A Distributed Fiber Optic Sensing System Based on Inverse Conjugate Convolution Algorithm

Abstract

This invention discloses a distributed optical fiber sensing system based on an anti-conjugate convolution algorithm, belonging to the field of optical sensing technology. This invention achieves signal detection of strain and suppresses the effects of linewidth and sweep frequency nonlinearity by measuring the probe pulse signal and performing anti-conjugate convolution with the return signal, thereby improving detection resolution. Through a polarization diversity collection system and a frequency division multiplexing weighted superposition algorithm, it suppresses polarization fading and coherence fading of the signal. Compared with traditional OFDR systems, this system and algorithm can suppress the effects of sweep frequency nonlinearity and linewidth, extend the detection distance limitation of OFDR, and flexibly control the conjugate relationship between the signal-to-noise ratio and resolution of the probe signal through corresponding algorithms, enabling the system to adapt to different application scenarios.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical sensing technology, and particularly relates to a distributed optical fiber sensing system based on a deconvolution algorithm. BACKGROUND

[0002] Compared with traditional sensors, distributed optical fiber sensing technology has the characteristics of corrosion resistance, high temperature resistance and high sensitivity, and can be applied in harsh environmental conditions or high precision sensing conditions. Among them, optical frequency domain reflectometry (OFDR) has high resolution and sensitivity. However, the sensing resolution, dynamic response capability and sensing distance of the OFDR system are often restricted by the nonlinearity of the system sweep, the linewidth and the signal decay, which further affects the reliability and accuracy of the sensing data. SUMMARY

[0003] In view of the above technical problems existing in the prior art, the present application provides a distributed optical fiber sensing system based on a deconvolution algorithm, which is reasonable in design, overcomes the shortcomings of the prior art, and has good effects.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] A kind of distributed optical fiber sensing system based on anti-conjugate convolution algorithm, including narrow line width laser 10, optical modulation system 20, probe optical fiber 30, polarization diversity collection system 40, probe pulse signal measurement system 50 and signal processing system 60.Narrow line width laser 10 emitted single frequency laser passes through first beam splitter 11, second beam splitter 12 twice respectively into different systems;Intensity modulator 21 is modulated by intensity modulator system 20 to single frequency laser, then enter optical filter 24 and injection locking system 25 to complete the frequency modulation of laser;Probe optical fiber 30 will probe pulse in turn optical fiber amplifier 31, first circulator 32, single mode optical fiber 33, and probe pulse back light enters polarization diversity collection system 40 through first circulator 32;Polarization diversity collection system 40 is divided into local oscillator light path and signal light path, one of narrow line width laser as local oscillator light enters second polarization controller 41 and polarization diversity collector 42 in turn, and signal back light enters polarization diversity collector 42, and local oscillator light and signal light of different polarization directions are interfered and enter first balanced photodetector 43, second balanced photodetector 44 respectively;Probe pulse signal measurement system 50 makes probe pulse and narrow line width laser interfere and simultaneously enters second 2×2 coupler 51 and third balanced photodetector 52 in turn;Signal processing system 60 fuses and carries out band-pass filtering to the two different polarization direction back light signals obtained, and the amplitude of the frequency shift of the probe pulse signal is taken and the phase of the deconvolution is taken and fused as the conjugate signal of probe pulse, which is convolved with the back light signal after band-pass filtering, and finally weight superposition frequency division multiplexing algorithm is carried out to obtain data.

[0006] Narrow line width laser 10 divides laser into two paths by first beam splitter 11, one of which enters optical modulation system 20, and the other passes through second beam splitter 12 and is divided into two, which are used as local oscillator light sources for polarization diversity collection system 40 and probe pulse signal measurement system 50 respectively;

[0007] Optical modulation system 20 is configured to modulate the input laser in frequency and form probe light pulse;

[0008] Probe optical fiber 30 includes optical fiber amplifier 31, first circulator 32 and single mode optical fiber 33, probe light pulse is amplified by optical fiber amplifier 31 and then enters single mode optical fiber 33 through first circulator 32, and the scattering phenomenon of optical fiber due to the random fluctuation of refractive index, scattering back light enters polarization diversity collection system 40 through first circulator 32;

[0009] Polarization diversity collection system 40 is configured to interfere the scattering back light of different polarization directions with local oscillator light for measurement to suppress polarization decay;

[0010] Probe pulse signal measurement system 50 is configured to interfere probe pulse signal with local oscillator light for measurement.

[0011] The signal processing system 60 is configured to process the probe pulse signal and the return signal, and to compensate and optimize the return signal by using an anti-conjugate convolution algorithm and a frequency division multiplexing algorithm with weight superposition, so as to suppress the sweep frequency nonlinearity, the influence of laser linewidth and signal attenuation.

[0012] The narrow linewidth laser 10 splits the laser into two paths through the first beam splitter 11. One path enters the optical modulation system 20, and the other path is split into two beams through the second beam splitter 12, which serve as the local oscillator light sources for the polarization diversity collection system 40 and the detection pulse signal measurement system 50, respectively.

[0013] Preferably, the anti-conjugate convolution algorithm includes:

[0014] Algorithm for extracting the anti-conjugate signal of the probe signal: The probe pulse signal is divided into two paths for processing. One path multiplies the probe signal by a frequency shift coefficient and then takes the amplitude of the Fourier transform. The other path performs a deconvolution operation on the probe signal and then takes the phase of the Fourier transform. The two signals are multiplied and fused, and then passed through a frequency selection network to obtain the anti-conjugate signal of the probe signal, which is used as the convolution kernel of the anti-conjugate convolution algorithm.

[0015] Backlight signal fusion algorithm: The two backlight signals with orthogonal polarization directions acquired by the polarization diversity collection system 40 are fused and filtered by a frequency selective network to suppress the polarization attenuation of the signal caused by the change in polarization state in the optical fiber.

[0016] The fused return signal is convolved with the inverse conjugate of the detection signal to obtain the compensated return signal.

[0017] Preferably, the frequency division multiplexing algorithm with weighted superposition is configured to perform frequency selection, weighted phase matching, and weighted vector superposition on the compensated backlight signal to suppress coherent fading.

[0018] Preferably, the optical modulation system 20 includes an intensity modulator 21, an arbitrary waveform generator 22, a DC power supply 23, an optical filter 24, and an injection locking system 25;

[0019] The intensity modulator 21 is controlled by the arbitrary waveform generator 22 and is configured to intensity modulate the input laser to form an optical pulse;

[0020] Optical filter 24 is configured to perform bandpass selection on the modulated optical pulse;

[0021] The injection locking system 25 is configured to frequency modulate the optical pulse.

[0022] The intensity modulator 21 is controlled by the arbitrary waveform generator 22 and supplied with the required voltage by the DC power supply 23. It is used to modulate the narrow linewidth laser and output it in the form of pulses. The pulses then enter the optical filter 24 and the injection locking system 25 in sequence to complete the frequency modulation of the laser.

[0023] Preferably, the polarization diversity collection system 40 includes a second polarization controller 41, a polarization diversity collector 42, a first balanced photodetector 43, and a second balanced photodetector 44, configured to perform interferometric measurements of scattered return light and local oscillator light with different polarization directions to suppress polarization attenuation; wherein,

[0024] The second polarization controller 41 is configured to control the polarization state of the local oscillator light;

[0025] Polarization diversity collector 42 is configured to simultaneously perform interferometric measurements of signal light and local oscillator light in two orthogonal directions;

[0026] Both the first balanced photodetector 43 and the second balanced photodetector 44 are configured to convert interference signals into electrical signals.

[0027] The second polarization controller 41 is used to control the polarization state of the local oscillator light. The polarization diversity collection system interferes with the signal light and the local oscillator light in two orthogonal directions at the same time and then enters the first balanced photodetector 43 and the second balanced photodetector 44 to perform coherent measurements at the same time, so as to avoid signal polarization attenuation caused by polarization direction mismatch between the local oscillator light and the signal light.

[0028] The polarization diversity collector 42 includes a polarization-maintaining fiber beam splitter 45, a first polarization beam splitter 46, a second polarization beam splitter 47, and a first 2×2 coupler 48. First, the local oscillator light and the return light signal enter the polarization-maintaining fiber beam splitter 45 to form two signal lights with the same polarization state. Then, these two beams of light are coupled into the first polarization beam splitter 46 and the second polarization beam splitter 47 to form two interference signal lights with orthogonal polarization states. Finally, these two beams of polarized light with orthogonal polarization states enter the first 2×2 coupler 48 for coupling and distribution, providing two coupled signal lights with orthogonal phases for subsequent entry into the first balanced photodetector 43 and the second balanced photodetector 44.

[0029] Preferably, the detection pulse signal measurement system 50 includes a second 2×2 coupler 51 and a third balanced photodetector 52; wherein,

[0030] The second 2×2 coupler 51 is configured to interfere with the probe pulse signal and the local oscillator light;

[0031] The third balanced photodetector 52 is configured to convert the interference signal into an electrical signal.

[0032] The probe pulse signal measurement system 50 uses a narrow-linewidth laser as the local oscillator and the probe pulse as the signal light for coherent measurement, so as to facilitate subsequent data extraction and compensation processing.

[0033] Preferably, both the polarization diversity collection system 40 and the probe pulse signal measurement system 50 use the laser emitted by the narrow linewidth laser 10 as the local oscillator light for interferometric measurement.

[0034] Preferably, the signal processing system 60 uses an anti-conjugate convolution algorithm to suppress the nonlinearity of laser linewidth and sweep frequency modulation, and uses a weighted frequency division multiplexing algorithm to improve the signal-to-noise ratio and resolution of the signal.

[0035] Preferably, the signal processing system 60 uses an anti-conjugate convolution algorithm and a frequency division multiplexing algorithm with weighted superposition to detect strain signals in a distributed optical fiber sensing system, and flexibly controls the conjugate relationship between signal-to-noise ratio and resolution.

[0036] Preferably, the injection locking system 25 includes a first polarization controller 26, a distributed feedback laser 27, and a second circulator 28, configured to achieve wide-range frequency modulation of the laser.

[0037] The signal processing system 60 includes an algorithm for extracting the anti-conjugate signal of the probe pulse, an anti-conjugate convolution algorithm, and a frequency division multiplexing algorithm with weighted superposition. The probe pulse is multiplied by a frequency shift coefficient to obtain its amplitude and deconvoluted to obtain its phase. After fusion, the anti-conjugate signal of the probe pulse is extracted through a frequency selection network. The return signal is convolved with the anti-conjugate signal after passing through the frequency selection network to obtain the compensated return signal. The compensated return signal is then output through the frequency division multiplexing algorithm with weighted superposition, thereby suppressing the problem of coherent fading.

[0038] This invention provides a distributed optical fiber sensing system based on the anti-conjugate convolution algorithm, comprising the following construction steps:

[0039] Step 1: Connect the narrow linewidth laser 10 sequentially to the first beamsplitter 11 and the second beamsplitter 12. One path serves as the probe pulse source, and the other path enters the second beamsplitter 12. These two paths serve as the local oscillator sources for the polarization diversity collection system 40 and the probe pulse signal measurement system 50, respectively. Connect one optical path from the first beamsplitter 11 to the intensity modulator 21, which is controlled by the arbitrary waveform generator 22. Connect the optical path from the intensity modulator 21 to the optical filter 24, which is then connected to the injection locking system 25. Specifically, it is first connected to the first polarization controller 26 and then to the transmitting port of the second circulator 28. Connect the receiving port of the second circulator 28 to the distributed feedback laser 27, and connect the output of the second circulator 28 to the third beamsplitter 29.

[0040] Step 2: Based on completing Step 1, connect one of the optical paths of the third beam splitter 29 to the transmitting end of the fiber amplifier 31 and the first circulator 32 in sequence, connect the receiving end of the first circulator 32 to the single-mode fiber, and connect its output end to the polarization diversity collection system 40.

[0041] Step 3: Based on steps 1 and 2, connect one path of the second beam splitter 12 to the second polarization controller 41 and then to the local oscillator receiver of the polarization diversity collector 42. Connect the output of the first circulator 32 to the signal receiver of the polarization diversity collector 42. Connect both paths to the first balanced photodetector 43 and the second balanced photodetector 44, and then to the signal processing system 60. Simultaneously, connect the other beam path of the second beam splitter 12 and one beam path of the third beam splitter 29 sequentially to the second 2×2 coupler 51 and the third balanced photodetector 52, and then to the signal processing system 60.

[0042] Step 4: The acquired probe pulse signal is divided into two paths for simultaneous processing. One path multiplies the probe pulse signal by a frequency shift coefficient and obtains its amplitude signal through Fourier transform. The other path performs a deconvolution operation on the probe pulse signal and obtains its phase signal through Fourier transform. The amplitude signal and phase signal are fused and then filtered out by a frequency selection network to obtain the anti-conjugate signal of the probe signal, which is used as the convolution kernel of the anti-conjugate convolution algorithm.

[0043] Step 5: The two orthogonal interference signals are obtained by a fusion algorithm to obtain a fused return signal, and this signal is then bandpass filtered by a frequency selection network. The fused return signal is convolved with the anti-conjugate signal to obtain a compensated return signal, and a frequency division multiplexing algorithm with weighted superposition is used to suppress the coherent attenuation of the signal.

[0044] The beneficial technical effects of this invention are as follows:

[0045] This invention addresses the problems of reduced sensing resolution, insufficient dynamic response, and shortened reliable sensing distance in OFDR systems caused by sweep frequency nonlinearity, linewidth, and signal attenuation. By employing real-time measurement of the probe pulse and using an anti-conjugate convolution algorithm to compensate for inaccurate positioning and signal distortion caused by sweep frequency nonlinearity and linewidth, the system is no longer limited to linear sweep frequency conditions, achieving improved sensing distance and dynamic response while maintaining a certain level of resolution. Simultaneously, a polarization diversity collection system is employed to enable coherent measurement of signals in two orthogonal directions. A fusion algorithm is used to fuse and superimpose the signals from the two orthogonal directions, ensuring that changes in the polarization state of scattered light along the fiber direction do not cause signal attenuation in coherent measurements, thus solving the problem of signal polarization attenuation. The system utilizes a weighted frequency division multiplexing algorithm to perform optimal matching phase search and optimal superposition weighting algorithms on optical signals from different frequency bands for vector phase matching and weighted vector superposition, thereby improving the signal-to-noise ratio, reducing the probability of dead zones and the risk of demodulation failure, and thus solving the problem of signal coherence attenuation.

[0046] This application describes a distributed optical fiber sensing system using an anti-conjugate convolution algorithm. By measuring the probe pulse signal and performing anti-conjugate convolution with the return signal, it achieves signal detection of strain, suppresses the effects of linewidth and sweep frequency nonlinearity, and improves detection resolution. Through a polarization diversity collection system and a frequency division multiplexing weighted superposition algorithm, it suppresses polarization and coherence attenuation of the signal. Compared to traditional OFDR systems, this system and algorithm can suppress the effects of sweep frequency nonlinearity and linewidth, extend the distance limitation of OFDR detection, and flexibly control the conjugate relationship between the signal-to-noise ratio and resolution of the probe signal through corresponding algorithms, enabling the system to adapt to different application scenarios. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the overall system structure of the present invention;

[0048] Among them, 10-narrow linewidth laser; 11-first beam splitter; 12-second beam splitter; 20-optical modulation system; 21-intensity modulator; 22-arbitrary waveform generator; 23-DC power supply; 24-optical filter; 25-injection locking system; 26-first polarization controller; 27-distributed feedback laser; 28-second circulator; 29-beam splitter; 30-probe fiber; 31-fiber amplifier; 32-first circulator; 33-single-mode fiber; 40-polarization diversity collection system; 41-second polarization controller; 42-polarization diversity collector; 43-first balanced photodetector; 44-second balanced photodetector; 45-polarization-maintaining fiber beam splitter; 46-first polarization beam splitter; 47-second polarization beam splitter; 48-first 2×2 coupler; 50-probe pulse signal measurement system; 51-second 2×2 coupler; 52-third balanced photodetector; 60-signal processing system;

[0049] Figure 2 This is a schematic diagram of the polarization diversity collection system and a block diagram of its signal fusion algorithm principle;

[0050] Figure 2 (a) is a schematic diagram of the polarization diversity collection system; (b) is a block diagram of the fusion algorithm.

[0051] Figure 3 This is a flowchart of the anti-conjugate convolution algorithm. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0053] like Figure 1 As shown, the present invention discloses a distributed optical fiber sensing system based on an anti-conjugate convolution algorithm, comprising a narrow linewidth laser 10, an optical modulation system 20, a probe optical fiber 30, a polarization diversity collection system 40, a probe pulse signal measurement system 50, and a signal processing system 60.

[0054] The single-frequency laser emitted by the narrow-linewidth laser 10 enters different systems twice, through the first beam splitter and the second beam splitter respectively; the optical modulation system 20 modulates the intensity of the single-frequency laser through the intensity modulator 21, and then enters the optical filter 24 and the injection locking system 25 to complete the frequency modulation of the laser; the probe fiber 30 transmits the probe pulse sequentially through the fiber amplifier 31, the first circulator 32, and the single-mode fiber 33, and the return light of the probe pulse enters the polarization diversity collection system 40 through the first circulator 32; the polarization diversity collection system 40 is divided into a local oscillator optical path and a signal optical path, one beam of the narrow-linewidth laser as the local oscillator light sequentially enters the second polarization controller 41 and the polarization diversity collector 42, while the signal... The return light enters the polarization diversity collector 42. After interference between the local oscillator light and the signal light with different polarization directions, they enter the first balanced photodetector 43 and the second balanced photodetector 44 respectively. The probe pulse signal measurement system 50 causes the probe pulse and the narrow linewidth laser to interfere and enter the second 2×2 coupler 51 and the third balanced photodetector 52 in sequence. The signal processing system 60 fuses the two acquired return light signals with different polarization directions and performs bandpass filtering. The probe pulse signal is frequency shifted to obtain the amplitude and deconvoluted to obtain the phase, and then fused into the conjugate signal of the probe pulse. This convolution is performed with the bandpass filtered return light signal, and finally a frequency division multiplexing algorithm with weighted superposition is used to obtain the data.

[0055] The narrow linewidth laser 10 enters the first beam splitter 11, one path of which serves as a probe pulse source, and the other path enters the second beam splitter 12, with the two paths serving as the local oscillator sources for the polarization diversity collection system 40 and the probe pulse signal measurement system 50, respectively.

[0056] The optical modulation system 20 includes an intensity modulator 21, an optical filter 24, and an injection locking system 25 arranged in sequence; wherein the intensity modulator 21 is controlled by an arbitrary waveform generator 22 and supplied with the required voltage by a DC power supply 23, and is used to modulate a narrow linewidth laser and output it in the form of pulses, which then enter the optical filter 24 and the injection locking system 25 in sequence to complete the frequency modulation of the laser.

[0057] The detection fiber 30 includes a fiber amplifier 31, a first circulator 32, and a single-mode fiber 33 arranged in sequence; wherein the fiber amplifier 31 amplifies the power of the detection pulse light and enters the single-mode fiber 33 through the first circulator 32; due to the random fluctuation of the refractive index of the fiber, the scattering phenomenon occurs, and the scattered light enters the polarization diversity collection system 40 through the first circulator 32.

[0058] The polarization diversity collection system 40 includes a second polarization controller 41, a polarization diversity collector 42, a first balanced photodetector 43, and a second balanced photodetector 44 arranged sequentially. The second polarization controller 41 is used to control the polarization state of the local oscillator light. The polarization diversity collection system interferes with the local oscillator light in two orthogonal directions simultaneously before the signal light enters the first balanced photodetector 43 and the second balanced photodetector 44, thereby performing coherent measurements simultaneously to avoid signal polarization attenuation caused by polarization mismatch between the local oscillator light and the signal light. The polarization diversity collector 42 includes a polarization-maintaining fiber beamsplitter 45, a first polarization beamsplitter 46, a second polarization beamsplitter 47, and a first 2×2 coupler 48. First, the local oscillator light and the return signal enter the polarization-maintaining fiber beamsplitter 45 to form two beams of signal light with the same polarization state. Then, these two beams are coupled into the first polarization beamsplitter 46 and the second polarization beamsplitter 47 to form two beams of interference signal light with orthogonal polarization states. Finally, these two beams of orthogonal polarized light enter the first 2×2 fiber coupler 48 for coupling and distribution, providing two beams of coupled signal light with orthogonal phases for subsequent entry into the first balanced photodetector 43 and the second balanced photodetector 44. The system structure is as follows: Figure 2 As shown in (a) above, the specific fusion algorithm is as follows: Figure 2 As shown in (b) of the diagram.

[0059] The detection pulse signal measurement system 50 includes a second 2×2 coupler 51 and a third balanced photodetector 52 arranged in sequence; it uses a narrow linewidth laser as the local oscillator light and the detection pulse as the signal light to perform coherent measurement for subsequent data extraction and compensation processing.

[0060] The signal processing system 60 includes an algorithm for extracting the inverse conjugate signal of the probe pulse, an inverse convolution algorithm, and a weighted frequency division multiplexing algorithm. The probe pulse is multiplied by a frequency shift coefficient to obtain its amplitude, and its phase is obtained by deconvolution. After fusion, the inverse conjugate signal of the probe pulse is extracted through a frequency selection network. The return signal is then convolved with the inverse conjugate signal after passing through the frequency selection network to obtain the compensated return signal. The compensated return signal is then output through the weighted frequency division multiplexing algorithm, thereby suppressing the problem of coherent fading. The specific algorithm flow is as follows: Figure 3 As shown.

[0061] The distributed optical fiber sensing system based on the anti-conjugate convolution algorithm described above includes the following construction steps:

[0062] Step 1: Connect the narrow linewidth laser 10 sequentially to the first beamsplitter 11 and the second beamsplitter 12. One path serves as the probe pulse source, and the other path enters the second beamsplitter 12. These two paths serve as the local oscillator sources for the polarization diversity collection system 40 and the probe pulse signal measurement system 50, respectively. Connect one optical path from the first beamsplitter 11 to the intensity modulator 21, which is controlled by the arbitrary waveform generator 22. Connect the optical path from the intensity modulator 21 to the optical filter 24, which is then connected to the injection locking system 25. Specifically, it is first connected to the first polarization controller 26 and then to the transmitting port of the second circulator 28. Connect the receiving port of the second circulator 28 to the distributed feedback laser 27, and connect the output of the second circulator 28 to the third beamsplitter 29.

[0063] Step 2: Based on completing Step 1, connect one of the optical paths of the third beam splitter 29 to the transmitting end of the fiber amplifier 31 and the first circulator 32 in sequence, connect the receiving end of the first circulator 32 to the single-mode fiber, and connect its output end to the polarization diversity collection system 40.

[0064] Step 3: After completing Steps 1 and 2, connect one path of the second beam splitter 12 to the second polarization controller 41 and then to the local oscillator receiver of the polarization diversity collector 42. Connect the output of the first circulator 32 to the signal receiver of the polarization diversity collector 42. Connect both paths to the first balanced photodetector 43 and the second balanced photodetector 44, and then to the signal processing system 60. Simultaneously, connect the other beam path of the second beam splitter 12 and one beam path of the third beam splitter 29 sequentially to the second 2×2 coupler 51 and the third balanced photodetector 52, and then to the signal processing system 60.

[0065] Step 4: The acquired probe pulse signal is divided into two paths for simultaneous processing. One path multiplies the probe pulse signal by a frequency shift coefficient and obtains its amplitude signal through Fourier transform. The other path performs a deconvolution operation on the probe pulse signal and obtains its phase signal through Fourier transform. The amplitude signal and phase signal are fused and then filtered out by a frequency selection network to obtain the anti-conjugate signal of the probe signal, which is used as the convolution kernel of the anti-conjugate convolution algorithm.

[0066] Step 5: The two orthogonal interference signals are obtained by a fusion algorithm to obtain a fused return signal, and this signal is then bandpass filtered by a frequency selection network. The fused return signal is convolved with the anti-conjugate signal to obtain a compensated return signal, and a frequency division multiplexing algorithm with weighted superposition is used to suppress the coherent attenuation of the signal.

[0067] When the laser emitted by the narrow-linewidth laser passes through the intensity modulation system, its intensity is modulated. The modulated laser then undergoes bandpass frequency selection via a laser filter before entering the injection-locked system, achieving wide-range frequency modulation. A portion of the frequency-modulated laser light is amplified and enters the probe fiber as a probe pulse to form a measurement return signal, while the remaining portion enters the probe pulse signal measurement system. The measurement return signal passes through a circulator and enters the polarization diversity collection system, where it undergoes interferometry with the narrow-linewidth laser to suppress polarization attenuation. The probe pulse signal enters the probe pulse signal measurement system, where it undergoes interferometry with the return signal simultaneously, and then enters the processing system. An anti-conjugate convolution algorithm is used to suppress the linewidth and sweep frequency modulation nonlinearities of the laser. This invention's system, by measuring the probe pulse signal and performing anti-conjugate convolution with the return signal, achieves the detection of strain signals and suppresses the effects of linewidth and sweep frequency nonlinearities, while also improving detection resolution. The polarization diversity collection system and the frequency division multiplexing weighted superposition algorithm further suppress polarization and coherence attenuation of the signal. Compared to traditional OFDR systems, this system and its algorithm can suppress the effects of sweep frequency nonlinearity and linewidth, extend the detection distance of OFDR, and flexibly control the conjugate relationship between the signal-to-noise ratio and resolution of the detected signal through corresponding algorithms, so as to adapt the system to different application scenarios.

[0068] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A distributed optical fiber sensing system based on an anti-convolution algorithm, characterized in that: The system comprises a narrow linewidth laser (10), an optical modulation system (20), a probe optical fiber (30), a polarization diversity collection system (40), a probe pulse signal measurement system (50), and a signal processing system (60); wherein, The narrow linewidth laser (10) divides the laser into two paths through a first beam splitter (11), one of which enters the optical modulation system (20), and the other of which is divided into two beams through a second beam splitter (12) to serve as the local oscillator light source of the polarization diversity collection system (40) and the probe pulse signal measurement system (50); The optical modulation system (20) is configured to frequency modulate the input laser and form a probe light pulse; The probe optical fiber (30) comprises a fiber amplifier (31), a first circulator (32), and a single-mode optical fiber (33), the probe light pulse is amplified by the fiber amplifier (31) and then enters the single-mode optical fiber (33) through the first circulator (32), and the scattered back light enters the polarization diversity collection system (40) through the first circulator (32); The polarization diversity collection system (40) is configured to interfere the scattered back light with different polarization directions with the local oscillator light for polarization fading suppression; the polarization diversity collection system (40) comprises a second polarization controller (41), a polarization diversity collector (42), a first balanced photodetector (43), and a second balanced photodetector (44); The probe pulse signal measurement system is configured to interfere the probe pulse signal with the local oscillator light; The signal processing system (60) is configured to process the probe pulse signal and the back light signal, and compensate and optimize the back light signal through the deconvolution algorithm and the weight superposition frequency division multiplexing algorithm to suppress the sweep frequency nonlinearity, the laser linewidth influence, and the signal fading; The deconvolution algorithm comprises: The deconvolution algorithm comprises: The back light signal fusion algorithm: the two back light signals with orthogonal polarization directions obtained by the polarization diversity collection system (40) are fused, and are filtered through a frequency selection network for filtering processing, which is used to suppress the polarization fading of the signal caused by the change of the polarization state in the optical fiber; The back light signal after fusion is convolved with the deconvolution signal of the probe signal to obtain the compensated back light signal.

2. The distributed optical fiber sensing system based on the anti-convolution algorithm of claim 1, wherein: The weight superposition frequency division multiplexing algorithm is configured to select frequency, weight phase matching, and weight vector superposition for the compensated back light signal to suppress the coherent fading.

3. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 1, wherein: The optical modulation system (20) comprises an intensity modulator (21), an arbitrary waveform generator (22), a direct current power supply (23), an optical filter (24), and an injection locking system (25); The intensity modulator (21) is controlled by the arbitrary waveform generator (22) and is configured to intensity modulate the input laser to form an optical pulse; The optical filter (24) is configured to perform band-pass selection on the modulated optical pulse. The injection locking system (25) is configured to perform frequency modulation on the optical pulse.

4. The distributed optical fiber sensing system based on the deconvolution algorithm according to claim 1, wherein: The second polarization controller (41) is configured to control the polarization state of the local light; The polarization diversity collector (42) is configured to simultaneously interfere the signal light in two orthogonal directions with the local light; The first balanced photodetector (43) and the second balanced photodetector (44) are both configured to convert the interference signal into an electrical signal.

5. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 1, wherein: The probe pulse signal measurement system (50) comprises a second 2x2 coupler (51) and a third balanced photodetector (52); wherein, The second 2x2 coupler (51) is configured to interfere the probe pulse signal with the local light; The third balanced photodetector (52) is configured to convert the interference signal into an electrical signal.

6. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 1, wherein: The polarization diversity collector system (40) and the probe pulse signal measurement system (50) both interfere the laser emitted by the narrow linewidth laser (10) as the local light.

7. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 1, wherein: The signal processing system (60) realizes the suppression of the laser linewidth and the sweep modulation nonlinearity through the deconvolution algorithm, and improves the signal signal-to-noise ratio and resolution through the weight superposition frequency division multiplexing algorithm.

8. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 1, wherein: The signal processing system (60) realizes the detection of the strain signal in the distributed optical fiber sensing system through the deconvolution algorithm and the weight superposition frequency division multiplexing algorithm, and flexibly controls the conjugate relationship between the signal-to-noise ratio and the resolution.

9. The distributed optical fiber sensing system based on the deconvolution algorithm of claim 3, wherein: The injection locking system (25) comprises a first polarization controller (26), a distributed feedback laser (27) and a second circulator (28), and is configured to realize large range frequency modulation of the laser.

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