A two-stage differential F-P cavity detection resonant inertial sensor and its detection method

Abstract

The application discloses a two-stage differential F-P cavity detection resonant inertial sensor and a detection method thereof, and relates to the field of micro-electro-mechanical systems and inertial sensors. The sensor comprises an upper-layer MEMS core sensing layer integrated with an F-P cavity and a lower-layer structure substrate. The MEMS core sensing layer comprises a plurality of groups of optical resonant sensitive units. Each group of optical resonant sensitive units comprises: an inertial sensing unit for sensing external acceleration and generating an inertial force; a force amplification unit for amplifying the inertial force; a resonance and optical detection unit for generating a resonance frequency drift amount based on the amplified force, and for converting the resonance frequency drift amount into a periodic reflection interference optical signal by using an F-P cavity interference principle after detecting light is emitted into the F-P cavity through an optical fiber; and a structure substrate for providing electrostatic driving signals and a grounding loop for the optical resonant sensitive units. The application can realize high sensitivity and strong anti-electromagnetic interference capability.

Description

Technical Field

[0001] This application relates to the fields of microelectromechanical systems and inertial sensor technology, and in particular to a resonant inertial sensor with two-stage differential FP cavity detection and its detection method. Background Technology

[0002] Currently, conventional microelectromechanical systems (MEMS) inertial sensors primarily employ electrical detection mechanisms to acquire mechanical displacement or motion signals. However, in complex electromagnetic environments such as those with strong electromagnetic radiation and high-frequency communication, these electrical detection schemes have significant limitations. Because the original electrical signals of the sensors are relatively weak, they are highly susceptible to crosstalk from external stray electromagnetic fields, leading to output signal distortion and severely reducing measurement accuracy. Unlike electrical detection, optical detection uses optical signals as the physical carrier to read displacement changes, possessing inherent electromagnetic insulation properties in its physical mechanism. Among these, optical interferometry based on Fabry-Perot (FP) cavities offers extremely high displacement resolution, capable of accurately characterizing sub-nanometer-level mechanical deformations. Therefore, combining the large dynamic range and digital frequency output advantages of resonant sensors with the high resolution and electromagnetic interference resistance of FP cavity optical detection to develop novel inertial sensors with all-optical interfaces is a crucial pathway to achieving next-generation ultra-high precision and highly environmentally adaptable motion sensing technology. Summary of the Invention

[0003] The purpose of this application is to provide a resonant inertial sensor with two-stage differential FP cavity detection and its detection method, which can achieve high sensitivity and strong anti-electromagnetic interference capability.

[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a resonant inertial sensor with two-stage differential FP cavity detection, characterized in that the sensor comprises: an upper MEMS core sensing layer integrating an FP cavity and a lower structural substrate.

[0005] The MEMS core sensing layer includes several sets of optical resonant sensing units, each set of optical resonant sensing units comprising: An inertial sensing unit is used to sense external acceleration and generate inertial force.

[0006] A force amplification unit, connected to the inertial sensing unit, is used to amplify the inertial force to obtain the amplified force.

[0007] The resonant and optical detection unit, connected to the force amplification unit, is used to generate a resonant frequency drift based on the amplified force. After the probe light is injected into the FP cavity through an optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle.

[0008] The structural substrate is used to provide an electrostatic drive signal and a grounding loop for the optical resonant sensing unit.

[0009] Optionally, the MEMS core sensing layer has an overall rectangular structure, and several sets of optical resonant sensing units are arranged symmetrically in four quadrants.

[0010] Optionally, the inertial sensing unit includes: a mass block, a central anchor point, a first flexible hinge, a second flexible hinge, a third flexible hinge, a fourth flexible hinge, a first lever anchor point, and a second lever anchor point.

[0011] The mass block is connected to the central anchor point, the first lever anchor point, and the second lever anchor point via the first flexible hinge, the second flexible hinge, the third flexible hinge, and the fourth flexible hinge, respectively, forming a four-way symmetrical support for generating inertial force under acceleration.

[0012] The central anchor point is located at the geometric center of the mass block and is used to provide fixed support for the suspended structure.

[0013] Optionally, the force amplification unit includes: a first lever structure, a second lever structure, a first fulcrum, and a second fulcrum; The first lever structure is connected to the mass block at one end, with the first fulcrum serving as the lever's support point, and connected to the resonance and optical detection unit at the other end.

[0014] The second lever structure has one end connected to the mass block, with the second fulcrum serving as the lever's support point, and the other end connected to the resonance and optical detection unit.

[0015] The first lever structure and the second lever structure are used to amplify the inertial force to obtain an amplified force.

[0016] Optionally, the resonance and optical detection unit includes: a resonant beam, a comb structure, a resonant beam anchor point, a first comb anchor point, a second comb anchor point, a third comb anchor point, an optical fiber, and a conversion module.

[0017] The resonant beam is arranged horizontally, with one end connected to the first lever structure and the second lever structure, and the other end fixed to the anchor point of the resonant beam, which is used to generate the resonant frequency drift according to the amplified force.

[0018] The comb structure is arranged on both sides of the resonant beam to transmit corresponding driving electrical signals, so that the resonant beam maintains a stable mechanical vibration state.

[0019] The comb structure includes: fixed comb teeth and movable comb teeth; the comb teeth are arranged alternately.

[0020] The fixed comb teeth are fixed to the resonant beam.

[0021] The movable comb teeth are respectively fixed on the first comb anchor point, the second comb anchor point and the third comb anchor point.

[0022] The optical fiber is fixed between the first comb anchor point and the second comb anchor point, with its end face aligned with the side wall of the resonant beam, forming an FP cavity.

[0023] The conversion module is used to convert the resonant frequency drift generated by the resonant beam into a periodic reflected interference light signal after the probe light is injected into the FP cavity through the optical fiber.

[0024] Optionally, when subjected to the same acceleration, the resonant beam with a four-quadrant symmetrical layout will generate two reverse stresses, namely tension and compression, which will correspondingly generate reverse resonant frequency drift.

[0025] Optionally, the structural substrate is a rectangular planar structure containing several sets of electrode units, which are arranged symmetrically in four quadrants.

[0026] Optionally, each group of electrode units includes: The first grounding electrode extends longitudinally inward through the lead wire, with the end electrode located directly below the projection area of ​​the central anchor point, and is used to form a ground signal connection.

[0027] The first driving electrode extends longitudinally inward through a lead wire, with the end electrode located directly below the projection area of ​​the first comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0028] The second driving electrode extends longitudinally through the lead wire, with the end electrode located directly below the projection area of ​​the second comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0029] The third driving electrode extends longitudinally through the lead wire, with the end electrode located directly below the projection area of ​​the third comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0030] The second grounding electrode extends laterally inward through a lead wire, with the end electrode located directly below the projection area of ​​the vertically arranged resonant beam anchor point, used to form a ground signal connection.

[0031] All electrode lead-out pads are distributed around the perimeter of the structural substrate and are located outside the projection of the MEMS core sensing layer. They are used to connect external drive signals and ground signals to form a closed electrostatic drive and grounding loop.

[0032] Optionally, the upper layer is silicon-based; the lower layer is a glass electrode substrate.

[0033] Secondly, this application provides a detection method for a resonant inertial sensor with two-stage differential FP cavity detection. The method is based on the aforementioned two-stage differential FP cavity detection resonant inertial sensor and includes: For each set of optical resonant sensitive units, a driving electrical signal is applied to the comb structure to maintain the inherent resonant frequency of the resonant beam.

[0034] When an external acceleration occurs, the mass block senses the acceleration and generates an inertial force.

[0035] The inertial force is amplified using a force amplification unit to obtain the amplified force.

[0036] Based on the amplified force, a resonant frequency drift is generated. After the probe light is injected into the FP cavity through the optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle.

[0037] Acceleration is obtained by performing second-order differential demodulation on all periodic reflected interference light signals.

[0038] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a resonant inertial sensor with two-stage differential FP cavity detection and its detection method. The sensor employs a dual-layer structure design with an upper MEMS core sensing layer integrating an FP cavity and a lower structural substrate. This allows for layered arrangement of sensing and electrical support functions, resulting in a well-organized layout and clear functional division, effectively improving the overall integration and operational stability of the sensor. The MEMS core sensing layer incorporates several sets of optical resonant sensing units, enabling multi-channel signal comparison detection in conjunction with the two-stage differential detection method. This effectively suppresses detection interference and improves the overall accuracy and reliability of inertial detection. The inertial sensing unit within the optical resonant sensing unit accurately senses external acceleration and outputs inertial force, effectively converting acceleration into a mechanical force signal, providing a valid sensing basis signal for subsequent detection. The force amplification unit within the optical resonant sensing unit amplifies the inertial force, strengthening the effective sensing signal intensity and improving the difficulty in identifying weak inertial signals, thus effectively enhancing the sensor's detection sensitivity. The resonant and optical detection units in the optical resonant sensing unit can generate a resonant frequency drift based on the amplified force. Utilizing the FP cavity interference principle, the frequency drift is converted into a periodic reflected interference light signal, enabling optical visualization and quantifiable detection of micro-resonance changes. The detection method is stable and reliable. The lower substrate provides electrostatic drive signals and a grounding loop for the optical resonant sensing unit, ensuring normal operation of each sensing unit and integrity of the electrical circuit, guaranteeing continuous and stable device operation. This application, through the integrated coordination of a double-layer structure, inertial force sensing, force signal amplification, FP cavity optical resonant detection, and supporting electrical components, combined with a two-stage differential detection mechanism, effectively improves the detection sensitivity, measurement accuracy, and operational stability of the resonant inertial sensor, comprehensively optimizing the sensor's inertial detection performance. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A side view of the overall structure of a resonant inertial sensor with two-stage differential FP cavity detection provided in an embodiment of this application; Figure 2 A top view of the upper structure of a resonant inertial sensor with two-stage differential FP cavity detection provided in an embodiment of this application; Figure 3 A top view of the lower structure of a resonant inertial sensor with two-stage differential FP cavity detection provided in an embodiment of this application; Figure 4 A cross-sectional view of a resonant inertial sensor with two-stage differential FP cavity detection provided in an embodiment of this application; Figure 5 A schematic diagram of the dynamic operation of a resonant inertial sensor with two-stage differential FP cavity detection provided in an embodiment of this application; Figure 6 A schematic flowchart illustrating a detection method for a resonant inertial sensor with two-stage differential FP cavity detection, provided in an embodiment of this application; Figure label: 1-Central anchor point; 2-First flexible hinge; 3-Mass block; 4-Second flexible hinge; 5-First lever structure; 6-First lever anchor point; 7-First fulcrum; 8-First comb anchor point; 9-Fiber optic cable; 10-Second comb anchor point; 11-Comb structure; 12-Resonant beam; 13-Resonant beam anchor point; 14-Third comb anchor point; 15-Second fulcrum; 16-Second lever anchor point; 17-Second lever structure; 18-Third flexible hinge; 19-Fourth flexible hinge; 20-Sensitive unit; 21-First grounding electrode; 22-First driving electrode; 23-Second driving electrode; 24-Second grounding electrode; 25-Third driving electrode. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] This application aims to address the problems of traditional electrical detection resonant sensors being susceptible to electromagnetic interference and significantly affected by parasitic parameters. A two-layer structure is proposed: the upper layer is a MEMS core sensing layer integrating an FP cavity, and the lower layer is a structural substrate. The upper MEMS core sensing layer with integrated FP cavity comprises four sets of optical resonant sensing units. Each set of optical resonant sensing units consists of a central anchor point, four flexible hinges, two lever structures, two fulcrums, two lever anchor points, three comb anchor points, one comb structure, a resonant beam, and an optical fiber. The lower structural substrate consists of a single structural substrate, multiple pairs of grounding electrodes, and multiple pairs of driving electrodes. Its working principle is as follows: when there is an external acceleration input, the inertial force generated by the mass block is amplified by the lever mechanism and converted into axial stress acting on the FP sensing cavity, causing a shift in its inherent resonant frequency; simultaneously, the probe light enters the FP cavity formed by the fiber end face and the sidewall of the resonant beam through the optical fiber, converting the mechanical vibration of the resonator into periodic modulation of the reflected interference light intensity. Based on a four-quadrant symmetrical layout, the system performs two-stage differential demodulation on the frequency changes of multiple sets of output optical signals. By demodulating the frequency changes of the output optical signals, the acceleration can be accurately calculated. This application adopts a non-contact optical detection scheme, combining the large dynamic range of the resonant sensor with the high displacement resolution of the FP interferometer, exhibiting extremely high performance under strong electromagnetic interference and complex thermal environments.

[0043] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1: In one exemplary embodiment, a resonant inertial sensor with two-stage differential FP cavity detection is provided. The sensor adopts a two-layer structure with silicon-glass bonding: the upper layer is a MEMS core sensing layer with integrated FP cavity, and the lower layer is a structural substrate.

[0045] The MEMS core sensing layer includes several sets of optical resonant sensing units, each set of optical resonant sensing units comprising: An inertial sensing unit is used to sense external acceleration and generate inertial force.

[0046] A force amplification unit, connected to the inertial sensing unit, is used to amplify the inertial force to obtain the amplified force.

[0047] The resonant and optical detection unit, connected to the force amplification unit, is used to generate a resonant frequency drift based on the amplified force. After the probe light is injected into the FP cavity through an optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle.

[0048] The structural substrate is used to provide an electrostatic drive signal and a grounding loop for the optical resonant sensing unit.

[0049] The inertial sensing unit includes: a mass block, a central anchor point, a first flexible hinge, a second flexible hinge, a third flexible hinge, a fourth flexible hinge, a first lever anchor point, and a second lever anchor point.

[0050] The mass block is connected to the central anchor point, the first lever anchor point, and the second lever anchor point via the first flexible hinge, the second flexible hinge, the third flexible hinge, and the fourth flexible hinge, respectively, forming a four-way symmetrical support for generating inertial force under acceleration.

[0051] The central anchor point is located at the geometric center of the mass block and is used to provide fixed support for the suspended structure.

[0052] The force amplification unit includes: a first lever structure, a second lever structure, a first fulcrum, and a second fulcrum.

[0053] The first lever structure is connected to the mass block at one end, with the first fulcrum serving as the lever's support point, and connected to the resonance and optical detection unit at the other end.

[0054] The second lever structure has one end connected to the mass block, with the second fulcrum serving as the lever's support point, and the other end connected to the resonance and optical detection unit.

[0055] The first lever structure and the second lever structure are used to amplify the inertial force to obtain an amplified force.

[0056] The resonance and optical detection unit includes: a resonant beam, a comb structure, a resonant beam anchor point, a first comb anchor point, a second comb anchor point, a third comb anchor point, an optical fiber, and a conversion module.

[0057] The resonant beam is arranged horizontally, with one end connected to the first lever structure and the second lever structure, and the other end fixed to the anchor point of the resonant beam, which is used to generate the resonant frequency drift according to the amplified force.

[0058] The comb structure is arranged on both sides of the resonant beam to transmit corresponding driving electrical signals, so that the resonant beam maintains a stable mechanical vibration state.

[0059] The comb structure includes: fixed comb teeth and movable comb teeth; the comb teeth are arranged alternately.

[0060] The fixed comb teeth are fixed to the resonant beam.

[0061] The movable comb teeth are respectively fixed on the first comb anchor point, the second comb anchor point and the third comb anchor point.

[0062] The optical fiber is fixed between the first comb anchor point and the second comb anchor point, with its end face aligned with the side wall of the resonant beam, forming an FP cavity.

[0063] The conversion module is used to convert the resonant frequency drift generated by the resonant beam into a periodic reflected interference light signal after the probe light is injected into the FP cavity through the optical fiber.

[0064] When subjected to the same acceleration, the resonant beam with a symmetrical layout in the four quadrants will generate two reverse stresses, namely tension and compression, which will generate a corresponding reverse resonant frequency drift.

[0065] The structural substrate is a rectangular planar structure containing several sets of electrode units, which are arranged symmetrically in four quadrants.

[0066] Each electrode unit includes: The first grounding electrode extends longitudinally inward through the lead wire, with the end electrode located directly below the projection area of ​​the central anchor point, and is used to form a ground signal connection.

[0067] The first driving electrode extends longitudinally inward through a lead wire, with the end electrode located directly below the projection area of ​​the first comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0068] The second driving electrode extends longitudinally through the lead wire, with the end electrode located directly below the projection area of ​​the second comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0069] The third driving electrode extends longitudinally through the lead wire, with the end electrode located directly below the projection area of ​​the third comb anchor point, and is used to transmit the corresponding driving electrical signal.

[0070] The second grounding electrode extends laterally inward through a lead wire, with the end electrode located directly below the projection area of ​​the vertically arranged resonant beam anchor point, used to form a ground signal connection.

[0071] All electrode lead-out pads are distributed around the perimeter of the structural substrate and are located outside the projection of the MEMS core sensing layer. They are used to connect external drive signals and ground signals to form a closed electrostatic drive and grounding loop.

[0072] In summary, this application has the following beneficial effects: (1) This application adopts a differential coupling mechanism with a four-quadrant symmetrical layout combined with mechanical lever amplification, which takes into account both high sensitivity and strong noise resistance. The inertial force generated by the external input acceleration is amplified by the levers in each quadrant and acts on the symmetrically arranged resonant beam in a differential form (one side is under tension and the other side is under compression), causing the frequency drift in the opposite direction, thereby multiplying the detection sensitivity of the system; at the same time, the strict symmetrical topology automatically cancels the cross-axis coupling error caused by lateral vibration in the mechanical transmission, and effectively eliminates the frequency drift that may be caused by the external environment through differential calculation, ensuring extremely high single-axis measurement accuracy.

[0073] (2) This application proposes to combine a Fabry-Perot (FP) interferometer cavity with a micromechanical resonant sensitive structure, using the offset of the natural frequency of the resonant beam to characterize the external input acceleration, and using a non-contact FP cavity to optically read the vibration state of the resonant beam. This mechanism can effectively overcome the problem of narrow linear measurement range in traditional optical intensity modulation mechanisms, and expand the dynamic measurement range of the sensor; at the same time, by using an optical interface to replace the traditional electrical reading method, the interference of parasitic parameters on signal reading and transmission is avoided, thereby enhancing the detection stability and accuracy of the sensor over a wide range.

[0074] (3) This application constructs a two-level differential mechanism for mechanics and signals based on a four-quadrant symmetrical layout. In terms of mechanical structure, the external acceleration is amplified by the symmetrically arranged lever mechanism, so that the resonant beams on both sides generate reverse axial stresses under tension and compression respectively, thereby increasing the frequency response of the target axis and offsetting the cross-axis coupling error caused by the non-sensitive axial vibration. In terms of signal demodulation, the reverse frequency offset signals output by multiple pairs of FP cavities are differentially calculated. The combination of the two-level differential mechanism can effectively improve the measurement accuracy and stability of the sensor.

[0075] Specifically, such as Figure 1 As shown, the upper integrated FP cavity MEMS core sensing layer contains four sets of optical resonant sensing units. Each set of optical resonant sensing units consists of a central anchor point, four flexible hinges, two lever structures, two fulcrums, two lever anchor points, three comb anchor points, one comb structure, a resonant beam, and an optical fiber. The lower structure substrate consists of a single structural substrate, multiple pairs of ground electrodes, and multiple pairs of driving electrodes. The mass block 3 is integrated into the upper structure and suspended by four flexible hinges, the central anchor point 1, and two lever anchor points. The two lever structures are connected to the mass block 3 through two fulcrums, amplifying the inertial force generated by the acceleration of the mass block 3 and transmitting it to the resonant beam 12. When there is an acceleration input, the displacement of the mass block 3 is amplified by the lever mechanism, causing axial stress in the resonant beam 12, thereby changing its inherent resonant frequency.

[0076] Each fiber 9 is aligned with its corresponding FP cavity. The FP cavity is formed by the end face of the fiber 9 and the sidewall of the resonant beam 12. After the probe light enters the FP cavity through the fiber 9, it converts the mechanical vibration of the resonant beam 12 into periodic modulation of the intensity of the reflected interference light. By demodulating the frequency change of the output optical signal, the magnitude of the external acceleration can be calculated. Relying on the four-quadrant symmetrical layout, the system performs two-stage differential demodulation on the frequency changes of multiple sets of output optical signals. By demodulating the frequency changes of the output optical signals, the acceleration can be accurately calculated.

[0077] like Figure 2 As shown, the upper silicon-based FP cavity MEMS sensing structure is generally rectangular, with a four-quadrant symmetrical layout. Only one sensing unit, 20, is described here. Within each quadrant, each set of internal mass blocks 3 is located in the central region of the structure, and their outer edges are connected to the central anchor point 1 and the lever anchor point via four flexible hinges. The lever structure is located on the left or right side of the mass block 3, with the fulcrum positioned on one side of the lever structure, between the flexible hinge and the resonant beam 12. The central anchor point 1 is located at the geometric center of the mass block 3, providing fixed support for the suspended structure. The mass block 3 is divided by the first flexible hinge 2, the second flexible hinge 4, the third flexible hinge 18, and the fourth flexible hinge 19. The first lever structure 5 is connected to the central anchor point 1, the first lever anchor point 6, and the second lever anchor point 16, forming a four-way symmetrical support. Furthermore, in each quadrant, the first lever structure 5 is located on one side of the mass block 3, with one end connected to the mass block 3 and the first fulcrum 7 serving as the lever's support point, and the other end connected to the resonant beam 12. Similarly, the second lever structure 17 has one end connected to the mass block 3, the second fulcrum 15 serving as the lever's support point, and the other end connected to the resonant beam 12. Further, in each quadrant, the resonant beam 12 is horizontally arranged between the lever structure and the outer anchor point; one end is connected to the ends of the first lever structure 5 and the second lever structure 17, and the other end is fixed to the resonant beam anchor point 13. Furthermore, within each quadrant, a comb structure 11 is arranged on both sides of the resonant beam 12. This comb structure 11 consists of movable comb teeth and fixed comb teeth. The fixed comb teeth are fixed by the first comb anchor point 8, the second comb anchor point 10, and the third comb anchor point 14, while the movable comb teeth are located on the resonant beam 12. The fixed and movable comb teeth combine to form the comb structure 11. Furthermore, within each quadrant, an optical fiber 9 is fixed in the groove formed by the first comb anchor point 8, the second comb anchor point 10, and the substrate. The end face of the optical fiber 9 is precisely aligned with the side wall of the resonant beam 12, forming a gap between them. This gap is the cavity of the FP cavity.

[0078] like Figure 3As shown, the lower glass electrode substrate is a rectangular planar structure. Only the area below one of the sensitive units 20 is described here. The first ground electrode 21 is located at the center of the top edge of the structural substrate. The first ground electrode 21 extends longitudinally inward through a lead wire, and its end electrode is located directly below the projection area of ​​the central anchor point 1, used to form a ground signal connection. The first driving electrode 22 and the second driving electrode 23 are arranged horizontally on the sides of the structural substrate, with the second driving electrode 23 located inside the first driving electrode 22. The first driving electrode 22 extends longitudinally inward through a lead wire, and its end electrode is located directly below the projection area of ​​the horizontally arranged first comb anchor point 8, used to transmit the corresponding driving electrical signal. The second driving electrode 23 extends longitudinally inward through a lead wire, and its end electrode... The first electrode is located directly below the projection area of ​​the horizontally arranged second comb anchor point 10, and is used to transmit the corresponding drive electrical signal; the second drive electrode 25 extends longitudinally inward through the lead wire, and its end electrode is located directly below the projection area of ​​the horizontally arranged third comb anchor point 14, and is used to transmit the corresponding drive electrical signal; the second ground electrode 24 is located on the outside of the sensitive structure, extends laterally inward through the lead wire, and its end electrode is located directly below the projection area of ​​the vertically arranged resonant beam anchor point 13, and is used to form a ground signal connection; all electrode lead-out pads are distributed around the perimeter of the structural substrate, and are all located outside the projection of the upper structure, and are used to connect the external drive signal and the ground signal to form a closed electrostatic drive and grounding loop.

[0079] like Figure 4 As shown, this application clearly demonstrates the vertical bonding relationship of the upper and lower double-layer structure. The lower layer is a flat structural substrate, and the upper core is firmly bonded to the lower substrate, with electrodes between the two layers. This structure achieves both mechanical support and electrical interconnection. Specifically, in the central region of the device, the central anchor point 1, the first lever anchor point 6, the first comb anchor point 8, the second comb anchor point 10, and the resonant beam anchor point 13 are directly bonded and fixed to the lower structural substrate, providing core physical support for the entire sensing network; the mass block 3 is connected to the central anchor point 1 through the first flexible hinge 2, and a precise gap is maintained between the bottom of the mass block 3 and the first flexible hinge 2 and the lower structural substrate, keeping it in a suspended state, thereby ensuring that the mass block can undergo frictionless free displacement in the horizontal direction when sensing acceleration. In the optical detection area, the first comb anchor point 8, the second comb anchor point 10, and the outermost resonant beam anchor point 13 are tightly bonded to the structural substrate, providing a stable mechanical shape for the electrostatically driven comb teeth and resonant beam on both sides; the comb structure 11 is suspended above the substrate to allow in-plane high-frequency vibration; the optical fiber 9 is arranged in the etched grooves corresponding to the first comb anchor point 8 and the second comb anchor point 10, and is precisely aligned with the sidewall of the suspended resonant beam 12 to form an FP cavity.

[0080] like Figure 5As shown, this application clearly demonstrates the dynamic correspondence between the deformation of the mechanical structure and the length of the FP interferometer cavity under acceleration input. In the initial state without acceleration input (e.g.) Figure 5 (As shown in the upper part), the lever structure and the resonant beam maintain stable resonance. At this time, the initial FP cavity gap d1 is maintained between the fixed fiber end face and the side wall of the resonant beam. When the sensor senses an acceleration input along the sensitive axis (such as...) Figure 5 As shown in the lower half, the inertial displacement generated by the mass block causes the lever mechanism to deflect; the lever mechanism mechanically amplifies this force and applies it to the end of the resonant beam. As the resonant beam is subjected to force, its natural resonant frequency drifts, and simultaneously the FP cavity gap between the fiber end face and the deformed resonant beam sidewall changes from the initial d1 to d2. After the probe light enters the FP cavity, this real-time physical change in the gap (d1 to d2) directly causes periodic optical modulation of the reflected interference light intensity.

[0081] This application specifies the readout frequencies for the four quadrants as follows: f 1, f 2, f 3, f 4. [The sentence is incomplete and requires more context to be translated accurately.] f 1 and f 2. Perform difference calculations. f 3 and f 4. Perform differential calculations, and then perform differential calculations again on the obtained difference values. Combined with the four-quadrant symmetrical layout design, the system can accurately calculate the magnitude of the external acceleration by extracting and processing the optical frequency offset signals output from each quadrant and performing two-level differential demodulation.

[0082] First-order differences include: △ f 12 = f 1- f 2 and △ f 34 = f 3- f 4.

[0083] The second difference is △ f=f 12 - f 34 .

[0084] When expanded, it becomes: △ f=f 1- f 2- f 3+ f 4.

[0085] The △ f That is, the frequency change that is ultimately used to characterize the external acceleration after two levels of differential processing.

[0086] Example 2: In one exemplary embodiment, such as Figure 6 As shown, a detection method for a resonant inertial sensor with two-stage differential FP cavity detection is provided. The method is based on the resonant inertial sensor with two-stage differential FP cavity detection described in Example 1, and includes: S1: For each set of optical resonant sensitive units, apply a driving electrical signal to the comb structure to maintain the inherent resonant frequency of the resonant beam.

[0087] S2: When an external acceleration occurs, the mass block senses the acceleration and generates an inertial force.

[0088] S3: The inertial force is amplified using a force amplification unit to obtain the amplified force.

[0089] S4: Based on the amplified force, a resonant frequency drift is generated. After the probe light is injected into the FP cavity through the optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle.

[0090] S5: Acceleration is obtained by performing second-order differential demodulation based on all periodic reflected interference light signals.

[0091] By implementing steps S1 to S5, the offset of the resonant beam's natural frequency is used to characterize the external input acceleration. Optical interferometry is used to read the vibration state of the resonant beam through a non-contact FP cavity. This effectively overcomes the narrow linear measurement range problem in traditional optical intensity modulation mechanisms, expanding the sensor's dynamic measurement range. Simultaneously, using an optical interface instead of the traditional electrical reading method avoids interference from parasitic parameters on signal reading and transmission, thereby enhancing the sensor's detection stability and accuracy over a wide measurement range. In terms of mechanical structure, the external acceleration is amplified by a symmetrically arranged lever mechanism, causing the resonant beams on both sides to experience tensile and compressive axial stresses respectively. This increases the frequency response of the target axis and offsets the cross-axis coupling error caused by insensitive axial vibration. Regarding signal demodulation, differential calculation of the reverse frequency offset signals output from multiple pairs of FP cavities, combined with a two-stage differential mechanism, effectively improves the sensor's measurement accuracy and stability.

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A resonant inertial sensor with two-stage differential FP cavity detection, characterized in that, The sensor includes: an upper MEMS core sensing layer with an integrated FP cavity and a lower structural substrate; The MEMS core sensing layer includes several sets of optical resonant sensing units, each set of optical resonant sensing units comprising: An inertial sensing unit is used to sense external acceleration and generate inertial force. A force amplification unit, connected to the inertial sensing unit, is used to amplify the inertial force to obtain the amplified force. The resonant and optical detection unit, connected to the force amplification unit, is used to generate a resonant frequency drift based on the amplified force. After the probe light is injected into the FP cavity through an optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle. The structural substrate is used to provide an electrostatic drive signal and a grounding loop for the optical resonant sensing unit.

2. The resonant inertial sensor with two-stage differential FP cavity detection according to claim 1, characterized in that, The MEMS core sensing layer has an overall rectangular structure, with several sets of optical resonant sensing units arranged symmetrically in four quadrants.

3. The resonant inertial sensor with two-stage differential FP cavity detection according to claim 2, characterized in that, The inertial sensing unit includes: a mass block, a central anchor point, a first flexible hinge, a second flexible hinge, a third flexible hinge, a fourth flexible hinge, a first lever anchor point, and a second lever anchor point. The mass block is connected to the central anchor point, the first lever anchor point, and the second lever anchor point via the first flexible hinge, the second flexible hinge, the third flexible hinge, and the fourth flexible hinge, respectively, forming a four-way symmetrical support for generating inertial force under acceleration. The central anchor point is located at the geometric center of the mass block and is used to provide fixed support for the suspended structure.

4. The resonant inertial sensor with two-stage differential FP-cavity detection according to claim 3, characterized in that, The force amplification unit includes: a first lever structure, a second lever structure, a first fulcrum, and a second fulcrum; The first lever structure has one end connected to the mass block, with the first fulcrum serving as the lever's support point, and the other end connected to the resonance and optical detection unit; The second lever structure has one end connected to the mass block, with the second fulcrum serving as the lever's support point, and the other end connected to the resonance and optical detection unit; The first lever structure and the second lever structure are used to amplify the inertial force to obtain an amplified force.

5. The resonant inertial sensor with two-stage differential FP cavity detection according to claim 4, characterized in that, The resonance and optical detection unit includes: a resonant beam, a comb structure, a resonant beam anchor point, a first comb anchor point, a second comb anchor point, a third comb anchor point, an optical fiber, and a conversion module; The resonant beam is arranged horizontally, with one end connected to the first lever structure and the second lever structure, and the other end fixed to the anchor point of the resonant beam, which is used to generate the resonant frequency drift according to the amplified force. The comb structure is arranged on both sides of the resonant beam to transmit corresponding driving electrical signals, so that the resonant beam maintains a stable mechanical vibration state. The comb structure includes: fixed comb teeth and movable comb teeth; the comb teeth are arranged alternately. The fixed comb teeth are fixed on the resonant beam; The movable comb teeth are respectively fixed on the first comb anchor point, the second comb anchor point and the third comb anchor point; The optical fiber is fixed between the first comb anchor point and the second comb anchor point, with its end face aligned with the side wall of the resonant beam, forming an FP cavity; The conversion module is used to convert the resonant frequency drift generated by the resonant beam into a periodic reflected interference light signal after the probe light is injected into the FP cavity through the optical fiber.

6. The resonant inertial sensor with two-stage differential FP cavity detection according to claim 5, characterized in that, When subjected to the same acceleration, the resonant beam with a symmetrical layout in the four quadrants will generate two reverse stresses, namely tension and compression, which will generate a corresponding reverse resonant frequency drift.

7. The resonant inertial sensor with two-stage differential FP cavity detection according to claim 6, characterized in that, The structural substrate is a rectangular planar structure containing several sets of electrode units, which are arranged symmetrically in four quadrants.

8. The resonant inertial sensor with two-stage differential FP-cavity detection according to claim 7, characterized in that, Each electrode unit includes: The first grounding electrode extends longitudinally inward through the lead wire, with the end electrode located directly below the projection area of ​​the central anchor point, and is used to form a ground signal connection. The first driving electrode extends longitudinally inward through a lead wire, with the end electrode located directly below the projection area of ​​the first comb anchor point, and is used to transmit the corresponding driving electrical signal. The second driving electrode extends longitudinally inward through the lead wire, with the end electrode located directly below the projection area of ​​the second comb anchor point, and is used to transmit the corresponding driving electrical signal. The third driving electrode extends longitudinally inward through the lead wire, with the end electrode located directly below the projection area of ​​the third comb anchor point, and is used to transmit the corresponding driving electrical signal. The second grounding electrode extends laterally inward through the lead wire, with the end electrode located directly below the projection area of ​​the vertically arranged resonant beam anchor point, and is used to form a ground signal connection. All electrode lead-out pads are distributed around the perimeter of the structural substrate and are located outside the projection of the MEMS core sensing layer. They are used to connect external drive signals and ground signals to form a closed electrostatic drive and grounding loop.

9. The resonant inertial sensor with two-stage differential FP-cavity detection according to claim 8, characterized in that, The upper layer is silicon-based; the lower layer is a glass electrode substrate.

10. A detection method for a resonant inertial sensor with two-stage differential FP-cavity detection, characterized in that, The method is implemented based on the resonant inertial sensor with two-stage differential FP cavity detection as described in any one of claims 1-9, and the method includes: For each set of optical resonant sensitive units, a driving electrical signal is applied to the comb structure to maintain the inherent resonant frequency of the resonant beam; When an external acceleration occurs, the mass block senses the acceleration and generates an inertial force; The inertial force is amplified using a force amplification unit to obtain the amplified force. Based on the amplified force, a resonant frequency drift is generated. After the probe light is injected into the FP cavity through the optical fiber, the resonant frequency drift is converted into a periodic reflected interference light signal using the FP cavity interference principle. Acceleration is obtained by performing second-order differential demodulation on all periodically reflected interference light signals.

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