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

Abstract

The invention relates to the technical field of microwave photons, and discloses a diaphragm type optical fiber micro-vibration measuring device and method based on a single-passband microwave photonic filter. Comprising a broadband light source module, a three-port circulator, an AU diaphragm optical fiber micro-vibration sensor, an erbium-doped optical fiber amplifier, a polarization controller, an electro-optical modulator, a power supply module, a radio frequency source module, a photoelectric detector, a data acquisition card and a computer, wherein the broadband light source module is connected with one port of the three-port circulator through an optical fiber connecting line. The wavelength change of the interference spectrum of the Au diaphragm optical fiber micro-vibration sensor is converted into the change of the center frequency of a single-passband microwave photon filter by adopting a microwave photon filtering technology, and a certain frequency is modulated; namely, the radio-frequency signal of the passband edge linear region of the single-passband microwave photonic filter converts the passband frequency change into the intensity change of the radio-frequency signal, so that the micro-vibration detection is realized, and the measurement cost can be reduced to the maximum extent.

Description

Technical Field

[0001] The invention relates to the field of microwave photon technology, and in particular to a diaphragm-type optical fiber micro-vibration measuring device and method based on a single-passband microwave photon filter. Background Art

[0002] The optical fiber diaphragm vibration sensor is based on optical signal transmission and sensing of physical quantity changes. It is completely unaffected by electromagnetic interference and can work stably in harsh electromagnetic environments such as high electromagnetic fields, high magnetic fields, and high radiation fields. For example, it can accurately measure relevant physical quantities near high-voltage transmission lines and around large motor equipment. At the same time, the optical fiber diaphragm vibration sensor uses the principle of light interference and is extremely sensitive to small changes in physical quantities. It can achieve high-precision and high-sensitivity measurements and can be used to measure micro-vibrations, pressure changes, temperature changes, etc.

[0003] Traditional fiber optic diaphragm vibration sensors mostly use lighter and thinner polymer diaphragms. Although they can perform vibration tests more accurately, thinner polymer diaphragms are prone to cracking or damage when facing large vibration shocks or long-term vibration environments. For example, in an industrial environment, if there are vibration shocks caused by frequent start-ups and stops of large equipment around the sensor, the polymer diaphragm may not be able to withstand it and be damaged. In addition, temperature has a great influence on the elastic modulus of the diaphragm. In a high temperature environment, the diaphragm may become soft, reducing its response accuracy to vibration; in a low temperature environment, it may become brittle, increasing the risk of cracking; in some chemical environments, such as in petrochemical plants or transformer oil, polymer diaphragms may be exposed to various corrosive chemicals such as acids, alkalis, and organic solvents. These chemicals may corrode the diaphragm, making its surface rough, with holes or dissolution, thereby affecting the optical and mechanical properties of the sensor and shortening the service life of the sensor;

[0004] Moreover, in traditional vibration demodulation, since the interference spectrum is periodic, when the optical path difference caused by the vibration changes beyond the range of one cycle, it is difficult to accurately distinguish whether the change caused by the vibration is within the current cycle or has crossed over to the next cycle, thereby 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 interference spectra, these methods may encounter difficulties in practical applications. Summary of the invention

[0005] The object of the present invention is to provide a diaphragm-type optical fiber micro-vibration measurement device and method based on a single-passband microwave photon filter, which can effectively solve the problems in the background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The invention discloses a diaphragm-type optical fiber micro-vibration measuring device and method based on a single-passband microwave photon filter, comprising a broadband light source module, a three-port circulator, an AU diaphragm optical fiber micro-vibration sensor, an erbium-doped optical fiber amplifier, a polarization controller, an electro-optic modulator, a power module, a radio frequency source module, a photodetector, a data acquisition card and a computer, wherein the broadband light source module is connected to one port of the three-port circulator through an optical fiber connecting line, two ports of the three-port circulator are connected to the AU diaphragm optical fiber micro-vibration sensor through an optical fiber connecting line, three ports of the three-port circulator are connected to the input end of the erbium-doped optical fiber amplifier through an optical fiber connecting line, the output end of the erbium-doped optical fiber amplifier is connected to the input end of the polarization controller through an optical fiber connecting line, the output end of the polarization controller is connected to the input end of the electro-optic modulator through an optical fiber connecting line, two electrical ports of the electro-optic modulator are respectively connected to the power module and the radio frequency source module, the output end of the electro-optic modulator is sequentially connected to the dispersion compensation optical fiber and the input end of the photodetector through an optical fiber connecting line, the data acquisition card is connected to the output end of the photodetector, and the data acquisition card is also connected to the computer through a connecting line.

[0008] The method of the diaphragm type optical fiber micro-vibration measuring device based on the single-passband microwave photon filter comprises the following steps:

[0009] S1. The light emitted by the broadband light source module is output through the port two of the three-port circulator and incident on the AU diaphragm optical fiber micro-vibration sensor. Therefore, the external micro-vibration causes the cavity length of the Fabry-Perot interferometer (FPI) formed by the AU diaphragm optical fiber micro-vibration sensor to change. The change in the 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 light beam reaches the reflection surface of the AU diaphragm optical fiber micro-vibration sensor, its reflectivity is relatively low, which causes the incident light beam to have only limited reflection in the resonant cavity, thereby forming a double-beam interference phenomenon. The reflection spectrum generated by the double-beam interference can be expressed by the following formula:

[0010]

[0011] Among them, I 1 and I 2 are the reflected light intensities of the two reflective surfaces of the optical fiber end face and the gold foil, respectively, and θ is the phase difference caused by the optical path difference after the light is reflected once in the cavity of the AU diaphragm optical fiber micro-vibration sensor, which is expressed as:

[0012]

[0013] Where: l is the cavity length of the AU diaphragm optical fiber micro-vibration sensor cavity, n is the refractive index of the cavity, λ 0 is the wavelength of the incident light;

[0014] Set the initial length of the FPI cavity to l0 ,but:

[0015] l=l 0 -Δd 0 ;

[0016] When the sound wave propagates in the cavity of the AU diaphragm optical fiber micro-vibration sensor, the pressure change caused by it acts on the elastic sheet, causing the sheet to produce elastic deformation. The magnitude of this deformation is related to the pressure difference, that is, it is related to the vibration amplitude of the sound wave. According to the principle of elastic mechanics, assuming that the elastic sheet is subjected to the pressure p caused by the vibration of the sound wave, the deformation amount generated at the center of the sheet is:

[0017]

[0018] Where p is the lateral pressure difference on the constant elastic sheet, R is the effective radius of the constant elastic sheet, h is the thickness of the sheet, μ is the Poisson's ratio of the material, and E is the Young's modulus of the material;

[0019] For the selected material, μ and E are known quantities. From the above formula, we can know that for different d and R 0 The sensitivity and measuring range of the sensor can be determined. When these two parameters are determined, the diaphragm deformation Δd 0 Proportional to the pressure p;

[0020] When a broadband light source module is selected as the light source, interference peaks of different frequencies will appear. At this time, the free spectral range of the interference spectrum is expressed as:

[0021]

[0022] Among them, λ 1 and λ 2 are the wavelengths of the peaks and troughs of two adjacent interference peaks in the spectrum. By reading the value of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm optical fiber micro-vibration sensor:

[0023]

[0024] The interference light reflected by the S2 and AU diaphragm optical fiber micro-vibration sensors is output through port three of the three-port circulator, firstly passes through an erbium-doped fiber amplifier for optical power amplification, then enters a polarization controller to control the polarization state of the transmission light beam, and then is connected to an electro-optic modulator. This electro-optic modulator is connected to a power module to apply a bias voltage. The electro-optic modulator is also connected to a 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.

[0025] S3. By monitoring the change of the passband center frequency of the single-passband microwave photon filter, the change of vibration can be observed more intuitively. The expression of the passband center frequency is as follows:

[0026]

[0027] Among them, D and L refer to the dispersion value of the dispersion device and the length of the dispersion medium, Δω is the change of the AU diaphragm fiber micro-vibration sensor of the interference spectrum. It can be seen that the position f of the passband center frequency is determined by the dispersion coefficient D and length L of the dispersion compensation fiber and the free spectral range Δω of the interference spectrum. By setting the sizes of these three parameters, the filtering response with different center passband positions can be obtained, that is, the passband can be tunable. Substitution get:

[0028]

[0029] As can be seen from the above, the external micro-vibration signal will cause the change of the cavity length of the AU diaphragm optical fiber micro-vibration sensor. Since the air cavity is kept closed, the refractive index n is constant. Therefore, under the same external conditions, the change of the passband center frequency only depends on the cavity length L. cav changes, namely:

[0030]

[0031] The interference light reflected by the S4 and AU diaphragm optical fiber micro-vibration sensors is output through the third port of the three-port circulator, firstly passes through the erbium-doped fiber amplifier for optical power amplification, then enters the polarization controller to control the polarization state of the transmission light beam, and then is connected to the electro-optic modulator. The electro-optic modulator is connected to the power module to apply bias voltage. The electro-optic modulator is also connected to the RF source module. The frequency of the RF signal output by the RF source module is adjusted to the linear region of the passband edge of the single-passband microwave photon filter. The signal output by the electro-optic modulator is then connected to the dispersion compensation fiber. The output of the dispersion compensation fiber is connected to the optical input port of the photodetector. The photodetector converts the optical signal into an electrical signal. The electrical output end of the photodetector is connected to the data acquisition card, and finally processed and displayed by a computer.

[0032] As a further optimization scheme of the present invention, the AU diaphragm optical fiber micro-vibration sensor includes a large sleeve, a small sleeve, and an optical fiber ceramic ferrule. The large sleeve and the small sleeve are made of acrylic material, and the optical fiber ceramic ferrule can be nested and assembled therewith. The inner diameter of the large sleeve is larger than the outer diameter of the small sleeve, and the inner diameter of the small sleeve is larger than the size of the large sleeve. The end face of the optical fiber ceramic ferrule can be used as a first reflection surface, and the second reflection surface uses gold foil as a reflection material, and there is an air cavity between the two end faces.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In the present invention, microwave photon filtering technology is used to convert the wavelength change of the interference spectrum of the AU diaphragm optical fiber micro-vibration sensor into the change of the center frequency of the single-passband filter, and by modulating a certain frequency, that is, the radio frequency signal in the linear region of the passband edge of the single-passband microwave photon filter, the passband frequency change is converted into the intensity change of the radio frequency signal to achieve micro-vibration detection, which can minimize the measurement cost and better meet the vibration detection needs in various environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the main structure of the present invention;

[0036] Figure 2 It is a schematic structural diagram of the Au diaphragm optical fiber micro-vibration sensor of the present invention.

[0037] In the figure: 1. Broadband light source module; 2. Three-port circulator; 3. AU diaphragm optical fiber micro-vibration sensor; 4. Erbium-doped fiber amplifier; 5. Polarization controller; 6. Photoelectric modulator; 7. Power module; 8. RF source module; 9. Dispersion compensation optical fiber; 10. Photodetector; 11. Data acquisition card; 12. Computer. DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0039] like Figure 1As shown, the diaphragm type optical fiber micro-vibration measuring device based on the single-passband microwave photon filter provided by the present invention 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-optic modulator 6, a power module 7, a radio frequency source module 8, a photodetector 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 through an optical fiber connecting line, the second port of the three-port circulator 2 is connected to the AU diaphragm optical fiber micro-vibration sensor 3 through an optical fiber connecting line, and the three ports of the three-port circulator 2 are .... The optical fiber 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 optical fiber connecting line, the output end of the polarization controller 5 is connected to the optical fiber input end of the electro-optic modulator 6 through the optical fiber connecting line, the two electrical ports of the electro-optic modulator 6 are respectively connected to the power module 7 and the radio frequency source module 8, the optical fiber output end of the optoelectronic modulator 6 is connected to the dispersion compensation optical fiber 9 and the input end of the photoelectric detector 10 in sequence through the connecting line, the data acquisition card 11 is connected to the output end of the photoelectric detector 10, and the data acquisition card 11 is also connected to the computer 12 through the connecting line.

[0040] like Figure 1-Figure 2 As shown, the method of the diaphragm type optical fiber micro-vibration measuring device based on the single-passband microwave photon filter comprises the following steps:

[0041] S1, the light emitted by the broadband light source module 1 is output through the port 2 of the three-port circulator 2 and incident on the AU diaphragm optical 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 optical fiber micro-vibration sensor 3 to change. The change in the cavity length causes the phase difference generated by the interference light to change, thereby causing the wavelength of the interference spectrum to shift, that is, when the incident light beam reaches the reflection surface of the AU diaphragm optical fiber micro-vibration sensor 3, its reflectivity is relatively low, which causes the incident light beam to have only limited reflection in the resonant cavity, thereby forming a double-beam interference phenomenon. The reflection spectrum generated by the double-beam interference can be expressed by the following formula:

[0042]

[0043] Among them, I 1 and I 2 are the reflected light intensities of the optical fiber end face and the gold foil two reflection surfaces, and θ is the phase difference caused by the optical path difference after the light is reflected once in the AU diaphragm optical fiber micro-vibration sensor 3 cavity, which is expressed as:

[0044]

[0045] Where: l is the cavity length of the AU diaphragm optical fiber micro-vibration sensor 3, n is the refractive index of the cavity, λ 0is the wavelength of the incident light;

[0046] Set the initial length of the FPI cavity to l 0 ,but:

[0047] l=l 0 -Δd 0 ;

[0048] When the sound wave propagates in the cavity of the AU diaphragm optical fiber micro-vibration sensor 3, the pressure change caused by it acts on the elastic sheet, causing the sheet to produce elastic deformation. The magnitude of this deformation is related to the pressure difference, that is, it is related to the vibration amplitude of the sound wave. According to the principle of elastic mechanics, assuming that the elastic sheet is subjected to the pressure p caused by the vibration of the sound wave, the deformation amount generated at the center of the sheet is:

[0049]

[0050] Where p is the lateral pressure difference on the constant elastic sheet, R is the effective radius of the constant elastic sheet, h is the thickness of the sheet, μ is the Poisson's ratio of the material, and E is the Young's modulus of the material;

[0051] For the selected material, μ and E are known quantities. From the above formula, we can know that for different d and R 0 The sensitivity and measuring range of the sensor can be determined. When these two parameters are determined, the diaphragm deformation Δd 0 Proportional to the pressure p;

[0052] When the broadband light source module 1 is selected as the light source, interference peaks of different frequencies will appear. At this time, the free spectral range of the interference spectrum is expressed as:

[0053]

[0054] Among them, λ 1 and λ 2 are the wavelengths of the peaks and troughs of two adjacent interference peaks in the spectrum. By reading the value of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm optical fiber micro-vibration sensor 3:

[0055]

[0056] The interference light reflected by the S2 and AU diaphragm optical fiber micro-vibration sensors 3 is output through the port three of the three-port circulator 2, firstly 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 transmission light beam, and then is connected to the electro-optic modulator 6. This electro-optic modulator 6 is connected to the power module 7 to apply bias voltage. The electro-optic modulator 6 is also connected to the RF source module 8. The frequency of the RF signal output by the RF source module 8 is adjusted to the passband edge linear region position of the single-passband microwave photon filter.

[0057] S3. By monitoring the change of the passband center frequency of the single-passband microwave photon filter, the change of vibration can be observed more intuitively. The expression of the passband center frequency is as follows:

[0058]

[0059] Wherein, D and L refer to the dispersion value of the dispersion device and the length of the dispersion medium, Δω is the change of the interference spectrum, from which it can be seen that the position f of the passband center frequency is jointly determined by the dispersion coefficient D and length L of the dispersion compensation fiber and the free spectral range Δω of the interference spectrum. By setting the values ​​of these three parameters, the filtering response with different center passband positions can be obtained, that is, the passband can be tunable. Substitution get:

[0060]

[0061] As can be seen from the above, the external micro-vibration signal will cause the cavity length of the AU diaphragm optical fiber micro-vibration sensor 3 to change. Since the air cavity is kept closed, the refractive index n is constant. Therefore, under the same external conditions, the change of the passband center frequency only depends on the cavity length L. cav changes, namely:

[0062]

[0063] The interference light reflected by the S4 and AU diaphragm optical fiber micro-vibration sensors 3 is output through the port three of the three-port circulator 2, firstly 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 transmission light beam, and then is connected to the electro-optic modulator 6. This electro-optic modulator 6 is connected to the power module 7 to apply 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 photon filter. The signal output by the electro-optic modulator 6 is then connected to the dispersion compensation optical fiber 9. The output of the dispersion compensation optical 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 end of the photodetector 10 is connected to the data acquisition card 11, and finally processed and displayed by the computer 12.

[0064] The AU diaphragm optical fiber micro-vibration sensor 3 includes a large sleeve 15, a small sleeve 14, and an optical fiber ceramic ferrule 13. The large sleeve 15 and the small sleeve 14 are made of acrylic material, and the optical fiber ceramic ferrule 13 can be nested and assembled therewith. The inner diameter of the large sleeve 15 is larger than the outer diameter of the small sleeve 14, and the inner diameter of the small sleeve 14 is larger than the size of the large sleeve 15. The end face of the optical fiber ceramic ferrule 13 can be used as a first reflection surface, and the second reflection surface uses gold foil as a reflection material. There is an air cavity between the two end faces. The cavity length of the AU diaphragm optical fiber micro-vibration sensor 3 is observed under a spectrometer and adjusted through a precision adjustment frame. After determining the cavity length, epoxy resin is used for bonding again. The AU film is used to enhance its reflection of the light beam, thereby improving the contrast of the interference spectrum, so as to achieve good observation of the interference spectrum when the vibration changes. In addition, gold has good ductility and can be made into a very thin foil, and can withstand a certain external force without breaking to a certain extent.

[0065] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

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

2. The method of the diaphragm type optical fiber micro-vibration measuring device based on the single-passband microwave photon filter according to claim 1 is characterized in that: The following steps are involved: S1. The light emitted by the broadband light source module (1) is output through the port 2 of the three-port circulator (2) and incident on the AU diaphragm optical 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 optical fiber micro-vibration sensor (3) to change. The change in cavity length causes the phase difference generated by the interference light to change, thereby causing the wavelength of the interference spectrum to shift. That is, when the incident light beam reaches the reflection surface of the AU diaphragm optical fiber micro-vibration sensor (3), its reflectivity is relatively low, which causes the incident light beam to have only limited reflection in the resonant cavity, thereby forming a double-beam interference phenomenon. The reflection spectrum generated by the double-beam interference can be expressed by the following formula: Among them, I1 and I2 are the reflected light intensities of the optical fiber end face and the gold foil two reflection surfaces, respectively, and θ is the phase difference caused by the optical path difference after the light is reflected once in the cavity of the AU diaphragm optical fiber micro-vibration sensor (3), which is expressed as: Where: l is the cavity length of the AU membrane optical fiber micro-vibration sensor (3), n is the refractive index of the cavity, and λ0 is the wavelength of the incident light; Assuming the initial cavity length of the FPI cavity is l0, then: l = l0 - Δd0; When the sound wave propagates in the cavity of the AU diaphragm optical fiber micro-vibration sensor (3), the pressure change caused by it acts on the elastic sheet, causing the sheet to produce elastic deformation. The magnitude of this deformation is related to the pressure difference, that is, it is related to the vibration amplitude of the sound wave. According to the principle of elastic mechanics, assuming that the elastic sheet is subjected to the pressure p caused by the vibration of the sound wave, the deformation amount generated at the center of the sheet is: Where p is the lateral pressure difference on the constant elastic sheet, R is the effective radius of the constant elastic sheet, h is the thickness of the sheet, μ is the Poisson's ratio of the material, and E is the Young's modulus of the material; For the selected material, μ and E are known quantities. From the above formula, it can be seen that by selecting different d and R0, the sensitivity and measurement range of the sensor can be determined. When these two parameters are determined, the diaphragm deformation Δd0 is proportional to the pressure p; When the broadband light source module (1) is selected as the light source, interference peaks of different frequencies will appear. At this time, the free spectral range of the interference spectrum is expressed as: Among them, λ1 and λ2 are the wavelengths of the peak and trough of two adjacent interference peaks in the spectrum. By reading the value of the free spectrum from the spectrum, we can calculate the cavity length of the standard AU diaphragm optical fiber micro-vibration sensor (3): The interference light reflected by the S2 and AU diaphragm optical fiber micro-vibration sensors (3) is output through the third port of the three-port circulator (2), firstly passes through the erbium-doped optical fiber amplifier (4) for optical power amplification, then enters the polarization controller (5) to control the polarization state of the transmission light beam, and then is connected to the electro-optic modulator (6). The electro-optic modulator (6) is connected to the power module (7) to apply 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 passband edge linear region position of the single-passband microwave photon filter. S3. By monitoring the change of the passband center frequency of the single-passband microwave photon filter, the change of vibration can be observed more intuitively. The expression of the passband center frequency is as follows: Where D and L refer to the dispersion value of the dispersion device and the length of the dispersion medium, Δω is the change of the AU diaphragm optical fiber micro-vibration sensor (3) of the interference spectrum. It can be seen that the position f of the passband center frequency is determined by the dispersion coefficient D and length L of the dispersion compensation optical fiber and the free spectral range Δω of the interference spectrum. By setting the values ​​of these three parameters, the filtering response with different center passband positions can be obtained, that is, the passband can be tunable. Substitution get: As can be seen from the above, external micro-vibration signals will cause the cavity length of the AU diaphragm optical fiber micro-vibration sensor (3) to change. Since the air cavity is kept closed, the refractive index n is constant. Therefore, under the same external conditions, the change of the passband center frequency only depends on the cavity length L. cav changes, namely: The interference light reflected by the S4 and AU diaphragm optical fiber micro-vibration sensors (3) is output through the third port of the three-port circulator (2), firstly passes through the erbium-doped optical fiber amplifier (4) for optical power amplification, then enters the polarization controller (5) to control the polarization state of the transmission light beam, and then is connected to the electro-optic modulator (6). The electro-optic modulator (6) is connected to the power module (7) to apply 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 passband edge linear region position of the single-passband microwave photon filter. The signal output by the electro-optic modulator (6) is then connected to the dispersion compensation optical fiber (9). The output of the dispersion compensation optical 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 end of the photodetector (10) is connected to the data acquisition card (11), and finally processed and displayed by the computer (12).

3. The diaphragm-type optical fiber micro-vibration measurement device and method based on a single-passband microwave photon filter according to claim 1 is characterized in that: The AU diaphragm optical fiber micro-vibration sensor (3) comprises a large sleeve (15), a small sleeve (14), and an optical fiber ceramic ferrule (13). The large sleeve (15) and the small sleeve (14) are made of acrylic material, and the optical fiber ceramic ferrule (13) can be nested and assembled therewith. The inner diameter of the large sleeve (15) is larger than the outer diameter of the small sleeve (14), and the inner diameter of the small sleeve (14) is larger than the size of the large sleeve (15). The end face of the optical fiber ceramic ferrule (13) can be used as a first reflection surface, and the second reflection surface uses gold foil as a reflection material, and an air cavity is between the two end faces.

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