A distributed acoustic wave sensing system based on optical neural network and all-optical integration method

Abstract

This invention discloses a distributed acoustic wave sensing system and all-optical integration method based on an optical neural network, relating to the fields of fiber optic sensing and artificial intelligence. The system comprises a DAS optical path integration component, an external connection component, and a signal processing integrated chip. The system combines an integrated optical delay line, a quasi-three-port detection structure, and a pure optical neural network module to achieve all-optical integration of the DAS sensing system and pure optical signal processing. This system offers advantages such as reduced photoelectric conversion, enhanced parallel processing capabilities, increased processing speed, reduced energy consumption, improved system stability, and a simplified system architecture.

Description

Technical Field

[0001] The present invention relates to the fields of optical fiber sensing technology and artificial intelligence technology, and in particular to a distributed acoustic wave sensing system based on an optical neural network and an all-optical integration method. Background Art

[0002] Distributed acoustic sensing (DAS) uses a narrow-linewidth laser to emit continuous light, which is pulse-modulated and then transmitted through a sensing fiber. Photodetectors analyze the Rayleigh backscattered (RBS) signal generated by the sensing fiber, leveraging principles such as phase shifts and interference effects to monitor and locate subtle events and changes in the fiber, thereby transforming the fiber network into a continuous, high-resolution acoustic and vibration monitoring system. With its many advantages, including high sensitivity, high accuracy, fast response, wide coverage, and real-time monitoring, DAS is widely used in oil and gas exploration, pipeline and cable monitoring, perimeter security, and other fields, possessing significant application value and promising prospects.

[0003] Traditional DAS sensing systems utilize a "photoelectric conversion + analog-to-digital conversion + digital signal processing" approach for signal processing. This requires the use of a series of electrical components, such as photodetectors, to assist in signal demodulation. The signal undergoes multiple conversions between light and electricity, each of which can introduce noise and distortion, degrading signal quality. Furthermore, electronic components operate slowly when large computational workloads or high precision are required, making them insufficient for applications requiring real-time, accurate responses. Furthermore, the introduction of photoelectric conversion complicates the overall system design and makes it susceptible to electromagnetic interference, significantly increasing maintenance costs and energy consumption while reducing system stability.

[0004] Optical Neural Networks (ONNs) are a technology that uses optical components rather than traditional electronic components to perform neural network operations. They exploit optical phenomena such as interference, diffraction, and nonlinear effects to perform weighted and activation function operations, simulating the computation and data processing of traditional neural networks. ONNs process and transmit signals in the form of light through optical components. Compared to neural network operations performed by traditional electronic components, ONNs offer advantages such as high speed, low latency, low energy consumption, and parallel processing capabilities. They hold great promise for application in fields such as artificial intelligence, image and signal processing, and quantum computing.

[0005] Therefore, it is an urgent problem for those skilled in the art to propose a distributed acoustic wave sensing system and an all-optical integration method based on optical neural networks to solve the difficulties existing in the existing technology. Summary of the Invention

[0006] In view of this, the present invention provides a long-distance, broadband-response distributed optical fiber acoustic wave sensing system and method based on photon integration to solve the problems existing in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A distributed acoustic wave sensing system based on optical neural network, comprising: a DAS optical path integrated part, an external part and a signal processing integrated chip; wherein,

[0009] The DAS optical path integration part includes: narrow linewidth laser, intensity modulator, and first optical amplifier;

[0010] The external parts include: circulator, sensing optical fiber;

[0011] The signal processing integrated chip includes: a second optical amplifier, a first coupler, an optical delay line, a second coupler, a third coupler, a first polarization beam splitter, a second polarization beam splitter, a fourth coupler, a fifth coupler, a sixth coupler, an information conversion module, a space-time signal combination module, a pure optical neural network module, and a photoelectric conversion and control module.

[0012] In the above system, optionally, the narrow linewidth laser, the intensity modulator, and the first optical amplifier in the DAS optical path integrated part are connected in sequence; the intensity modulator is connected to the first output terminal of the photoelectric conversion and control module of the signal processing integrated chip;

[0013] An output end of the first optical amplifier is connected to a first port of a circulator of the external part;

[0014] Narrow linewidth laser, used to output continuous narrow linewidth high coherence laser to the intensity modulator;

[0015] The intensity modulator is modulated by the photoelectric conversion and control module to modulate the continuous detection light input by the narrow linewidth laser into pulsed detection light and output it to the first optical amplifier;

[0016] The first optical amplifier is used to amplify the power of the pulsed detection light modulated by the intensity modulator and output the amplified power to the first port of the circulator.

[0017] In the above system, optionally, in the external part, the second port of the circulator is connected to the sensing optical fiber, and the third port of the circulator is connected to the input end of the second optical amplifier of the signal processing integrated chip;

[0018] A circulator, configured to output the pulsed detection light received by the first port of the circulator from the second port of the circulator to the sensing optical fiber, and output the Rayleigh backscattered light (RBS) signal received by the second port of the circulator from the third port of the circulator to the second optical amplifier of the signal processing integrated chip;

[0019] The sensing optical fiber is used to receive the pulsed detection light input from the second port of the circulator and generate a Rayleigh backscattered light RBS signal.

[0020] In the above system, optionally, the first coupler, optical delay line, second coupler, third coupler, first polarization beam splitter, second polarization beam splitter, fourth coupler, fifth coupler, and sixth coupler in the signal processing integrated chip constitute a temperature control and vibration isolation module.

[0021] Optionally, the above system includes a second optical amplifier configured to amplify the Rayleigh backscattered light (RBS) signal input from the third port of the circulator and output the amplified signal to the first coupler of the temperature control and vibration isolation module.

[0022] In the above system, optionally, the first coupler is configured to split the optical signal inputted by the second optical amplifier into two paths, one path being outputted from the first output port of the first coupler to the second coupler, and the other path being outputted from the second output port of the first coupler to the optical delay line;

[0023] an optical delay line, configured to transmit an optical signal input from the second output port of the first coupler to a third coupler while eliminating multipath interference and achieving phase matching and timing synchronization;

[0024] a second coupler, configured to split the optical signal input from the first output port of the first coupler into three paths, one path outputting from the first output port of the second coupler to the first polarization beam splitter, one path outputting from the second output port of the second coupler to the fifth coupler, and one path outputting from the third output port of the second coupler to the second polarization beam splitter;

[0025] a third coupler, configured to split the optical signal input from the optical delay line into three paths, one path outputting from the first output port of the third coupler to the fourth coupler, one path outputting from the second output port of the third coupler to the fifth coupler, and one path outputting from the third output port of the third coupler to the sixth coupler;

[0026] a first polarization beam splitter, configured to transmit the optical signal input from the first output port of the second coupler to the fourth coupler while generating a 2π3 phase shift;

[0027] a second polarization beam splitter, configured to transmit the optical signal input from the third output port of the second coupler to the sixth coupler while generating a 4π3 phase shift;

[0028] a fourth coupler, configured to couple the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and output the coupled optical signal to the first input port of the information conversion module;

[0029] a fifth coupler, configured to couple the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and output the coupled optical signal to the second input port of the information conversion module;

[0030] The sixth coupler is used to couple the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and output the optical signal to the third input port of the information conversion module.

[0031] The above system may optionally include an information conversion module configured to convert the light intensity signals inputted by the fourth coupler, the fifth coupler, and the sixth coupler into phase signals, and output the phase signals to the spatiotemporal signal combination module;

[0032] The spatiotemporal signal combination module is controlled by the photoelectric conversion and control module and is used to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module;

[0033] The pure optical neural network module is used to identify and classify the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module and output it to the photoelectric conversion and control module;

[0034] The photoelectric conversion and control module receives an external trigger signal Trigger, is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the time information, position information, and event information input by the pure optical neural network module into electrical signal output.

[0035] In the above-mentioned system, optionally, the pure optical neural network is implemented using a lookup table, wherein the optical memory is composed of a non-volatile waveguide phase shifter; the signal of the pure optical neural network module is an analog optical signal, which is a time-space two-dimensional graph, and the phase information is represented by intensity.

[0036] In the above system, optionally, the first optical amplifier and the second optical amplifier are semiconductor optical amplifiers.

[0037] An all-optical integration method for a distributed acoustic wave sensing system based on an optical neural network, applied to any of the above-mentioned distributed acoustic wave sensing systems based on an optical neural network, comprises the following steps:

[0038] S1. The narrow-linewidth laser transmits continuous narrow-linewidth high-coherence laser light to the intensity modulator. The intensity modulator is modulated by the photoelectric conversion and control module, modulates the continuous detection light input by the narrow-linewidth laser into pulsed detection light, and outputs it to the first optical amplifier. The first optical amplifier amplifies the power of the pulsed detection light modulated by the intensity modulator and outputs it to the first port of the circulator.

[0039] S2, the circulator outputs the pulsed detection light input to the first port from the second port to the sensing fiber, and outputs the Rayleigh backscattered light RBS signal received at the second port from the third port to the second optical amplifier;

[0040] S3, the second optical amplifier amplifies the Rayleigh backscattered light (RBS) signal input from the third port of the circulator and outputs it to the first coupler. The first coupler splits the optical signal input from the optical amplifier into two paths, one path output from the first output port of the first coupler to the second coupler, and the other path output from the second output port of the first coupler to the optical delay line. The optical delay line transmits the optical signal input from the second output port of the first coupler to the third coupler, while eliminating multipath interference and achieving phase matching and timing synchronization.

[0041] S4. The second coupler splits the optical signal input from the first output port of the first coupler into three paths, one path is output from the first output port of the second coupler to the first polarization beam splitter, one path is output from the second output port of the second coupler to the fifth coupler, and one path is output from the third output port of the second coupler to the second polarization beam splitter; the first polarization beam splitter transmits the optical signal input from the first output port of the second coupler to the fourth coupler, while generating a 2π3 phase shift; the second polarization beam splitter transmits the optical signal input from the third output port of the second coupler to the sixth coupler, while generating a 4π3 phase shift; the third coupler splits the optical signal input from the optical delay line into three paths, one path is output from the first output port of the third coupler to the fourth coupler, one path is output from the second output port of the third coupler to the fifth coupler, and one path is output from the third output port of the third coupler to the sixth coupler;

[0042] S5, the fourth coupler couples the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and outputs the optical signal to the information conversion module; the fifth coupler couples the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and outputs the optical signal to the information conversion module; the sixth coupler couples the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and outputs the optical signal to the information conversion module;

[0043] S6, the information conversion module converts the light intensity signals input by the fourth coupler, the fifth coupler, and the sixth coupler into phase signals, and outputs the phase signals to the spatiotemporal signal combination module;

[0044] S7, the spatiotemporal signal combination module is controlled by the photoelectric conversion and control module to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module;

[0045] S8, the pure optical neural network module identifies and classifies the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module, and then outputs it to the photoelectric conversion and control module;

[0046] S9, the photoelectric conversion and control module receives an external trigger signal Trigger, which is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the time information, position information, and event information input by the pure optical neural network module into electrical signal output.

[0047] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a distributed acoustic wave sensing system and an all-optical integration method based on an optical neural network, which has the following beneficial effects:

[0048] 1) Adopting full optical path design to eliminate a series of losses caused by photoelectric conversion, improve system stability and simplify system architecture;

[0049] 2) Use pure optical neural networks (ONN) for signal recognition and classification, enhance parallel processing capabilities, increase data processing speed, and increase data processing capacity;

[0050] 3) By adopting the method of all-optical integration, the overall system volume and weight can be reduced, the system power consumption can be reduced, and the system durability and reliability can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0052] Figure 1 This is a structural block diagram of a distributed acoustic wave sensing system based on optical neural network disclosed in the present invention;

[0053] Figure 2 This is a flow chart of a possible method 1 for implementing the information conversion module, spatiotemporal signal combination module, and pure optical neural network module disclosed in the present invention;

[0054] Figure 3 This is a structural diagram of the three-input lookup table in the second method that may be implemented by the information conversion module, spatiotemporal signal combination module, and pure optical neural network module of the present invention;

[0055] Figure 4 The cross-sectional structure diagram of the non-volatile waveguide phase shifter of FEBTO crystal integrated with optical memory in ONN disclosed by the present invention;

[0056] Figure 5 The present invention discloses an all-optical integration method for a distributed acoustic wave sensing system based on an optical neural network. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] In this application, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or apparatus comprising the element.

[0059] See also Figure 1 As shown, the present invention discloses a distributed acoustic wave sensing system based on optical neural network, including: DAS optical path integrated part, external part and signal processing integrated chip; wherein,

[0060] The DAS optical path integration part includes: narrow linewidth laser, intensity modulator, and first optical amplifier;

[0061] The external part includes: circulator, sensor fiber; the first port of the circulator Figure 1 Indicated by a, the second port of the circulator Figure 1 Indicated by b, the third port of the circulator Figure 1 Indicated by c;

[0062] The signal processing integrated chip includes: a second optical amplifier, a first coupler, an optical delay line, a second coupler, a third coupler, a first polarization beam splitter, a second polarization beam splitter, a fourth coupler, a fifth coupler, a sixth coupler, an information conversion module, a spatiotemporal signal combination module, a pure optical neural network module ONN, and a photoelectric conversion and control module;

[0063] First polarization beam splitter Figure 1 Indicated by PS1, the second polarization beam splitter Figure 1 Indicated by PS2.

[0064] Furthermore, the narrow linewidth laser, intensity modulator, and first optical amplifier in the DAS optical path integration part are connected in sequence; the intensity modulator is connected to the first output terminal of the photoelectric conversion and control module of the signal processing integrated chip;

[0065] An output end of the first optical amplifier is connected to a first port of a circulator of the external part;

[0066] Narrow linewidth laser, used to output continuous narrow linewidth high coherence laser to the intensity modulator;

[0067] The intensity modulator is modulated by the photoelectric conversion and control module to modulate the continuous detection light input by the narrow linewidth laser into pulsed detection light and output it to the first optical amplifier;

[0068] The first optical amplifier is used to amplify the power of the pulsed detection light modulated by the intensity modulator and output the amplified power to the first port of the circulator.

[0069] Specifically, the narrow linewidth laser has a wavelength of 1550nm and a linewidth of 100kHz. Due to the limited coherence length, the autocorrelation structure of the present invention is required for phase demodulation. This design fully considers the core components with limited performance in current optoelectronic integration.

[0070] Furthermore, in the external connection part, the second port of the circulator is connected to the sensing optical fiber, and the third port of the circulator is connected to the input end of the second optical amplifier of the signal processing integrated chip;

[0071] A circulator, configured to output the pulsed detection light received by the first port of the circulator from the second port of the circulator to the sensing optical fiber, and output the Rayleigh backscattered light (RBS) signal received by the second port of the circulator from the third port of the circulator to the second optical amplifier of the signal processing integrated chip;

[0072] The sensing optical fiber is used to receive the pulsed detection light input from the second port of the circulator and generate a Rayleigh backscattered light RBS signal.

[0073] Furthermore, the first coupler, optical delay line, second coupler, third coupler, first polarization beam splitter, second polarization beam splitter, fourth coupler, fifth coupler, and sixth coupler in the signal processing integrated chip form a temperature-controlled vibration isolation module. This module significantly reduces the impact of external temperature and vibration on system stability.

[0074] Furthermore, the second optical amplifier is used to amplify the Rayleigh backscattered light RBS signal input from the third port of the circulator and output it to the first coupler of the temperature control and vibration isolation module.

[0075] Furthermore, the first coupler is used to split the optical signal input from the second optical amplifier into two paths, one path is output from the first output port of the first coupler to the second coupler, and the other path is output from the second output port of the first coupler to the optical delay line;

[0076] an optical delay line, configured to transmit an optical signal input from the second output port of the first coupler to a third coupler while eliminating multipath interference and achieving phase matching and timing synchronization;

[0077] a second coupler, configured to split the optical signal input from the first output port of the first coupler into three paths, one path outputting from the first output port of the second coupler to the first polarization beam splitter, one path outputting from the second output port of the second coupler to the fifth coupler, and one path outputting from the third output port of the second coupler to the second polarization beam splitter;

[0078] a third coupler, configured to split the optical signal input from the optical delay line into three paths, one path outputting from the first output port of the third coupler to the fourth coupler, one path outputting from the second output port of the third coupler to the fifth coupler, and one path outputting from the third output port of the third coupler to the sixth coupler;

[0079] a first polarization beam splitter, configured to transmit an optical signal input from the first output port of the second coupler to a fourth coupler while generating a stable 2π3 phase shift;

[0080] a second polarization beam splitter, configured to transmit the optical signal input from the third output port of the second coupler to the sixth coupler, while generating a stable 4π3 phase shift;

[0081] a fourth coupler, configured to couple the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and output the coupled optical signal to the first input port of the information conversion module;

[0082] a fifth coupler, configured to couple the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and output the coupled optical signal to the second input port of the information conversion module;

[0083] The sixth coupler is used to couple the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and output the optical signal to the third input port of the information conversion module.

[0084] Specifically, the length of the optical delay line needs to consider factors such as spatial resolution, system bandwidth, delay line loss, and system stability. Based on the above-mentioned all-optical integration method of a distributed acoustic wave sensing system based on an optical neural network, if the spatial resolution of the system is 10m, the intensity modulator pulse width should be 50ns, and if the required maximum delay time is 100ns, the length of the optical delay line should be 20m. The current practices of optical delay lines include optical waveguide delay lines, optical fiber external connections, and integrated delay lines, among which the average size of optical waveguide delay lines is basically 50cm 2 Above, the size of the external optical fiber is generally several hundred cm 3 , and the integrated optical delay line is only a few cm 2 , small in size, but its loss is extremely large and cannot be used in practice.

[0085] The design of the optical delay line in the system can adopt an optimal solution, which is to achieve delay by making a microring resonator on a low-loss silicon nitride waveguide. When the wavelength of the optical signal meets the resonance condition of the ring optical waveguide, the optical signal will circulate in the ring optical waveguide, thereby achieving the delay effect. In order to reduce losses, multiple microring resonators are connected in series. The total length of the delay line is 20m, and the loss sources include waveguide loss, coupling loss, bending loss and amplification loss, totaling approximately 240dB. Then, a pump light source is added, and the delay line is divided into 20 sections. SOAs are added at the connection position of each section. Each SOA can provide 12dB of gain, thereby offsetting the loss and achieving a balance between gain and attenuation.

[0086] Based on the above-mentioned all-optical integration method for a distributed acoustic wave sensing system based on an optical neural network, if the spatial resolution of the system is 10m, the intensity modulator pulse width should be 50ns. If the required maximum delay time is 100ns, the length of the optical delay line should be 20m. The design of the optical delay line in this system can adopt an optimal solution. Under the premise of silicon-based integration, multiple microring resonators are cascaded, where each microring resonator is an erbium-doped microring resonator. By adjusting the pump light power and ring size, the design is optimized to ensure that the optical path length of each microring resonator is 1cm, the gain is 2dB, and the total attenuation of each microring resonator is 2dB. In addition, multiple pump light sources are distributed throughout the delay line to ensure that each microring resonator receives appropriate pump power. Ultimately, 2000 microrings are required to achieve the desired delay distance and actual gain-attenuation balance.

[0087] Furthermore, an information conversion module is used to convert the light intensity signals input by the fourth coupler, the fifth coupler and the sixth coupler into phase signals and output them to the spatiotemporal signal combination module;

[0088] The spatiotemporal signal combination module is controlled by the photoelectric conversion and control module and is used to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module ONN;

[0089] The pure optical neural network module ONN is used to identify and classify the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module and output it to the photoelectric conversion and control module;

[0090] The photoelectric conversion and control module receives an external trigger signal Trigger, is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the time information, position information, and event information input by the pure optical neural network module ONN into electrical signal output.

[0091] Furthermore, the pure optical neural network (ONN) is implemented using a lookup table, where the optical memory consists of non-volatile waveguide phase shifters. The ONN module's signal is an analog optical signal, a two-dimensional time-space graph, with intensity representing phase information. The ONN performs signal recognition and classification, enhancing parallel processing capabilities, increasing data processing speed, and increasing data processing capacity.

[0092] See also Figure 2 As shown, the first method for implementing the information conversion module, the spatiotemporal signal combination module, and the pure optical neural network module includes the following steps:

[0093] Step 1: The information conversion module and the spatiotemporal signal combination module are composed of an optical neural network. The input information is the three analog light intensity information representing the phase output by the three-port structure, and the output information is a analog light intensity signal representing the optical phase.

[0094] Step 2: The pure optical neural network module is composed of multiple microring resonators, which are connected through couplers to realize nonlinear signal processing and feature extraction, and finally classify and identify the processed signals.

[0095] See also Figure 3 As shown, the second method that may be implemented by the information conversion module, the spatiotemporal signal combination module, and the pure optical neural network module includes the following steps:

[0096] Step 1: The information conversion module, spatiotemporal signal combination module, and pure optical neural network module are implemented using a lookup table (LUT), where the optical memory uses an optical on-chip memory made of non-volatile materials. The lookup table is specifically a three-input lookup table, in which the three analog optical signals input use intensity to represent the phase information. After passing through the lookup table, an analog optical intensity signal representing the optical phase is output. The cross-sectional structure of the non-volatile waveguide phase shifter integrated with FEBTO crystal is shown in the figure. Figure 4 As shown, the phase shifter can be used as a basic building block of photonic memory.

[0097] Step 2: The obtained simulated light intensity signal representing the light phase enters the pure optical neural network module for final classification and recognition.

[0098] Furthermore, the first optical amplifier and the second optical amplifier are semiconductor optical amplifiers SOA.

[0099] and Figure 1 Corresponding to the system, the present invention also discloses an all-optical integration method of a distributed acoustic wave sensing system based on an optical neural network, which is applied to any of the above-mentioned distributed acoustic wave sensing systems based on an optical neural network. For specific steps, see Figure 5 As shown:

[0100] S1. The narrow-linewidth laser transmits continuous narrow-linewidth high-coherence laser light to the intensity modulator. The intensity modulator is modulated by the photoelectric conversion and control module, modulates the continuous detection light input by the narrow-linewidth laser into pulsed detection light, and outputs it to the first optical amplifier. The first optical amplifier amplifies the power of the pulsed detection light modulated by the intensity modulator and outputs it to the first port of the circulator.

[0101] S2, the circulator outputs the pulsed detection light input to the first port from the second port to the sensing fiber, and outputs the Rayleigh backscattered light RBS signal received at the second port from the third port to the second optical amplifier;

[0102] S3. The second optical amplifier amplifies the Rayleigh backscattered light (RBS) signal input from the third port of the circulator and outputs it to the first coupler. The first coupler uses a 1*2 optical coupler (splitting ratio of 50:50), which splits the optical signal input from the optical amplifier into two paths. One path is output from the first output port of the first coupler to the second coupler, and the other path is output from the second output port of the first coupler to the optical delay line. The length of the optical delay line is 20m. It transmits the optical signal input from the second output port of the first coupler to the third coupler, while eliminating multipath interference and achieving phase matching and timing synchronization.

[0103] S4. The second coupler adopts a 1*3 optical coupler (splitting ratio is 33:33:33), which divides the optical signal input from the output port 1 of the first coupler into three paths, one path is output from the first output port of the second coupler to the first polarization beam splitter, one path is output from the second output port of the second coupler to the fifth coupler, and one path is output from the third output port of the second coupler to the second polarization beam splitter; the first polarization beam splitter transmits the optical signal input from the first output port of the second coupler to the fourth coupler, and simultaneously generates a 2π3 phase shift; the second polarization beam splitter transmits the optical signal input from the third output port of the second coupler to the sixth coupler, and simultaneously generates a 4π3 phase shift; the third coupler adopts a 1*3 optical coupler (splitting ratio is 33:33:33), which divides the optical signal input from the optical delay line into three paths, one path is output from the first output port of the third coupler to the fourth coupler, one path is output from the second output port of the third coupler to the fifth coupler, and one path is output from the third output port of the third coupler to the sixth coupler;

[0104] S5, the fourth coupler couples the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and outputs the optical signal to the information conversion module; the fifth coupler couples the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and outputs the optical signal to the information conversion module; the sixth coupler couples the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and outputs the optical signal to the information conversion module;

[0105] S6, the information conversion module converts the light intensity signals input by the fourth coupler, the fifth coupler, and the sixth coupler into phase signals, and outputs the phase signals to the spatiotemporal signal combination module;

[0106] S7, the spatiotemporal signal combination module is controlled by the photoelectric conversion and control module to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module ONN;

[0107] S8, the pure optical neural network module ONN performs operations such as recognition and classification on the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module, and then outputs it to the photoelectric conversion and control module;

[0108] S9, the photoelectric conversion and control module receives an external trigger signal Trigger, which is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the three types of information of time, position, and event type input by the pure optical neural network module ONN into electrical signal output.

[0109] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0110] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A distributed acoustic wave sensing system based on optical neural network, characterized in that: include: DAS optical path integrated part, external part and signal processing integrated chip; among them, The DAS optical path integration part includes: narrow linewidth laser, intensity modulator, and first optical amplifier; The external parts include: circulator, sensing optical fiber; The signal processing integrated chip includes: a second optical amplifier, a first coupler, an optical delay line, a second coupler, a third coupler, a first polarization beam splitter, a second polarization beam splitter, a fourth coupler, a fifth coupler, a sixth coupler, an information conversion module, a spatiotemporal signal combination module, a pure optical neural network module, and a photoelectric conversion and control module; The narrow linewidth laser, intensity modulator, and first optical amplifier in the DAS optical path integration part are connected in sequence; the intensity modulator is connected to the first output terminal of the photoelectric conversion and control module of the signal processing integrated chip; An output end of the first optical amplifier is connected to a first port of a circulator of the external part; Narrow linewidth laser, used to output continuous narrow linewidth high coherence laser to the intensity modulator; The intensity modulator is modulated by the photoelectric conversion and control module to modulate the continuous narrow-linewidth high-coherence laser light input by the narrow-linewidth laser into a pulsed detection light and output it to the first optical amplifier; a first optical amplifier, configured to amplify the power of the pulsed detection light modulated by the intensity modulator and output the amplified power to the first port of the circulator; In the external connection part, the second port of the circulator is connected to the sensing optical fiber, and the third port of the circulator is connected to the input end of the second optical amplifier of the signal processing integrated chip; A circulator, configured to output the pulsed detection light received by the first port of the circulator from the second port of the circulator to the sensing optical fiber, and output the Rayleigh backscattered light (RBS) signal received by the second port of the circulator from the third port of the circulator to the second optical amplifier of the signal processing integrated chip; The sensing optical fiber is used to receive the pulsed detection light input from the second port of the circulator and generate a Rayleigh backscattered light RBS signal; The first coupler, the optical delay line, the second coupler, the third coupler, the first polarization beam splitter, the second polarization beam splitter, the fourth coupler, the fifth coupler, and the sixth coupler in the signal processing integrated chip constitute a temperature control and vibration isolation module; The second optical amplifier is used to amplify the Rayleigh backscattered light RBS signal input from the third port of the circulator and output it to the first coupler of the temperature control and vibration isolation module; a first coupler, configured to split the optical signal input from the second optical amplifier into two paths, one path being output from the first output port of the first coupler to the second coupler, and the other path being output from the second output port of the first coupler to the optical delay line; an optical delay line, configured to transmit an optical signal input from the second output port of the first coupler to a third coupler while eliminating multipath interference and achieving phase matching and timing synchronization; a second coupler, configured to split the optical signal input from the first output port of the first coupler into three paths, one path outputting from the first output port of the second coupler to the first polarization beam splitter, one path outputting from the second output port of the second coupler to the fifth coupler, and one path outputting from the third output port of the second coupler to the second polarization beam splitter; a third coupler, configured to split the optical signal input from the optical delay line into three paths, one path outputting from the first output port of the third coupler to the fourth coupler, one path outputting from the second output port of the third coupler to the fifth coupler, and one path outputting from the third output port of the third coupler to the sixth coupler; The first polarization beam splitter is used to transmit the optical signal input from the first output port of the second coupler to the fourth coupler, and generate Phase shift; The second polarization beam splitter is used to transmit the optical signal input from the third output port of the second coupler to the sixth coupler, and generate Phase shift; a fourth coupler, configured to couple the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and output the coupled optical signal to the first input port of the information conversion module; a fifth coupler, configured to couple the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and output the coupled optical signal to the second input port of the information conversion module; a sixth coupler, configured to couple the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and output the coupled optical signal to the third input port of the information conversion module; an information conversion module, configured to convert the light intensity signals inputted by the fourth coupler, the fifth coupler, and the sixth coupler into phase signals, and output the phase signals to the spatiotemporal signal combination module; The spatiotemporal signal combination module is controlled by the photoelectric conversion and control module and is used to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module; The pure optical neural network module is used to identify and classify the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module and output it to the photoelectric conversion and control module; The photoelectric conversion and control module receives an external trigger signal Trigger, is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the time information, position information, and event information input by the pure optical neural network module into electrical signal output.

2. A distributed acoustic wave sensing system based on optical neural network according to claim 1, characterized in that: The pure optical neural network is implemented using a lookup table, in which the optical memory is composed of non-volatile waveguide phase shifters; the signal of the pure optical neural network module is an analog light signal, which is a two-dimensional time-space graph, and the phase information is represented by intensity.

3. The distributed acoustic wave sensing system based on optical neural network according to claim 1, characterized in that: The first optical amplifier and the second optical amplifier are semiconductor optical amplifiers.

4. An all-optical integration method for a distributed acoustic wave sensing system based on an optical neural network, characterized in that: A distributed acoustic wave sensing system based on an optical neural network as claimed in any one of claims 1 to 3, comprising the following steps: S1. The narrow-linewidth laser transmits continuous narrow-linewidth, high-coherence laser light to the intensity modulator. The intensity modulator is modulated by the photoelectric conversion and control module, modulating the continuous narrow-linewidth, high-coherence laser light input from the narrow-linewidth laser into pulsed probe light and outputting it to the first optical amplifier. The first optical amplifier amplifies the power of the pulsed probe light modulated by the intensity modulator and outputs it to the first port of the circulator. S2, the circulator outputs the pulsed detection light input to the first port from the second port to the sensing fiber, and outputs the Rayleigh backscattered light (RBS) signal received at the second port from the third port to the second optical amplifier; S3. The second optical amplifier amplifies the Rayleigh backscattered light (RBS) signal input from the third port of the circulator and outputs it to the first coupler. The first coupler splits the optical signal input from the optical amplifier into two paths: one path is output from the first output port of the first coupler to the second coupler, and the other path is output from the second output port of the first coupler to the optical delay line. The optical delay line transmits the optical signal input from the second output port of the first coupler to the third coupler, while eliminating multipath interference and achieving phase matching and timing synchronization. S4. The second coupler divides the optical signal input from the first output port of the first coupler into three paths. One path is output from the first output port of the second coupler to the first polarization beam splitter, one path is output from the second output port of the second coupler to the fifth coupler, and one path is output from the third output port of the second coupler to the second polarization beam splitter. The first polarization beam splitter transmits the optical signal input from the first output port of the second coupler to the fourth coupler, and generates Phase shift; the second polarization beam splitter transmits the optical signal input from the third output port of the second coupler to the sixth coupler, and generates Phase shift; the third coupler divides the optical signal input from the optical delay line into three paths, one path is output from the first output port of the third coupler to the fourth coupler, one path is output from the second output port of the third coupler to the fifth coupler, and one path is output from the third output port of the third coupler to the sixth coupler; S5, the fourth coupler couples the optical signal input from the first polarization beam splitter and the optical signal input from the first output port of the third coupler, and outputs the optical signal to the information conversion module; the fifth coupler couples the optical signal input from the second output port of the second coupler and the optical signal input from the second output port of the third coupler, and outputs the optical signal to the information conversion module; the sixth coupler couples the optical signal input from the second polarization beam splitter and the optical signal input from the third output port of the third coupler, and outputs the optical signal to the information conversion module; S6, the information conversion module converts the light intensity signals input by the fourth coupler, the fifth coupler, and the sixth coupler into phase signals, and outputs them to the spatiotemporal signal combination module; S7, the spatiotemporal signal combination module is controlled by the photoelectric conversion and control module to integrate multiple sets of spatiotemporal two-dimensional phase signals input by the information conversion module to form an overall spatiotemporal two-dimensional phase signal, which is then transmitted to the pure optical neural network module; S8, the pure optical neural network module identifies and classifies the overall spatiotemporal two-dimensional phase signal input by the spatiotemporal signal combination module, and then outputs it to the photoelectric conversion and control module; S9, the photoelectric conversion and control module receives an external trigger signal Trigger, which is used to set the detection light pulse parameters, control the working status of the spatiotemporal signal combination module and the first intensity modulator, and convert the time information, position information, and event information input by the pure optical neural network module into electrical signal output.

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