CN113375837B - Automatic measurement method and device for temperature coefficient of optical quantum BOTDR optical fiber - Google Patents
Automatic measurement method and device for temperature coefficient of optical quantum BOTDR optical fiber Download PDFInfo
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- CN113375837B CN113375837B CN202110656335.9A CN202110656335A CN113375837B CN 113375837 B CN113375837 B CN 113375837B CN 202110656335 A CN202110656335 A CN 202110656335A CN 113375837 B CN113375837 B CN 113375837B
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Abstract
The invention provides a method and a device for automatically measuring a temperature coefficient of a BOTDR optical fiber of a photon. The device includes: the direct detection type optical fiber temperature distribution tester, the constant temperature box and the computer are connected in sequence; a plurality of test light paths for placing sample optical fibers are arranged in the constant temperature box, and the environmental temperature of the sample optical fibers is simulated; the direct detection type optical fiber temperature distribution tester is used for measuring the distribution of backward elastic scattering light quantum power and Brillouin-Stokes component light quantum power of a sample optical fiber; the computer obtains a power ratio based on the backward elastic scattering light quantum power distribution data of the sample optical fiber and the backward Brillouin-Stokes component light quantum power distribution data of the sample optical fiber, and obtains the temperature calibration coefficients of the sample optical fibers of all channels based on the power ratio.
Description
Technical Field
The invention belongs to the field of optical fiber temperature measurement, and particularly relates to an automatic measurement method and device for a temperature coefficient of a BOTDR optical fiber with light quantum.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The direct detection type optical fiber temperature distribution tester (also called a light quantum Brillouin optical time domain reflectometer, called PB-OTDR for short) has been widely used in the fields of power cable temperature measurement monitoring, intelligent pipe gallery temperature monitoring, oil transportation and storage facility temperature monitoring, fire early warning and the like because of the characteristics of distributed continuity, long testing distance, high measuring precision, corrosion resistance, intrinsic safety, electromagnetic interference resistance, no need of frequency scanning, capability of forming a sensing network and the like, but in the using process of the PB-OTDR, whether the alarm threshold setting of the temperature detection and the fire early warning is accurate or not depends seriously on the accurate calibration of the optical fiber temperature coefficient.
The traditional detection modes of the spontaneous brillouin scattering signal carrying temperature information include direct detection and heterodyne detection. The direct detection generally adopts an optical filter with high resolution, such as a Fabry-Perot interferometer, a Mach-Zehnder interferometer and a high-resolution fiber Bragg grating, but the detection is difficult because the signal power is low and the Brillouin frequency shift is small; and the interferometer is easily influenced by the external environment, and the measurement precision is lower. In order to improve the signal-to-noise ratio and the measurement accuracy of the system, a heterodyne detection method is generally adopted to measure the spontaneous brillouin scattering signal. However, the heterodyne detection system has a relatively complex structure, and a brillouin gain spectrum is usually obtained by scanning the spectrum point by point, so that the time resolution of measurement is reduced, and tens of seconds to several minutes are usually required. Obviously, an optical fiber temperature distribution tester (BOTDR for short) operating in a swept-frequency mode needs to repeatedly construct a brillouin gain spectrum as a testing device to calculate a temperature coefficient of a sample optical fiber, and for sample optical fibers of different batches, different processes and different particle doping ratios, a calibration process of the temperature coefficient of the sample optical fiber is complicated, time-consuming, large in error and without universality due to factors such as large span of the brillouin gain spectrum frequency range, different numbers of brillouin gain peaks contained in the brillouin gain spectrum, and diversification of the brillouin gain spectrum types caused by mutual coupling among multiple acoustic wave fields.
At present, the calibration of the temperature coefficients of sample optical fibers of different batches, different processes and different particle doping ratios in a PB-OTDR system mainly depends on manual calibration, and the calibration of the temperature length of the sample optical fibers is realized by manually analyzing backward elastic scattered light power distribution traces and backward Brillouin scattered light power distribution traces of the sample optical fibers, wherein the calibration accuracy of the coefficients can be influenced due to more subjective factors in manual analysis; moreover, the calibration efficiency of the manual temperature coefficient is very low, so that the requirements of the PB-OTDR in the production and use processes are difficult to meet; meanwhile, manual stability factor calibration also causes labor cost increase.
Disclosure of Invention
The invention provides a method and a device for automatically measuring the temperature coefficient of a BOTDR optical fiber, which aim to solve the problems, and automatically test optical fibers with different batches, different processes and different particle doping ratios, and automatically analyze backward scattering light quantum power distribution data obtained by testing, so that sample optical fiber temperature distribution data is obtained, and the accurate test of the temperature coefficient of the optical fiber is realized.
According to some embodiments, the invention adopts the following technical scheme:
in a first aspect, the invention provides an automatic temperature coefficient measuring device for a BOTDR optical fiber with optical quantum.
An automatic measuring device for temperature coefficient of a BOTDR optical fiber of light quantum comprises: the direct detection type optical fiber temperature distribution tester, the constant temperature box and the computer are sequentially connected;
a plurality of test light paths for placing sample optical fibers are arranged in the constant temperature box, and the environmental temperature of the sample optical fibers is simulated;
the direct detection type optical fiber temperature distribution tester is used for measuring the distribution of backward elastic scattering light quantum power and Brillouin-Stokes component light quantum power of a sample optical fiber;
the computer obtains a power ratio based on the backward elastic scattering light quantum power distribution data of the sample optical fiber and the backward Brillouin-Stokes component light quantum power distribution data of the sample optical fiber, and obtains the temperature calibration coefficients of the sample optical fibers of all channels based on the power ratio.
Further, the direct probing type optical fiber temperature distribution tester includes: the optical isolator comprises a first laser light source, a second laser light source, a first optical switch connected with the first laser light source and the second laser light source, a multi-form pulse modulator connected with the first optical switch, an optical isolator connected with the multi-form pulse modulator, a polarization scrambler connected with the optical isolator, a circulator connected with the polarization scrambler, a second optical switch and a third optical switch connected with the circulator, a control processor, a programmable attenuator and a cascade filter connected with the third optical switch, a control processor and a fourth optical switch connected with the programmable attenuator, wherein the fourth optical switch is respectively connected with a power receiving end, the cascade attenuator and the control processor, the power receiving end is connected with the control processor, and the second optical switch is respectively connected with the control processor and a thermostat.
Further, the first laser light source outputs a broadband spontaneous amplified radiation laser light source which is used for measuring the distribution of the backward elastic scattered light quantum power of the sample optical fiber;
and the second laser light source outputs a high-coherence laser light source which is used for measuring the distribution of the quantum power of the backward Brillouin-Stokes component light of the sample optical fiber.
Further, the first light switch is controlled by a computer and used for switching output channels of the first laser light source and the second laser light source;
the second optical switch is used for switching the optical path of the optical fiber of the tested sample;
the third optical switch is used for switching an echo receiving channel of the backward scattering light quantum;
and the fourth optical switch is used for switching an echo receiving channel of the backward scattering light quantum.
Further, the multi-form pulse modulator is used for modulating and generating different form detection pulses;
the optical isolator is used for inhibiting the backscattering signal from damaging the laser;
the polarization scrambler is used for eliminating polarization noise;
the circulator is used for transmitting and collecting optical signals.
Further, the programmable attenuator is used for switching attenuation gears to realize unsaturated detection of a power receiving end;
the cascade filter is used for high rejection ratio extraction of the backscattering Brillouin-Stokes light quantum signals;
the power receiving end is used for receiving the backward scattering light quantum signals and converting the electric pulses.
Further, the control processor is controlled by a computer and is configured to distribute initialization of instructions of the first optical switch, the second optical switch, the third optical switch, and the fourth optical switch, switching of a test channel, and a recording control signal of the number of channels, a driving control signal of the multi-modal pulse modulator, a control signal of an attenuation gear of the programmable attenuator, a power receiving end synchronously triggering a receiving signal, and returning initial state and current configuration information of the first optical switch, the second optical switch, the third optical switch, the fourth optical switch, the multi-modal pulse modulator, and the programmable attenuator, and light quantum power distribution data collected by the power receiving end.
In a second aspect, the invention provides a method for automatically measuring the temperature coefficient of a BOTDR optical fiber of a light quantum.
A method for automatically measuring the temperature coefficient of a BOTDR optical fiber with light quantum comprises the following steps:
after the automatic measuring device for the temperature coefficient of the BOTDR optical fiber of the light quantum in the first aspect finishes the light quantum power test, reading an elastic scattering light quantum power data point number RN, a Brillouin-Stokes backscattering light quantum power data point number BN, an elastic scattering light quantum distance data point number DN _ R, a Brillouin-Stokes backscattering light quantum distance data point number DN _ B, a simulation temperature data point number TN, elastic scattering sample optical fiber link distance data RMT [ OSC ] [ 1-DN _ R ], Brillouin-Stokes scattering sample optical fiber link distance data BMT [ OSC ] [ 1-DN _ B ], original elastic scattering light quantum power distribution data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ], and original Brillouin-Stokes backscattering light quantum power distribution data BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ];
analyzing RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the tail end PTE _ R [ OSC ] of the sample optical fiber elastic scattering light quantum power distribution curve as TE _ R;
analyzing the RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the attenuation ratio required by the test result of the fiber elastic scattering light quantum power distribution undistorted curve of the sample;
analyzing the data of distributed RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ] and BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ] [ 1-TN ] read by the computer to obtain a power ratio RSR [ OSC ] [ 1-TN ] and a sample optical fiber temperature coefficient STC [ OSC ];
and outputting the sample optical fiber temperature calibration coefficient STC [ OSC ] of all the channels until the measurement of all the channels is completed.
Compared with the prior art, the invention has the beneficial effects that:
the invention adopts a direct detection type optical fiber temperature distribution tester (PB-OTDR for short) as a test device to automatically test optical fibers of different batches, different processes and different particle doping ratios, and automatically analyzes the backward scattering light quantum power distribution data obtained by the test, thereby obtaining the sample optical fiber temperature distribution data and realizing the accurate test of the optical fiber temperature coefficient.
The automatic measurement method and the device provided by the invention realize the automatic analysis of the temperature coefficient of the sample optical fiber by deeply analyzing the backward spontaneous Brillouin-Stokes and Rayleigh component scattered light quantum power test data based on the characteristic that the backward Rayleigh scattered light quantum power of the sample optical fiber is insensitive to the temperature fluctuation of the surrounding environment, realize the accurate measurement of the distributed temperature of the PB-OTDR access optical fiber link on the basis of the automatic analysis, solve the problem that the traditional method depends on the inaccurate measurement result of the temperature of the optical fiber sensing link caused by the low calibration efficiency of the manual temperature coefficient and the easy influence of the subjective factor of human beings, realize the high-efficiency and high-accuracy automatic test of the temperature coefficient of the sampling optical fiber, and provide an advanced means for the comprehensive distributed test of the high-accuracy temperature distribution data in the fields of the surface temperature of a power cable, the temperature of a cable dense area, the temperature of a fire alarm system, the temperature of a steam pipeline, the temperature of an oil pipeline and the like, meanwhile, the application range of the direct detection type optical fiber temperature distribution tester is further expanded, application scenes are added for the PB-OTDR, and the rapid development of the industry of the direct detection type optical fiber temperature distribution tester is promoted.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of an automatic temperature coefficient measuring device for a BOTDR optical fiber of light quantum in accordance with the present invention;
FIG. 2 is a structural diagram of an automatic temperature coefficient measuring device for a BOTDR optical fiber of light quantum in accordance with the present invention;
FIG. 3 is a flow chart of the method for automatically measuring the temperature coefficient of the BOTDR optical fiber of the light quantum of the present invention;
FIG. 4 is a flow chart of a method for analyzing the positioning of the end of an elastic scattering link fiber according to the present invention;
FIG. 5 is a flowchart of the programmed attenuator attenuation step calculation of the present invention;
fig. 6 is a flow chart of the calculation of the temperature coefficient of the optical fiber based on the elastic scattering distribution data and the brillouin-stokes distribution data according to the present invention.
The specific implementation mode is as follows:
the invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present invention, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be determined according to specific situations by persons skilled in the relevant scientific or technical field, and are not to be construed as limiting the present invention.
At present, in a traditional BOTDR system, calibration of temperature coefficients of sample optical fibers of different batches, different processes and different particle doping ratios requires repeated construction of a brillouin gain spectrum to calculate the temperature coefficient of the sample optical fiber, and for the sample optical fibers of different batches, different processes and different particle doping ratios, the calibration process of the temperature coefficient of the sample optical fiber is complicated, time-consuming, large in error and free of universality due to factors such as large frequency range span of the brillouin gain spectrum, different numbers of brillouin gain peaks contained in the brillouin gain spectrum, and diversification of brillouin gain spectrum types caused by mutual coupling among multiple acoustic wave fields.
In view of the above problems, the present invention provides the following embodiments:
example one
The embodiment provides an automatic measuring device for temperature coefficient of a BOTDR optical fiber of light quantum.
An automatic measuring device for temperature coefficient of a BOTDR optical fiber of light quantum comprises: the direct detection type optical fiber temperature distribution tester, the constant temperature box and the computer are sequentially connected;
a plurality of test light paths for placing sample optical fibers are arranged in the constant temperature box, and the environmental temperature of the sample optical fibers is simulated;
the direct detection type optical fiber temperature distribution tester is used for measuring the distribution of backward elastic scattering light quantum power and Brillouin-Stokes component light quantum power of a sample optical fiber;
the computer obtains a power ratio based on the backward elastic scattering light quantum power distribution data of the sample optical fiber and the backward Brillouin-Stokes component light quantum power distribution data of the sample optical fiber, and obtains the temperature calibration coefficients of the sample optical fibers of all channels based on the power ratio.
Specifically, the present invention uses a direct detection type optical fiber temperature distribution tester (PB-OTDR for short) as a testing device to automatically test optical fibers of different batches, different processes and different particle doping ratios, and automatically analyze the backscattered light quantum power distribution data obtained by the test, so as to obtain the sample optical fiber temperature distribution data, and implement accurate testing of the optical fiber temperature coefficient, and a typical apparatus schematic diagram is shown in fig. 1, and the components are as follows:
(1) the direct detection type optical fiber temperature distribution tester mainly comprises laser devices (101, 102), optical switches (103, 108, 109, 112), a multi-form pulse modulator (104), an optical isolator (105), a polarization scrambler (106), a circulator (107), a programmable attenuator (110), a cascade filter (111), a power receiving end (113) and the like, and is shown in detail in figure 2.
(2) The high-precision incubator is used for simulating the environmental temperature of the sample optical fiber, and the typical temperature regulation precision is +/-1 ℃.
(3) And the sample optical fiber testing optical path is used for accessing the sample optical fiber.
(4) The control computer provides control signals such as initialization of instructions of an optical switch (103), an optical switch (108), an optical switch (109) and an optical switch (112), switching of a test channel and recording of the number of channels in the direct detection type optical fiber temperature distribution tester (1), a driving control signal of a multi-form pulse modulator (104), a control signal of an attenuation gear of a programmable attenuator (110), a power receiving end (113) synchronously triggers a receiving signal and a temperature regulation and control signal of a high-precision incubator (2), receives and processes information such as test device configuration information and optical quantum power distribution data read in the direct detection type optical fiber temperature distribution tester (1) and feedback information such as the running state and the temperature value of the high-precision incubator (2).
The typical embodiment of the present invention is shown in fig. 2, and a direct detection type optical fiber temperature distribution tester (optical quantum brillouin optical time domain reflectometer, PB-OTDR for short) is used as a test device to automatically test optical fibers of different batches, different processes and different particle doping ratios, and automatically analyze the backscattered light quantum power distribution data obtained by the test, so as to obtain sample optical fiber temperature distribution data, and realize accurate test of an optical fiber temperature coefficient, and specifically comprises the following components:
(101) the laser light source is typically a broadband spontaneous amplification radiation laser light source, the typical value of the output power is 50mW, the typical value of the flatness of the output spectrum is less than or equal to 1dB, and the laser light source is used for measuring the distribution of the backward elastic scattered light quantum power of a sample optical fiber.
(102) The laser light source is typically a high-coherence laser light source, the typical value of the line width of the light source is less than 1kHz, the typical value of the output power is 30mW, and the method is used for measuring the distribution of the quantum power of the backward Brillouin-Stokes component light of the sample optical fiber.
(103) The optical switch, 1 x 2 optical switch, is controlled by the control computer (4), switches the output channels of the laser light source (101) and the laser light source (102).
(104) The multi-form pulse modulator is generally an electro-optical modulator, an acousto-optical modulator and a gain optical switch, is typically an acousto-optical modulator with a high extinction ratio, has an extinction ratio typical value larger than 50dB, and is used for modulating and generating detection pulses with different forms.
(105) And the optical isolator is used for inhibiting the damage of the backscattering signal to the laser, and the typical value of the isolation degree is more than or equal to 30 dB.
(106) And the polarization scrambler is used for eliminating polarization noise.
(107) And a circulator for transmitting and collecting the optical signal.
(108) The optical switch, 1 XN optical switch, is controlled by control computer (4), switches over the sample optic fibre light path of being surveyed, and the general value of N is 2 ~ 32.
(109) The optical switch, 1 x 2 optical switch, is controlled by the control computer (4), switches the echo receiving channel of the back scattering light quantum.
(110) And the programmable attenuator is controlled by the control computer (4) and is used for realizing the unsaturated detection of the power receiving end (113) by switching the attenuation gear.
(111) And the cascade filter is used for high rejection ratio extraction of the backscattering Brillouin-Stokes light quantum signal, and the typical rejection ratio is higher than 25 dB.
(112) The optical switch, 1 x 2 optical switch, is controlled by the control computer (4), switches the echo receiving channel of the back scattering light quantum.
(113) And the power receiving end is used for receiving the backscattered light quantum signals and converting electric pulses, and the typical quantum conversion efficiency value is 10%.
(114) And the control processor is controlled by a control computer (4) and distributes control signals such as initialization of instructions of the optical switch (103), the optical switch (108), the optical switch (109) and the optical switch (112), switching of test channels and recording of the number of channels, a driving control signal of the polymorphic pulse modulator (104), a control signal of an attenuation gear of the programmable attenuator (110), a power receiving end (113) synchronously triggers a receiving signal and returns initial state and current configuration information of the optical switch (103), the optical switch (108), the optical switch (109), the optical switch (112), the polymorphic pulse modulator (104) and the programmable attenuator (110) and optical quantum power distribution data collected by the power receiving end (113).
Example two
As shown in FIG. 3, the present embodiment provides an automatic measurement method for temperature coefficient of BOTDR optical fiber.
The method adopts a direct detection type optical fiber temperature distribution tester (optical quantum Brillouin optical time domain reflectometer, PB-OTDR for short) as test equipment, automatically tests optical fibers of different batches, different processes and different particle doping ratios, and automatically analyzes backward scattering light quantum power distribution data obtained by the test, thereby obtaining sample optical fiber temperature distribution data and realizing accurate test of optical fiber temperature coefficients, and the specific steps are as follows:
step 101: the control computer (4) remotely controls the start of the direct detection type optical fiber temperature distribution tester (1) and then turns to the step 102;
step 102: the control computer (4) reads the channel positions CP [ 1-2 ] of the optical switch (103), the optical switch (109) and the optical switch (112) in the direct detection type optical fiber temperature distribution tester (1), the number N of the optical switch channels of the optical switch (108), the attenuation gear of the programmable attenuator (110) and other initial state parameters, and then the step 103 is carried out;
step 103: prompting a user to check the access condition of the sample optical fiber, remotely controlling and starting the high-precision incubator (2) by the control computer (4), and turning to the step 104;
step 104: the control computer (4) reads initial state parameters such as the temperature value of the high-precision incubator (2) and the like, and then the step 105 is carried out;
step 105: inputting the length FL [ 1-N ] of each channel sample optical fiber and the analog temperature ST by a user, setting a spatial resolution parameter SR to be 1m, setting a sampling resolution SAR to be 0.1m, and turning to the step 106, wherein the test range ML is the length FL [ 1-N ] +100m of the sample optical fiber;
step 106: initializing the optical switch (108) and turning to step 107, where the current channel count variable OSC is 1;
step 107: the control computer (4) remotely controls the optical switch (108) to switch to the OSC channel, and then the step 108 is carried out;
step 108: remotely starting the optical switch (103), the optical switch (109) and the optical switch (112) by the control computer (4) at a channel position CP [1], respectively setting the channel number of the optical switch (108) at OSCs [ 1-N ], measuring the distributed elastic scattered light quantum power of the N links under the condition of setting the simulation temperature as ST, recording data, and turning to the step 109;
step 109: the control computer (4) remotely starts the optical switch (103), the optical switch (109) and the optical switch (112) to be arranged at a channel position CP [2], the channel numbers of the optical switch (108) are respectively arranged at OSCs [ 1-N ], the simulation temperature is set as distributed Brillouin-Stokes backscattered light quantum power measurement of N links under the ST condition, data is recorded, and the operation is switched to the step 110;
step 110: after the PB-OTDR optical fiber temperature coefficient automatic measuring device finishes the optical quantum power test, the control computer (4) reads an elastic scattering optical quantum power data point RN, a Brillouin-Stokes backscattering optical quantum power data point BN, an elastic scattering optical quantum distance data point DN _ R, a Brillouin-Stokes backscattering optical quantum distance data point DN _ B, a simulation temperature data point TN, elastic scattering sample optical fiber link distance data RMT [ OSC ] [ 1-DN _ R ], Brillouin-Stokes scattering sample optical fiber link distance data BMT [ OSC ] [ 1-DN _ B ], original elastic scattering optical quantum power distribution data RP [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ], original Brillouin-Stokes scattering optical quantum power distribution data BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ], go to step 111;
step 111: analyzing RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the end PTE _ R [ OSC ] of the sample optical fiber elastic scattered light quantum power distribution curve as TE _ R, wherein the specific steps are shown in step 201;
step 112: analyzing RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the attenuation ratio required by the test result of the fiber elastically scattered light quantum power distribution undistorted curve of the sample, and the specific steps are shown in step 301;
step 113: analyzing the distributed RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ] and BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ] [ 1-TN ] data read by the control computer (4) to obtain a power ratio RSR [ OSC ] [ 1-TN ] and a sample optical fiber temperature coefficient STC [ OSC ], turning to step 114 in step 401;
step 114: judging whether OSC is more than or equal to N, if so, turning to step 116, otherwise, turning to step 115;
step 115: assigning OSC to OSC +1, proceeding to step 107;
step 116: and outputting the temperature calibration coefficient STC [ OSC ] of the sample optical fiber of all channels, and finishing.
In this embodiment, a flow of the method for analyzing and positioning the end of the elastic scattering link optical fiber is shown in fig. 4, and a distribution trace end TE _ R is obtained by performing fast analysis on original elastic scattering light quantum power distribution data, and the specific steps are as follows:
step 201: reading original elastic scattering distribution data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1], a spatial resolution SR and a sampling resolution SAR, and turning to step 202;
step 202: cutting a signal with delt _ L length forward from the tail end RPDATA [ OSC ] [ DN _ R-100/SAR ] [ RN-100/SAR ] of the original elastic scattering power distribution test data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1], wherein the delt _ L is k SAR, the typical value of k is 1000, and turning to step 203;
step 203: roughly dividing the intercepted delt _ L signal into n sections at an interval delt _ T, and turning to the step 204;
step 204: calculating a difference value delt _ d [ i ] between a starting point and an end point from the first section, wherein i is 1-n, calculating section by section, if the difference value of the mth section (m is less than or equal to n) is delt _ d [ m ], delt _ d [ m ] -AVE (delt _ d [ 1- (m-1) ]) is greater than the optical fiber end judgment threshold Thr, stopping the operation, and turning to the step 205;
step 205: integrating the m-1 th segment and the m-th segment into one segment, expanding the data points into 2 × delt _ T, and turning to the step 206;
step 206: calculating the light quantum power distribution data P (x) of each point in the integrated data with the length of 2 × delt _ T point by point, calculating P (x) -P (x + SAR), converting the original distribution data into differential distribution data RPDATA _ DF, and turning to step 207;
step 207: finding a maximum value DF _ Max of the differential distribution data, and turning to the step 208;
step 208: the output distribution trace terminal PTE _ R [ OSC ].
In this embodiment, the original elastic scattering scattered light quantum power distribution data is subjected to automatic analysis of a saturation distortion curve and retest processing is started, a calculation flow of attenuation gears of the programmable attenuator is shown in fig. 5, and the specific steps are as follows:
step 301: reading original elastic scattering distribution data RPDATA [ OSC ] [ (1+100 × SAR) -DN _ R ] [ 1-RN ] [1], spatial resolution SR and sampling resolution SAR, and turning to step 302;
step 302: finding out the maximum value RPMAX [ OSC ] of the light quantum power as RMA, and turning to step 303;
step 303: locating the point POS at which the first of the signals is the maximum value RMA, and going to step 304;
step 304: taking POS as a starting point, searching a point POS _ O with a first value not being RMA, and going to step 305;
step 305: calculating the corresponding optical fiber length FL _1 between the POS point and the POS _ O point, and turning to step 306;
step 306: judging whether FL _1 > THR _1(THR _1 ═ 20 × SAR) is true, if true, turning to step 307, and if false, turning to step 308;
step 307: the control computer (4) increases the attenuation ratio set value of the programmable attenuator (110) by 1 gear, and then the step 108 is carried out;
step 308: if the test data is normal, go to step 114.
In this embodiment, a calculation flow for further analyzing the original elastic scattering distribution data and the original brillouin-stokes backscattering distribution data to obtain an optical fiber temperature coefficient is shown in fig. 6, and the specific steps are as follows:
step 401: reading original elastic scattering distribution test data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ], original Brillouin-Stokes backscattering distribution data BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ] [ 1-TN ], and turning to step 402;
step 402: calculating a ratio RSR [ OSC ] [ 1-TN ] of the elastic scattering distribution test data and the Brillouin-Stokes backscattering distribution data under the conditions of the temperatures ST [ I ] ═ T0+ I5 and I [ 1-TN ], and turning to step 403;
step 403: calculating the average value RSR _ AVE [ 1-TN ] of the power ratio RSR [ OSC ] [ 1-TN ], and turning to step 404;
step 404: judging whether I is greater than or equal to TN, if so, turning to step 406, otherwise, turning to step 405;
step 405: assigning I to be I +1, and turning to step 402;
step 406: outputting the calculated RSR _ AVE [ 1-TN ] under each temperature condition, and turning to step 407;
step 407: calculating the temperature change amount delt _ ST and the light quantum power conversion rate delt _ RSR by taking ST [1] as a reference temperature and RSR _ AVE [1] as a reference light quantum power ratio, and turning to step 408;
step 408: calculating the fiber temperature calibration coefficient STC [ OSC ] according to the ratio of delt _ RSR/delt _ ST, and turning to the step 409;
step 409: outputting STC [ OSC ].
The invention solves the problems that the traditional sweep BOTDR testing technology needs to repeatedly construct the Brillouin gain spectrum to calculate the temperature coefficient of the sample optical fiber, and for sample optical fibers of different batches, different processes and different particle doping ratios, the calibration process of the temperature coefficient of the sample optical fiber is complicated, time-consuming, large in error and free of universality due to factors such as large frequency range span of the Brillouin gain spectrum, different numbers of Brillouin gain peaks contained in the Brillouin gain spectrum, diversification of the Brillouin gain spectrum type caused by mutual coupling among multiple acoustic wave fields and the like; the calibration accuracy of the temperature coefficient in the PB-OTDR system is improved, the efficiency is improved, and the labor cost is reduced; the application range of the direct detection type optical fiber temperature distribution tester is further expanded, and application scenes are added for the PB-OTDR.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (9)
1. An automatic measuring device for temperature coefficient of a BOTDR optical fiber of light quantum is characterized by comprising: the direct detection type optical fiber temperature distribution tester, the constant temperature box and the computer are sequentially connected;
a plurality of test light paths for placing sample optical fibers are arranged in the constant temperature box, and the environmental temperature of the sample optical fibers is simulated;
the direct detection type optical fiber temperature distribution tester is used for measuring the distribution of backward elastic scattering light quantum power and Brillouin-Stokes component light quantum power of a sample optical fiber;
the computer obtains a power ratio based on the backward elastic scattering light quantum power distribution data of the sample optical fiber and the backward Brillouin-Stokes component light quantum power distribution data of the sample optical fiber, and obtains the temperature calibration coefficients of the sample optical fibers of all channels based on the power ratio;
the direct detection type optical fiber temperature distribution tester includes: the optical isolator comprises a first laser light source, a second laser light source, a first optical switch connected with the first laser light source and the second laser light source, a multi-form pulse modulator connected with the first optical switch, an optical isolator connected with the multi-form pulse modulator, a polarization scrambler connected with the optical isolator, a circulator connected with the polarization scrambler, a second optical switch and a third optical switch connected with the circulator, a control processor, a programmable attenuator and a cascade filter connected with the third optical switch, a control processor and a fourth optical switch connected with the programmable attenuator, wherein the fourth optical switch is respectively connected with a power receiving end, the cascade attenuator and the control processor, the power receiving end is connected with the control processor, and the second optical switch is respectively connected with the control processor and a thermostat.
2. The automatic temperature coefficient measuring device of the BOTDR optical fiber with the optical quantum according to claim 1, wherein the first laser light source outputs a broadband self-amplifying radiation laser light source for distribution measurement of backward elastic scattered light quantum power of the sample optical fiber;
and the second laser light source outputs a high-coherence laser light source which is used for measuring the distribution of the quantum power of the backward Brillouin-Stokes component light of the sample optical fiber.
3. The automatic temperature coefficient measuring device of a photon BOTDR optical fiber according to claim 1, characterized in that the first optical switch is controlled by a computer for switching the output channels of the first laser light source and the second laser light source;
the second optical switch is used for switching the optical path of the optical fiber of the tested sample;
the third optical switch is used for switching a first echo receiving channel of the backward scattering light quantum;
the fourth optical switch is used for switching a second echo receiving channel of the backward scattering light quantum.
4. The apparatus of claim 1, wherein the multi-mode pulse modulator is used for modulation and generation of different detection pulses;
the optical isolator is used for inhibiting the backscattering signal from damaging the laser;
the polarization scrambler is used for eliminating polarization noise;
the circulator is used for transmitting and collecting optical signals.
5. The automatic measurement device for the temperature coefficient of a photon BOTDR optical fiber according to claim 1, characterized in that the programmable attenuator is used for switching attenuation gears to realize the unsaturated detection of a power receiving end;
the cascade filter is used for extracting the high rejection ratio of the backward scattering Brillouin-Stokes optical quantum signal;
the power receiving end is used for receiving the backward scattering light quantum signals and converting the electric pulses.
6. The apparatus according to claim 1, wherein the control processor is controlled by a computer and configured to distribute initialization of the first optical switch, the second optical switch, the third optical switch, and the fourth optical switch, switching of the test channels, and recording control signals of the number of channels, driving control signals of the multi-modal pulse modulator, control signals of the attenuation stage of the programmable attenuator, and synchronously triggering and receiving signals at the power receiving end, so as to return the initial state and current configuration information of the first optical switch, the second optical switch, the third optical switch, and the fourth optical switch, the multi-modal pulse modulator, and the programmable attenuator, and the optical quantum power distribution data collected by the power receiving end.
7. A method for automatically measuring the temperature coefficient of a BOTDR optical fiber of a light quantum is characterized by comprising the following steps:
after the automatic temperature coefficient measuring device of the optical quantum BOTDR optical fiber of any claim 1-6 completes the optical quantum power test, reading an elastic scattering light quantum power data point number RN, a Brillouin-Stokes backscattering light quantum power data point number BN, an elastic scattering light quantum distance data point number DN _ R, a Brillouin-Stokes backscattering light quantum distance data point number DN _ B, a simulation temperature data point number TN, elastic scattering sample optical fiber link distance data RMT [ OSC ] [ 1-DN _ R ], Brillouin-Stokes scattering sample optical fiber link distance data BMT [ OSC ] [ 1-DN _ B ], original elastic scattering light quantum power distribution data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ], and original Brillouin-Stokes backscattering light quantum power distribution data BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ];
analyzing RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the tail end PTE _ R [ OSC ] of the sample optical fiber elastic scattering light quantum power distribution curve as TE _ R;
analyzing the RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1] to obtain the attenuation ratio required by the test result of the fiber elastic scattering light quantum power distribution undistorted curve of the sample;
analyzing the data of distributed RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ] and BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ] [ 1-TN ] read by the computer to obtain a power ratio RSR [ OSC ] [ 1-TN ] and a sample optical fiber temperature coefficient STC [ OSC ];
and outputting the sample optical fiber temperature calibration coefficient STC [ OSC ] of all the channels until the measurement of all the channels is completed.
8. The method for automatically measuring the temperature coefficient of the BOTDR optical fiber based on the optical quantum, as claimed in claim 7, wherein the obtaining of the PTE _ R [ OSC ] ═ TE _ R at the end of the elastic scattered optical quantum power distribution curve of the sample optical fiber comprises:
reading original elastic scattering distribution data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1], a spatial resolution SR and a sampling resolution SAR;
intercepting a signal with delt _ L length from the tail end RPDATA [ OSC ] [ DN _ R-100/SAR ] [ RN-100/SAR ] of original elastic scattering power distribution test data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [1], wherein the delt _ L is k SAR, and the typical value of k is 1000;
roughly dividing the intercepted delt _ L signal into n sections at an interval delt _ T;
calculating a difference value delt _ d [ i ] between a starting point and an end point from a first section, wherein i is 1-n, calculating section by section, and stopping operation if the difference value of an mth section (m is less than or equal to n) is delt _ d [ m ], delt _ d [ m ] -AVE (delt _ d [ 1- (m-1) ]) is greater than an optical fiber end judgment threshold Thr;
integrating the m-1 th segment and the m-th segment into one segment, and expanding the data points into 2 × delt _ T;
calculating P (x) -P (x + SAR) point by point for each point of light quantum power distribution data P (x) in the integrated data with the length of 2 × delt _ T, and converting the original distribution data into differential distribution data RPDATA _ DF;
searching a maximum value DF _ Max of the differential distribution data;
the output distribution trace terminal PTE _ R [ OSC ].
9. The method of claim 7, wherein the power ratio RSR [ OSC ] [ 1-TN ], and the sample fiber temperature coefficient STC [ OSC ] are obtained by:
step 401: reading original elastic scattering distribution test data RPDATA [ OSC ] [ 1-DN _ R ] [ 1-RN ] [ 1-TN ], original Brillouin-Stokes backscattering distribution data BSPDATA [ OSC ] [ 1-DN _ B ] [ 1-BN ] [ 1-TN ], and turning to step 402;
step 402: calculating a ratio RSR [ OSC ] [ 1-TN ] of the elastic scattering distribution test data and the Brillouin-Stokes backscattering distribution data under the conditions of the temperatures ST [ I ] ═ T0+ I5 and I [ 1-TN ], and turning to step 403;
step 403: calculating the average value RSR _ AVE [ 1-TN ] of the power ratio RSR [ OSC ] [ 1-TN ], and turning to step 404;
step 404: judging whether I is greater than or equal to TN, if so, turning to step 406, otherwise, turning to step 405;
step 405: assigning I to be I +1, and turning to step 402;
step 406: outputting the calculated RSR _ AVE [ 1-TN ] under each temperature condition, and turning to step 407;
step 407: calculating the temperature change amount delt _ ST and the light quantum power conversion rate delt _ RSR by taking ST [1] as a reference temperature and RSR _ AVE [1] as a reference light quantum power ratio, and turning to step 408;
step 408: calculating the fiber temperature calibration coefficient STC [ OSC ] according to the ratio of delt _ RSR/delt _ ST, and turning to the step 409;
step 409: outputting STC [ OSC ].
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