FP acceleration sensor and broadband acceleration detection method

Abstract

The invention discloses an FP acceleration sensor and a broadband acceleration detection method, and belongs to the technical field of vibration detection. The FP acceleration sensor comprises N spring harmonic oscillator structures, an external frame and an optical fiber; the value of N is 1 or 2; the spring harmonic oscillator structure comprises an outer spring beam, an inner spring beam, an inner mass block and an outer mass block surrounding the inner mass block; two ends of the outer spring beam are respectively connected with the outer frame and the outer mass block; two ends of the inner spring beam are respectively connected with the outer mass block and the inner mass block; the response sensitivity of the working interval between the first-order resonant frequency and the second-order resonant frequency of the spring harmonic oscillator structure is kept consistent with the response sensitivity of the working interval below the first-order resonant frequency. An opening is etched on one side of the outer mass block, the detection optical fiber is fixed in the opening, and the end face of the detection optical fiber and the side face of the inner mass block form an FP resonant cavity. The detection frequency band of the sensor is widened on the premise that the sensitivity of the sensor is not reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of vibration detection, and more specifically, relates to an FP acceleration sensor and a broadband acceleration detection method. Background Art

[0002] Acceleration detection technology has very wide applications in many fields such as underwater acoustic detection, inertial navigation, earthquake warning, and structural health monitoring. For acceleration detection, compared with electrical detection methods, optical detection technology has become a research and application hotspot due to its advantages of high detection sensitivity, strong anti-electromagnetic interference ability, and easy networking and multiplexing.

[0003] As an optical vibration detection technology, the optical Fabry-Perot sensor has the advantages of small volume, high sensitivity, low noise, and easy multiplexing and networking. Its structure mainly consists of a sensitive transducer material and an FP (Fabry - Perot) resonant cavity, which converts the vibration information to be measured into changes in the reflection spectrum, and performs acceleration detection by demodulating the phase information of the reflection spectrum, while effectively reducing the influence of noise.

[0004] However, in the existing optical Fabry-Perot sensors, the working frequency band and the response sensitivity restrict each other. The response sensitivity of the sensor and the resonant frequency are in an inverse square relationship. When broadening the working frequency band of the sensor, due to the increase in the resonant frequency, the response sensitivity will be sacrificed significantly. Summary of the Invention

[0005] Aiming at the defects of the related technology, the purpose of the present invention is to provide an FP acceleration sensor and a broadband acceleration detection method, aiming to solve the technical problem that in the existing technology, with the increase in the resonant frequency of the acceleration sensor, the response sensitivity is sacrificed significantly.

[0006] To achieve the above purpose, the present invention provides an FP acceleration sensor, which includes N spring resonator structures, an external frame, and a detection optical fiber; where the value of N is: 1 or 2;

[0007] The spring resonator structure includes an outer spring beam and an inner spring beam, as well as an inner mass block and an outer mass block surrounding the inner mass block; both the outer spring beam and the inner spring beam are elastic beam structures in four-way parallel connection. The two ends of the outer spring beam are respectively connected to the external frame and the outer mass block, and the two ends of the inner spring beam are respectively connected to the outer mass block and the inner mass block;

[0008] Both the first-order resonant mode and the second-order resonant mode of the spring resonator structure are in-plane vibration modes;

[0009] The working interval between the first-order resonant frequency and the second-order resonant frequency is consistent with the response sensitivity of the working interval at the first-order resonant frequency;

[0010] One side of the outer mass block is etched with an opening, the detection optical fiber is fixed in the opening, and the end face of the detection optical fiber and the side face of the inner mass block form an FP resonant cavity.

[0011] Optionally, the response sensitivities of the two working intervals of the spring oscillator structure are adjusted by the stiffness coefficient ratio of the outer spring beam and the inner spring beam and the mass ratio of the outer mass block and the inner mass block.

[0012] Optionally, when the FP acceleration sensor includes two spring oscillator structures, the sensitive axes of the first spring oscillator structure and the second spring oscillator structure are coaxial;

[0013] The size of the second spring oscillator structure is larger than that of the first spring oscillator structure; the frequency band missing range corresponding to the first-order resonance frequency of the first spring oscillator structure is the same as the frequency band range between the first-order and second-order resonance frequencies of the second spring oscillator structure.

[0014] Optionally, the free spectral ranges of the FP resonant cavities of the first spring oscillator structure and the second spring oscillator structure do not overlap spectrally.

[0015] Optionally, an optical fiber slot is provided in the opening, and the detection optical fiber is fixed in the optical fiber slot by an adhesive method.

[0016] Optionally, the outer frame, the optical fiber slot, the first spring oscillator structure and the second spring oscillator structure are all integrally etched and processed from silicon material using a silicon microfabrication process.

[0017] In a second aspect, the present invention further provides an optical sensing system, including: a broadband light source, an FP acceleration sensor, an optical signal real-time acquisition module and a signal demodulation module, wherein, the FP acceleration sensor is the FP acceleration sensor according to any one of the first aspect;

[0018] The broadband light source is used to output an original detection optical signal;

[0019] The FP acceleration sensor is used to modulate the original detection optical signal injected into the FP resonant cavity under the action of the acceleration signal to be measured, and form an FP reflected interference optical signal with a spectral phase change;

[0020] The optical signal real-time acquisition module is used to real-time acquire the spectral phase change amount of the FP reflected interference optical signal;

[0021] The signal demodulation module is used to extract the harmonic signal of the spectral phase change amount, and calculate the magnitude of the acceleration to be measured according to the amplitude and phase of the harmonic signal.

[0022] In a third aspect, the present invention further provides a broadband acceleration detection method, characterized in that the acceleration detection is performed by using the optical sensing system as described in the second aspect.

[0023] By the above technical solution conceived by the present invention, compared with the prior art, the following beneficial effects can be achieved:

[0024] 1. An FP acceleration sensor provided by the present invention, through etching a cascaded spring resonator structure, the vibration mode of the first-order resonance frequency is the in-plane co-directional translation of the inner and outer mass blocks, and the vibration mode of the second-order resonance frequency is the in-plane reverse translation of the inner and outer mass blocks. There will be no vibration modes such as distortion and rotation in the frequency band between the first-order resonance frequency and the second-order resonance frequency. Thus, compared with the traditional acceleration sensor, an additional working frequency band (the frequency band between the first-order resonance frequency and the second-order resonance frequency) can be introduced, and then the detection frequency band of the sensor is broadened without reducing the sensitivity of the sensor.

[0025] 2. An FP acceleration sensor provided by the present invention adopts a cascaded spring resonator structure with two different sizes, which solves the problem of frequency band loss at the peak of the first-order resonance frequency of a single cascaded spring resonator structure. The second spring resonator structure compensates for the missing frequency band of the first spring resonator structure, and then constitutes a complete broadband. Further, the free spectral ranges of the two FP resonators have a certain difference, so that they can be distinguished in the Fourier transform spectrum of the composite spectrum, and further real-time demodulation is performed according to the frequency determination algorithm. The complete acceleration sensor composed of two cascaded spring resonator structures can realize the detection of broadband and high-sensitivity acceleration signals. Both of the two double-cascaded spring resonator structures are planar structures, with mature and controllable processes, and can realize three-dimensional acceleration measurement by three identical structures, having the characteristics of small volume, high performance, and integration.

[0026] 3. An optical sensing system provided by the present invention only includes a light source module, an FP acceleration sensor, a signal real-time acquisition module, and a signal demodulation module. The devices involved are fewer and the detection device is simple. Based on the designed acceleration sensor, it has high sensitivity and a wide working frequency band. The optical sensor converts the acceleration signal to be measured into a change in the reflected spectrum, and by demodulating the phase information of the reflected spectrum instead of the light intensity signal, it can effectively reduce the interference of light source noise and environmental noise; the optical sensor is a completely passive structure, can work under strong electromagnetic interference, and has excellent performance, small volume, easy integration, and can perform long-distance detection, which can improve the detection performance of optical acceleration and expand the application fields of optical acceleration, such as in many fields such as natural disaster warning, vector underwater acoustic detection, structural health monitoring, and inertial navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the first spring resonator structure of the FP acceleration sensor in the embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the structure of the FP acceleration sensor in the embodiment of the present invention.

[0029] Figure 3 Schematic block diagram of the optical sensing system in the embodiment of the present invention.

[0030] In the above-mentioned drawings, the same reference numerals have the same meaning, and the reference numerals are:

[0031] 1 is a broadband light source, 2 is an FP acceleration sensor, 3 is an optical signal real-time acquisition module, 4 is a signal demodulation module, 21 is an external frame, 22 is a detection optical fiber, 23 is an optical fiber slot, 24 is an FP resonator cavity, 25 is a first spring resonator structure, 251 is a first outer spring beam, 252 is a first inner spring beam, 253 is a first outer mass block, 254 is a first inner mass block, 26 is a second spring resonator structure, 261 is a second outer spring beam, 262 is a second inner spring beam, 263 is a second outer mass block, and 264 is a second inner mass block. Specific embodiments

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The following describes the content involved in the above embodiments in conjunction with a preferred embodiment.

[0034] Embodiment 1

[0035] As Figure 1 shown, the present invention provides an FP acceleration sensor, and the FP acceleration sensor 2 includes N spring resonator structures, an external frame 21, and a detection optical fiber 22; wherein, the value of N is: 1 or 2;

[0036] When the value of N is 1, the first spring resonator structure 25 includes a first outer spring beam 251 and a first inner spring beam 252, as well as a first inner mass block 254 and a first outer mass block 253 surrounding the first inner mass block 254; both the first outer spring beam 251 and the first inner spring beam 252 are elastic beam structures in four-way parallel connection. The two ends of the first outer spring beam 251 are respectively connected to the external frame 21 and the first outer mass block 253, and the two ends of the first inner spring beam 252 are respectively connected to the first outer mass block 253 and the first inner mass block 254;

[0037] The working interval between the first-order resonance frequency and the second-order resonance frequency of the first spring resonator structure 25 is consistent with the response sensitivity of the working interval at the first-order resonance frequency;

[0038] One side of the first outer mass block 253 is etched with an opening, the detection optical fiber 22 is fixed in the opening, and the end face of the detection optical fiber 22 and the side face of the first inner mass block 254 form an FP resonator 24.

[0039] As Figure 1 shown, four-way elastic beam structures are symmetrically distributed on the inner and outer sides of the first outer mass block 253 of the first spring resonator structure 25, that is, the first outer spring beam 251 and the first inner spring beam 252; enough space is reserved for the sensing optical path between the two first outer spring beams 251 on the same side of the first outer mass block 253. Among them, an optical fiber slot 23 is arranged in the opening, and the detection optical fiber 22 is fixed in the optical fiber slot 23 by an adhesive method. That is, the optical fiber slot 23 is etched on the external frame 21, the detection optical fiber 22 is fixed in the optical fiber slot 23 by an adhesive method, and forms an FP resonator 24 with the side face of the first inner mass block 254.

[0040] In the embodiment of the present invention, the vibration mode of the first-order resonance frequency of the first spring resonator structure 25 is the in-plane co-directional translation of the first outer mass block 253 and the first inner mass block 254, and the vibration mode of its second-order resonance frequency is the in-plane reverse translation of the first outer mass block 253 and the first inner mass block 254. Among them, the response sensitivities of the two working intervals of the first spring resonator structure 25 are adjusted by the stiffness coefficient ratio of the first outer spring beam 251 and the first inner spring beam 252 and the mass ratio of the first outer mass block 253 and the first inner mass block 254. The first-order resonance frequency and the second-order resonance frequency are changed, so that the response sensitivities of the working interval below the first-order resonance frequency and the working interval between the first-order resonance frequency and the second-order resonance frequency are consistent.

[0041] When an external acceleration acts on the sensitive axis of the cascaded spring resonator structure, due to the inertia of the inner and outer mass blocks, they cannot move synchronously with the outer frame and lag behind. The inner and outer elastic cantilever beams will be compressed and stretched, restricting the mass blocks to move near their equilibrium positions. And due to the selection of the mass ratio of the inner and outer mass blocks, within the working frequency band, the displacement amplitude of the inner mass block is higher than that of the outer mass block. Therefore, the side of the inner mass block is the optimal choice for constructing the FP resonator cavity.

[0042] The side of the first inner mass block 254 and the end face of the detection optical fiber 22 construct an optical microcavity (FP resonator cavity 24). Under the action of an external acceleration, the cavity length of the FP resonator cavity 24 will be modulated, and then converted into a phase change of the interference spectrum, so that the external acceleration to be measured can be calculated through the white light phase demodulation algorithm.

[0043] Based on the problem of frequency band missing at the first resonance frequency peak of a single cascaded spring resonator structure, in another embodiment, further improvements are made.

[0044] Optionally, when the FP acceleration sensor 2 includes 2 spring resonator structures, the sensitive axes of the first spring resonator structure 25 and the second spring resonator structure 26 are coaxial;

[0045] The size of the second spring resonator structure 26 is larger than that of the first spring resonator structure 25; the frequency band missing range corresponding to the first resonance frequency of the first spring resonator structure 25 is the same as the frequency band range between the first and second resonance frequencies of the second spring resonator structure 26.

[0046] As Figure 2 shown, the first spring resonator structure 25 and the second spring resonator structure 26 are etched on the FP acceleration sensor 2. The outer frame 21 is connected to the first outer mass block 253 through the first outer spring beam 251, and the first outer mass block 253 is connected to the first inner mass block 254 through the first inner spring beam 252. The second spring resonator structure 26 has the same structure and similar function as the first spring resonator structure 25. The first spring resonator structure 25 and the second cascaded spring resonator structure 26 are used to broaden the working frequency band of the sensor and ensure that the response sensitivity is not reduced. The sensitive axes of the two spring resonator structures are coaxial to ensure the detection accuracy of the acceleration signal.

[0047] Optionally, the free spectral range of the FP resonator cavity of the first spring resonator structure 25 does not overlap with the spectrum of the free spectral range of the FP resonator cavity of the second spring resonator structure 26.

[0048] When constructing an FP resonator with the end faces of two cascaded spring resonator structures and the detection optical fiber 22, it is necessary to ensure that the free spectral ranges of the two FP resonators do not overlap spectrally, so that they can be distinguished in the Fourier transform spectrum of the composite spectrum, and further real-time demodulation can be performed based on the frequency determination algorithm.

[0049] As Figure 2 shown, in a specific embodiment, the width of the first outer spring beam 251 of the first spring resonator structure 25 is 45 μm, the length is 2.5 mm, the width of the first inner spring beam 252 is 35 μm, the length is 2 mm, and the mass ratio of the first inner mass block 254 to the first outer mass block 253 is 0.4; the width of the second outer spring beam 261 of the second spring resonator structure 26 is 50 μm, the length is 2 mm, the width of the second inner spring beam 262 is 25 μm, the length is 2 mm, and the mass ratio of the second inner mass block 264 to the second outer mass block 263 is 0.35. The constructed FP acceleration sensor realizes a flat working range of 1 - 1780 Hz, the acceleration response sensitivity is 11.55 dBre rad / g, and the noise level is 409 ng / √Hz@100 Hz, achieving the perception of wide-band and highly sensitive weak vibration signals.

[0050] In the embodiment of the present invention, a single micro double-cascaded spring resonator structure (the first spring resonator structure 25) is used as the acceleration component sensing unit, and three acceleration component sensing units are orthogonally combined in space, and the sensing directions are respectively on the X, Y, and Z axes, so as to realize the detection of spatial acceleration signals.

[0051] Optionally, the external frame 21, the optical fiber slot 23, the first spring resonator structure 25, and the second spring resonator structure 26 are all integrally etched and processed from silicon material using silicon microfabrication technology.

[0052] In the example of the present invention, the manufacturing method of the spring resonator structure goes through steps such as glue coating, drying, exposure and development, and transfers the designed sensing structure profile onto the silicon substrate photoresist. The spring resonator structure deposits a silicon nitride mask layer on the upper and lower surfaces of the inner and outer mass blocks and the external frame through plasma-enhanced chemical vapor deposition (PECVD), and uses a deep silicon etching process to etch the silicon substrate step by step up and down, so as to release the inner and outer mass blocks and the inner and outer spring beams. The optical fiber slot structure is additionally etched during the upper surface etching process, and the silicon nitride mask is selectively removed by dry etching at the end of all structure forming processes to ensure the integrity of all sensing structures.

[0053] For the first spring resonator structure 25, a single-crystalline silicon substrate is used as the processing substrate, and the integrated forming of the sensing structure is completed based on the MEMS silicon microfabrication process. The main steps are as follows: Deposit silicon nitride on the silicon substrate by PECVD, and fabricate a mask using the photolithography process; then use dry etching to pierce through the silicon wafer to form an inner and outer folded cantilever beam and a mass block structure; finally, remove the silicon nitride.

[0054] Furthermore, the overall one-time forming of two cascaded spring resonator structures avoids combined processes such as adhesive adhesion, welding, and screw fastening, simplifies the assembly steps, and avoids problems such as solder joint aging and rusting, and fragile glued structures. The working performance is stable; the cascaded spring resonator structure is based on the MEMS silicon microfabrication process, with small size, light weight, high consistency, and can be mass-produced.

[0055] Among them, the first outer spring beam 251 and the first inner spring beam 252 can be elastic beam structures such as elastic folded cantilever beams, elastic mesh cantilever beams, spring films, and elastic disks. The processing technology may vary according to different structures. The same applies to the second outer spring beam 261 and the second inner spring beam 262.

[0056] In the embodiment of the present invention, by etching the cascaded spring resonator structure on the silicon substrate, the first-order resonance frequency vibration mode is the in-plane translational motion of the inner and outer mass blocks in the same direction, and the second-order resonance frequency vibration mode is the in-plane translational motion of the inner and outer mass blocks in the opposite direction. Thus, compared with the traditional acceleration sensor, an additional working frequency band can be introduced. By adjusting the mass ratio of the inner and outer mass blocks and the stiffness coefficient ratio of the inner and outer spring beams, the response sensitivities of the two working frequency bands can be kept consistent. Thereby, the technical problem that the response sensitivity of the acceleration sensor in the prior art is greatly sacrificed as the resonance frequency increases is solved. The detection of wide-band and high-sensitive acceleration signals is realized.

[0057] Embodiment Two

[0058] The present invention also provides an optical sensing system, including: a broadband light source 1, an FP acceleration sensor 2, an optical signal real-time acquisition module 3, and a signal demodulation module 4. Among them, the FP acceleration sensor 2 is the FP acceleration sensor described in any one of Embodiment One;

[0059] The broadband light source 1 is used to output an original detection optical signal;

[0060] The FP acceleration sensor 2 is used to modulate the original detection optical signal injected into the FP resonant cavity under the action of the acceleration signal to be measured, and form an FP reflected interference optical signal with a spectral phase change;

[0061] The optical signal real-time acquisition module 3 is used to real-time collect the spectral phase change amount of the FP reflected interference optical signal;

[0062] The signal demodulation module 4 is used to extract the harmonic signal of the spectral phase change amount, and calculate the magnitude of the acceleration to be measured according to the amplitude and phase of the harmonic signal.

[0063] As Figure 3 shown, an embodiment of the present invention provides an optical sensing system, including a broadband light source 1, an FP acceleration sensor 2, an optical signal real-time acquisition module 3, and a signal demodulation module 4. Among them, the FP acceleration sensor 2 is the FP acceleration sensor in Embodiment 1.

[0064] The broadband light source 1 is used to output an original detection optical signal. In the present invention example, the wavelength range used is the communication band, which is 1526 - 1563 nm; in other embodiments, the broadband light source can remain flat within a certain wavelength range.

[0065] The FP acceleration sensor 2 is used to modulate the original detection optical signal injected into the resonant cavity under the action of the acceleration to be measured, and form an FP reflection interference optical signal with a spectral phase change. Specifically, the side surface of the first inner mass block 254 in the first spring resonator structure 25 and the end surface of the detection optical fiber 22 form an FP resonant cavity 24. After the original detection optical signal is injected into the resonant cavity of the FP acceleration sensor 2 through the detection optical fiber 22, the reflected light at the two end surfaces forms an FP interference optical signal; when an external acceleration acts on the external frame 21, due to the inertia of the first inner mass block 254, it cannot move synchronously with the external frame 21 and lags behind. The internal and external elastic cantilever beams will be compressed and stretched, restricting the first inner mass block 254 to move near its equilibrium position. Furthermore, the cavity length of the FP resonant cavity 24 changes, resulting in a spectral phase change of the FP interference optical signal formed by the reflected light at the two end surfaces.

[0066] The optical signal real-time acquisition module 3 is used to real-time acquire the change amount of the reflected interference spectral phase corresponding to the cavity length change; in the embodiment of the present invention, the optical signal real-time acquisition module 3 is a high-speed spectral detector.

[0067] The signal demodulation module 4 is used to extract the harmonic signal of the phase change amount according to the corresponding demodulation method. The amplitude and phase of this harmonic signal have a corresponding relationship with the acceleration to be measured, so as to obtain the information of the acceleration to be measured, that is, through the demodulation algorithm operation, the amplitude and phase information of the acceleration signal to be measured are restored.

[0068] The optical sensor of the present invention can effectively reduce the interference of the light source noise and the environmental noise by converting the vibration information to be measured into the change of the reflection spectrum and demodulating the phase information of the reflection spectrum instead of the light intensity signal.

[0069] The optical sensor of the present invention has a completely passive structure, can operate under strong electromagnetic interference, and has excellent performance, small size, easy integration, and can perform long-distance detection. It can improve the detection performance of optical acceleration and expand the application fields of optical acceleration, such as in many fields such as natural disaster warning, vector underwater acoustic detection, structural health monitoring, inertial navigation, etc.

[0070] The optical sensing system for detecting acceleration of the present invention only includes a light source module, an FP acceleration sensor, a signal real-time acquisition module, and a signal demodulation module. The devices involved are fewer, the detection device is simple, and it has high sensitivity and a wide operating frequency band. A micro-optical Fabry-Perot acceleration sensor is prepared by micro-electromechanical processing technology (MEMS), which has the advantages of small size, light weight, high consistency, and mass production.

[0071] Embodiment III

[0072] The present invention also provides a broadband acceleration detection method, which is characterized in that the optical sensing system described in Embodiment II is used for acceleration detection.

[0073] Specifically, the broadband acceleration detection method includes the following steps:

[0074] Step S1: Inject the original detection optical signal generated by the broadband light source into the resonant cavity of the first spring resonator structure 25 of the FP acceleration sensor through the detection optical fiber, and form an FP interference optical signal with the reflected light on the end face of the detection optical fiber 22 and the side face of the first inner mass 254; the acceleration to be measured drives the first inner mass 254 to generate mechanical vibration, and the mechanical vibration generated by the first inner mass 254 causes the cavity length of the Fabry-Perot cavity formed by the end face of the detection optical fiber 22 and the side face of the first inner mass 254 to change, resulting in a change in the reflection interference spectrum phase of the interference light beam formed by the reflected light of the two end faces; similarly, the original detection optical signal generated by the broadband light source enters the resonant cavity of the second spring resonator structure 26 through another path to form an interference optical signal, and the second inner mass 264 is modulated by the external acceleration to interfere with the spectrum phase information;

[0075] Step S2: Real-time collect the phase change amount in the reflection interference spectrum corresponding to the change in the detection cavity length;

[0076] Step S3: Extract the harmonic signal of the phase change amount according to the corresponding demodulation method. The amplitude and phase of this harmonic signal are in a corresponding relationship with the acceleration to be measured, so as to obtain the information of the acceleration to be measured.

[0077] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A FP acceleration sensor, characterized in that: The FP acceleration sensor comprises N spring resonator structures, an external frame, and a detection optical fiber; wherein the value of N is: 1 or 2; The spring resonator structure comprises an outer spring beam and an inner spring beam, as well as an inner mass block and an outer mass block surrounding the inner mass block; the outer spring beam and the inner spring beam are both four-way parallel elastic beam structures, the two ends of the outer spring beam are respectively connected to the external frame and the outer mass block, and the two ends of the inner spring beam are respectively connected to the outer mass block and the inner mass block; The response sensitivity of the working range between the first-order resonant frequency and the second-order resonant frequency of the spring resonator structure is consistent with that of the working range below the first-order resonant frequency; A hole is etched on one side of the outer mass block, the detection optical fiber is fixed in the hole, and the end face of the detection optical fiber and the side face of the inner mass block form an FP resonant cavity.

2. The FP acceleration sensor according to claim 1, wherein: The response sensitivity of the two working intervals of the spring resonator structure is adjusted by the stiffness coefficient ratio of the outer spring beam and the inner spring beam, and the mass ratio of the outer mass block and the inner mass block.

3. The FP acceleration sensor according to claim 2, wherein: When the FP acceleration sensor includes two spring resonator structures, the sensitive axes of the first spring resonator structure and the second spring resonator structure are coaxial; The second spring resonator structure has a larger size than the first spring resonator structure; The frequency band missing range corresponding to the first-order resonant frequency of the first spring resonator structure is the same as the frequency band range between the first-order and second-order resonant frequencies of the second spring resonator structure.

4. The FP acceleration sensor according to claim 3, wherein: The free spectral range of the FP resonant cavity of the first spring resonator structure and the free spectral range of the FP resonant cavity of the second spring resonator structure are not spectrally overlapped.

5. The FP acceleration sensor according to claim 3, wherein: An optical fiber slot is arranged in the opening, and the detection optical fiber is fixed in the optical fiber slot by gluing.

6. The FP acceleration sensor according to claim 5, wherein: The external frame, the optical fiber slot, the first spring resonator structure and the second spring resonator structure are all made of silicon material and processed by integrated etching using a silicon microfabrication process.

7. An optical sensing system, characterized in that: include: A wide-spectrum light source, an FP acceleration sensor, an optical signal real-time acquisition module, and a signal demodulation module, wherein the FP acceleration sensor is the FP acceleration sensor according to any one of claims 1 to 6; The broadband light source is used to output an original detection light signal; The FP acceleration sensor is used to modulate the original detection light signal injected into the FP resonant cavity under the action of the acceleration signal to be measured, so as to form a FP reflected interference light signal with a spectral phase change; The optical signal real-time acquisition module is used to acquire the spectral phase change of the FP reflected interference optical signal in real time; The signal demodulation module is used to extract the harmonic signal of the spectral phase change, and calculate the magnitude of the acceleration to be measured according to the amplitude and phase of the harmonic signal.

8. A broadband acceleration detection method, characterized in that: The optical sensing system as claimed in claim 7 is used for acceleration detection.

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