A long-distance distributed optical fiber performance rapid detection device and method based on distributed amplification and optical chirp chain

Abstract

The application discloses a long-distance distributed optical fiber performance rapid detection device and method based on distributed amplification and optical chirp chain and relates to the technical field of optical fiber performance detection. The device comprises a BOTDA data acquisition module and a data processing module. The BOTDA data acquisition module comprises a narrow linewidth laser, a fiber coupler, a microwave source, a first electro-optic modulator, a second electro-optic modulator, a tunable filter, a first doped fiber amplifier, a circulator, a wavelength division multiplexer, a Raman amplifier, an arbitrary waveform generator, a third electro-optic modulator, a fiber grating filter, a second doped fiber amplifier, a polarization maintaining controller, a fiber to be detected, a photodetector and a data acquisition card. The data processing module processes the BOTDA data, realizes the detection of the temperature and strain of the fiber to be detected, and extracts corresponding characteristic parameters by using a principal component analysis method. The application can realize rapid distributed optical fiber temperature and strain detection and can be applied to the online monitoring of an OPGW cable of a power system.

Description

Technical Field

[0001] This invention relates to the field of optical fiber performance testing technology, specifically to a device and method for rapid testing of long-distance distributed optical fiber performance based on distributed amplification and optical chirp chains. Background Technology

[0002] The power communication network is a crucial component of the power grid, serving as the foundation for grid dispatching, operation, and management informatization. It is a vital means of ensuring the safe, stable, and economical operation of the power grid. As the carrier of network information convergence and exchange within the power grid system, the power communication network carries important core businesses related to grid production and company operations. After years of development, it has formed a clear network structure and business carrying methods. Currently, the data and multimedia services carried by the power communication network for grid production dispatching and operation management are continuously increasing. Local areas are experiencing strain on fiber optic cables and bandwidth resources, placing higher demands on the security and reliability of communication channels. There is an urgent need to strengthen the weak links in the primary backbone communication system and optimize and improve the overall network security operation level to achieve safe, controllable, and manageable operation.

[0003] OPGW optical cables are massive in scale. Taking the State Grid Corporation of China's power backbone communication network as an example, according to the "2020 Statistical Annual Report on Power Communication System of State Grid Corporation of China," as of the end of 2020, the total mileage of OPGW optical cables in the power backbone communication network had reached more than 1.5692 million kilometers, with an average annual growth rate of over 50% in backbone network transmission bandwidth. As the main carrier of the power communication network, overhead cables, due to their unique erection method, will inevitably be affected by extreme weather such as seasonal icing and sandstorms during operation. At the same time, the high-altitude suspension will cause tensile forces such as gravity and tension, which can easily lead to local stress concentration and damage to optical fibers, and in severe cases, cause cable breakage. This can also manifest as increased attenuation. As the service life of the optical cable increases, its performance deteriorates, all of which will affect the reliable operation of OPGW optical cables to varying degrees. Approximately 25% of the optical fiber cables in the power backbone network have been in operation for over 15 years. In the past five years, over 60% of OPGW (Optical Plug-in Wi-Fi) failures were characterized by partial fiber core degradation. The OPGW optical fiber cables in the power backbone communication network face multiple challenges due to their large size, long service life, and frequent failures. For example, in 2018, there were 29 failures in the primary backbone communication network's OPGW optical fiber cables, an increase of 11 failures (61.1%) compared to the previous year, showing a significant upward trend. The average failure duration was 12.96 hours, the longest among all types of optical fiber cable failures (mainly due to difficulties in fault location and repair).

[0004] In summary, OPGW optical cables in the primary backbone communication network are characterized by their large size, long service life, frequent failures, and limited available resources in some sections. The reliable operation of OPGW optical cables has become a critical and challenging issue in ensuring safe, controllable, and manageable production. Therefore, it is urgent to strengthen the testing of optical cable performance during operation and maintenance, and to explore new methods beyond traditional OTDR-based attenuation testing to conduct in-depth performance testing. This is essential for identifying and eliminating potential hazards in optical cable operation in advance, and is a necessary means to address current bottlenecks in power grid safety. It is also a crucial foundational research topic for the effective support of the power communication network for the ubiquitous power internet of things and the construction of the "three types of networks and two networks."

[0005] Brillouin optical time domain analysis (BOTDA) is an emerging technology for strain detection of OPGW (Optical Wire Roofing) optical fibers in power system networks. It offers numerous advantages, including distributed operation, long-distance transmission, real-time performance, high accuracy, resistance to electromagnetic interference, high temperature and high voltage, long durability, and the ability to use spare OPGW cores for measurement without the need for additional sensors or power supply to the line. Distributed fiber optic sensing technology is well-suited for power system sensing, overcoming the challenges of strong electromagnetic interference and high-voltage insulation on high-voltage transmission lines, and is applicable to harsh environments and complex terrain. Distributed sensing-based monitoring technologies have been widely used in long-distance oil and gas pipeline leak monitoring, structural health monitoring of large buildings, geological disaster monitoring, and submarine cable monitoring. Applying fiber optic sensing technology to power systems is of great significance for ensuring the safe and stable operation of power systems.

[0006] The OPGW optical cable fault early warning system based on Brillouin fiber optic sensing technology primarily addresses the issues of inability to provide early warnings after OPGW optical cable faults are detected and the difficulty in fault location, thus improving the safe operation level of the line. The fault early warning function based on BOTDA technology focuses on resolving the potential safety hazards to the line operation caused by OPGW optical cable faults, better protecting the line's operational status and further enhancing the support and guarantee level for power production operations. The development of a long-distance, rapid stress monitoring system makes the large-scale application of Brillouin stress sensing technology in the power grid system possible. Proactively planning the inspection and management of potential risks fundamentally improves the security and reliability of the network, further supporting and strengthening the inherent security of the power communication network.

[0007] The increasing demands of power grid services and bandwidth requirements are placing higher demands on long-distance transmission systems, especially for UHV and EHV backbone communication networks, where transmission distances are constantly increasing. This also places longer distance requirements on their supporting stress monitoring systems. At the same time, the large size of optical cables puts a heavy burden on operators for maintenance, and the measurement speed of instruments is also one of the limiting factors for the widespread application of stress monitoring technology in maintenance work. Therefore, it is urgent to study how to optimize data demodulation methods while taking into account the measurement length and improve the efficiency of stress detection. Summary of the Invention

[0008] To address this, the present invention proposes a device and method for rapid detection of the performance of long-distance distributed optical fibers based on distributed amplification and optical chirp chains, in an attempt to solve or at least alleviate at least one of the problems mentioned above.

[0009] According to one aspect of the present invention, a rapid performance testing device for long-distance distributed optical fibers based on distributed amplification and optical chirped chains is provided. The device includes a BOTDA data acquisition module and a data processing module. The BOTDA data acquisition module includes: a narrow-linewidth laser 1, an optical fiber coupler 2, a microwave source 3, a first electro-optic modulator 4, a second electro-optic modulator 5, a tunable filter 6, a first erbium-doped fiber amplifier 7, a circulator 8, a wavelength division multiplexer 9, a Raman amplifier 10, an arbitrary waveform generator 11, a third electro-optic modulator 12, a fiber grating filter 13, a second erbium-doped fiber amplifier 14, a polarization-maintaining controller 15, the fiber under test 16, a photodetector 17, and a data acquisition card 18.

[0010] The optical signal output terminal of the narrow linewidth laser 1 is connected to the optical signal input terminal of the fiber coupler 2. The first optical signal output terminal of the fiber coupler 2 is connected to the input terminal of the first electro-optic modulator 4. The microwave signal output terminal of the microwave source 3 is connected to the microwave signal loading terminal of the first electro-optic modulator 4. The output terminal of the first electro-optic modulator 4 is connected to the input terminal of the second electro-optic modulator 5. The output terminal of the arbitrary waveform generator 11 is connected to the microwave loading terminal of the second electro-optic modulator 5. The output terminal of the second electro-optic modulator 5 is connected to the input terminal of the tunable filter 6. The output terminal of the tunable filter 6 is connected to the input terminal of the first erbium-doped fiber amplifier 7. The output terminal of the first erbium-doped fiber amplifier 7 is connected to the first optical signal port 8-1 of the circulator 8. The second optical signal port 8-2 of the circulator 8 is connected to the 1550-band input port of the wavelength division multiplexer 9. The output terminal of the Raman amplifier 10 is connected to the 1480-band input port of the wavelength division multiplexer 9. The signal is injected into the fiber under test 16 through the output terminal of the wavelength division multiplexer 9.

[0011] The second optical signal output terminal of the fiber coupler 2 is connected to the input terminal of the third electro-optic modulator 12. The output terminal of the arbitrary waveform generator 11 is connected to the microwave signal loading terminal of the third electro-optic modulator 12. The output terminal of the third electro-optic modulator 12 is connected to the input terminal of the fiber optic grating filter 13. The output terminal of the fiber optic grating filter 13 is connected to the input terminal of the second erbium-doped fiber amplifier 14. The output terminal of the second erbium-doped fiber amplifier 14 is connected to the input terminal of the polarization-maintaining controller 15. The output terminal of the polarization-maintaining controller 15 is connected to the other end of the fiber under test 16.

[0012] The optical signal port 8-3 of the circulator 8 is connected to the optical signal input terminal of the photodetector 17, and the electrical signal output terminal of the photodetector 17 is connected to the electrical signal input terminal of the data acquisition card 18; the data acquisition card 18 acquires the BOTDA data of the fiber optic cable 16 under test.

[0013] The data processing module is used to process the collected BOTDA data in order to detect the temperature and strain of the optical fiber 16 under test.

[0014] Furthermore, the data processing module processes the acquired BOTDA data to detect the temperature and strain of the optical fiber 16 under test. The specific steps include:

[0015] The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. The feature parameter r corresponding to each Brillouin center frequency shift is extracted. l ; Save multiple feature parameters r l A database is formed based on the frequency shift of the Brillouin center;

[0016] The arbitrary waveform generator 11 uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card 18 acquires two sets of BOTDA time-domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time-domain signals of the optical fiber under test 16 is extracted;

[0017] Calculate the relationship between feature parameter s and each feature parameter r in the database. l Distance D(s,r) l );

[0018] Choose distance D(s,r) l The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test 16.

[0019] The temperature and strain of the fiber under test 16 were obtained by calculating the Brillouin center frequency shift.

[0020] Furthermore, the data processing module extracts the feature parameter r. l The specific process of defining the characteristic parameter s includes:

[0021] For each set of Brillouin attenuation spectra generated by the simulation, the spectrum is truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two sets of Brillouin attenuation spectra corresponding to a Brillouin center frequency shift is calculated to obtain multiple sets of differentially distributed Brillouin attenuation spectra.

[0022] For each group of BOTDA time-domain signals of the fiber under test 16, the BOTDA time-domain signals are truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two groups of Brillouin attenuation spectra corresponding to the two groups of BOTDA time-domain signals is obtained to obtain multiple differentially distributed Brillouin attenuation spectra.

[0023] Based on the differential distribution of the Leyen attenuation spectrum, the corresponding characteristic parameters are extracted using principal component analysis.

[0024] Furthermore, the specific process of extracting corresponding feature parameters based on multiple differentially distributed Lyon attenuation spectra using principal component analysis in the data processing module includes:

[0025] The Lilliputian attenuation spectrum of multiple differential distributions is represented as g i Each group of differential distributions has a low-density spectrum g. i Containing N elements, the multiple sets of differentially distributed Lyon attenuation spectra are represented by a matrix as G = [g1, g2, ..., g...]. M ] Calculate its average value

[0026] Calculate the zero-return matrix based on the average value:

[0027] Calculate the covariance matrix based on the zero-return matrix: in The N eigenvalues ​​λ of the covariance matrix C j The principal component to be found: Cμ j =λ j μ j , where μ j For λ j The corresponding feature vector;

[0028] Arrange the N eigenvalues ​​in descending order, and select the orthogonal eigenvectors μ = [μ1, μ2, ..., μ] corresponding to the P largest eigenvalues. P ] N×P As a new orthogonal basis, where P is less than N;

[0029] The characteristic parameters are obtained by using the orthogonal basis μ and the zero-return matrix ψ.

[0030] Furthermore, the data processing module uses the Euclidean distance formula to calculate the relationship between the feature parameter s and each feature parameter r in the database. l Distance D(s,r) l ).

[0031] Furthermore, the narrow linewidth laser 1 in the BOTDA data acquisition module has an output optical power of 80mW and a center wavelength of 1550nm; the coupling ratio of the fiber coupler 2 is 90:10.

[0032] Furthermore, in the BOTDA data acquisition module, the center wavelength of the tunable filter 6 is 1550nm and the bandwidth is 12.5GHz; the output optical power of the Raman amplifier 10 is 300mW and the wavelength is 1480nm; the center wavelength of the fiber grating filter 13 is 1550.12nm; and the detection bandwidth of the photodetector 17 is 300MHz.

[0033] According to another aspect of the present invention, a method for rapid performance testing of long-distance distributed optical fibers based on distributed amplification and optical chirp chains is provided, the method comprising the following steps:

[0034] Step 1: Acquire BOTDA data of the optical fiber under test using the BOTDA data acquisition module; wherein, the BOTDA data acquisition module includes a narrow linewidth laser 1, an optical fiber coupler 2, a microwave source 3, a first electro-optic modulator 4, a second electro-optic modulator 5, a tunable filter 6, a first erbium-doped fiber amplifier 7, a circulator 8, a wavelength division multiplexer 9, a Raman amplifier 10, an arbitrary waveform generator 11, a third electro-optic modulator 12, a fiber grating filter 13, a second erbium-doped fiber amplifier 14, a polarization maintaining controller 15, a photodetector 17, and a data acquisition card 18;

[0035] Step 2: Process the collected BOTDA data to detect the temperature and strain of the optical fiber under test.

[0036] Furthermore, the specific process of acquiring BOTDA data of the optical fiber under test in step one includes:

[0037] The beam output from the narrow linewidth laser 1 is split into two paths by the fiber coupler 2. The upper branch beam, which has 90% power, enters the first electro-optic modulator 4. The carrier wave is suppressed and the upper and lower sideband signals with fixed frequency shifts provided by the microwave source 3 are output. The signals are then modulated into pulsed light by the second electro-optic modulator 5. The channel 1 of the arbitrary waveform generator 11 controls the pulse shape of the pulsed light. The tunable filter 6 filters out the high-frequency sidebands. The pulsed light is then amplified by the first erbium-doped fiber amplifier 7 to obtain low-frequency pump pulsed light. The low-frequency pump pulsed light is input from port 1 and output from port 2 of the circulator 8. It is simultaneously injected into one end of the fiber under test by the wavelength division multiplexer 9 along with the Raman light signal output from the Raman amplifier 10. The Raman light signal is distributedly amplified by the stimulated Brillouin scattering light signal in the fiber under test.

[0038] 10% of the light in the lower branch enters the third electro-optic modulator 12. The arbitrary waveform generator 11 outputs an amplitude-corrected microwave chirped signal and loads it onto the third electro-optic modulator 12 to form a double-sideband optical chirped chain signal. The low-frequency sideband is filtered out by the fiber grating filter 13, and the optical power is amplified by the second erbium-doped fiber amplifier 14. Then, the polarization state of the probe light is randomly shuffled by the polarization-maintaining controller 15 to prevent random birefringence in the single-mode fiber from causing signal intensity fluctuations. Finally, it is used as the probe light signal and input from the other end of the fiber under test.

[0039] The lower frequency shift pump light of the upper branch and the upper frequency shift probe light of the lower branch are simultaneously injected into the fiber under test to generate stimulated Brillouin interaction, and the Brillouin attenuation spectrum at the corresponding position is obtained in each chirped unit; the obtained Brillouin signal is output through port 3 of circulator 8, detected by photodetector 17 and acquired by data acquisition card 18.

[0040] Furthermore, the specific steps in step two for processing the acquired BOTDA data to detect the temperature and strain of the optical fiber under test include:

[0041] The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. The feature parameter r corresponding to each Brillouin center frequency shift is extracted. l ; Save multiple feature parameters r l A database is formed based on the frequency shift of the Brillouin center;

[0042] The arbitrary waveform generator 11 uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card 18 acquires two sets of BOTDA time-domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time-domain signals of the optical fiber under test is extracted;

[0043] Calculate the relationship between feature parameter s and each feature parameter r in the database. l Distance D(s,r) l );

[0044] Choose distance D(s,r) l The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test.

[0045] The temperature and strain of the optical fiber under test were obtained by calculating the Brillouin center frequency shift.

[0046] The beneficial technical effects of this invention are:

[0047] This invention proposes a rapid performance testing device and method for long-distance distributed optical fibers based on distributed amplification and optical chirped chains, enabling rapid distributed optical fiber temperature and strain detection. This invention can be applied to online monitoring of OPGW optical cables in power systems, enabling monitoring of rapid temperature and strain in long-distance applications such as lightning strikes and wind-induced vibrations. It solves the problems of long measurement times and inability to respond to dynamic changes in traditional distributed optical fiber sensing technology, expanding the application of long-distance Brillouin systems in power systems. Attached Figure Description

[0048] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example and not limitation, wherein:

[0049] Figure 1 This is a schematic diagram of the structure of the BOTDA data acquisition module in an embodiment of the present invention.

[0050] Figure 2 This is an example diagram of the 150km three-dimensional Brillouin attenuation spectrum measurement results in an embodiment of the present invention.

[0051] Figure 3 This is an example diagram showing the Brillouin attenuation spectrum measurement results at a certain fiber location acquired by the BOTDA data acquisition module in an embodiment of the present invention.

[0052] Figure 4 This is an example diagram showing the results of extracting feature parameters using principal component analysis in an embodiment of the present invention.

[0053] Figure 5 This is an example diagram showing the changes in tail temperature and Brillouin frequency shift at 150km in an embodiment of the present invention. Detailed Implementation

[0054] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0055] Those skilled in the art will recognize that embodiments of the present invention can be implemented as a system, apparatus, device, method, or computer program product. Therefore, this disclosure can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. It should be understood herein that any number of elements in the accompanying drawings is for illustrative purposes only and not as a limitation, and any naming is for distinction only and has no limiting meaning.

[0056] This invention provides a rapid performance testing device for long-distance distributed optical fibers based on distributed amplification and optical chirped chains. The device includes a BOTDA data acquisition module and a data processing module. Figure 1 As shown, the BOTDA data acquisition module includes: a narrow-linewidth laser 1, an optical fiber coupler 2, a microwave source 3, a first electro-optic modulator 4, a second electro-optic modulator 5, a tunable filter 6, a first erbium-doped fiber amplifier 7, a circulator 8, a wavelength division multiplexer 9, a Raman amplifier 10, an arbitrary waveform generator 11, a third electro-optic modulator 12, a fiber grating filter 13, a second erbium-doped fiber amplifier 14, a polarization-maintaining controller 15, an optical fiber under test 16, a photodetector 17, and a data acquisition card 18; wherein:

[0057] The optical signal output terminal of the narrow linewidth laser 1 is connected to the optical signal input terminal of the fiber coupler 2. The first optical signal output terminal of the fiber coupler 2 is connected to the input terminal of the first electro-optic modulator 4. The microwave signal output terminal of the microwave source 3 is connected to the microwave signal loading terminal of the first electro-optic modulator 4. The output terminal of the first electro-optic modulator 4 is connected to the input terminal of the second electro-optic modulator 5. The output terminal of the arbitrary waveform generator 11 is connected to the microwave loading terminal of the second electro-optic modulator 5. The output terminal of the second electro-optic modulator 5 is connected to the input terminal of the tunable filter 6. The output terminal of the tunable filter 6 is connected to the input terminal of the first erbium-doped fiber amplifier 7. The output terminal of the first erbium-doped fiber amplifier 7 is connected to the first optical signal port 8-1 of the circulator 8. The second optical signal port 8-2 of the circulator 8 is connected to the 1550-band input port of the wavelength division multiplexer 9. The output terminal of the Raman amplifier 10 is connected to the 1480-band input port of the wavelength division multiplexer 9. The signal is injected into the fiber under test 16 through the output terminal of the wavelength division multiplexer 9.

[0058] The second optical signal output terminal of the fiber coupler 2 is connected to the input terminal of the third electro-optic modulator 12. The output terminal of the arbitrary waveform generator 11 is connected to the microwave signal loading terminal of the third electro-optic modulator 12. The output terminal of the third electro-optic modulator 12 is connected to the input terminal of the fiber optic grating filter 13. The output terminal of the fiber optic grating filter 13 is connected to the input terminal of the second erbium-doped fiber amplifier 14. The output terminal of the second erbium-doped fiber amplifier 14 is connected to the input terminal of the polarization-maintaining controller 15. The output terminal of the polarization-maintaining controller 15 is connected to the other end of the fiber under test 16.

[0059] The optical signal port 8-3 of the circulator 8 is connected to the optical signal input terminal of the photodetector 17, and the electrical signal output terminal of the photodetector 17 is connected to the electrical signal input terminal of the data acquisition card 18. The data acquisition card 18 acquires BOTDA data.

[0060] In this embodiment, preferably, the narrow-linewidth laser 1 has an output optical power of 80mW and a center wavelength of 1550nm. The coupling ratio of the fiber coupler 2 is 90:10. The center wavelength of the tunable filter 6 is 1550nm, and the bandwidth is 12.5GHz. The output optical power of the Raman amplifier 10 is 300mW, and the wavelength is 1480nm. The center wavelength of the fiber Bragg grating filter 13 is 1550.12nm. The detection bandwidth of the photodetector 17 is 300MHz.

[0061] The specific process of acquiring BOTDA data of the optical fiber under test using the above-mentioned BOTDA data acquisition module is as follows:

[0062] A narrow-linewidth laser 1 serves as the system's light source, with an output wavelength set to 1550 nm and an output power of 80 mW. The beam output from the narrow-linewidth laser 1 is then split into two paths by a 90:10 fiber coupler 2. The upper branch beam, possessing 90% of the power component, enters the first electro-optic modulator 4, where the carrier wave is suppressed, and a fixed-frequency-shifted upper and lower sideband signal of 8.3 GHz (provided by a microwave source 3) is output. This signal is then modulated into a 40 ns pulse by the second electro-optic modulator 5. Channel 1 of the arbitrary waveform generator 11 controls the pulse shape of the pulse, and a tunable filter 6 filters out high-frequency sidebands. After amplification by the first erbium-doped fiber amplifier 7, a low-frequency pump pulse with a peak power of 100 mW is obtained. Pump light is input from port 1 of circulator 8 and output from port 2 of circulator 8. It is simultaneously injected into one end of the 150km fiber under test 16 through wavelength division multiplexer 9 along with the Raman light signal output from Raman amplifier 10. The Raman light signal is distributedly amplified to improve the signal quality and sensing distance of the stimulated Brillouin scattering light signal in the fiber under test 16.

[0063] 10% of the light in the lower branch enters the third electro-optic modulator 12. The arbitrary waveform generator 11 outputs a microwave chirped signal of 2.4 to 2.695 GHz after amplitude correction and loads it onto the third electro-optic modulator 12 to form a double-sideband optical chirped chain signal with a chirped period of 60 ns. The low-frequency sideband is filtered out by the fiber grating filter 13, and the optical power is amplified to 10 mW by the second erbium-doped fiber amplifier 14. Then, the polarization state of the probe light is randomly shuffled by the polarization maintaining controller 15 to prevent the signal intensity from fluctuating due to random birefringence in the single-mode fiber. Finally, it is input from the other end of the fiber under test 16 as the probe light signal.

[0064] The device consists of two paths: the upper path generates a down-frequency-shifted pulsed light, and the lower path generates an up-frequency-shifted probe light modulated by an optical chirped chain. The down-frequency-shifted pump light from the upper path and the up-frequency-shifted probe light from the lower path are simultaneously injected into the 150km sensing fiber optic cable 16, resulting in stimulated Brillouin interaction. Within each chirped unit, the corresponding Brillouin attenuation spectrum is obtained. The resulting Brillouin signal is output from port 3 via circulator 8, detected by photodetector 17, and then acquired by data acquisition card 18, forming a BOTDA system. The three-dimensional Brillouin attenuation spectrum measurement results are as follows: Figure 2 As shown.

[0065] The data processing module is used to process the acquired BOTDA data to detect the temperature and strain of the optical fiber 16 under test; the specific steps for processing the acquired BOTDA data include:

[0066] The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. The feature parameter r corresponding to each Brillouin center frequency shift is extracted. l ; Save multiple feature parameters r l A database is formed based on the frequency shift of the Brillouin center;

[0067] The arbitrary waveform generator 11 uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card 18 acquires two sets of BOTDA time-domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time-domain signals of the optical fiber under test 16 is extracted;

[0068] Calculate the relationship between feature parameter s and each feature parameter r in the database. l Distance D(s,r) l );

[0069] Choose distance D(s,r) l The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test 16.

[0070] The temperature and strain of the fiber 16 under test were obtained by calculating the Brillouin center frequency shift: using the formula v B -v B0 =C ε (ε-ε0)+C T (T-T0), where v B The Brillouin center shift at the final state; v B0 Let T be the initial Brillouin center frequency shift, T be the final temperature, ε be the final strain, T0 be the initial temperature, ε0 be the initial strain, and C be the final strain. ε For strain coefficient, a value of 0.0482 με / MHz can be used for ordinary single-mode optical fiber. T For temperature coefficient, a value of 1.12℃ / MHz can be used for ordinary single-mode optical fiber. Figure 5 This is an example diagram showing the changes in tail temperature and Brillouin frequency shift at 150km in an embodiment of the present invention.

[0071] In this embodiment, preferably, the data processing module extracts the feature parameter r. l The specific process of defining the characteristic parameter s includes:

[0072] For each set of Brillouin attenuation spectra generated by the simulation, the spectrum is truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two sets of Brillouin attenuation spectra corresponding to a Brillouin center frequency shift is calculated to obtain multiple sets of differentially distributed Brillouin attenuation spectra.

[0073] For each group of BOTDA time-domain signals of the fiber under test 16, the BOTDA time-domain signals are truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two groups of Brillouin attenuation spectra corresponding to the two groups of BOTDA time-domain signals is obtained to obtain multiple differentially distributed Brillouin attenuation spectra.

[0074] Based on the differential distribution of the Leyen attenuation spectrum, the corresponding characteristic parameters are extracted using principal component analysis.

[0075] First, for each set of Brillouin attenuation spectra generated by simulation, the spectrum is truncated according to the chirped period to obtain multiple Brillouin attenuation spectra at various locations. The difference between the two sets of Brillouin attenuation spectra corresponding to a Brillouin center frequency shift is then calculated to obtain multiple sets of differentially distributed Brillouin attenuation spectra. For each set of BOTDA time-domain signals of the fiber under test 16, the BOTDA time-domain signals are truncated according to the chirped period to obtain multiple sets of Brillouin attenuation spectra at various locations. The difference between the two sets of Brillouin attenuation spectra corresponding to the two sets of BOTDA time-domain signals is then calculated to obtain multiple sets of differentially distributed Brillouin attenuation spectra.

[0076] This is because the BOTDA system utilizes stimulated Brillouin scattering (SBS) between the probe light modulated by an optical chirped chain and the pump light modulated by a pulse. Since the probe light frequency is higher than the pump light and its frequency range covers the Brillouin spectrum, a Brillouin attenuation spectrum is obtained at each chirped unit. The signal along the entire fiber length is formed by cascading the Brillouin attenuation spectra from various locations. The spectrum is then truncated according to the chirped period to obtain the Brillouin attenuation spectrum at each location. Differential processing effectively reduces the impact of chirped modulation unevenness on signal demodulation, especially at locations with low signal-to-noise ratios.

[0077] Since the spatial resolution of the system is determined by the longer of the chirp period and the convolution time (the convolution of the pulse with the Brillouin eigenspectrum), a suitable pulse width must be selected to ensure that the convolution time is less than the chirp period. This prevents the SBS effect within a chirped unit from affecting the signals in adjacent chirped units. To improve the spatial resolution of this system, differential pulse pairing technology is used. To achieve a sensing distance of over 100 km, the pulse width should not be less than 40 ns. The first measurement uses a pulse width of 70 ns to 100 ns to obtain the Brillouin attenuation spectrum A1. The second measurement uses a pulse width of 40 ns to 70 ns, a difference of 30 ns, to obtain the Brillouin attenuation spectrum A2. For example, A1 is the Brillouin attenuation spectrum measured with a 70 ns pump pulse, and A2 is the Brillouin attenuation spectrum measured with a 40 ns pump pulse. Figure 3 As shown in the figure, the dotted line represents the Brillouin spectrum measured with a 70 ns pump pulse, the dashed line represents the Brillouin spectrum measured with a 40 ns pump pulse, and the solid line represents the differential Brillouin spectrum.

[0078] Finally, principal component analysis was used to extract the corresponding characteristic parameters based on the multiple sets of differentially distributed Lyon attenuation spectra. Specifically, the multiple sets of differentially distributed Lyon attenuation spectra are represented as g. i Each group of differential distributions has a low-density spectrum g. i Containing N elements, the multiple sets of differentially distributed Lyon attenuation spectra are represented by a matrix as G = [g1, g2, ..., g...]. M ] Calculate its average value

[0079] Calculate the zero-return matrix based on the average value:

[0080] Calculate the covariance matrix based on the zero-return matrix: in The N eigenvalues ​​λ of the covariance matrix C j The principal component to be found: Cμ j =λ j μ j , where μ j For λ j The corresponding feature vector;

[0081] Arrange the N eigenvalues ​​in descending order, and select the orthogonal eigenvectors μ = [μ1, μ2, ..., μ] corresponding to the P largest eigenvalues. P ] N×P As a new orthogonal basis, where P is less than N;

[0082] The characteristic parameters are obtained by using the orthogonal basis μ and the zero-return matrix ψ.

[0083] As an example, the process of extracting the corresponding feature parameters using principal component analysis can be specifically described as follows: assuming the simulation generates M Brillouin loss spectra, each containing N elements, and the database representation is G = [g1g2…g ... M The matrix size is N×M. First, calculate the average value of all data within each spectrum. Find the zero-return matrix of the reference database. Further solve the covariance matrix The N eigenvalues ​​λ of the covariance matrix j For the principal components we are looking for, Cμ j =λ j μ j j = 1, 2, ..., N, where μ j For λ j The corresponding eigenvectors, with all N eigenvalues ​​arranged in descending order, require only the first P eigenvalues ​​from the principal component analysis algorithm, where P is determined by... It is decided that the orthogonal eigenvectors corresponding to the selected P eigenvalues ​​are μ = [μ1, μ2, ..., μ...]. P ] N×P As a new orthogonal basis, feature parameters r = [r1, r2, ..., r] are extracted from all Brillouin spectra in the database based on the obtained orthogonal basis μ. P ] P×M =μ T ψ, where r l =[w1,w2,…,w P ] T Let l = 1, 2, ..., M, to complete the feature parameter extraction. Similarly, the feature parameter s of the measured data is obtained using the same feature extraction method. The results of the feature extraction are as follows: Figure 4 As shown, the dotted line represents the measured differential distribution Leyen attenuation spectrum, and the solid line represents the result of feature extraction.

[0084] In this embodiment, preferably, the Euclidean distance formula is used to calculate the relationship between the feature parameter s and each feature parameter r in the database. l Distance D(s,r) l The characteristic parameter s of the measurement data is compared with the characteristic parameter r of different Brillouin frequency shifts in the database. l To achieve optimal matching, the Euclidean distance formula is used as the optimal matching algorithm, as shown in the following equation:

[0085]

[0086] Where s k and The characteristic parameters s and r are respectively l The elements in the matrix are used to find the minimum value among the M calculated values ​​as the optimal matching result. The corresponding Brillouin center frequency shift is then the fitting result.

[0087] The data acquisition module proposed in this invention combines distributed amplification, optical chirped chains, and BOTDA technology to achieve rapid detection of temperature and strain in long-distance distributed optical fibers. The optical chirped chain technology completes frequency scanning within each chirped unit, making the system measurement time only related to the fiber length and the number of averages. The optical chirped chain technology and Brillouin attenuation spectrum structure improve the signal-to-noise ratio and reduce the number of averages required in the measurement, significantly reducing measurement time and enabling rapid detection of long-distance optical fiber performance. The proposed data processing module introduces dual-pulse differential technology and a principal component analysis pattern recognition algorithm to further improve sensing performance. The dual-pulse differential technology reduces optical chirped modulation noise and measurement errors introduced by pump pulse front-end distortion. The principal component analysis pattern recognition algorithm enables higher-precision extraction of intrinsic Brillouin frequency shift.

[0088] Another embodiment of the present invention proposes a rapid performance testing method for long-distance distributed optical fibers based on distributed amplification and optical chirped chains, the method comprising the following steps:

[0089] Step 1: Acquire BOTDA data of the optical fiber under test using the BOTDA data acquisition module; wherein, the BOTDA data acquisition module includes a narrow linewidth laser 1, an optical fiber coupler 2, a microwave source 3, a first electro-optic modulator 4, a second electro-optic modulator 5, a tunable filter 6, a first erbium-doped fiber amplifier 7, a circulator 8, a wavelength division multiplexer 9, a Raman amplifier 10, an arbitrary waveform generator 11, a third electro-optic modulator 12, a fiber grating filter 13, a second erbium-doped fiber amplifier 14, a polarization maintaining controller 15, a photodetector 17, and a data acquisition card 18;

[0090] Step 2: Process the collected BOTDA data to detect the temperature and strain of the optical fiber under test.

[0091] In this embodiment, preferably, the specific process of acquiring BOTDA data of the optical fiber under test in step one includes:

[0092] The beam output from the narrow linewidth laser 1 is split into two paths by the fiber coupler 2. The upper branch beam, which has 90% power, enters the first electro-optic modulator 4. The carrier wave is suppressed and the upper and lower sideband signals with fixed frequency shifts provided by the microwave source 3 are output. The signals are then modulated into pulsed light by the second electro-optic modulator 5. The channel 1 of the arbitrary waveform generator 11 controls the pulse shape of the pulsed light. The tunable filter 6 filters out the high-frequency sidebands. The pulsed light is then amplified by the first erbium-doped fiber amplifier 7 to obtain low-frequency pump pulsed light. The low-frequency pump pulsed light is input from port 1 and output from port 2 of the circulator 8. It is simultaneously injected into one end of the fiber under test by the wavelength division multiplexer 9 along with the Raman light signal output from the Raman amplifier 10. The Raman light signal is distributedly amplified by the stimulated Brillouin scattering light signal in the fiber under test.

[0093] 10% of the light in the lower branch enters the third electro-optic modulator 12. The arbitrary waveform generator 11 outputs an amplitude-corrected microwave chirped signal and loads it onto the third electro-optic modulator 12 to form a double-sideband optical chirped chain signal. The low-frequency sideband is filtered out by the fiber grating filter 13, and the optical power is amplified by the second erbium-doped fiber amplifier 14. Then, the polarization state of the probe light is randomly shuffled by the polarization-maintaining controller 15 to prevent random birefringence in the single-mode fiber from causing signal intensity fluctuations. Finally, it is used as the probe light signal and input from the other end of the fiber under test.

[0094] The lower frequency shift pump light of the upper branch and the upper frequency shift probe light of the lower branch are simultaneously injected into the fiber under test to generate stimulated Brillouin interaction, and the Brillouin attenuation spectrum at the corresponding position is obtained in each chirped unit; the obtained Brillouin signal is output through port 3 of circulator 8, detected by photodetector 17 and acquired by data acquisition card 18.

[0095] In this embodiment, preferably, the specific steps in step two for processing the acquired BOTDA data to detect the temperature and strain of the optical fiber under test include:

[0096] The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. The feature parameter r corresponding to each Brillouin center frequency shift is extracted. l ; Save multiple feature parameters r l A database is formed based on the frequency shift of the Brillouin center;

[0097] The arbitrary waveform generator 11 uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card 18 acquires two sets of BOTDA time-domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time-domain signals of the optical fiber under test is extracted;

[0098] Calculate the relationship between feature parameter s and each feature parameter r in the database. l Distance D(s,r) l );

[0099] Choose distance D(s,r) l The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test.

[0100] The temperature and strain of the optical fiber under test were obtained by calculating the Brillouin center frequency shift.

[0101] The function of the long-distance distributed optical fiber performance rapid detection method based on distributed amplification and optical chirped chain described in this embodiment of the invention can be explained by the aforementioned long-distance distributed optical fiber performance rapid detection device based on distributed amplification and optical chirped chain. Therefore, for the parts not described in detail in this embodiment, please refer to the above device embodiments, and they will not be repeated here.

[0102] It should be noted that although several units, modules, or sub-modules are mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more modules described above can be embodied in one module. Conversely, the features and functions of one module described above can be further divided and embodied by multiple modules.

[0103] Furthermore, although the operations of the method of the present invention are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0104] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A rapid performance testing device for long-distance distributed optical fibers based on distributed amplification and optical chirped chains, characterized in that, The device includes a BOTDA data acquisition module and a data processing module; The BOTDA data acquisition module includes: a narrow linewidth laser (1), an optical fiber coupler (2), a microwave source (3), a first electro-optic modulator (4), a second electro-optic modulator (5), a tunable filter (6), a first erbium-doped fiber amplifier (7), a circulator (8), a wavelength division multiplexer (9), a Raman amplifier (10), an arbitrary waveform generator (11), a third electro-optic modulator (12), a fiber grating filter (13), a second erbium-doped fiber amplifier (14), a polarization-maintaining controller (15), an optical fiber under test (16), a photodetector (17), and a data acquisition card (18); among which, The optical signal output terminal of the narrow linewidth laser (1) is connected to the optical signal input terminal of the fiber coupler (2). The first optical signal output terminal of the fiber coupler (2) is connected to the input terminal of the first electro-optic modulator (4). The microwave signal output terminal of the microwave source (3) is connected to the microwave signal loading terminal of the first electro-optic modulator (4). The output terminal of the first electro-optic modulator (4) is connected to the input terminal of the second electro-optic modulator (5). The output terminal of the arbitrary waveform generator (11) is connected to the microwave loading terminal of the second electro-optic modulator (5). The output terminal of the second electro-optic modulator (5) is connected to the input terminal of the second electro-optic modulator (5). The input of the tunable filter (6) is connected, the output of the tunable filter (6) is connected to the input of the first erbium-doped fiber amplifier (7), the output of the first erbium-doped fiber amplifier (7) is connected to the first optical signal port (8-1) of the circulator (8), the second optical signal port (8-2) of the circulator (8) is connected to the 1550nm wavelength input port of the wavelength division multiplexer (9), the output of the Raman amplifier (10) is connected to the 1480nm wavelength input port of the wavelength division multiplexer (9), and the signal is injected into the fiber under test (16) through the output of the wavelength division multiplexer (9). The second optical signal output terminal of the fiber coupler (2) is connected to the input terminal of the third electro-optic modulator (12), the output terminal of the arbitrary waveform generator (11) is connected to the microwave signal loading terminal of the third electro-optic modulator (12), the output terminal of the third electro-optic modulator (12) is connected to the input terminal of the fiber grating filter (13), the output terminal of the fiber grating filter (13) is connected to the input terminal of the second erbium-doped fiber amplifier (14), the output terminal of the second erbium-doped fiber amplifier (14) is connected to the input terminal of the polarization maintaining controller (15), and the output terminal of the polarization maintaining controller (15) is connected to the other end of the fiber under test (16). The third optical signal port (8-3) of the circulator (8) is connected to the optical signal input terminal of the photodetector (17), and the electrical signal output terminal of the photodetector (17) is connected to the electrical signal input terminal of the data acquisition card (18); the data acquisition card (18) acquires the BOTDA data of the fiber under test (16). The data processing module is used to process the collected BOTDA data in order to detect the temperature and strain of the optical fiber (16) under test.

2. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 1, characterized in that, The data processing module processes the acquired BOTDA data to detect the temperature and strain of the optical fiber (16) under test. The specific steps include: The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. Feature parameters corresponding to each Brillouin center frequency shift are extracted. ; Save multiple feature parameters A database is formed based on the frequency shift of the corresponding Brillouin center. The arbitrary waveform generator (11) uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card (18) acquires two sets of BOTDA time domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time domain signals of the fiber under test (16) is extracted; Calculate the feature parameter s and each feature parameter in the database. distance ; Select distance The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test (16); The temperature and strain of the fiber under test (16) were obtained by calculating the Brillouin center frequency shift.

3. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 2, characterized in that, The data processing module extracts feature parameters. The specific process of defining the characteristic parameter s includes: For each set of Brillouin attenuation spectra generated by the simulation, the spectrum is truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two sets of Brillouin attenuation spectra corresponding to a Brillouin center frequency shift is calculated to obtain multiple sets of differentially distributed Brillouin attenuation spectra. For each group of BOTDA time-domain signals of the fiber under test (16), the BOTDA time-domain signals are truncated according to the chirp period to obtain multiple Brillouin attenuation spectra at each position; the difference between the two groups of Brillouin attenuation spectra corresponding to the two groups of BOTDA time-domain signals is obtained to obtain multiple differentially distributed Brillouin attenuation spectra. Based on the differential distribution of the Leyen attenuation spectrum, the corresponding characteristic parameters are extracted using principal component analysis.

4. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 3, characterized in that, The specific process of extracting corresponding feature parameters based on multiple sets of differentially distributed Lyon attenuation spectra using principal component analysis in the data processing module includes: The Lille attenuation spectrum of multiple differential distributions is expressed as follows: The attenuation spectrum of each group's differential distribution It contains N elements, and multiple sets of differentially distributed Lyon attenuation spectra are represented by a matrix as follows: Calculate its average value : ; Calculate the zero-return matrix based on the average value: ; Calculate the covariance matrix based on the zero-return matrix: ,in The N eigenvalues ​​of the covariance matrix C The principal components we are looking for: ,in for The corresponding feature vector; Arrange the N eigenvalues ​​in descending order, and select the orthogonal eigenvectors corresponding to the P largest eigenvalues. As a new orthogonal basis, where P is less than N; Using orthogonal bases and zeroing matrix The characteristic parameters are calculated.

5. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 2, characterized in that, The data processing module uses the Euclidean distance formula to calculate the relationship between the feature parameter s and each feature parameter in the database. distance .

6. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 1, characterized in that, The narrow linewidth laser (1) in the BOTDA data acquisition module has an output optical power of 80mW and a center wavelength of 1550nm; the coupling ratio of the fiber coupler (2) is 90:

10.

7. The long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirped chain according to claim 1, characterized in that, The tunable filter (6) in the BOTDA data acquisition module has a center wavelength of 1550nm and a bandwidth of 12.5GHz; the Raman amplifier (10) has an output optical power of 300 mW and a wavelength of 1480nm; the fiber grating filter (13) has a center wavelength of 1550.12nm; and the photodetector (17) has a detection bandwidth of 300MHz.

8. A rapid method for detecting the performance of long-distance distributed optical fibers based on distributed amplification and optical chirped chains, characterized in that, The method is implemented based on the long-distance distributed optical fiber performance rapid testing device based on distributed amplification and optical chirp chain as described in any one of claims 1-7; the method includes the following steps: Step 1: Collect BOTDA data of the fiber under test using the BOTDA data acquisition module; wherein, the BOTDA data acquisition module includes a narrow linewidth laser (1), an optical fiber coupler (2), a microwave source (3), a first electro-optic modulator (4), a second electro-optic modulator (5), a tunable filter (6), a first erbium-doped fiber amplifier (7), a circulator (8), a wavelength division multiplexer (9), a Raman amplifier (10), an arbitrary waveform generator (11), a third electro-optic modulator (12), a fiber grating filter (13), a second erbium-doped fiber amplifier (14), a polarization maintaining controller (15), the fiber under test (16), a photodetector (17), and a data acquisition card (18); Step 2: Process the collected BOTDA data to detect the temperature and strain of the optical fiber under test.

9. The method for rapid performance testing of long-distance distributed optical fibers based on distributed amplification and optical chirped chains according to claim 8, characterized in that, The specific process of acquiring BOTDA data from the optical fiber under test in step one includes: The beam output from the narrow linewidth laser (1) is split into two paths by the fiber coupler (2). The upper branch beam with 90% power component enters the first electro-optic modulator (4), the carrier is suppressed and the upper and lower sideband signals with fixed frequency shift provided by the microwave source (3) are output, and then modulated into pulse light by the second electro-optic modulator (5). The first channel of the arbitrary waveform generator (11) controls the pulse shape of the pulse light, the tunable filter (6) filters out the high frequency sidebands, and then amplifies the light by the first erbium-doped fiber amplifier (7) to obtain low frequency pump pulse light. The low frequency pump pulse light is input from port 1 and output from port 2 of the circulator (8), and is injected into one end of the fiber under test by the wavelength division multiplexer (9) at the same time as the Raman light signal output by the Raman amplifier (10). The Raman light signal is distributedly amplified by the stimulated Brillouin scattering light signal in the fiber under test. 10% of the light in the lower branch enters the third electro-optic modulator (12). The arbitrary waveform generator (11) outputs an amplitude-corrected microwave chirped signal and loads it onto the third electro-optic modulator (12) to form a double-sideband optical chirped chain signal. The low-frequency sideband is filtered out by the fiber optic grating filter (13), and the optical power is amplified by the second erbium-doped fiber amplifier (14). Then, the polarization state of the probe light is randomly shuffled by the polarization maintaining controller (15) to prevent random birefringence in the single-mode fiber from causing fluctuations in signal intensity. Finally, the probe light signal is input from the other end of the fiber under test. The lower frequency shift pump light of the upper branch and the upper frequency shift probe light of the lower branch are simultaneously injected into the fiber under test to generate stimulated Brillouin effect, and the Brillouin attenuation spectrum at the corresponding position is obtained in each chirped unit; the obtained Brillouin signal is output through the third port of the circulator (8), and after being detected by the photodetector (17), it is collected by the data acquisition card (18).

10. The method for rapid performance testing of long-distance distributed optical fibers based on distributed amplification and optical chirped chains according to claim 8, characterized in that, Step two involves processing the acquired BOTDA data to detect the temperature and strain of the optical fiber under test. The specific steps include: The simulation generates multiple sets of Brillouin attenuation spectra corresponding to various Brillouin center frequency shifts. Each Brillouin center frequency shift corresponds to two sets of Brillouin attenuation spectra, which are generated using 70ns and 40ns probe pulse widths respectively, based on the sensing distance requirements. Feature parameters corresponding to each Brillouin center frequency shift are extracted. ; Save multiple feature parameters A database is formed based on the frequency shift of the corresponding Brillouin center. The arbitrary waveform generator (11) uses 70ns and 40ns probe pulse widths respectively, and the data acquisition card (18) acquires two sets of BOTDA time domain signals accordingly; the characteristic parameter s corresponding to the two sets of BOTDA time domain signals of the optical fiber under test is extracted; Calculate the feature parameter s and each feature parameter in the database. distance ; Select distance The feature parameter corresponding to the minimum value is the matching feature, and the Brillouin center frequency shift corresponding to the matching feature is the Brillouin center frequency shift corresponding to the fiber under test. The temperature and strain of the optical fiber under test were obtained by calculating the Brillouin center frequency shift.

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