Ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavity

Abstract

The invention belongs to the technical field of micro photoelectric mechanical systems and micro inertial devices, and particularly relates to a cascaded Fabry-Perot cavity-based ultra-wide optical bandwidth MOEMS gyroscope, which comprises a mass block, an optical structure, an anchoring structure, an electrostatic comb-shaped driving structure, a detection frame, an anchoring frame, an induction spring, a driving spring and a driving frame, the mass block is connected with the optical structure, anchoring structures are arranged at the four corners of the mass block respectively, electrostatic comb-shaped driving structures are arranged on the two sides of the mass block respectively, detection frames are connected to the two sides of the mass block respectively, and the mass block is connected with the anchoring frames through induction springs. On the basis of the Coriolis force measurement principle, the angular velocity is measured by detecting the wavelength or intensity change of an output harmonic peak caused by the structural change of the cascade cavity. Benefited from broadband tuning characteristics and high compactness of a cascade cavity structure, the device can be used in an optical bandwidth range exceeding 175 nm, and has a highly compact structure consisting of an all-silicon micro waveguide and a cavity.

Description

Technical Field

[0001] The invention belongs to the technical field of micro optoelectronic mechanical systems and micro inertial devices, and in particular relates to an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity. Background Art

[0002] As one of the core components of the integrated optical inertial measurement system, the size, accuracy, sensitivity and other indicators of the micro-opto-electromechanical (MOEMS) gyroscope directly determine the core indicators of inertial measurement integration, accuracy, resolution, zero drift stability and other core indicators. In recent years, based on different principles such as multilayer film interference, grating interference and disk cavity resonance, a variety of MOEMS gyroscopes have been developed and introduced, and have been widely used in applications such as national defense, consumer electronics and medical equipment. These methods usually rely on narrow linewidth, low-noise lasers or high-resolution spectrometers. The above equipment makes the traditional MOEMS gyroscopes less integrated and more expensive, which limits the application of such devices in inertial navigation and other aspects. Summary of the invention

[0003] In view of the technical problems of low integration and high cost caused by the need for high-performance lasers or spectrometers in the above-mentioned MOEMS gyroscope technology, the present invention provides an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity, which adopts a Bragg reflector structure composed of cascaded Fabry-Perot cavities, and based on the Coriolis force effect, calculates the Coriolis force displacement by detecting the spectrum or light intensity change of the cascade structure, and then infers the input angular velocity to realize the inertial measurement function. By utilizing the narrowband filtering effect generated by the cascade cavity, the device does not require high-performance light sources or spectrum analysis equipment such as narrow linewidth, low-noise lasers or high-resolution spectrometers, and can solve the problems of low integration and high cost of traditional MOEMS gyroscopes.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] An ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity comprises a mass block, an optical structure, an anchoring structure, an electrostatic comb drive structure, a detection frame, an anchoring frame, an induction spring, a drive spring and a drive frame, wherein the mass block is connected to the optical structure, the four corners of the mass block are respectively provided with anchoring structures, the two sides of the mass block are respectively provided with electrostatic comb drive structures, the two sides of the mass block are respectively connected to the detection frames, the mass block is connected to the anchoring frame through an induction spring, the optical structure is provided on the detection frame and the anchoring frame, and the mass block is connected to the drive frame through a drive spring.

[0006] The optical structure includes an input waveguide, a first Bragg reflector, a second Bragg reflector, a third Bragg reflector, a fourth Bragg reflector, a transmission waveguide and an output waveguide, wherein the first Bragg reflector is arranged in the optical path direction of the input waveguide, the second Bragg reflector is arranged in the optical path direction of the first Bragg reflector, one end of the transmission waveguide is arranged in the optical path direction of the second Bragg reflector, the third Bragg reflector is arranged in the optical path direction of the other end of the transmission waveguide, the fourth Bragg reflector is arranged in the optical path direction of the third Bragg reflector, and the output waveguide is arranged in the optical path direction of the fourth Bragg reflector.

[0007] The optical structure also includes a first cavity and a second cavity, the first cavity is cascaded with the second cavity, the input waveguide, the first Bragg reflector, the fourth Bragg reflector and the output waveguide are all arranged in the first cavity, and the second Bragg reflector, the third Bragg reflector and the transmission waveguide are all arranged in the second cavity.

[0008] The first cavity is arranged on the detection frame, and the second cavity is arranged on the anchoring frame.

[0009] The first cavity and the second cavity are both Fabry-Perot cavities.

[0010] A method for measuring an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity comprises the following steps:

[0011] S1, the signal light is input into the cascade cavity through the input waveguide, passes through the first cavity between the input waveguide and the transmission waveguide, continues to be transmitted along the transmission waveguide and is input into the output waveguide through the second cavity, and finally is output along the output waveguide to the photodetector or spectrometer for output signal analysis;

[0012] S2. Get the input angular velocity value Ω through the output signal intensity of the photoelectric detector or the spectrum signal of the spectrometer z .

[0013] In S2, the input angular velocity value Ω is obtained by outputting the signal intensity of the photoelectric detector or the spectrum signal of the spectrometer. z The method is:

[0014] S2.1, when the angular velocity Ω z During input, the mass block vibrates along the y-axis at the same time, driving the detection frame to detect the amplitude A along the y-axis. y Vibration, detection amplitude A y With the input angular velocity Ω z There is a linear relationship;

[0015] S2.2. The cascaded Fabry-Perot cavity acts as two tunable narrowband filters. The two cascaded Bragg mirror Fabry-Perot cavities are parallel to each other, and the cavity length is defined as the spacing L between the paired Bragg mirrors. C ;

[0016] S2.3, the minimum spacing of the detection frame relative to the anchoring frame becomes smaller, resulting in a decrease in the minimum cavity length of the Bragg mirror Fabry-Perot cavity and a decrease in the minimum resonance wavelength λ of the resonance peak output by the one-dimensional photonic crystal waveguide. T Reduce, λ T Follow L C Changes linearly;

[0017] S2.4. The process of converting angular velocity into detection amplitude and then into resonant wavelength is a linear transformation. Therefore, the input angular velocity can be deduced by detecting the resonant wavelength or resonant intensity of the resonant peak output by the one-dimensional photonic crystal waveguide through a spectrometer or a photodetector, thereby completing the measurement of the input angular velocity.

[0018] The detection amplitude A y With the input angular velocity Ω z The linear relationship is calculated as:

[0019] The electrostatic comb drive structure applies a force along the x-axis with a frequency of f to the drive frame. x The electrostatic driving force drives the frame and the mass block to vibrate, generating a driving displacement d along the x-axis direction. x =A x sin(2πf x t), where A x Drive amplitude, f x is the driving mode eigenfrequency;

[0020] When Ω z Rotating along the z-axis, the mass block is acted upon by the Coriolis force along the y-axis and vibrates along the y-axis, driving the detection frame to vibrate at the same frequency along the y-axis. The detection displacement is d y =A y sin(2πf x t), A y is the detection amplitude, A y With the input angular velocity Ω z Linear change:

[0021]

[0022] where Δω is the eigenfrequency difference between the drive mode and the sense mode.

[0023] The lambda T Follow L C The calculation method for linear change is:

[0024] Mechanical sensitivity S1 is defined as the perceived amplitude increment ΔA y With the rotation increment ΔΩ z The ratio is expressed as follows:

[0025]

[0026] In the detection process, it is assumed that the initial length of the cavity without angular velocity input is defined as L C0 , with Ω z The increase of A y will also increase;

[0027] L C =L C0 ―A y

[0028] At the same time, the central wavelength of the resonance peak also changes, which is expressed as:

[0029]

[0030] Where m is the order of the resonance peak;

[0031] Assuming the change in output intensity is ΔI, the optical sensitivity of the detection wavelength and intensity are defined as:

[0032]

[0033] Where Δλ is the wavelength shift, S 2w Indicates the optical sensitivity of the detection wavelength, S 2I represents the optical sensitivity of the detected intensity;

[0034] A certain amount of rotation is applied to the gyroscope. By detecting the wavelength and intensity at the output of the system, the input rotation can be inferred. The total sensitivity of the wavelength and intensity detection is expressed as

[0035] S W =S1×S 2w

[0036] S I =S1×S 2I

[0037] Where: S W It represents the total sensitivity of the detection wavelength, S I Represents the overall sensitivity of the detection intensity.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention is based on the Coriolis force measurement principle, and realizes angular velocity measurement by detecting the change in the output resonance peak wavelength or intensity caused by the change in the cascade cavity structure. Benefiting from the broadband tuning characteristics and high compactness of the cascade cavity structure, the device can be used in an optical bandwidth range exceeding 175nm, and has a highly compact structure consisting of an all-silicon microwave guide and a cavity. The device has two detection modes of wavelength or intensity, with sensitivities of 0.084nm / (deg / s) and 0.021% / (deg / s), respectively. Among them, the wavelength detection mode does not require equipment such as narrow linewidth, low-noise lasers or high-resolution spectrometers. Based on the above effects, the device has good application prospects in fields such as inertial navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0041] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0042] Figure 1 It is a structural schematic diagram of the present invention;

[0043] Figure 2 It is a schematic diagram of the optical structure of the present invention;

[0044] Figure 3 This is a diagram of the simulated mechanical vibration mode of the present invention;

[0045] Figure 4 This is a numerical diagram of mechanical sensitivity simulation of the present invention;

[0046] Figure 5 This is a graph showing the relationship between the first-order resonance peak (m=1) of the transmission spectrum resonance peak of the cascade cavity of the present invention and the cavity length;

[0047] Figure 6 This is a graph showing the relationship between the second-order resonance peak (m=2) of the transmission spectrum resonance peak of the cascade cavity of the present invention and the cavity length;

[0048] Figure 7It is a relationship diagram of the second-order resonance peak and the third-order resonance peak (m=3) of the transmission spectrum resonance peak of the cascade cavity of the present invention changing with the cavity length;

[0049] Figure 8 is a graph showing the relationship between the second-order resonance peak wavelength and the cavity length of the present invention;

[0050] Fig. 9 This is a diagram showing the relationship between the third-order resonance peak intensity and the cavity length of the present invention.

[0051] Among them: 1 is a mass block, 2 is an optical structure, 2-1 is an input waveguide, 2-2 is a first Bragg reflector, 2-3 is a second Bragg reflector, 2-4 is a third Bragg reflector, 2-5 is a fourth Bragg reflector, 2-6 is a transmission waveguide, 2-7 is an output waveguide, 2-8 is a first cavity, 2-9 is a second cavity, 3 is an anchoring structure, 4 is an electrostatic comb drive structure, 5 is a detection frame, 6 is an anchoring frame, 7 is an induction spring, 8 is a drive spring, and 9 is a drive frame. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0053] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0054] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0055] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0056] An ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavities, such as Figure 1 As shown, it includes a mass block 1, an optical structure 2, an anchoring structure 3, an electrostatic comb drive structure 4, a detection frame 5, an anchoring frame 6, an induction spring 7, a drive spring 8 and a drive frame 9. The mass block 1 is connected to the optical structure 2. The four corners of the mass block 1 are respectively provided with anchoring structures 3. The two sides of the mass block 1 are respectively provided with electrostatic comb drive structures 4. The two sides of the mass block 1 are respectively connected with detection frames 5. The mass block 1 is connected to the anchoring frame 6 through the induction spring 7. The optical structure 2 is arranged on the detection frame 5 and the anchoring frame 6. The mass block 1 is connected to the drive frame 9 through the drive spring 8. The MOEMS gyroscope consists of a mass block 1 and four completely decoupled frames, and the frames are connected by several folding springs. The decoupling frame includes a drive frame 9 and a detection frame 5. The large stiffness difference of the folding spring in the orthogonal direction is used to suppress the movement of the drive frame 9 and the detection frame 5 along the x-axis and y-axis respectively. The drive frame 9 is driven by the electrostatic comb drive structure 4.

[0057] Further, if Figure 2As shown, the optical structure 2 includes an input waveguide 2-1, a first Bragg reflector 2-2, a second Bragg reflector 2-3, a third Bragg reflector 2-4, a fourth Bragg reflector 2-5, a transmission waveguide 2-6 and an output waveguide 2-7. The first Bragg reflector 2-2 is arranged in the optical path direction of the input waveguide 2-1, the second Bragg reflector 2-3 is arranged in the optical path direction of the first Bragg reflector 2-2, one end of the transmission waveguide 2-3 is arranged in the optical path direction of the second Bragg reflector 2-3, the third Bragg reflector 2-4 is arranged in the optical path direction of the other end of the transmission waveguide 2-6, the fourth Bragg reflector 2-5 is arranged in the optical path direction of the third Bragg reflector 2-4, and the output waveguide 2-7 is arranged in the optical path direction of the fourth Bragg reflector 2-5. The optical structure 2 also includes a first cavity 2-8 and a second cavity 2-9, the first cavity 2-8 and the second cavity 2-9 are cascaded, the input waveguide 2-1, the first Bragg reflector 2-2, the fourth Bragg reflector 2-5 and the output waveguide 2-7 are all arranged in the first cavity 2-8, and the second Bragg reflector 2-3, the third Bragg reflector 2-4 and the transmission waveguide 2-6 are all arranged in the second cavity 2-9. The first cavity 2-8 is arranged on the detection frame 5, and the second cavity 2-9 is arranged on the anchoring frame 6. A pair of silicon-air Bragg mirrors is made by etching periodic air grooves at the end of the silicon microwave guide. Due to the large difference in the refractive index of silicon and air, three periods of silicon-air Bragg mirrors are sufficient to make the reflectivity close to 100%.

[0058] Further, preferably, both the first cavity 2-8 and the second cavity 2-9 adopt Fabry-Perot cavity.

[0059] During the working process: the signal light is input into the cascade cavity through the input waveguide 2-1, passes through the first cavity 2-8 between the input waveguide 2-1 and the transmission waveguide 2-6, continues to be transmitted along the transmission waveguide 2-6 and passes through the second cavity 2-9 to be input into the output waveguide 2-7, and finally outputs along the output waveguide 2-7 to the photodetector or spectrometer for output signal analysis; the input angular velocity value Ω is obtained through the output signal intensity of the photodetector or the spectrum signal of the spectrometer. z .

[0060] Among them, when the angular velocity Ω z During input, the mass block 1 vibrates along the y-axis at the same time, driving the detection frame 5 to detect the amplitude A along the y-axis. y Vibration, detection amplitude A y With the input angular velocity Ω z The cascaded Fabry-Perot cavity acts as two tunable narrowband filters. The two cascaded Bragg mirror Fabry-Perot cavities are parallel to each other, and the cavity length is defined as the spacing L between the paired Bragg mirrors. CThe minimum spacing of the detection frame 5 relative to the anchor frame 6 becomes smaller, resulting in a decrease in the minimum cavity length of the Bragg mirror Fabry-Perot cavity and a decrease in the minimum resonance wavelength λ of the resonance peak output by the one-dimensional photonic crystal waveguide. T Reduce, λ T Follow L C It changes linearly; the process of converting angular velocity into detection amplitude and then into resonant wavelength is a linear transformation. Therefore, the input angular velocity can be deduced by detecting the resonant wavelength or resonant intensity of the resonant peak output by the one-dimensional photonic crystal waveguide through a spectrometer or a photodetector, thereby completing the measurement of the input angular velocity.

[0061] The electrostatic comb drive structure 4 applies a current along the x-axis direction at a frequency of f to the drive frame 9. x The electrostatic driving force drives the frame 9 and the mass block 1 to vibrate, generating a driving displacement d along the x-axis direction. x =A x sin(2πf x t), where A x Drive amplitude, f x is the characteristic frequency of the driving mode. z Rotating along the z-axis, the mass block 1 is acted upon by the Coriolis force along the y-axis and vibrates along the y-axis, driving the detection frame 5 to vibrate at the same frequency along the y-axis. The detected displacement is d y =A y sin(2πf x t), A y is the detection amplitude, A y With the input angular velocity Ω z Linear change:

[0062]

[0063] Where Δω is the eigenfrequency difference between the drive mode and the sense mode. The mechanical sensitivity S1 is defined as the sensed amplitude increment ΔA y With the rotation increment ΔΩ z The ratio is expressed as follows.

[0064]

[0065] In the detection process, it is assumed that the initial length of the cavity without angular velocity input is defined as L C0 . With Ω z The increase of A y Will also increase.

[0066]

[0067] At the same time, the central wavelength of the resonance peak also changes, which can be expressed as

[0068]

[0069] Where m is the order of the resonance peak.

[0070] Assuming the change in output intensity is ΔI, the optical sensitivity of the detection wavelength and intensity are defined as

[0071]

[0072] where Δλ is the wavelength shift.

[0073] Here, a certain amount of rotation is applied to the gyroscope, and the input rotation can be inferred by detecting the wavelength and intensity at the output of the system. The total sensitivity of detecting wavelength and intensity can be expressed as

[0074] S W =S1×S 2w (7)

[0075] S I =S1×S 2I (8)

[0076] The specific implementation parameters are as follows:

[0077] Long beam length of driving spring: 400μm

[0078] Sensing spring beam length: 440 μm

[0079] Short beam length of driving spring: 50μm

[0080] Short beam length of sensing spring: 40μm

[0081] Spring width: 10μm

[0082] Dimensions of the detection mass block: 2000μm×2000μm

[0083] Detection mass: 0.43μg

[0084] The mass of the driving frame: 0.055 μg

[0085] Mass of sensing frame: 0.074 μg

[0086] Drive mode eigenfrequency: 5565.7Hz

[0087] Sensing mode eigenfrequency: 5751.2Hz

[0088] Microwave guide parameters: width 6μm, height 4μm

[0089] Parameters of the cascade waveguide structure: wavelength is 2μm

[0090] Silicon film thickness: 145nm

[0091] Air film thickness: 500nm

[0092] Number of periods of a single Bragg mirror: 3

[0093] Bragg period: 645nm

[0094] After simulation, the vibration modes of the driving mode and the detection mode are obtained, such as Figure 3 As shown. Thanks to the large difference in length between the long beam and the short beam of the folding spring, a large orthogonal stiffness difference is formed, so that the driving frame and the mass block only vibrate along the driving direction in the driving mode, and the detection frame and the mass block only vibrate along the detection direction in the detection mode, realizing a mechanical structure with full decoupling of the driving displacement and detection displacement signals. The characteristic frequencies of the driving mode and the detection mode are 5565.7Hz and 5751.2Hz respectively, and the frequency difference is f y –f x =185.5Hz.

[0095] exist Figure 3 In the mechanical process shown in the figure, the electrostatic comb drive structure 4 applies a force along the x-axis direction and a frequency f to the drive frame 9. x The electrostatic driving force drives the frame 9 and the mass block 1 to generate a driving displacement d along the x-axis direction. x =A x sin(2πf x t). When Ω z Rotating along the z-axis, the mass block 1 is acted upon by the Coriolis force along the y-axis and vibrates along the y-axis, driving the detection frame 5 to vibrate at the same frequency along the y-axis. The detected displacement is d y =A y sin(2πf x t). y With input angular velocity (Ω z ) changes linearly, such as Figure 4 shown.

[0096] The Bragg mirror uses the principle of constructive interference of light on the thin film interface to enhance reflection, so the cross-sectional size of the waveguide of the one-dimensional photonic crystal needs to be large enough to regard the silicon-air Bragg mirror as a thin film. Based on the Bragg mirror Fabry-Perot cavity theory, the structural dimensions of the one-dimensional photonic crystal waveguide are designed: the thickness of the silicon film in the silicon-air Bragg mirror is 145nm, the thickness of the air film is 500nm, the number of single Bragg periods is 3, the Bragg period is 645nm, and the cross-sectional width of the one-dimensional photonic crystal waveguide is 4μm and the height is 6μm. The transmission characteristics of a single cavity are analyzed using the finite-difference time-domain method, and the results are as follows: Figure 5 , Figure 6 , Figure 7 shown.

[0097] Cavity length L c The bandgap varies between 0 and 2 μm. The bandgap width is 1.5 to 3.2 μm, which determines the tunable range of the resonance peak. The left and right limit wavelengths can be expressed as

[0098] λ L =π(n si d si +n air d air ) / cos -1 (-ρ) (9)

[0099] λ R =π(n si d si +n air d air ) / cos -1 (ρ) (10)

[0100] ρ=(n si -n air ) / (n si +n air ) (11)

[0101] First, when λ changes in the range of 0 to 0.4 μm, only the first-order resonance peak is observed in the band gap. The resonance peak moves toward the long-wave direction with the increase of wavelength, and the peak intensity increases at the same time. c As L increases, the second-order resonance peak appears and moves toward the long-wave direction. However, the intensity of the peak value also decreases. c = 0.5 μm, the gap between the two cavities is equal to the length of one air chamber, so that the minimum width of the band gap increases from 1.46 to 3.17 μm, which is consistent with the formula. c When changing from 1.3 μm to 2 μm, the third-order peak and the second-order peak exist simultaneously. c With the increase of , the wavelengths of the two peaks increase, but the intensity changes are: the intensity of the third-order peak decreases, and the intensity of the third-order peak increases.

[0102] Figure 8 The second-order resonance peak λ is shown in T and L c The peak wavelength increases with the cavity length L c For example, for the second-order resonance peak, the wavelength increases with the increase of L in the range of 1.430 to 3.107 μm. c The change is approximately linear in the range of 0.5 to 2 μm. Assuming that L C0 Set to 2 μm. According to the slope of the blue fitting line, S2W It is 1.2nm / nm. Fig. 9 I and L represent the third-order resonance peak c The peak output intensity I varies with L c For example, for the third-order resonance peak, the intensity changes with L c In the range of 1.5 to 1.2 μm, the linear relationship is 9.2% to 92.7%. Assuming L C0 is set to 1.5 μm. According to the slope of the red fitting line, the S 2I It is 0.305% / nm.

[0103] For the case of measuring the input angular velocity by detecting the wavelength of the resonance peak, the optical bandwidth of the MOEMS gyroscope is 3.107μm-1.430μm=1.67μm, and the total sensitivity S of the detection wavelength is calculated. w The bandwidth of the measurement range is 21,429 deg / s, which is 0.084nm / (deg / s). For another case where the input angular velocity is obtained by detecting the resonance peak intensity, the optical bandwidth of the MOEMS gyroscope is 1.6μm-1.425μm=0.175μm, corresponding to 0.021% / (deg / s), and the measurement range is 4286deg / s. The MOEMS gyroscope has an ultra-compact structure and an ultra-wide optical bandwidth of 175nm, and can work in the mode of light intensity detection, avoiding the complex optical demodulation system at the output end, which is conducive to the on-chip integration of the sensor.

[0104] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. An ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity, characterized in that: The invention comprises a mass block (1), an optical structure (2), an anchoring structure (3), an electrostatic comb-shaped drive structure (4), a detection frame (5), an anchoring frame (6), an induction spring (7), a drive spring (8) and a drive frame (9), wherein the mass block (1) is connected to the optical structure (2), the four corners of the mass block (1) are respectively provided with anchoring structures (3), the two sides of the mass block (1) are respectively provided with electrostatic comb-shaped drive structures (4), the two sides of the mass block (1) are respectively connected to the detection frame (5), the mass block (1) is connected to the anchoring frame (6) via the induction spring (7), the optical structure (2) is arranged on the detection frame (5) and the anchoring frame (6), and the mass block (1) is connected to the drive frame (9) via the drive spring (8).

2. The ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavities according to claim 1, characterized in that: The optical structure (2) comprises an input waveguide (2-1), a first Bragg reflector (2-2), a second Bragg reflector (2-3), a third Bragg reflector (2-4), a fourth Bragg reflector (2-5), a transmission waveguide (2-6) and an output waveguide (2-7), wherein the first Bragg reflector (2-2) is arranged in the optical path direction of the input waveguide (2-1), the second Bragg reflector (2-3) is arranged in the optical path direction of the first Bragg reflector (2-2), one end of the transmission waveguide (2-3) is arranged in the optical path direction of the second Bragg reflector (2-3), the other end of the transmission waveguide (2-6) is arranged in the optical path direction of the third Bragg reflector (2-4), the fourth Bragg reflector (2-5) is arranged in the optical path direction of the fourth Bragg reflector (2-5), and the output waveguide (2-7) is arranged in the optical path direction of the fourth Bragg reflector (2-5).

3. The ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavities according to claim 2, characterized in that: The optical structure (2) further comprises a first cavity (2-8) and a second cavity (2-9), wherein the first cavity (2-8) and the second cavity (2-9) are cascaded, the input waveguide (2-1), the first Bragg reflector (2-2), the fourth Bragg reflector (2-5) and the output waveguide (2-7) are all arranged in the first cavity (2-8), and the second Bragg reflector (2-3), the third Bragg reflector (2-4) and the transmission waveguide (2-6) are all arranged in the second cavity (2-9).

4. The ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavities according to claim 3, characterized in that: The first cavity (2-8) is arranged on the detection frame (5), and the second cavity (2-9) is arranged on the anchoring frame (6).

5. The ultra-wide optical bandwidth MOEMS gyroscope based on cascaded Fabry-Perot cavities according to claim 3, characterized in that: The first cavity (2-8) and the second cavity (2-9) both adopt Fabry-Perot cavity.

6. A method for measuring an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, the signal light is input into the cascade cavity through the input waveguide (2-1), passes through the first cavity (2-8) between the input waveguide (2-1) and the transmission waveguide (2-6), continues to be transmitted along the transmission waveguide (2-6) and passes through the second cavity (2-9) to be input into the output waveguide (2-7), and finally output along the output waveguide (2-7) to the photodetector or spectrometer for output signal analysis; S2. Get the input angular velocity value Ω through the output signal intensity of the photoelectric detector or the spectrum signal of the spectrometer z .

7. The method for measuring an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity according to claim 6, characterized in that: In S2, the input angular velocity value Ω is obtained by outputting the signal intensity of the photoelectric detector or the spectrum signal of the spectrometer. z The method is: S2.1, when the angular velocity Ω z During input, the mass block (1) vibrates along the y-axis, driving the detection frame (5) to detect the amplitude A along the y-axis. y Vibration, detection amplitude A y With the input angular velocity Ω z There is a linear relationship; S2.

2. The cascaded Fabry-Perot cavity acts as two tunable narrowband filters. The two cascaded Bragg mirror Fabry-Perot cavities are parallel to each other, and the cavity length is defined as the spacing L between the paired Bragg mirrors. C ; S2.3, the minimum spacing between the detection frame (5) and the anchoring frame (6) becomes smaller, resulting in a decrease in the minimum cavity length of the Bragg mirror Fabry-Perot cavity and a decrease in the minimum resonance wavelength λ of the resonance peak output by the one-dimensional photonic crystal waveguide. T Reduce, λ T Follow L C Changes linearly; S2.

4. The process of converting angular velocity into detection amplitude and then into resonant wavelength is a linear transformation. Therefore, the input angular velocity can be deduced by detecting the resonant wavelength or resonant intensity of the resonant peak output by the one-dimensional photonic crystal waveguide through a spectrometer or a photodetector, thereby completing the measurement of the input angular velocity.

8. The method for measuring an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity according to claim 7, characterized in that: The detection amplitude A y With the input angular velocity Ω z The linear relationship is calculated as: The electrostatic comb drive structure (4) applies a force along the x-axis direction with a frequency of f to the drive frame (9). x The electrostatic driving force drives the frame (9) and the mass block (1) to vibrate, generating a driving displacement d along the x-axis direction. x =A x sin(2πf x t), where A x Drive amplitude, f x is the driving mode eigenfrequency; When Ω z Rotating along the z-axis, the mass block (1) is acted upon by the Coriolis force along the y-axis and vibrates along the y-axis, driving the detection frame (5) to vibrate along the y-axis at the same frequency. The detected displacement is d y =A y sin(2πf x t), A y is the detection amplitude, A y With the input angular velocity Ω z Linear change: where Δω is the eigenfrequency difference between the drive mode and the sense mode.

9. The method for measuring an ultra-wide optical bandwidth MOEMS gyroscope based on a cascaded Fabry-Perot cavity according to claim 7, characterized in that: The lambda T Follow L C The calculation method for linear change is: Mechanical sensitivity S1 is defined as the perceived amplitude increment ΔA y With the rotation increment ΔΩ z The ratio is expressed as follows: In the detection process, it is assumed that the initial length of the cavity without angular velocity input is defined as L C0 , with Ω z The increase of A y will also increase; L C =L C0 -HAS y At the same time, the central wavelength of the resonance peak also changes, which is expressed as: Where m is the order of the resonance peak; Assuming the change in output intensity is ΔI, the optical sensitivity of the detection wavelength and intensity are defined as: Where Δλ is the wavelength shift, S 2w Indicates the optical sensitivity of the detection wavelength, S 2I represents the optical sensitivity of the detected intensity; A certain amount of rotation is applied to the gyroscope. By detecting the wavelength and intensity at the output of the system, the input rotation can be inferred. The total sensitivity of the wavelength and intensity detection is expressed as S W =S1×S 2w S I =S1×S 2I Where: S W It represents the total sensitivity of the detection wavelength, S I Represents the overall sensitivity of the detection intensity.

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