fiber (14) with a preset length;
the coupler (11) comprises a trunk port (110) for receiving optical input, a first branch port (111) and a second branch port (112), wherein the first branch port (111) is connected with the input end of the isolator (12), the output end of the isolator (12) is connected with one end of the variable optical attenuator (13), and the other end of the variable optical attenuator (13) is connected with the second branch port (112) through an optical fiber (14) with a preset length; the spectral ratio of the first branch and the second branch is 1: n; let the insertion loss of the first branch be IL 1 The insertion loss of the isolator is L s The attenuation of the variable optical attenuator is L a The insertion loss of the second branch is IL 2 The attenuation of the optical fiber link with the preset length is L f The method comprises the steps of carrying out a first treatment on the surface of the The optical return loss of the assay device r=il 1 +L s +L a -IL 2 -L f The method comprises the steps of carrying out a first treatment on the surface of the By adjusting L a Different R values are obtained for the values of (a).
2. The assay of claim 1 wherein 7.ltoreq.N.ltoreq.9.
3. The assay of claim 1, wherein the predetermined length is 2km or less and 4km or less.
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| CN201810953479.9A CN109039442B (en) | 2018-08-21 | 2018-08-21 | Calibrating device and calibrating method for optical return loss |
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| CN109580186A (en) * | 2018-12-29 | 2019-04-05 | 苏州天步光电技术有限公司 | A kind of test method of 2-D optical fibre array |
| CN110686867B (en) * | 2019-10-30 | 2022-05-03 | 中国电子科技集团公司第四十一研究所 | Optical return loss calibration transfer device and method |
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| DE4013884A1 (en) * | 1990-04-30 | 1991-10-31 | Standard Elektrik Lorenz Ag | Fibre optic component reverse flow damping measurement appts. - has optical power divider splitting measurement light from reflectometer to measurement and reference branches |
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| EP1709414A1 (en) * | 2004-01-21 | 2006-10-11 | Agilent Technologies, Inc. | Determination of an optical property of a device under test (dut) by otdr measurement |
| KR20140051495A (en) * | 2012-10-12 | 2014-05-02 | 한국전자통신연구원 | Method for improving optical time domain reflectometer(otdr) performance |
| US8958060B2 (en) * | 2013-02-21 | 2015-02-17 | Verizon Patent And Licensing Inc. | Optical fiber mechanical bend stress test system with optical time-domain reflectometer |
| US20170272151A1 (en) * | 2016-03-17 | 2017-09-21 | Frank Giotto | Gigabit Ethernet Analyzer for Optical Time Domain Reflectometer |
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| US4883954A (en) * | 1987-07-02 | 1989-11-28 | Hildegard Esser | Method of measuring optical radiation energy reflected by a reflection area |
| DE4013884A1 (en) * | 1990-04-30 | 1991-10-31 | Standard Elektrik Lorenz Ag | Fibre optic component reverse flow damping measurement appts. - has optical power divider splitting measurement light from reflectometer to measurement and reference branches |
| US5673108A (en) * | 1995-03-31 | 1997-09-30 | Ando Electric Co., Ltd. | Light return loss measurement system and method |
| CN105553543A (en) * | 2015-12-24 | 2016-05-04 | 中国电子科技集团公司第四十一研究所 | Calibration device and method of coherent optical time domain reflectometer |
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