Three-wavelength optical fiber Fabry-Perot acoustic sensor demodulation method and system based on phase compensation

Abstract

The invention discloses a three-wavelength optical fiber Fabry-Perot acoustic sensor demodulation method and system based on phase compensation, and the method comprises the steps: carrying out the full-spectrum scanning of an optical fiber Fabry-Perot acoustic sensor in response to a scanning mode working instruction, synchronously collecting light intensity data, obtaining the interference spectrum of the sensor, and calculating the initial cavity length of the sensor; obtaining output wavelengths of three paths of signals of the laser, obtaining initial phases corresponding to the three paths of signals, constructing two paths of orthogonal signals, and demodulating the cavity length variation; whether the cavity length variation exceeds a threshold value or not is judged, if yes, the initial cavity length of the sensor is updated, and phase orthogonality of the two paths of reconstructed signals is stabilized. According to the invention, the problem that the demodulation precision is reduced due to large cavity length variation in the traditional three-wavelength demodulation technology is solved, a phase compensation scheme is provided to realize the quadrature phase maintenance of the reconstructed signal, and the rapid demodulation of sensors with good stability, large dynamic range, high precision and different cavity lengths can be realized.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a demodulation method and system for a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation. Background Art

[0002] Different from electrical acoustic wave sensors, fiber optic ultrasonic sensors have the advantages of high sensitivity, small size, anti-electromagnetic interference, intrinsic safety, and remote measurement. They play an important role in acoustic sensing applications in special environments, such as high-voltage power equipment operating status monitoring, biomedical imaging, and remote audio monitoring under flammable and explosive or strong electromagnetic interference. Fiber optic Fabry-Perot acoustic sensor is an optical sensor with small size, high sensitivity, strong anti-electromagnetic interference ability, and remote measurement. However, the demodulation technology of fiber optic Fabry-Perot sensor is relatively complex, which limits its large-scale application and development.

[0003] The intensity demodulation method is a demodulation method that uses the linear segments of the interference sensor fringes to convert the change in the optical path difference of the sensor into the change in the intensity of the output light. This method has a fast response speed, but the orthogonal working point will be greatly offset by the interference of the external environment, thereby distorting the detected signal. In addition, the intensity demodulation method has a small detection dynamic range and is difficult to detect large sound pressure signals. The dual-wavelength and three-wavelength orthogonal phase demodulation technology is widely used due to its high frequency response, high sensitivity and large dynamic range. Among them, the three-wavelength orthogonal phase demodulation technology is more suitable for engineering applications because it does not need to calculate the DC component of the interference spectrum.

[0004] The traditional three-wavelength orthogonal phase demodulation method can only be used to demodulate the fiber Fabry-Perot acoustic sensor with a small change in cavity length. When the cavity length of the sensor changes greatly, the original phases between the three wavelengths will shift from the orthogonal relationship. In addition, the cavity length of the fiber Fabry-Perot acoustic sensor is easily affected by the external environment and changes, which in turn causes the phase difference between the three optical signals to change, reducing the demodulation accuracy of the traditional three-wavelength demodulation technology. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed. Therefore, the present invention provides a three-wavelength fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation to solve the problem that the demodulation accuracy of the traditional three-wavelength demodulation technology decreases due to the large change of cavity length.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a demodulation method for a three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation, comprising: in response to a scanning mode working instruction, performing a full spectrum scan on the fiber Fabry-Perot acoustic sensor, synchronously collecting light intensity data, obtaining an interference spectrum of the sensor, and calculating an initial cavity length of the sensor;

[0009] Based on the initial cavity length of the sensor, the output wavelengths of the three laser signals are obtained, the initial phases corresponding to the three signals are obtained, two orthogonal signals are constructed, and the cavity length variation is demodulated;

[0010] Based on the demodulation results, it is determined whether the cavity length change exceeds the threshold. If it exceeds the threshold, the initial cavity length of the sensor is updated to stabilize the phase orthogonality of the two reconstructed signals.

[0011] As a preferred solution of the demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, the calculation of the initial cavity length of the sensor includes:

[0012] Perform full spectrum scanning on the optical fiber Fabry-Perot acoustic sensor that receives the optical signal to obtain the interference spectrum of the sensor, including the wavelength and the corresponding light intensity value;

[0013] According to the interference spectrum of the fiber Fabry-Perot acoustic sensor, the initial cavity length L0 is calculated and expressed as:

[0014]

[0015] Among them, λ m and λ m+q They respectively represent the light wavelengths corresponding to the mth and m+qth peaks in the interference spectrum, and q represents the order difference between the two peaks in the interference spectrum.

[0016] As a preferred solution of the demodulation method of the three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, wherein: the three-way signal output wavelength of the acquisition laser includes:

[0017] Through the working instructions of the laser three-wavelength switching mode, three specific wavelengths λ1, λ2 and λ3 are obtained, which are the three-way signal output wavelengths of the laser;

[0018] Perform rapid switching of three specific wavelengths λ1, λ2 and λ3, and separate the collected data according to the wavelength switching sequence to obtain corresponding light intensities I1, I2 and I3;

[0019] The constraints of the three specific wavelengths are expressed as:

[0020]

[0021] Wherein, k is a natural number, and n represents the refractive index of the Fabry-Perot cavity.

[0022] As a preferred solution of the demodulation method of the three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, the initial phases corresponding to the three signals are obtained including:

[0023] According to the three-way signal output wavelengths λ1, λ2 and λ3 of the laser, the initial phases corresponding to the three-way signals are calculated. The initial phases and phase changes are expressed as:

[0024]

[0025] Among them, θ i Indicates wavelength λ i The corresponding initial phase, ΔL represents the change in cavity length, Δθ i It represents the phase change caused by the cavity length change ΔL.

[0026] As a preferred solution of the demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, the corresponding light intensity is calculated according to the three wavelengths of the optical fiber Fabry-Perot acoustic sensor, which is expressed as:

[0027] I i =A+Bcos(θ i +Δθ i )(i=1,2,3)

[0028] Wherein, A represents the DC component of the interference signal, and B represents the AC amplitude of the interference signal.

[0029] As a preferred solution of the demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, constructing two orthogonal signals includes:

[0030] According to the light intensities I1, I2, I3 and initial phases θ1, θ2, θ3 corresponding to the three signals, two orthogonal signals F1 and F2 are constructed to demodulate the cavity length change, which is expressed as:

[0031]

[0032] Here, Δθ represents the phase change.

[0033] As a preferred solution of the demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation described in the present invention, wherein: the phase quadrature of the two-path reconstructed signals is stabilized including:

[0034] According to the two orthogonal signals constructed, the cavity length change of the optical fiber Fabry-Perot acoustic sensor is calculated, which is expressed as:

[0035]

[0036] Wherein, m is an integer;

[0037] Set a change threshold L' to determine whether the cavity length change ΔL obtained after demodulation is greater than the change threshold L';

[0038] If the cavity length change ΔL is greater than the threshold value L', the initial cavity length value L0 is replaced by L0+L', the initial phases corresponding to the three signals are recalculated, and the two orthogonal signals are reconstructed to compare the cavity length change with the change threshold, and the above steps are repeated until the cavity length change ΔL is less than the change threshold value L'.

[0039] In a second aspect, the present invention provides a three-wavelength fiber Fabry-Perot acoustic sensor demodulation system based on phase compensation, comprising:

[0040] An acquisition module, for responding to a scanning mode working instruction, performing a full spectrum scan on the optical fiber Fabry-Perot acoustic sensor, synchronously collecting light intensity data, acquiring the interference spectrum of the sensor, and calculating the initial cavity length of the sensor;

[0041] A demodulation module is used to obtain the output wavelengths of the three laser signals based on the initial cavity length of the sensor, obtain the initial phases corresponding to the three signals, construct two orthogonal signals, and demodulate the cavity length change;

[0042] The output module is used to determine whether the cavity length change exceeds a threshold based on the demodulation result. If it exceeds the threshold, the initial cavity length of the sensor is updated to stabilize the phase quadrature of the two-way reconstructed signals.

[0043] In a third aspect, the present invention provides an electronic device, comprising:

[0044] Memory and processor;

[0045] The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the three-wavelength optical fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation are implemented.

[0046] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the phase-compensation-based three-wavelength fiber Fabry-Perot acoustic sensor demodulation method.

[0047] Compared with the prior art, the present invention has the following beneficial effects: the present invention solves the problem that the traditional three-wavelength demodulation technology suffers from reduced demodulation accuracy due to the large change in cavity length, and proposes a phase compensation scheme to achieve orthogonal phase maintenance of the reconstructed signal, which can achieve good stability, large dynamic range, high accuracy, and fast demodulation of sensors with different cavity lengths. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0049] Figure 1 It is a schematic diagram of the overall process of a demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation according to an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of the interference spectrum of a Fabry-Perot acoustic sensor according to a demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation according to an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of the overall structure of a three-wavelength optical fiber Fabry-Perot acoustic sensor demodulation system based on phase compensation according to an embodiment of the present invention;

[0052] Figure 4 A Lissajous schematic diagram of two-path constructed signals of a demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation according to an embodiment of the present invention;

[0053] Figure 5 A schematic diagram of a demodulated cavity length variation result of a demodulation method for a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation according to an embodiment of the present invention;

[0054] Figure 6 A schematic diagram of the spectrum of a demodulated signal of a demodulation method for a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0056] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0057] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0058] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0059] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] Example 1

[0062] Reference Figure 1-Figure 3 , is an embodiment of the present invention, and provides a demodulation method for a three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation, such as Figure 1 As shown, including:

[0063] S101, in response to a scanning mode working instruction, performing a full spectrum scan on the optical fiber Fabry-Perot acoustic sensor, synchronously collecting light intensity data, obtaining the interference spectrum of the sensor, and calculating the initial cavity length of the sensor.

[0064] Specifically, the optical fiber Fabry-Perot acoustic sensor is scanned by a full spectrum scanning mode of a laser.

[0065] Preferably, calculating the initial cavity length of the sensor includes:

[0066] Perform full spectrum scanning on the optical fiber Fabry-Perot acoustic sensor that receives the optical signal to obtain the interference spectrum of the sensor, including the wavelength and the corresponding light intensity value;

[0067] According to the interference spectrum of the fiber Fabry-Perot acoustic sensor, the initial cavity length L0 is calculated and expressed as:

[0068]

[0069] Among them, λ m and λ m+q They represent the light wavelengths corresponding to the mth and m+qth peaks in the interference spectrum respectively, q represents the order difference between the two peaks in the interference spectrum, and if adjacent peaks are selected, q=1.

[0070] Specifically, in this embodiment, the full spectrum scanning mode of the modulated grating Y-branch laser is used to perform full spectrum scanning on the fiber Fabry-Perot acoustic sensor to obtain the interference spectrum of the sensor. Figure 2 This is the interference spectrum without external sound driving (here only the partial spectrum from 1540nm to 1555nm is intercepted). According to the interference spectrum, through the peak tracking method, it can be obtained that the initial cavity length L0 of the sensor is 204.78μm.

[0071] S102, based on the initial cavity length of the sensor, the output wavelengths of the three laser signals are obtained, the initial phases corresponding to the three signals are obtained, two orthogonal signals are constructed, and the cavity length variation is demodulated.

[0072] Preferably, obtaining the three-way signal output wavelength of the laser includes:

[0073] Through the working instructions of the laser three-wavelength switching mode, three specific wavelengths λ1, λ2 and λ3 are obtained, which are the three-way signal output wavelengths of the laser;

[0074] Perform rapid switching of three specific wavelengths λ1, λ2 and λ3, and separate the collected data according to the wavelength switching sequence to obtain corresponding light intensities I1, I2 and I3;

[0075] The constraints for the three specific wavelengths are expressed as:

[0076]

[0077] Wherein, k is a natural number, n represents the refractive index of the Fabry-Perot cavity, and preferably, n=1.

[0078] Specifically, according to the initial cavity length L0 of the sensor, the three signal output wavelengths λ1, λ2, and λ3 of the laser are determined to be 1544.656 nm, 1547 nm, and 1549.344 nm, respectively.

[0079] Preferably, obtaining the initial phases corresponding to the three signals includes:

[0080] According to the three-way signal output wavelengths λ1, λ2 and λ3 of the laser, the initial phases corresponding to the three-way signals are calculated. The initial phases and phase changes are expressed as:

[0081]

[0082] Among them, θ i Indicates wavelength λ i The corresponding initial phase, ΔL represents the change in cavity length, Δθ i It represents the phase change caused by the cavity length change ΔL.

[0083] Preferably, the corresponding light intensity is calculated according to the three wavelengths of the optical fiber Fabry-Perot acoustic sensor, which is expressed as:

[0084] I i =A+Bcos(θ i +Δθ i )(i=1,2,3)

[0085] Wherein, A represents the DC component of the interference signal, and B represents the AC amplitude of the interference signal.

[0086] Preferably, constructing two orthogonal signals includes:

[0087] According to the light intensities I1, I2, I3 and initial phases θ1, θ2, θ3 corresponding to the three signals, two orthogonal signals F1 and F2 are constructed to demodulate the cavity length change, which is expressed as:

[0088]

[0089] Wherein, Δθ represents the phase change amount. When ΔL<<L0, Δθ1, Δθ2, and Δθ3 are approximately equal and are all represented by Δθ in this embodiment.

[0090] S103, based on the demodulation result, determine whether the cavity length change exceeds a threshold value, and if so, update the initial cavity length of the sensor to stabilize the phase quadrature of the two-way reconstructed signals.

[0091] Preferably, the cavity length change of the optical fiber Fabry-Perot acoustic sensor is calculated based on the two constructed orthogonal signals, which is expressed as:

[0092]

[0093] Where m is an integer, and mπ is used to compensate for phase jump;

[0094] Set a change threshold L' to determine whether the cavity length change ΔL obtained after demodulation is greater than the change threshold L';

[0095] If the cavity length change ΔL is greater than the threshold value L', the initial cavity length value L0 is replaced by L0+L', the initial phases corresponding to the three signals are recalculated, and the two orthogonal signals are reconstructed to compare the cavity length change with the change threshold. The above steps are repeated until the cavity length change ΔL is less than the change threshold value L'.

[0096] Specifically, the change threshold L' can be set to 500 nm to 700 nm. Preferably, in this embodiment, the change threshold L' is set to 600 nm.

[0097] It should be noted that the present invention solves the problem of reduced demodulation accuracy due to large changes in cavity length in traditional three-wavelength demodulation technology, and proposes a phase compensation scheme to achieve orthogonal phase maintenance of the reconstructed signal, which can achieve good stability, large dynamic range, high accuracy and fast demodulation of sensors with different cavity lengths.

[0098] The present invention can improve the detection capability of tiny cavity length changes by adopting multi-wavelength signals and phase demodulation technology, thereby improving the overall sensitivity of the sensor; the phase compensation technology can effectively reduce the influence of environmental factors (such as temperature fluctuations) on the measurement results, making the sensor more stable and reliable; the method of using three wavelengths and orthogonal signals simplifies the demodulation process, reduces complex signal processing steps, and improves the response speed of the system. By accurately controlling and demodulating the three-wavelength signals, higher-precision cavity length change measurement can be achieved; it is suitable for a variety of application scenarios, especially occasions requiring high-precision and high-sensitivity monitoring.

[0099] The above is a schematic scheme of a three-wavelength fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation in this embodiment. It should be noted that the technical scheme of the three-wavelength fiber Fabry-Perot acoustic sensor demodulation system based on phase compensation and the technical scheme of the three-wavelength fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation mentioned above belong to the same concept. The details of the technical scheme of the three-wavelength fiber Fabry-Perot acoustic sensor demodulation system based on phase compensation in this embodiment that are not described in detail can all be referred to the description of the technical scheme of the three-wavelength fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation mentioned above.

[0100] The demodulation system of the three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation in this embodiment is as follows: Figure 3 ,include:

[0101] An acquisition module, for responding to a scanning mode working instruction, performing a full spectrum scan on the optical fiber Fabry-Perot acoustic sensor, synchronously collecting light intensity data, acquiring the interference spectrum of the sensor, and calculating the initial cavity length of the sensor;

[0102] The demodulation module is used to obtain the output wavelengths of the three laser signals based on the initial cavity length of the sensor, obtain the initial phases corresponding to the three signals, construct two orthogonal signals, and demodulate the cavity length change;

[0103] The output module is used to determine whether the cavity length change exceeds a threshold based on the demodulation result. If it exceeds the threshold, the initial cavity length of the sensor is updated to stabilize the phase quadrature of the two-way reconstructed signals.

[0104] Specifically, the acquisition module includes a fiber circulator 201, a fiber Fabry-Perot acoustic sensor 202, and a photodetector 203; the demodulation module includes a laser control unit 204, a modulated grating Y-branch laser 205, and a synchronous acquisition unit 206; and the output module includes a data processing unit 207.

[0105] In this embodiment, the laser control unit 204 is connected to the modulated grating Y-branch laser 205, driving the modulated grating Y-branch laser 205 to output optical signals of different wavelengths. The optical signal is transmitted to the optical fiber circulator 201 through the optical fiber, and the optical signal from the modulated grating Y-branch laser 205 is introduced into the optical fiber Fabry-Perot acoustic sensor 202. The reflected light signal passes through the optical fiber circulator 201 again and is detected by the photodetector 203 and converted into an electrical signal, which is then collected by the high-speed analog-to-digital converter ADC of the synchronous sampling unit and transmitted to the data processing unit 207.

[0106] The laser control unit 204 is a microcontroller such as a single chip microcomputer, a host computer or an FPGA core board, and has a built-in current lookup table corresponding to the laser wavelength. The microcontroller selects the full spectrum scanning mode or the three-wavelength switching mode according to the received user instructions.

[0107] In this embodiment, the laser control unit 204 is implemented using FPGA, and the FPGA realizes the synchronous control and output of the current source current, thereby controlling the output wavelength of the modulated grating Y-branch laser 205, and its tuning band can cover the C band, specifically 1527nm to 1567nm; the FPGA has a built-in wavelength current wavelength lookup table, and through clock synchronization, the photodetector 203 and the synchronous acquisition unit 206 work synchronously to transmit the collected data to the data processing unit 207, and the clock synchronization is set to 600kHz; according to the command issued by the data processing unit 207, the full spectrum scanning mode or the three-wavelength switching mode is selected, and the wavelength switching rate is 600kHz.

[0108] Among them, the modulated grating Y-branch laser 205 is a distributed Bragg reflection laser based on the vernier tuning principle, which can realize the tuning of the output wavelength, and the optical power at different output wavelengths is consistent; the modulated grating Y-branch laser 205 controls the output wavelength and optical power through five injection currents, namely the left reflector current, the right reflector current, the phase current, the gain current, and the semiconductor optical amplifier current, and can achieve a wavelength switching speed of nanoseconds in the multi-wavelength switching mode.

[0109] The photoelectric detector 203 is a high-speed photoelectric detector with an optical fiber input interface and direct current coupling, which converts the detected light intensity signal into an analog signal.

[0110] The synchronous acquisition unit 206 acquires the electrical signal converted by the photodetector 203 through clock synchronization.

[0111] The data processing unit 207 separates the collected digital signals according to the switching order of the three wavelengths, constructs two orthogonal signals to demodulate the cavity length change, and determines whether the cavity length change exceeds the threshold. If it exceeds, the initial cavity length of the sensor is updated to stabilize the phase orthogonality of the two reconstructed signals.

[0112] Specifically, in step S101 of the demodulation method of the three-wavelength fiber Fabry-Perot acoustic sensor 202 based on phase compensation, the laser control unit 204 controls the modulated grating Y-branch laser 205 to operate in the full-spectrum scanning mode, performs a full-spectrum scan on the fiber Fabry-Perot acoustic sensor 202, and synchronously collects light intensity data through the synchronous acquisition unit 206 to obtain the interference spectrum of the sensor.

[0113] In step S102, the laser control unit 204 switches the modulated grating Y-branch laser 205 to the three-wavelength switching mode, and drives the modulated grating Y-branch laser 205 to quickly switch between three specific wavelengths λ1, λ2 and λ3 according to the current lookup table corresponding to the built-in laser wavelengths. Through clock synchronization, the synchronous acquisition unit 206 works synchronously, and the data processing unit 207 separates the collected data according to the wavelength switching order to obtain the corresponding light intensity.

[0114] It should be noted that the system of the present invention uses only a single tunable MG-Y laser and a single photodetector to construct an acoustic sensing system. The optical path structure is simple, crosstalk between optical paths is reduced, the stability is high, and the application value is great.

[0115] This embodiment further provides an electronic device, which is applicable to the demodulation of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation, and includes:

[0116] The memory and processor described above; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as proposed in the above embodiment.

[0117] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the demodulation method of a three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation as proposed in the above embodiment is implemented.

[0118] The storage medium proposed in this embodiment and the demodulation method for a three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation proposed in the above embodiment belong to the same inventive concept. The technical details not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0119] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0120] Example 2

[0121] Reference Figure 4-Figure 6 , which is an embodiment of the present invention, provides a demodulation method for a three-wavelength fiber Fabry-Perot acoustic sensor based on phase compensation. In order to verify its beneficial effects, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0122] By implementing the method of the present invention, Figure 4 When a 20kHz high sound pressure signal is applied from the outside, the Lissajous figure of the signals F1 and F2 is constructed using the phase compensation method of the present scheme. The figure is a perfect circle, indicating that the signals F1 and F2 satisfy a good orthogonal relationship. Figure 5 This is the result diagram of the cavity length change obtained by demodulation, which is 750nm; Figure 6 The frequency spectrum of the demodulated signal after Fourier transformation is shown in the figure. It can be seen from the figure that the frequency of the demodulated signal is consistent with the frequency of the applied sound signal, which verifies the effectiveness of the demodulation effect of the present invention.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A demodulation method for a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation, characterized in that: include: In response to the scanning mode working instruction, the optical fiber Fabry-Perot acoustic sensor is subjected to full spectrum scanning, light intensity data is synchronously collected, the interference spectrum of the sensor is obtained, and the initial cavity length of the sensor is calculated; Based on the initial cavity length of the sensor, the output wavelengths of the three laser signals are obtained, the initial phases corresponding to the three signals are obtained, two orthogonal signals are constructed, and the cavity length variation is demodulated; Based on the demodulation results, it is determined whether the cavity length change exceeds the threshold. If it exceeds the threshold, the initial cavity length of the sensor is updated to stabilize the phase orthogonality of the two reconstructed signals.

2. The demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 1, characterized in that: The calculating of the initial cavity length of the sensor comprises: Perform full spectrum scanning on the optical fiber Fabry-Perot acoustic sensor that receives the optical signal to obtain the interference spectrum of the sensor, including the wavelength and the corresponding light intensity value; According to the interference spectrum of the fiber Fabry-Perot acoustic sensor, the initial cavity length L0 is calculated and expressed as: Among them, λ m and λ m+q They respectively represent the light wavelengths corresponding to the mth and m+qth peaks in the interference spectrum, and q represents the order difference between the two peaks in the interference spectrum.

3. The demodulation method of the three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 2 is characterized in that: The three-way signal output wavelength of the acquisition laser includes: Through the working instructions of the laser three-wavelength switching mode, three specific wavelengths λ1, λ2 and λ3 are obtained, which are the three-way signal output wavelengths of the laser; Perform rapid switching of three specific wavelengths λ1, λ2 and λ3, and separate the collected data according to the wavelength switching sequence to obtain corresponding light intensities I1, I2 and I3; The constraints of the three specific wavelengths are expressed as: Wherein, k is a natural number, and n represents the refractive index of the Fabry-Perot cavity.

4. The demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 3 is characterized in that: The obtaining of the initial phases corresponding to the three signals comprises: According to the three-way signal output wavelengths λ1, λ2 and λ3 of the laser, the initial phases corresponding to the three-way signals are calculated. The initial phases and phase changes are expressed as: Among them, θ i Indicates wavelength λ i The corresponding initial phase, ΔL represents the change in cavity length, Δθ i It represents the phase change caused by the cavity length change ΔL.

5. The demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 4, characterized in that: According to the three wavelengths of the fiber optic Fabry-Perot acoustic sensor, the corresponding light intensity is calculated and expressed as: I i =A+Bcos(θ i +Δθ i (i=1,2,3) Wherein, A represents the DC component of the interference signal, and B represents the AC amplitude of the interference signal.

6. The demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 5, characterized in that: Constructing two orthogonal signals includes: According to the light intensities I1, I2, I3 and initial phases θ1, θ2, θ3 corresponding to the three signals, two orthogonal signals F1 and F2 are constructed to demodulate the cavity length change, which is expressed as: Here, Δθ represents the phase change.

7. The demodulation method of a three-wavelength optical fiber Fabry-Perot acoustic sensor based on phase compensation as claimed in claim 6, characterized in that: The phase quadrature of the two-path reconstructed signals is stabilized, including: According to the two orthogonal signals constructed, the cavity length change of the optical fiber Fabry-Perot acoustic sensor is calculated, which is expressed as: Wherein, m is an integer; Set a change threshold L' to determine whether the cavity length change ΔL obtained after demodulation is greater than the change threshold L'; If the cavity length change ΔL is greater than the threshold value L', the initial cavity length value L0 is replaced by L0+L', the initial phases corresponding to the three signals are recalculated, and the two orthogonal signals are reconstructed to compare the cavity length change with the change threshold, and the above steps are repeated until the cavity length change ΔL is less than the change threshold value L'.

8. A three-wavelength fiber Fabry-Perot acoustic sensor demodulation system based on phase compensation, characterized in that: include, An acquisition module, for responding to a scanning mode working instruction, performing a full spectrum scan on the optical fiber Fabry-Perot acoustic sensor, synchronously collecting light intensity data, acquiring the interference spectrum of the sensor, and calculating the initial cavity length of the sensor; A demodulation module is used to obtain the output wavelengths of the three laser signals based on the initial cavity length of the sensor, obtain the initial phases corresponding to the three signals, construct two orthogonal signals, and demodulate the cavity length change; The output module is used to determine whether the cavity length change exceeds a threshold based on the demodulation result. If it exceeds the threshold, the initial cavity length of the sensor is updated to stabilize the phase quadrature of the two-way reconstructed signals.

9. An electronic device, characterized in that: include: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the three-wavelength fiber Fabry-Perot acoustic sensor demodulation method based on phase compensation according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: It stores computer executable instructions, which, when executed by a processor, can implement the steps of the phase-compensation-based three-wavelength fiber Fabry-Perot acoustic sensor demodulation method described in any one of claims 1 to 7.

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