Diaphragm-type optical fiber micro-vibration measurement apparatus and method based on single-pass band microwave photonic filter

Abstract

A diaphragm-type optical fiber micro-vibration measurement apparatus and method based on a single-pass band microwave photonic filter. The apparatus comprises a broadband light source module (1), a three-port circulator (2), an AU diaphragm optical fiber micro-vibration sensor (3), an erbium-doped optical fiber amplifier (4), a polarization controller (5), an electro-optical modulator (6), a power supply module (7), a radio-frequency source module (8), a dispersion compensation optical fiber (9), a photoelectric detector (10), a data acquisition card (11) and a computer (12), wherein the broadband light source module (1) is connected to one port of the three-port circulator (2) by means of an optical fiber connection line.

Description

Diaphragm-type fiber optic micro-vibration measurement device and method based on single-passband microwave photonic filter

[0001] This application claims priority to Chinese Patent Application No. 202411903240.2, filed with the Chinese Patent Office on December 23, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of microwave photonics technology, and for example to a diaphragm-type fiber optic micro-vibration measurement device and method based on a single-passband microwave photonic filter. Background Technology

[0003] Fiber optic diaphragm vibration sensors are based on optical signal transmission and sensing of changes in physical quantities. They are completely unaffected by electromagnetic interference and can operate stably in harsh electromagnetic environments such as high electromagnetic fields, high magnetic fields, and high radiation fields. In scenarios such as near high-voltage transmission lines and around large motor equipment, they can accurately measure relevant physical quantities. At the same time, fiber optic diaphragm vibration sensors utilize principles such as light interference to be extremely sensitive to minute changes in physical quantities, enabling high-precision and high-sensitivity measurements. They can be used to measure micro-vibrations, pressure changes, temperature changes, etc.

[0004] Traditional fiber optic diaphragm vibration sensors often use lightweight and thin polymer diaphragms. While these can perform vibration testing with relatively high accuracy, the thin polymer diaphragms are prone to breakage or damage under significant vibration impacts or prolonged vibration environments. For example, in industrial environments, if the sensor is surrounded by large equipment that frequently starts and stops, generating vibration impacts, these polymer diaphragms may not be able to withstand the impact and could be damaged. Furthermore, temperature has a significant impact on the elastic modulus of the diaphragm. At high temperatures, the diaphragm may soften, reducing its vibration response accuracy; at low temperatures, it may become brittle, increasing the risk of breakage. In some chemical environments, such as in petrochemical plants or transformer oil, the polymer diaphragm may come into contact with various corrosive chemicals such as acids, alkalis, and organic solvents. These chemicals may corrode the diaphragm, causing surface roughness, pores, or dissolution, thereby affecting the sensor's optical and mechanical properties and shortening its lifespan.

[0005] Furthermore, in traditional vibration demodulation, since the interference spectrum is periodic, when the change in optical path difference caused by vibration exceeds the range of one cycle, it is difficult to accurately distinguish whether the change caused by vibration is within the current cycle or has crossed into the next cycle, thus limiting the measurement range. In addition, traditional demodulation methods are based on tracking the wavelength or phase of the interference spectrum, but due to the complexity and susceptibility of the interference spectrum, these methods may encounter difficulties in practical applications. Summary of the Invention

[0006] This application provides a diaphragm-type fiber optic micro-vibration measurement device and method based on a single-passband microwave photonic filter, which can effectively solve the problems in the background art.

[0007] The technical solution adopted in this application is as follows:

[0008] A diaphragm-type fiber optic micro-vibration measurement device based on a single-passband microwave photonic filter includes a broadband light source module, a three-port circulator, an AU diaphragm fiber optic micro-vibration sensor, an erbium-doped fiber amplifier, a polarization controller, an electro-optic modulator, a power supply module, an RF source module, a dispersion compensation fiber, a photodetector, a data acquisition card, and a computer. The broadband light source module is connected to one port of the three-port circulator via an optical fiber cable. The second port of the three-port circulator is connected to the AU diaphragm fiber optic micro-vibration sensor via an optical fiber cable. The third port of the three-port circulator is connected to the input of the erbium-doped fiber amplifier via an optical fiber cable. The output of the erbium-doped fiber amplifier is connected to the input of the polarization controller via an optical fiber cable. The output of the polarization controller is connected to the input of the electro-optic modulator via an optical fiber cable. The two electrical ports of the electro-optic modulator are connected to the power supply module and the RF source module, respectively. The output of the electro-optic modulator is connected to the dispersion compensation fiber and the input of the photodetector via optical fiber cables. The data acquisition card is connected to the output of the photodetector and is also connected to the computer via a cable.

[0009] A method for measuring micro-vibrations in a diaphragm-type optical fiber based on a single-passband microwave photonic filter, applied to the aforementioned device, the method comprising:

[0010] The light emitted by the broadband light source module is output from port two of the three-port circulator and incident on the AU diaphragm fiber optic micro-vibration sensor. Therefore, external micro-vibrations cause a change in the cavity length of the Fabry-Perot interferometer (FPI) formed by the AU diaphragm fiber optic micro-vibration sensor. This change in cavity length leads to a change in the phase difference generated by the interference light, thus shifting the wavelength of the interference spectrum. That is, when the incident beam reaches the reflecting surface of the AU diaphragm fiber optic micro-vibration sensor, its reflectivity is relatively low. This results in only limited reflection of the incident beam within the resonant cavity, thus forming a two-beam interference phenomenon. The reflection spectrum generated by the two-beam interference can be expressed by the following formula:

[0011] ;

[0012] in, and These are the reflected light intensities from the fiber end face and the gold foil, respectively. The phase difference caused by the optical path difference after light is reflected once within the cavity of the AU diaphragm fiber optic micro-vibration sensor is expressed as:

[0013] ;

[0014] In the formula: The cavity length of the AU diaphragm fiber optic micro-vibration sensor cavity is given. Let be the refractive index of the cavity. The wavelength of the incident light;

[0015] Set the initial cavity length of the FPI cavity to be ,but:

[0016] ;

[0017] When sound waves propagate within the cavity of the AU diaphragm fiber optic micro-vibration sensor, the resulting pressure change acts on the elastic sheet, causing elastic deformation. The magnitude of this deformation is related to the pressure difference, i.e., to the amplitude of the sound wave vibration. According to the principles of elasticity, it is assumed that the elastic sheet is subjected to pressure caused by the sound wave vibration. The effect is that the deformation generated at the center of the thin sheet is:

[0018] ;

[0019] In the formula, This refers to the lateral pressure difference experienced by a constant elastic sheet. The effective radius of the constant elastic sheet, For the thickness of the thin slice, The Poisson's ratio of the material, The Young's modulus of the material;

[0020] For the selected material and Given the quantities, it can be seen from the above formula that different choices... and This allows us to determine the sensor's sensitivity and measurement range. Once these two parameters are determined, the diaphragm deformation... With pressure Proportional;

[0021] When a broadband light source module is selected as the light source, interference peaks of different frequencies will appear. The free spectral range of the interference spectrum at this time is expressed as:

[0022] ;

[0023] in, and The wavelengths of the peaks and troughs of two adjacent interference peaks in the spectrum are given. By reading the values ​​of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm fiber optic micro-vibration sensor.

[0024] ;

[0025] The interference light reflected back from the AU diaphragm fiber micro-vibration sensor is output from port three of the three-port circulator. It is first amplified by the erbium-doped fiber amplifier, then enters the polarization controller to control the polarization state of the transmitted beam, and then enters the electro-optic modulator. This electro-optic modulator is connected to the power module to apply a bias voltage. The electro-optic modulator is also connected to the radio frequency source module. The frequency of the radio frequency signal output by the radio frequency source module is adjusted to the linear region of the passband edge of the single passband microwave photonic filter.

[0026] By monitoring the changes in the center frequency of a single-passband microwave photonic filter, the vibration changes can be observed more intuitively. The expression for the center frequency of the passband is as follows:

[0027] ;

[0028] in, and This refers to the dispersion value of the dispersive device and the length of the dispersive medium. Given the free spectral range of the interference spectrum, the location of the passband center frequency can be determined. The dispersion coefficient of dispersion-compensating fiber and length and the free spectral range of the interference spectrum Together, we can determine that by setting the values ​​of these three parameters, we can obtain filter responses with different center passband positions, thus achieving passband tunability.

[0029] Will Substitution ,get:

[0030] ;

[0031] As mentioned above, external micro-vibration signals will cause changes in the cavity length of the AU diaphragm fiber optic micro-vibration sensor. Due to the sealed air cavity, the refractive index... Since it is constant, under the same external conditions, the change in the passband center frequency depends only on the cavity length. The change, namely:

[0032] ;

[0033] The interference light reflected from the AU diaphragm fiber micro-vibration sensor is output from port three of a three-port circulator. It first undergoes optical power amplification via an erbium-doped fiber amplifier, then enters a polarization controller to control the polarization state of the transmitted beam, and finally connects to an electro-optic modulator. This modulator is connected to a power supply module to apply a bias voltage. Simultaneously, the modulator is connected to an RF source module, whose output RF signal frequency is adjusted to the linear region of the passband edge of a single-passband microwave photonic filter. The signal output from the electro-optic modulator is then connected to a dispersion-compensating fiber. The output of the dispersion-compensating fiber is connected to the optical input port of a photodetector, which converts the optical signal into an electrical signal. The electrical output of the photodetector is connected to a data acquisition card, and finally, the signal is processed and displayed by a computer.

[0034] In one embodiment, the AU diaphragm fiber optic micro-vibration sensor includes a large sleeve and a small sleeve, and a fiber optic ceramic ferrule. The large sleeve and the small sleeve are made of acrylic material, and the fiber optic ceramic ferrule can be nested and assembled with them. The inner diameter of the large sleeve is larger than the outer diameter of the small sleeve, while the inner diameter of the small sleeve is larger than the size of the fiber optic ceramic ferrule. The end face of the fiber optic ceramic ferrule can serve as a first reflective surface, and the second reflective surface uses gold foil as the reflective material. An air cavity is formed between the two end faces.

[0035] This application has the following technical effects:

[0036] In this application, microwave photonic filtering technology is used to convert the wavelength change of the interference spectrum of the AU diaphragm fiber micro-vibration sensor into the change of the center frequency of a single passband filter. By modulating the radio frequency signal of the linear region of the passband edge of the single passband microwave photonic filter at a certain frequency, the passband frequency change is converted into the intensity change of the radio frequency signal, thereby realizing micro-vibration detection. This can minimize the measurement cost and better meet the vibration detection needs in various environments. Attached Figure Description

[0037] Figure 1 is a schematic diagram of the main structure of this application;

[0038] Figure 2 is a schematic diagram of the Au diaphragm fiber optic micro-vibration sensor structure of this application.

[0039] In the diagram: 1. Broadband light source module; 2. Three-port circulator; 3. Au diaphragm fiber micro-vibration sensor; 4. Erbium-doped fiber amplifier; 5. Polarization controller; 6. Optoelectronic modulator; 7. Power supply module; 8. Radio frequency source module; 9. Dispersion compensation fiber; 10. Photodetector; 11. Data acquisition card; 12. Computer. Detailed Implementation

[0040] As shown in Figure 1, the diaphragm-type fiber optic micro-vibration measurement device based on a single-passband microwave photonic filter provided in this application includes a broadband light source module 1, a three-port circulator 2, an AU diaphragm fiber optic micro-vibration sensor 3, an erbium-doped fiber amplifier 4, a polarization controller 5, an electro-optic modulator 6, a power supply module 7, an RF source module 8, a dispersion compensation fiber 9, a photodetector 10, a data acquisition card 11, and a computer 12. The broadband light source module 1 is connected to one port of the three-port circulator 2 via an optical fiber connection cable. The second port of the three-port circulator 2 is connected to the AU diaphragm fiber optic micro-vibration sensor 3 via an optical fiber connection cable. The port is connected to the input end of the erbium-doped fiber amplifier 4 via an optical fiber connection cable. The output end of the erbium-doped fiber amplifier 4 is connected to the input end of the polarization controller 5 via an optical fiber connection cable. The output end of the polarization controller 5 is connected to the optical fiber input end of the electro-optic modulator 6 via an optical fiber connection cable. The two electrical ports of the electro-optic modulator 6 are connected to the power supply module 7 and the radio frequency source module 8 respectively. The optical fiber output end of the opto-modulator 6 is connected to the dispersion compensation fiber 9 and the input end of the photodetector 10 via connection cables. The data acquisition card 11 is connected to the output end of the photodetector 10. The data acquisition card 11 is also connected to the computer 12 via a connection cable.

[0041] As shown in Figures 1 and 2, the method for measuring the micro-vibration of a diaphragm-type fiber optic cable based on a single-passband microwave photonic filter includes the following steps:

[0042] S1. The light emitted by the broadband light source module 1 is output through port two of the three-port circulator 2 and incident on the AU diaphragm fiber optic micro-vibration sensor 3. Therefore, external micro-vibrations cause a change in the cavity length of the Fabry-Perot interferometer (FPI) formed by the AU diaphragm fiber optic micro-vibration sensor 3. The change in cavity length causes a change in the phase difference generated by the interference light, thereby shifting the wavelength of the interference spectrum. That is, when the incident beam reaches the reflecting surface of the AU diaphragm fiber optic micro-vibration sensor 3, its reflectivity is relatively low. This causes the incident beam to undergo only limited reflection in the resonant cavity, thus forming a two-beam interference phenomenon. The reflection spectrum generated by the two-beam interference can be expressed by the following formula:

[0043] ;

[0044] in, and These are the reflected light intensities from the fiber end face and the gold foil, respectively. The phase difference caused by the optical path difference after light is reflected once within the 3-cavity AU diaphragm fiber optic micro-vibration sensor is expressed as:

[0045] ;

[0046] In the formula: The cavity length of the AU diaphragm fiber optic micro-vibration sensor is 3 cavities. Let be the refractive index of the cavity. The wavelength of the incident light;

[0047] Set the initial cavity length of the FPI cavity to be ,but:

[0048] ;

[0049] When sound waves propagate within the cavity 3 of the AU diaphragm fiber optic micro-vibration sensor, the resulting pressure change acts on the elastic sheet, causing elastic deformation. The magnitude of this deformation is related to the pressure difference, i.e., to the amplitude of the sound wave vibration. According to the principles of elasticity, it is assumed that the elastic sheet is subjected to pressure caused by the sound wave vibration. The effect is that the deformation generated at the center of the thin sheet is:

[0050] ;

[0051] In the formula, This refers to the lateral pressure difference experienced by a constant elastic sheet. The effective radius of the constant elastic sheet, For the thickness of the thin slice, The Poisson's ratio of the material, The Young's modulus of the material;

[0052] For the selected material and Given the quantities, it can be seen from the above formula that different choices... and This allows us to determine the sensor's sensitivity and measurement range. Once these two parameters are determined, the diaphragm deformation... With pressure Proportional;

[0053] When broadband light source module 1 is selected as the light source, interference peaks of different frequencies will appear. The free spectral range of the interference spectrum at this time is expressed as:

[0054] ;

[0055] in, and The wavelengths of the peaks and troughs of two adjacent interference peaks in the spectrum are given. By reading the values ​​of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm fiber optic micro-vibration sensor 3.

[0056] .

[0057] The interference light reflected back from the S2 and AU diaphragm fiber micro-vibration sensor 3 is output from port 3 of the three-port circulator 2. It first passes through the erbium-doped fiber amplifier 4 for optical power amplification, then enters the polarization controller 5 to control the polarization state of the transmitted beam, and then enters the electro-optic modulator 6. This electro-optic modulator 6 is connected to the power supply module 7 to apply a bias voltage. The electro-optic modulator 6 is also connected to the radio frequency source module 8. The frequency of the radio frequency signal output by the radio frequency source module 8 is adjusted to the linear region of the passband edge of the single-passband microwave photonic filter.

[0058] S3. By monitoring the change in the center frequency of the passband of a single-passband microwave photonic filter, the vibration changes can be observed more intuitively. The expression for the center frequency of the passband is as follows:

[0059] ;

[0060] in, and This refers to the dispersion value of the dispersive device and the length of the dispersive medium. Given the free spectral range of the interference spectrum, the location of the passband center frequency can be determined. The dispersion coefficient of dispersion-compensating fiber and length and the free spectral range of the interference spectrum Together, we can determine that by setting the values ​​of these three parameters, we can obtain filter responses with different center passband positions, thus achieving passband tunability.

[0061] Will Substitution ,get:

[0062] ;

[0063] As mentioned above, external micro-vibration signals will cause a change in the cavity length of the AU diaphragm fiber optic micro-vibration sensor. Due to the sealed air cavity, the refractive index... Since it is constant, under the same external conditions, the change in the passband center frequency depends only on the cavity length. The change, namely:

[0064] .

[0065] The interference light reflected from the S4 and AU diaphragm fiber micro-vibration sensors 3 is output from port 3 of the three-port circulator 2. It first passes through the erbium-doped fiber amplifier 4 for optical power amplification, then enters the polarization controller 5 to control the polarization state of the transmitted beam, and then enters the electro-optic modulator 6. This electro-optic modulator 6 is connected to the power supply module 7 to apply a bias voltage. The electro-optic modulator 6 is also connected to the radio frequency source module 8. The frequency of the radio frequency signal output by the radio frequency source module 8 is adjusted to the linear region of the passband edge of the single-passband microwave photonic filter. The signal output by the electro-optic modulator 6 is then connected to the dispersion compensation fiber 9. The output of the dispersion compensation fiber 9 is connected to the optical input port of the photodetector 10. The photodetector 10 converts the optical signal into an electrical signal. The electrical output of the photodetector 10 is connected to the data acquisition card 11, and finally processed and displayed by the computer 12.

[0066] The AU diaphragm fiber optic micro-vibration sensor 3 includes a large sleeve 15, a small sleeve 14, and a fiber optic ceramic ferrule 13. The large sleeve 15 and the small sleeve 14 are made of acrylic material, and the fiber optic ceramic ferrule 13 can be nested and assembled with them. The inner diameter of the large sleeve 15 is larger than the outer diameter of the small sleeve 14, while the inner diameter of the small sleeve 14 is larger than the size of the fiber optic ceramic ferrule 13. The end face of the fiber optic ceramic ferrule 13 can serve as the first reflecting surface, and the second reflecting surface uses gold foil as the reflecting material. There is an air cavity between the two end faces. The cavity length of the AU diaphragm fiber optic micro-vibration sensor 3 is adjusted by a precision adjustment frame under a spectrometer. After determining the cavity length, epoxy resin is used for bonding. Au film is used to enhance its reflection of the light beam, thereby improving the contrast of the interference spectrum and enabling good observation of the interference spectrum when the vibration changes. In addition, gold has good ductility and can be made into very thin foils, and can withstand a certain amount of external force without breaking.

Claims

1. A diaphragm-type fiber optic micro-vibration measurement device based on a single-passband microwave photonic filter, comprising a broadband light source module (1), a three-port circulator (2), an AU diaphragm fiber optic micro-vibration sensor (3), an erbium-doped fiber amplifier (4), a polarization controller (5), an electro-optic modulator (6), a power supply module (7), a radio frequency source module (8), a dispersion compensation fiber (9), a photodetector (10), a data acquisition card (11), and a computer (12). The broadband light source module (1) is connected to one port of the three-port circulator (2) via an optical fiber connection line. The two ports of the three-port circulator (2) are connected to the AU diaphragm fiber optic micro-vibration sensor (3) via optical fiber connection lines. The three ports of the three-port circulator (2) are connected via optical fibers. The connecting line is connected to the input end of the erbium-doped fiber amplifier (4). The output end of the erbium-doped fiber amplifier (4) is connected to the input end of the polarization controller (5) through the fiber connecting line. The output end of the polarization controller (5) is connected to the fiber input end of the photoelectric modulator (6) through the fiber connecting line. The two electrical ports of the electro-optic modulator (6) are connected to the power supply module (7) and the radio frequency source module (8) respectively. The fiber output end of the electro-optic modulator (6) is connected to the dispersion compensation fiber (9) and the input end of the photodetector (10) in sequence through the fiber connecting line. The data acquisition card (11) is connected to the output end of the photodetector (10). The data acquisition card (11) is also connected to the computer (12) through the connecting line.

2. The diaphragm-type fiber optic micro-vibration measurement device based on a single-passband microwave photonic filter according to claim 1, wherein, The AU diaphragm fiber optic micro-vibration sensor (3) includes a large sleeve (15) and a small sleeve (14), and a fiber optic ceramic ferrule (13). The large sleeve (15) and the small sleeve (14) are made of acrylic material, and the fiber optic ceramic ferrule (13) can be nested and assembled with them. The inner diameter of the large sleeve (15) is larger than the outer diameter of the small sleeve (14), while the inner diameter of the small sleeve (14) is larger than the size of the fiber optic ceramic ferrule (13). The end face of the fiber optic ceramic ferrule (13) can be used as the first reflective surface, and the second reflective surface uses gold foil as the reflective material. There is an air cavity between the two end faces.

3. A method for measuring micro-vibrations in diaphragm-type optical fibers based on a single-passband microwave photonic filter, applied to the device described in claim 1, the method comprising: The light emitted by the broadband light source module (1) is output through port two of the three-port circulator (2) and incident on the AU diaphragm fiber micro-vibration sensor (3). Therefore, the external micro-vibration causes the cavity length of the Fabry-Perot interferometer (FPI) formed by the AU diaphragm fiber micro-vibration sensor (3) to change. The change in cavity length causes the phase difference generated by the interference light to change, thereby shifting the wavelength of the interference spectrum. That is, when the incident beam reaches the reflective surface of the AU diaphragm fiber micro-vibration sensor (3), its reflectivity is relatively low. This causes the incident beam to undergo only limited reflection in the resonant cavity, thus forming a two-beam interference phenomenon. The reflection spectrum generated by the two-beam interference can be expressed by the following formula: ;in, and These are the reflected light intensities from the fiber end face and the gold foil, respectively. The phase difference caused by the optical path difference after light is reflected once in the cavity of the AU diaphragm fiber micro-vibration sensor (3) is expressed as: In the formula: The cavity length of the AU diaphragm fiber optic micro-vibration sensor (3) is given by: Let be the refractive index of the cavity. The wavelength of the incident light; Set the initial cavity length of the FPI cavity to be ,but: ； When the sound wave propagates in the cavity of the AU diaphragm fiber micro-vibration sensor (3), the pressure change it causes acts on the elastic sheet, resulting in elastic deformation of the sheet. The magnitude of this deformation is related to the pressure difference, that is, to the vibration amplitude of the sound wave. According to the principle of elasticity, it is assumed that the elastic sheet is subjected to pressure caused by the vibration of the sound wave. The effect is that the deformation generated at the center of the thin sheet is: In the formula, This refers to the lateral pressure difference experienced by a constant elastic sheet. The effective radius of the constant elastic sheet, For the thickness of the thin slice, The Poisson's ratio of the material, The Young's modulus of the material; For the selected material and Given the quantities, it can be seen from the above formula that different choices... and This allows us to determine the sensor's sensitivity and measurement range. Once these two parameters are determined, the diaphragm deformation... With pressure Proportional; When the broadband light source module (1) is selected as the light source, interference peaks of different frequencies will appear. The free spectral range of the interference spectrum at this time is expressed as: ;in, and The wavelengths of the peaks and troughs of two adjacent interference peaks in the spectrum are given. By reading the values ​​of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm fiber optic micro-vibration sensor (3): ； The interference light reflected back from the AU diaphragm fiber micro-vibration sensor (3) is output from the port three of the three-port circulator (2). It first passes through the erbium-doped fiber amplifier (4) for optical power amplification, then enters the polarization controller (5) to control the polarization state of the transmitted beam, and then enters the electro-optic modulator (6). This electro-optic modulator (6) is connected to the power module (7) to apply a bias voltage. The photoelectric modulator (6) is also connected to the radio frequency source module (8). The frequency of the radio frequency signal output by the radio frequency source module (8) is adjusted to the linear region of the passband edge of the single passband microwave photonic filter. By monitoring the changes in the center frequency of a single-passband microwave photonic filter, the vibration changes can be observed more intuitively. The expression for the center frequency of the passband is as follows: ;in, and This refers to the dispersion value of the dispersive device and the length of the dispersive medium. Given the free spectral range of the interference spectrum, the location of the passband center frequency can be determined. The dispersion coefficient of dispersion-compensating fiber and length and the free spectral range of the interference spectrum Together, we can determine that by setting the values ​​of these three parameters, we can obtain filter responses with different center passband positions, thus achieving passband tunability. Will Substitution ,get: ； As can be seen from the above, external micro-vibration signals will cause changes in the cavity length of the AU diaphragm fiber optic micro-vibration sensor (3). Due to the sealed air cavity, the refractive index Since it is constant, under the same external conditions, the change in the passband center frequency depends only on the cavity length. The change, namely: ； The interference light reflected back from the AU diaphragm fiber micro-vibration sensor (3) is output from the port three of the three-port circulator (2). It is first amplified by the erbium-doped fiber amplifier (4), then enters the polarization controller (5) to control the polarization state of the transmitted beam, and then enters the electro-optic modulator (6). This electro-optic modulator (6) is connected to the power supply module (7) to apply a bias voltage. The electro-optic modulator (6) is also connected to the radio frequency source module (8). The frequency of the radio frequency signal output by the radio frequency source module (8) is adjusted to the linear region of the passband edge of the single passband microwave photonic filter. The signal output by the electro-optic modulator (6) is then connected to the dispersion compensation fiber (9). The output of the dispersion compensation fiber (9) is connected to the optical input port of the photodetector (10). The photodetector (10) converts the optical signal into an electrical signal. The electrical output of the photodetector (10) is connected to the data acquisition card (11), and finally processed and displayed by the computer (12).

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