A cavity optomechanical graphene fiber accelerometer, preparation method and measurement system

Abstract

The present invention claims protection for a cavity optomechanical graphene fiber accelerometer, a preparation method thereof, and a measurement system. The cavity optomechanical graphene thin-film fiber accelerometer includes a single-mode fiber, an optical microcavity, an optical thin film, and a vacuum encapsulation tube. Among them, the fiber FPI is the sensitive element of the fiber accelerometer and is composed of a fiber end face, an optical microcavity, and an optical thin film; the optical thin film is composed of a graphene thin film and a mass block. The introduction of a chromium / gold metal thin film enhances the reflectivity of the optical thin film, and the introduction of a graphene thin film improves the sensitivity of the fiber accelerometer. The present invention uses an optical thin film composed of a graphene / quartz mass block to form a fiber FPI at the fiber end face to sense the change of external acceleration, and realizes the detection of the mechanical resonance frequency of the optical thin film by demodulating the interference light intensity of the fiber FPI, thereby realizing the measurement of external acceleration. It is beneficial to the miniaturization and integration of the sensor, can achieve high-precision measurement of acceleration, and has the advantage of anti-electromagnetic interference.

Description

Technical Field

[0001] The present invention relates to an acceleration sensing system, and particularly to a preparation method and a measurement system of a cavity optomechanical graphene optical fiber accelerometer, belonging to the field of optical fiber sensors. Background Art

[0002] Accelerometers are widely used in fields such as smart devices, automotive driving systems, industrial equipment, aviation navigation systems, border security, earthquake early warning, oil exploration, and structural health monitoring of major infrastructure, providing strong guarantees for national defense construction and people's livelihood. Currently, accelerometers mainly have two types: electronic and optical fiber. Among them, electronic acceleration sensor technology is mature and the cost is low. However, the sensor is prone to failure when used in some extreme environments such as strong electromagnetic radiation, humid and corrosive, or high-temperature environments. Compared with electronic acceleration sensors, optical fiber acceleration sensors are corrosion-resistant, high-temperature-resistant, have strong anti-electromagnetic interference ability, high stability, can work in complex environments, and at the same time are small in size, high in sensitivity, and easy for distributed sensing, having many advantages that electronic accelerometers cannot match. Therefore, in recent years, the research on optical fiber acceleration sensors has been more in-depth and extensive.

[0003] Graphene is a typical two-dimensional material with atomic-level thickness, high carrier mobility, and high mechanical strength. It has excellent optical, electrical, and mechanical properties and has important application prospects in materials science, micro-nano devices, energy, biomedicine, and drug delivery, and is considered a revolutionary material in the future. Due to the excellent optical, electrical, and mechanical properties of graphene, it is a very promising functional thin film material in micro-nano mechanical resonant devices such as accelerometers.

[0004] In the prior art, Fan et al. (Xuge Fan*, Fredrik Forsberg, Anderson D. Smith, Stephan Stefan Wagner, Henrik Andreas C. Fischer, Mikael Max C. Lemme*, Frank Niklaus*, Graphene ribbons with suspended masses astransducers in ultra-small nanoelectromechanical accelerometers, NatureElectron,2, 394 - 404(2019). Xuge Fan*, Fredrik Forsberg, Anderson D. Smith. Stephan Stefan Wagner,Mikael Max C. Lemme* and Frank Niklaus*,“NEMS accelerometers based on suspended graphene membranes with attached masses”,*Nano Letters*, 19, 10, 6788 - 6799 (2019)) reported a piezoresistive accelerometer with a suspended mass on a graphene strip. The sensitive structure size is two orders of magnitude smaller than that of traditional silicon - based accelerometers. However, it uses an on - chip integration method and a resistive demodulation method, which is not conducive to the miniaturization of the device and is vulnerable to electromagnetic interference.

[0005] Therefore, the present invention selects graphene thin - film materials to be combined with optical fibers to achieve acceleration sensing. Its basic principle is: a beam of light (excitation light) is used to excite the graphene thin - film of the suspended mass to generate mechanical resonance; another beam of light (detection light) is used to detect the mechanical resonance frequency of the graphene thin - film of the suspended mass. When an external acceleration is input, it causes the mass to displace, thereby causing a change in the internal stress of the graphene thin - film, and then causing a change in the mechanical resonance frequency of the graphene thin - film. By demodulating the detection light signal, the magnitude of the external acceleration can be demodulated.

[0006] Fan Shangchun et al. (Patent Invention Publication No. CN109782022B) proposed a graphene resonant fiber optic accelerometer based on pressure sensitivity, which uses a graphene membrane to directly sense the pressure in the cavity to achieve acceleration measurement. It needs to first use an elastic diaphragm to convert the external acceleration into a pressure change in the gas - sealed cavity, thereby changing the air pressure of the sealed graphene thin - film. The device needs to use structures such as ceramic ferrules and gas - sealed cavities, with a complex structure and a large volume, which is not conducive to the miniaturization of the device and vacuum packaging, and is vulnerable to environmental thermal noise and other influences. In addition, the ferrule installed on the elastic thin sheet serves as the sensitive mass. Compared with the nano - graphene thin - film, the elastic thin sheet has a larger stiffness, which is not conducive to efficient energy conversion. Therefore, the present invention directly selects the graphene thin - film of the suspended mass to sense the external acceleration, and conducts all - fiber integrated and vacuum micro - packaging, which is conducive to the miniaturization of the device, improves the energy conversion efficiency, and avoids the influence of environmental thermal noise and the like. Summary of the Invention

[0007] The present invention aims to solve the above - mentioned problems of the prior art. A cavity optomechanical graphene fiber optic accelerometer, a preparation method, and a measurement system are proposed. The technical solution of the present invention is as follows:

[0008] A cavity optomechanical graphene thin-film fiber accelerometer, which comprises a single-mode fiber, an optical microcavity, an optical thin film and a vacuum encapsulation tube. The single-mode fiber includes a first end face and a second end face; the optical microcavity is located on the second end face of the single-mode fiber, the graphene thin film is located on the other end of the optical microcavity, the optical thin film is suspended on the end face of the optical microcavity, and the second end face of the single-mode fiber, the optical microcavity and the optical thin film together form a fiber FPI; the vacuum encapsulation tube is sleeved outside the fiber FPI to vacuum-encapsulate the fiber FPI, and the first end face of the single-mode fiber is exposed outside the vacuum encapsulation tube. The single-mode fiber is used for the transmission of excitation light and detection light. The optical microcavity can form an optical resonant cavity for the excitation of cavity optomechanical effects. The optical thin film can reflect optical signals for demodulation and, at the same time, act as a mechanical resonator to sense external acceleration. The fiber FPI can be used to provide interference light to realize acceleration detection based on cavity optomechanics.

[0009] Further, the optical thin film includes a graphene thin film and a mass block; there is a metal thin film plated on the side of the mass block near the graphene, and the plated metal is composed of a gold metal thin film or a gold / chromium metal thin film; by changing the shape and size of the mass block, as well as the geometric shape and size of the graphene thin film, the working frequency and working range of the accelerometer can be changed.

[0010] Further, the fiber FPI is prepared in the following manner: First, an optical microcavity is prepared on the cut end face of the single-mode fiber. Second, an optical thin film is prepared on the end face of the prepared optical microcavity. Third, after the transfer of the graphene thin film, metal thin films chromium and gold are successively prepared on the graphene thin film substrate. Finally, the shape of the optical thin film on the end face of the optical microcavity is etched by means of microfabrication methods such as plasma etching, femtosecond laser etching or focused ion beam (FIB). Then, the processed optical thin film, the optical microcavity and the cut fiber end face form an FPI.

[0011] Further, the preparation of the optical thin film is carried out by combining the double-layer or multi-layer graphene thin film transfer technology, the quartz thin film transfer technology and the fiber end face polishing technology and combining the laser microfabrication technology;

[0012] The preparation of the metal thin films chromium and gold is carried out by means of magnetron sputtering coating or evaporation coating;

[0013] The shape etching of the optical thin film on the end face of the optical microcavity is carried out by means of microfabrication methods including plasma etching, femtosecond laser etching or focused ion beam FIB.

[0014] A preparation method for a cavity optomechanical graphene fiber accelerometer according to any one of the above, which includes the following steps:

[0015] Step 1: Take a section of single-mode optical fiber. The single-mode optical fiber includes a first end face and a second end face. Fabricate an optical microcavity on the second end face of the single-mode optical fiber.

[0016] Step 2: Fabricate an optical thin film on the other end of the optical microcavity. The optical thin film consists of a mass block of a certain size suspended by a suspended graphene film. The second end face of the single-mode optical fiber, the optical microcavity, and the optical thin film together form an optical fiber FPI.

[0017] Step 3: Take a section of vacuum encapsulation tube. First, insert the optical fiber FPI into the vacuum encapsulation tube, with the first end face of the single-mode optical fiber exposed outside the vacuum encapsulation tube. Then, fuse one end of the vacuum encapsulation tube facing the same direction as the first end face of the single-mode optical fiber to the single-mode optical fiber. Next, evacuate the inside of the vacuum encapsulation tube, and then heat-melt and seal one end of the vacuum encapsulation tube facing the same direction as the second end face of the single-mode optical fiber.

[0018] Further, the graphene film suspending the mass block in Step 2 specifically includes: transferring a quartz film to the second end face of the optical microcavity, using femtosecond laser combined with wet etching technology for shape pre-preparation, then transferring the graphene film and using precision microfabrication technology including femtosecond laser again to pattern the mass block and the graphene film, so that the mass block is suspended under the suspended graphene film.

[0019] A measurement system based on the cavity optomechanical graphene optical fiber accelerometer according to any one of the above, comprising a first light source, a second light source, a single-mode optical fiber, an optical fiber acceleration sensing probe, an electro-optic modulator, an optical circulator, a signal generator, an optical isolator, a tunable optical filter, a PD detector, an electrical spectrum analyzer or a vector network analyzer or a lock-in amplifier. The optical fiber acceleration sensing probe is realized by an optical fiber FPI structure. The optical fiber FPI is composed of an optical fiber end face, an optical microcavity, and an optical thin film; the optical thin film is composed of a graphene film and a mass block; there is a metal film plated on the side of the mass block close to the graphene.

[0020] The excitation light emitted by the first light source sequentially passes through the optical isolator, the electro-optic modulator, the optical coupler, the optical circulator, and the optical fiber acceleration sensing probe. The excitation light reaches the optical fiber FPI structure, and directly acts on the optical thin film after passing through the optical fiber end face, driving the optical thin film to generate mechanical resonance; the light reflected by the graphene film and the optical fiber end face will pass through the optical circulator and then be filtered by the tunable optical filter; the detection light emitted by the second light source sequentially passes through the optical isolator, the optical circulator, and the optical fiber acceleration sensing probe. The optical signal will be reflected twice in the optical fiber acceleration sensing probe, and the reflected light will pass through the optical circulator and then enter the PD detector to be converted into an electrical signal, and the electrical signal will then enter the electrical spectrum analyzer or the vector network analyzer or the lock-in amplifier.

[0021] The advantages and beneficial effects of the present invention are as follows:

[0022] Aiming at the deficiencies of existing micro-nano mechanical accelerometers in terms of electromagnetic interference resistance and resolution, the present invention proposes a preparation method and a measurement system for a cavity optomechanical graphene fiber accelerometer. This accelerometer has the advantages of higher sensitivity, better electromagnetic interference resistance, higher detection accuracy, and larger working range.

[0023] The fiber accelerometer of the present invention uses the fiber FPI to detect the acceleration signal and demodulates the acceleration through the mechanical resonance frequency of the optical thin film, combining the advantages of both resonant accelerometers and optical accelerometers; and uses the vacuum encapsulation tube to vacuum encapsulate the fiber FPI, isolating the fiber FPI from the external environment by using the vacuum environment inside the vacuum encapsulation tube, so that heat, gas molecules, etc. cannot act on the resonant optical thin film through heat conduction and heat convection, avoiding the influence of heat conduction and heat convection noise on the sensing of the acceleration signal.

[0024] The present invention proposes a fully fiber-integrated accelerometer, directly preparing a graphene thin film microcavity with a suspended quartz mass on the end face of a single-mode fiber, enabling the excitation light and the detection light to directly act on the graphene thin film through the single-mode fiber, integrating the optical cavity and the mechanical oscillator fiber without coupling, and having high excitation and detection efficiency. In addition, based on the cavity optomechanical effect, the accelerometer makes full use of the high-dynamic sensing advantage of the FP cavity optomechanical effect, and realizes external acceleration sensing by detecting the change in the resonance frequency of the graphene thin film, having the advantages of high dynamics and high resolution.

[0025] The graphene fiber accelerometer of the present invention uses the graphene thin film to suspend a micron-thick quartz mass to sense acceleration, which not only enhances the sensitivity of the two-dimensional material to inertial force but also makes full use of the advantages of the two-dimensional material of the graphene thin film: being thin, flexible, and having high strength, making the accelerometer have the advantages of high sensitivity and high precision. Description of the Drawings

[0026] Figure 1 It is a flowchart of the sample preparation of the graphene fiber accelerometer according to the preferred embodiment provided by the present invention.

[0027] Figure 2 It is a diagram of the preparation method and measurement system of a cavity optomechanical graphene fiber accelerometer according to the present invention.

[0028] Figure 3 It is a schematic diagram of the graphene thin film structure of a cavity optomechanical graphene fiber accelerometer according to the present invention. Detailed Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and detailedly described in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention.

[0030] The technical solution for the present invention to solve the above technical problems is as follows:

[0031] As Figure 1 shown, a graphene film fiber optic accelerometer includes a single-mode fiber, an optical microcavity, an optical film, and a vacuum encapsulation tube. The single-mode fiber includes a first end face and a second end face; the optical microcavity is fabricated on the second end face of the single-mode fiber, the graphene film is fabricated on the other end of the optical microcavity, the optical film is suspended on the end face of the optical microcavity, and the second end face of the single-mode fiber, the optical microcavity, and the optical film together form a fiber FPI; the vacuum encapsulation tube is sleeved outside the fiber FPI to vacuum encapsulate the fiber FPI, and the first end face of the single-mode fiber is exposed outside the vacuum encapsulation tube.

[0032] A method for fabricating a graphene fiber optic accelerometer includes the following steps:

[0033] 1. Take a section of single-mode fiber. The single-mode fiber includes a first end face and a second end face. Fabricate an optical microcavity on the second end face of the single-mode fiber, and the cavity length of the optical microcavity is between 5 - 200 μm.

[0034] 2. Fabricate an optical film on the other end of the optical microcavity. The optical film consists of a suspended graphene film hanging a mass block of a certain size. The second end face of the single-mode fiber, the optical microcavity, and the optical film together form a fiber FPI.

[0035] 3. For the graphene film to hang the mass block, the quartz film can be transferred to the second end face of the optical microcavity, and the shape can be pre-prepared using femtosecond laser combined with wet etching technology. Then, the graphene film is transferred, and the mass block and the graphene film are patterned using precision microfabrication technologies such as femtosecond laser again, so that the mass block hangs below the suspended graphene film.

[0036] 4. Take a section of vacuum encapsulation tube. First, insert the fiber FPI into the vacuum encapsulation tube, and the first end face of the single-mode fiber is exposed outside the vacuum encapsulation tube. Then, weld the end of the vacuum encapsulation tube facing the same direction as the first end face of the single-mode fiber to the single-mode fiber. Next, evacuate the inside of the vacuum encapsulation tube, and then heat-melt and seal the end of the vacuum encapsulation tube facing the same direction as the second end face of the single-mode fiber.

[0037] A method for detecting acceleration of a graphene fiber optic accelerometer includes the following steps:

[0038] 1. The light source emits excitation light, which is modulated by an electro-optic modulator, and then reaches the optical microcavity through an optical coupler and a circulator. After passing through the optical microcavity, it reaches the optical thin film. Due to photothermal and optomechanical effects, the optical thin film is optically excited and generates mechanical resonance.

[0039] 2. The light source emits a detection optical signal, which is reflected at one end of the optical microcavity after passing through the optical coupler and the circulator, and will be reflected again at the other end of the optical microcavity (i.e., the optical thin film). The two reflected optical signals form an interference at one end of the optical fiber. Since the mechanical vibration of the optical thin film will cause a periodic change in the cavity length, the mechanical resonance frequency of the optical thin film can be monitored by demodulating the change in the intensity of the detection optical signal.

[0040] 3. When there is an external force, the mass block generates an acceleration, thereby generating an additional displacement, which changes the internal stress of the graphene thin film and the mechanical resonance frequency of the optical thin film; affecting the detection optical signal.

[0041] 4. The external acceleration can be calculated based on the change in the mechanical resonance frequency of the optical thin film.

[0042] The present invention has the advantages of small volume, light weight, anti-electromagnetic interference, high precision, and high sensitivity.

[0043] S1: Couple the excitation optical signal with the first wavelength and the detection optical signal with the second wavelength into the above-mentioned fiber optic accelerometer probe together, so that the excitation optical signal drives the resonant thin film to generate resonance.

[0044] S2: Obtain the detection optical signal reflected by the fiber optic accelerometer probe to obtain the frequency response curve (i.e., the spectrum) and the mechanical resonance frequency of the fiber optic accelerometer probe.

[0045] S3: Calculate the magnitude of the acceleration according to the offset of the mechanical resonance frequency in the spectrum.

[0046] The described FPI prepares an optical microcavity on the end face of a common single-mode optical fiber by flattening the end face of the optical fiber. The available preparation methods include: fusing a quartz glass tube, or forming a microcavity by polymerizing a support structure using two-photon polymerization, or directly ablating a microcavity on the flattened single-mode optical fiber by laser ablation and other microcavity processing methods. The length of the optical microcavity is 5 - 200 μm; an optical thin film is prepared at the other end of the optical microcavity. The optical thin film includes two structures. One is a mass block suspended by a graphene thin film, with a thickness of 1 - 20 μm, which is prepared by two-photon polymerization, or quartz thin film transfer, or the method of fusing a single-mode optical fiber and then cutting, polishing, and grinding. The other is a graphene thin film, and the available preparation methods include wet transfer of single-layer or multi-layer graphene thin films; finally, a shape is engraved on the prepared optical thin film layer by using femtosecond laser or FIB microfabrication. In order to improve the sensitivity of the device, it is advisable to reduce the width of the fixed support beam, and pay attention to leaving thin film materials at the position of the fiber core.

[0047] Example 1: A graphene fiber accelerometer sensor is fabricated by combining the technology of fusing a single-mode optical fiber and then cutting, polishing, and grinding with wet transfer of graphene.

[0048] The steps are as follows:

[0049] 1. Take an SM28 single-mode optical fiber, flatten the end face of the optical fiber, and then place it in an optical fiber fusion splicer.

[0050] 2. Take a quartz capillary with an outer diameter of 148 μm and an inner diameter of 50 μm, remove the outer coating, clean it, flatten the end face, and place it at the other end of the optical fiber fusion splicer. Set the parameters of the fusion splicer and fuse the capillary quartz tube with the single-mode optical fiber.

[0051] 3. Place the sample of the single-mode optical fiber integrated with the quartz capillary obtained in step 2 under a precision cutting knife and cut it at the position where the length of the quartz capillary is 20 μm to obtain a single-mode optical fiber with an optical microcavity of a certain length connected to the end face.

[0052] 4. Place the single-mode optical fiber with the optical microcavity in the optical fiber fusion splicer. Take a coreless optical fiber, flatten the end face of the optical fiber, and place it at the other end of the optical fiber fusion splicer. Set the parameters of the fusion splicer and fuse the capillary quartz tube with the coreless optical fiber.

[0053] 5. Place the sample of the single-mode optical fiber / quartz capillary / coreless optical fiber integrated obtained in step 4 under a precision cutting knife and cut it at the position where the length of the coreless optical fiber is 10 μm to obtain a single-mode optical fiber with a closed optical microcavity of a certain length connected to the end face.

[0054] 6. Place the sample of the single-mode optical fiber / quartz capillary / coreless optical fiber integrated obtained in step 5 in an optical fiber end face polishing instrument and polish the thickness of the coreless optical fiber to 2 μm to obtain a single-mode optical fiber with a closed optical microcavity of a certain length connected to the end face.

[0055] 7. Shape the coreless fiber film on the end face of the optical microcavity of the single-mode fiber obtained in step 6 using femtosecond laser to obtain a cantilever-supported quartz mass block with a size of 4μm×4μm.

[0056] 8. Clean the sample obtained in step 7 with HF solution with a concentration of 1% to remove the processing debris introduced by femtosecond laser processing.

[0057] 9. Take a 1cm*1cm 6-8 layer CVD copper-based graphene film and transfer the multi-layer graphene film to the end face of the optical microcavity obtained in step 8 using wet transfer technology to obtain a graphene quartz film.

[0058] 10. Use femtosecond laser micromachining to etch the structure of the optical film on the end face of the optical microcavity of the single-mode fiber obtained in step 9, release the mass block, and obtain an optical film supported only by the graphene film. Taking the double-ended fixed beam as an example, in order to improve the sensitivity, the smaller the width-to-length ratio of the fixed beam, the higher the sensitivity. Here, a double-ended fixed beam with a width of 3μm and a length of 10μm is taken as an example. Figure 3 It is a three-dimensional schematic diagram of the micro-structure of the optical film. So far, the graphene film and the quartz film together constitute the optical film. The optical film, the optical microcavity and the fiber end face form a fiber FPI, which together constitute an accelerometer probe.

[0059] The systems, devices, modules or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions.

[0060] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the said element.

[0061] The above embodiments should be understood as being only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the content recorded in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A cavity optomechanical graphene film fiber accelerometer, characterized in that, It includes a single-mode optical fiber, an optical microcavity, an optical thin film, and a vacuum encapsulation tube. The single-mode optical fiber includes a first end face and a second end face; the optical microcavity is located on the second end face of the single-mode optical fiber, the graphene thin film is located on the other end of the optical microcavity, the optical thin film is suspended on the end face of the optical microcavity, and the second end face of the single-mode optical fiber, the optical microcavity, and the optical thin film together form an optical fiber FPI; the vacuum encapsulation tube is sleeved outside the optical fiber FPI to vacuum-encapsulate the optical fiber FPI, and the first end face of the single-mode optical fiber is exposed outside the vacuum encapsulation tube. The single-mode optical fiber is used for the transmission of excitation light and detection light; the optical microcavity can form an optical resonator for the excitation of cavity optomechanical effects; the optical thin film can reflect optical signals for demodulation and, at the same time, act as a mechanical resonator to sense external acceleration; the optical fiber FPI can be used to provide interference light to realize acceleration detection based on cavity optomechanical effects; The optical thin film includes a graphene thin film and a mass block; there is a metal thin film plated on the side of the mass block near the graphene, and the plated metal is composed of a gold metal thin film or a gold / chromium metal thin film; by changing the shape and size of the mass block and the geometric shape and size of the graphene thin film, the operating frequency and operating range of the accelerometer can be changed; The optical fiber FPI is prepared in the following way: First, an optical microcavity is prepared on the cut and flattened end face of the single-mode optical fiber. Second, an optical thin film is prepared on the end face of the prepared optical microcavity. Third, after the graphene thin film is transferred, metal thin films chromium and gold are successively prepared on the graphene thin film substrate. Finally, the shape of the optical thin film on the end face of the optical microcavity is etched by using plasma etching, femtosecond laser etching, or focused ion beam FIB microfabrication method; then the processed optical thin film, the optical microcavity, and the cut and flattened optical fiber end face form an FPI.

2. The cavity optomechanical graphene film fiber optic accelerometer according to claim 1, wherein The preparation of the optical thin film is carried out by combining the double-layer or multi-layer graphene thin film transfer technology, the quartz thin film transfer technology, and the optical fiber end face polishing technology and combining the laser microfabrication technology; The preparation of the metal thin films chromium and gold is carried out by using magnetron sputtering coating or evaporation coating; The shape etching of the optical thin film on the end face of the optical microcavity is carried out by using microfabrication methods including plasma etching, femtosecond laser etching, or focused ion beam FIB.

3. A preparation method of the cavity optomechanical graphene film optical fiber accelerometer according to any one of claims 1-2, characterized in that, It includes the following steps: Step 1: Take a section of single-mode optical fiber. The single-mode optical fiber includes a first end face and a second end face. An optical microcavity is made on the second end face of the single-mode optical fiber; Step 2: Make an optical thin film on the other end of the optical microcavity. The optical thin film is composed of a suspended graphene thin film hanging a mass block of a certain size. The second end face of the single-mode optical fiber, the optical microcavity, and the optical thin film together form an optical fiber FPI; Step 3: Take a section of vacuum encapsulation tube. First, insert the optical fiber FPI into the vacuum encapsulation tube. The first end face of the single-mode optical fiber is exposed outside the vacuum encapsulation tube. Then, weld the end of the vacuum encapsulation tube facing the first end face of the single-mode optical fiber to the single-mode optical fiber. Next, evacuate the inside of the vacuum encapsulation tube, and then heat-melt and seal the end of the vacuum encapsulation tube facing the second end face of the single-mode optical fiber.

4. The preparation method of a cavity optomechanical graphene thin film fiber accelerometer according to claim 3, characterized in that, The graphene film suspension mass in step 2 specifically includes: transferring the quartz film to the second end face of the optical microcavity, pre-preparing the shape using femtosecond laser combined with wet etching technology, then transferring the graphene film and using precision microfabrication technologies including femtosecond laser again to pattern the mass and the graphene film, so that the mass is suspended below the suspended graphene film.

5. A measurement system for the cavity optomechanical graphene thin film fiber accelerometer according to any one of claims 1-2, comprising a first light source, a second light source, a single-mode fiber, a fiber optic acceleration sensing probe, an electro-optic modulator, an optical circulator, a signal generator, an optical isolator, a tunable optical filter, a PD detector, an electrical spectrum analyzer or a vector network analyzer or a lock-in amplifier, characterized in that, The fiber optic acceleration sensing probe is realized by a fiber optic FPI structure. The fiber optic FPI consists of a fiber optic end face, an optical microcavity, and an optical film. The optical film consists of a graphene film and a mass. There is a metal film plated on the side of the mass near the graphene. The excitation light emitted by the first light source sequentially passes through an optical isolator, an electro-optic modulator, an optical coupler, an optical circulator, and a fiber optic acceleration sensing probe. The excitation light reaches the fiber optic FPI structure and directly acts on the optical film after passing through the fiber optic end face, driving the optical film to generate mechanical resonance. The light reflected by the graphene film and the fiber optic end face will pass through the optical circulator and then be filtered by a tunable optical filter. The detection light emitted by the second light source sequentially passes through an optical isolator, an optical circulator, and a fiber optic acceleration sensing probe. The optical signal will be reflected twice in the fiber optic acceleration sensing probe, and the reflected light will enter the PD detector through the optical circulator and be converted into an electrical signal, and the electrical signal will then enter an electrical spectrum analyzer or a vector network analyzer or a lock-in amplifier.

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