High-precision cavity light force micro gyroscope based on magnetostrictive material driving and angular velocity measuring method

Abstract

The invention discloses a high-precision cavity light force micro gyroscope based on magnetostriction material driving and an angular velocity measurement method, and belongs to the technical field of high-precision angular velocity measurement. The gyroscope comprises a base, a mechanical structure, a magnetostriction driving structure and optical structures, and the optical structures are located at the two ends of the mechanical structure; the magnetostriction driving structure is located below the mechanical structure. The magnetostrictive material is integrated in the driving frame of the gyroscope, a capacitance comb tooth structure required by electrostatic driving is not needed, the risk of electrostatic attraction failure is avoided, the driving stability and the environmental adaptability are improved, the driving frame is compatible with an SOI processing technology, and the angular velocity detection sensitivity and the long-term working reliability of the cavity light force micro gyroscope can be effectively guaranteed.

Description

Technical Field

[0001] This application belongs to the field of high-precision angular velocity measurement technology, and in particular relates to a high-precision cavity optical microgyroscope driven by magnetostrictive materials and an angular velocity measurement method. Background Technology

[0002] In recent years, with the deep integration of micro-nano manufacturing and optoelectronic technology, cavity optical force sensor systems have demonstrated irreplaceable advantages in the precise detection of physical quantities such as minute displacements, masses, temperatures, accelerations, and angular velocities, thanks to their high detection sensitivity. They hold great potential, especially in aerospace, resource exploration, and biomedical applications where stringent requirements for detection accuracy and environmental adaptability exist. The core of a cavity optical force sensor is the energy exchange and signal conversion achieved through the strong coupling between light and a mechanical oscillator. Its performance directly depends on the driving efficiency of the mechanical oscillator and the stability of the opto-mechanical coupling.

[0003] Traditional cavity optical gyroscopes primarily employ electrostatic comb actuation. The driving force provided by the electrostatic comb depends on the electrostatic force between the comb teeth, requiring precise design of the comb tooth parameters. However, in practice, process errors such as device layer thickness variations and machining burrs can easily lead to uneven comb tooth spacing, resulting in electrostatic attraction. Secondly, electrostatic comb actuation requires applying a driving voltage via gold wire bonding or external probes, causing cross-coupling between the optical and electrical structures, severely impacting the gyroscope's measurement accuracy and stability. Furthermore, the complexity of gold wire bonding and issues such as poor probe contact further reduce the long-term reliability of the driving system. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the prior art by providing a high-precision cavity optical gyroscope and angular velocity measurement method based on magnetostrictive material driving, which solves the problems of complex manufacturing process and cross-coupling of optical and electrical structures in the driving method of traditional cavity optical gyroscopes.

[0005] The objective of this application is achieved through the following technical solution: A high-precision cavity optical micro-gyroscope driven by magnetostrictive materials, the gyroscope comprising: The base has a front side for fixing the mechanical structure and a back side for fixing the magnetostrictive drive structure. A mechanical structure includes a mass block and a support beam. The mass block includes a driving mass block, a core mass block, and a detection mass block. The core mass block is located at the center of the gyroscope and is connected to the driving mass block and the detection mass block respectively via cantilever arms. The driving mass block cooperates with a magnetostrictive drive structure to enable the gyroscope to achieve vibration output, thereby decoupling the motion between the driving and detection modes. The support beam includes a driving support beam and a detection support beam, which cooperate with the driving mass block and the detection mass block to achieve motion decoupling between the driving and detection modes. A magnetostrictive driving structure, comprising a multilayer magnetostrictive film, wherein the multilayer magnetostrictive film bulges outward, and the direction of the outward bulging is aligned with the driving direction of the gyroscope chip; An optical structure, comprising a cavity optical system and a waveguide structure, wherein the cavity optical system and the waveguide structure are coupled, and the optical structure is fixed to both ends of the mechanical structure.

[0006] Furthermore, the driving mass block and the detection mass block are rigidly connected by a U-shaped beam embedded inside the detection mass block.

[0007] Furthermore, the cavity optical system includes an optical microcavity, which is symmetrically arranged on the detection mass block to form a differential detection configuration.

[0008] Furthermore, the magnetostrictive drive structure is electrically connected to an external magnetic field generating device. By adjusting the intensity and frequency of the external magnetic field, the magnetostrictive material is made to undergo directional elastic deformation, thereby driving the drive mass block and the core mass block to perform simple harmonic motion along the drive direction.

[0009] Furthermore, the mechanical structure is fixedly connected to the base by fixed columns located at the four corners, and the height of the fixed columns is consistent with the suspension height of the mechanical structure.

[0010] Furthermore, the magnetostrictive drive structure is fixed to the base by sputtering deposition, low-temperature bonding, or annealing bonding processes.

[0011] Furthermore, the magnetostrictive drive structure is placed inside a vacuum cavity.

[0012] Furthermore, the optical microcavity includes a two-dimensional photonic crystal microcavity.

[0013] On the other hand, the present invention also provides a method for measuring the angular velocity of a high-precision cavity optical force micro-gyroscope driven by a magnetostrictive material. This method is based on the aforementioned cavity optical force micro-gyroscope and includes: The magnitude and direction of angular velocity are characterized by measuring the offset of the oscillation frequency of the detection mass block.

[0014] The beneficial effects of this application are as follows: (1) This application adopts a magnetostrictive drive structure to replace the traditional complex electrostatic drive push-pull comb, retaining only the mechanical and optical structures, fundamentally solving the spatial overlap and cross-coupling of the electrical and optical structures, which not only improves the detection accuracy and long-term stability of the gyroscope, but also simplifies the processing flow and reduces the complexity of the process.

[0015] (2) This application adopts a magnetostrictive drive structure, which can more accurately control the drive amplitude and phase compared with the electrostatic force drive of the traditional electrostatic comb, and meet the stringent requirements of cavity optical force gyroscope for drive stability.

[0016] (3) This application adopts a magnetostrictive drive structure, which is smaller in size, more compact in structure, more stable, and more suitable for the integration requirements of inertial navigation systems compared with traditional electrostatic drive gyroscopes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the high-precision cavity optical micro-gyroscope driven by magnetostrictive materials according to the present invention; Figure 2 This is a side view of the gyroscope and magnetostrictive structure of the present invention being bonded together.

[0018] Figure 3 This is a schematic diagram illustrating the working principle of the gyroscope of this invention.

[0019] Explanation of reference numerals in the attached drawings: 1. Fixed column; 2. Mechanical structure; 3. Optical structure; 4. Magnetostrictive drive structure; 5. Base. Detailed Implementation

[0020] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0021] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Traditional cavity optical gyroscopes primarily employ electrostatic comb actuation. The driving force provided by the electrostatic comb depends on the electrostatic force between the comb teeth, requiring precise design of the comb tooth parameters. However, in practice, process errors such as device layer thickness variations and machining burrs can easily lead to uneven comb tooth spacing, resulting in electrostatic attraction. Secondly, electrostatic comb actuation requires applying a driving voltage via gold wire bonding or external probes, causing cross-coupling between the optical and electrical structures, severely impacting the gyroscope's measurement accuracy and stability. Furthermore, the complexity of gold wire bonding and issues such as poor probe contact further reduce the long-term reliability of the driving system.

[0023] To address the aforementioned technical problems, the following embodiments of a high-precision cavity optical micro-gyroscope driven by magnetostrictive materials are proposed in this application.

[0024] Reference Figure 1 and Figure 2 ,like Figure 1 The diagram shows a high-precision cavity optical micro-gyroscope driven by magnetostrictive materials. Figure 2 The image shows a side view of the gyroscope and magnetostrictive structure in conjunction. The gyroscope includes a fixed post 1, a mechanical structure 2, an optical structure 3, a magnetostrictive drive structure 4, and a base 5. The fixed post 1 is located at the four corners of the mechanical structure 2, the optical structure 3 is located at both ends of the mechanical structure 2, and the magnetostrictive drive structure 4 and base 5 are located at the lower part of the mechanical structure 2. The optical structure 3 includes a cavity optical system and a waveguide structure, which are coupled. The cavity optical system consists of a pair of optical microcavities, each a two-dimensional photonic crystal. The mechanical structure 2 includes a mass block and a support beam. The mass block includes a core mass block, a detection mass block, and a drive mass block. The core mass block is located at the center of the gyroscope and is connected to the drive mass block and the detection mass block via cantilever arms. The support beam includes a drive support beam and a detection support beam. In the optical structure 3, parallelograms represent microcavities, and lines represent waveguides.

[0025] In this embodiment, the magnetostrictive drive structure 4 uses Terfenol-D, Fe-Ga, or Ni-Co alloys with high magnetostriction coefficients, fast response characteristics, and low energy loss. The mass block of the mechanical structure 2 comprises a drive mass block and a detection mass block, which are rigidly connected by a U-shaped beam embedded inside the detection mass block. This nested structure effectively isolates the motion coupling between the drive mode and the detection mode, preventing vibration in the drive direction from being transmitted to the detection direction, thereby reducing the interference of orthogonal errors on the detection signal.

[0026] The driving mass block, as the core carrier of vibration excitation, works in conjunction with the magnetostrictive driving structure 4 to achieve precise vibration output. A two-dimensional photonic crystal microcavity, namely optical structure 3 in Figure 1, is symmetrically arranged on the upper and lower parts of the detection mass block to form a differential detection configuration, which can effectively cancel common-mode noise such as temperature drift and external vibration, and further improve the signal-to-noise ratio of the detection signal.

[0027] The magnetostrictive drive structure 4 and the base 5 are bonded together using a low-temperature adhesive bonding or annealing process. This fixes the magnetostrictive drive structure 4, mechanical structure 2, and optical structure 3, ensuring efficient transfer of drive deformation to the mechanical structure. The base 5 is the supporting silicon layer in the SOI wafer.

[0028] The magnetostrictive drive structure is composed of multiple layers of magnetostrictive thin films. Its unique stacked structure enhances bending drive efficiency, reduces the required magnetic field, and mitigates temperature drift and stress warpage, thereby generating acceleration sufficient for gyroscope drive requirements and adapting to the vibration excitation needs of a single mass. The out-of-plane bulge direction is precisely aligned with the drive direction of the gyroscope chip, ensuring efficient transmission of driving force to the drive mass. The entire assembly is placed within a vacuum chamber to avoid the influence of air damping on the oscillator's vibration characteristics. Simultaneously, the power supply is connected to the external environment via a turntable pin, without interfering with the turntable's rotation.

[0029] The core mechanism of using magnetostrictive materials to drive a gyroscope and generate mechanical displacement signals is that, upon applying a magnetic field, the magnetostrictive film produces intrinsic strain. Due to the constrained bonding, it cannot freely expand or contract, and the strain is converted into bending moment. In a multilayer film structure, this manifests as out-of-plane bulging. This upward / downward bulging generates stable acceleration, driving the gyroscope oscillator to achieve target vibration. A signal generator performs frequency sweeping, a multi-turn loop coil provides the magnetic field, an RF power amplifier increases the current in the coil, and a bias converter provides a bias magnetic field for the magnetostrictive material. The magnetostrictive material utilizes the magnetostrictive effect to convert the voltage signal into controllable shear motion. The driving magnetic field parameters must be strictly matched to the resonant frequency of the gyroscope's driving mode. Resonance driving enables the oscillator to achieve maximum driving displacement, laying the foundation for the subsequent generation and detection of Coriolis force.

[0030] Optical structure 3 and mechanical structure 2 are active layers suspended on base 5, and the two parts are directly connected.

[0031] Optical structure 3 employs a two-dimensional photonic crystal microcavity structure, which boasts advantages such as high Q-value, narrow linewidth, and strong optical field confinement. The two-dimensional photonic crystal introduced in optical structure 3 is a cavity-type two-dimensional photonic crystal with a triangular lattice. At the center of the structure, air holes are removed to load line defects, and then rectangular air grooves are introduced through etching to form the basic waveguide structure. Subsequently, width modulation is achieved through minute displacements of the microcavity holes. Utilizing the refractive index distribution changes caused by the hole displacement, a high-Q-value microcavity is formed in a localized region of the waveguide, while other hole positions remain unchanged, ensuring structural periodicity and optical field confinement. Its microcavity thickness is 250 nm, matching the device layer thickness in SOI technology, facilitating integrated fabrication. Operating in the communication C-band, near 1550 nm, through COMSOL finite element simulation and FDTD algorithm optimization, the final optical resonant wavelength is 1542.037 nm, with a quality factor (Q) as high as 102802. This high Q-value effectively reduces optical field loss and improves displacement detection sensitivity.

[0032] The magnetostrictive drive structure 4 serves as the source of acceleration in the driving direction and is electrically connected to the signal generator, causing the driving mass and the core mass to undergo simple harmonic motion along the driving direction. The signal generator is a mature, existing technology product, model RIGOL DG4162, with a multi-turn toroidal coil attached close to the bottom of the thin film. The multi-turn toroidal coil has an inner diameter of 46mm, an outer diameter of 57mm, a height of 10mm, 400 turns, and a wire diameter of 0.4mm. The RF power amplifier is model HMC1099PM5E, and the biaser is model RBTK70V25.

[0033] The optical structure 3 and the detection mass block constitute the detection structure of the cavity optical force micro gyroscope. The cavity optical force system of the optical structure 3 is distributed on both sides of the gap between the detection mass block and the outer periphery of the structure.

[0034] The magnetostrictive drive structure 4 applies mechanical shearing motion to the base of the cavity optical micro gyroscope, causing the core mass block in the mechanical structure 2 to vibrate with the same frequency, stable amplitude, and slightly lagging phase as the base. The frequency of the voltage applied to the magnetostrictive drive structure 4, the frequency of the shearing vibration generated by the magnetostrictive drive structure 4 through the magnetostrictive effect, and the frequency of the gyroscope's mechanical oscillator vibration are the same.

[0035] Reference Figure 3 ,like Figure 3 The diagram shown illustrates the working principle of a gyroscope. The detection principle is as follows: First, under the influence of the Coriolis force, the coupling system of the microcavity optomechanical structure optical gyroscope proposed in this project will satisfy the following set of coupling equations: (1-1) (1-2) Equation (1-1) describes the optical resonance mode in the microcavity optomechanical structure, and equation (1-2) describes the mechanical oscillation mode. This refers to the optical radiation pressure / optical gradient force generated in the microcavity. This refers to the thermal noise force of the system. The Coriolis force generated by the applied angular velocity... Under the influence of the microcavity optical-mechanical structure, the detection mass block and the connected cantilever have an additional displacement: (1-3) Therefore, the total displacement y of the detection mass block under laser excitation, Coriolis force, and thermal noise contribution is: (1-4) Substituting this into equations (1-1) and (1-2), we can obtain the relationship between the mechanical oscillation frequency of the detection mass block and the laser parameters (amplitude, wavelength) and angular velocity in the microcavity photomechanical system: (1-5) in, To excite the laser's operating frequency, This is the resonant frequency of the optical mode in the optical microcavity. Optomechanical coupling rate, The photon energy within the cavity, This refers to the optical cavity attenuation rate. For a well-designed and manufactured microcavity optomechanical system, the mass of the detection mass block, the optical resonance characteristics of the microcavity, the mechanical resonance characteristics of the detection mass block, and the optomechanical coupling rate can be determined.

[0036] Therefore, under fixed excitation laser wavelength and amplitude, and with fixed drive conditions, the final oscillation frequency of the detection mass changes only with the magnitude and direction of the applied angular velocity. Thus, the magnitude and direction of the angular velocity can be characterized by measuring the offset of the detection mass's oscillation frequency. Furthermore, as shown in equation (1-5), the angular velocity detection sensitivity of the optical gyroscope in a microcavity optomechanical system can be improved by increasing the laser power, among other things. This effect is called the photoelastic effect in a cavity optomechanical system.

[0037] This embodiment provides a high-precision cavity optical micro-gyroscope driven by magnetostrictive materials. It adopts a mechanical structure design of "single mass block + decoupling frame", which includes a driving mass block, a detection mass block and a core mass block. The mechanical oscillator is elastically supported and suspended from the base by a folded beam to reduce the vibration interference of the base. The driving structure is composed of multiple layers of magnetostrictive thin films. The special stacked structure can improve the bending driving efficiency, reduce the required magnetic field, and improve temperature drift and stress warping, thereby generating acceleration that meets the driving requirements of the gyroscope and adapts to the vibration excitation requirements of the single mass block. The outward bulge direction is precisely aligned with the driving direction of the gyroscope chip, ensuring efficient transmission of driving force to the driving mass block. The optical detection structure adopts a triangular lattice cavity-type two-dimensional photonic crystal microcavity. Specific air hole loading line defects are removed in the middle of the structure, and rectangular air grooves are etched to form waveguides. Then, a high-Q-value microcavity is formed by modulating the displacement of the holes in the central region. The microcavities are symmetrically arranged on the upper and lower parts of the detection mass block to form a differential configuration to cancel common-mode noise. In terms of process, a peel-off process is used. The magnetostrictive material and SOI wafer are bonded together through low-temperature adhesive bonding or annealing crystallization process to form a three-layer configuration of "magnetostrictive material-substrate-optical / mechanical structure" to achieve wafer-level integration. During detection, based on the Coriolis effect, an applied angular velocity causes the detection mass block to generate additional displacement. The high-Q-value characteristics of the microcavity are used to capture the displacement change, and the magnitude and direction of the angular velocity are characterized by measuring the frequency offset. Compared with cavity optical gyroscopes driven by electrostatic combs, the driving method proposed in this patent can largely suppress the cross-coupling between optical and electrical structures, while simplifying the manufacturing process, thereby improving the detection accuracy and stability of the gyroscope.

[0038] This embodiment discloses a high-precision cavity optical force micro-gyroscope driven by magnetostrictive materials, mainly applied to novel high-precision micro-gyroscopes based on cavity optical force systems. Based on the magnetostrictive effect of magnetostriction, a mechanical shearing motion is applied in the driving direction of the cavity optical force micro-gyroscope by using an external signal generator and a multi-turn loop coil to provide a magnetic field, thereby achieving driving. Angular velocity detection is achieved using an optical structure composed of a cavity optical force system and a waveguide, utilizing its high sensitivity and anti-electromagnetic interference characteristics to realize micro-nano-level displacement detection. The overall structure of the cavity optical force micro-gyroscope is simplified. By eliminating traditional electrical structures and retaining optical and mechanical structures, the coupling between electrical and optical structures is greatly reduced, improving the detection accuracy of the cavity optical force micro-gyroscope. The ease of monolithic integration using magnetostriction simplifies the fabrication and integration process of the cavity optical force micro-gyroscope. Compared with the traditional cavity optical micro gyroscope that uses electrostatically driven push-pull comb teeth, the cavity optical micro gyroscope structure of the present invention has significant advantages in terms of stability, environmental adaptability and integration, and is suitable for fields with extremely high precision requirements such as inertial navigation, attitude control and motion measurement.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-precision cavity optical micro-gyroscope driven by magnetostrictive materials, characterized in that, The gyroscope includes: The base has a front side for fixing the mechanical structure and a back side for fixing the magnetostrictive drive structure. A mechanical structure includes a mass block and a support beam. The mass block includes a driving mass block, a core mass block, and a detection mass block. The core mass block is located at the center of the gyroscope and is connected to the driving mass block and the detection mass block respectively via cantilever arms. The driving mass block cooperates with a magnetostrictive drive structure to enable the gyroscope to achieve vibration output, thereby decoupling the motion between the driving and detection modes. The support beam includes a driving support beam and a detection support beam, which cooperate with the driving mass block and the detection mass block to achieve motion decoupling between the driving and detection modes. A magnetostrictive driving structure, comprising a multilayer magnetostrictive film, wherein the multilayer magnetostrictive film bulges outward, and the direction of the outward bulging is aligned with the driving direction of the gyroscope chip; An optical structure, comprising a cavity optical system and a waveguide structure, wherein the cavity optical system and the waveguide structure are coupled, and the optical structure is fixed to both ends of the mechanical structure.

2. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 1, characterized in that, The driving mass block and the detection mass block are rigidly connected by a U-shaped beam embedded inside the detection mass block.

3. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 1, characterized in that, The cavity optical system includes an optical microcavity, which is symmetrically arranged on the detection mass block to form a differential detection configuration.

4. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 1, characterized in that, The magnetostrictive drive structure is electrically connected to an external magnetic field generating device. By adjusting the intensity and frequency of the external magnetic field, the magnetostrictive material is made to undergo directional elastic deformation, thereby driving the drive mass block and the core mass block to perform simple harmonic motion along the drive direction.

5. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 1, characterized in that, The mechanical structure is fixedly connected to the base by fixed columns located at the four corners, and the height of the fixed columns is consistent with the suspension height of the mechanical structure.

6. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 1, characterized in that, The magnetostrictive drive structure is fixed to the base by sputtering deposition, low-temperature bonding, or annealing bonding processes.

7. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 4, characterized in that, The magnetostrictive drive structure is placed inside the vacuum chamber.

8. The high-precision cavity optical micro-gyroscope driven by magnetostrictive materials as described in claim 3, characterized in that, The optical microcavity includes a two-dimensional photonic crystal microcavity.

9. A method for measuring the angular velocity of a high-precision cavity optical micro-gyroscope driven by a magnetostrictive material, the method being implemented based on the cavity optical micro-gyroscope according to any one of claims 1-8, characterized in that, The method includes: The magnitude and direction of angular velocity are characterized by measuring the offset of the oscillation frequency of the detection mass block.

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