Chip-level wide-spectrum resonant mode optical gyroscope based on differential detection and working method of chip-level wide-spectrum resonant mode optical gyroscope

Abstract

The invention belongs to the technical field of optical gyroscopes, and particularly relates to a chip-level wide-spectrum resonant optical gyroscope based on differential detection and a working method thereof. The working light source ASE is connected with the coupler through the polarizer; the coupler is connected with a photoelectric detector PD I, a photoelectric detector PD II, a straight waveguide PM and an optical echo wall micro resonant cavity. The photoelectric detector PD I and the photoelectric detector PD II output detection signals to the signal processing circuit structure AMSP, the amplitude modulation signal circuit structure AMSP transmits alternating current signals with rotating speed information to the lock-in amplifier LIA, and after the alternating current signals pass through the low-pass filter LPF, high-frequency useless signals are filtered out, so that useful direct-current gyroscope rotating speed signals are output. The invention is used for solving the problems of high modulation frequency and obvious RIN noise when a resonant fiber-optic gyroscope driven by a wide-spectrum light source in the prior art inhibits relative intensity noise.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical gyroscopes, and in particular relates to a chip-level wide-spectrum resonant optical gyroscope based on differential detection and a working method thereof. Background Art

[0002] A gyroscope, a sensor that accurately determines the angular velocity of a moving object, is a widely used inertial navigation instrument in modern aviation, navigation, and aerospace. In recent years, the rapid development of inertial technology, driven by the demands of major engineering projects, has placed higher demands on inertial components. While ensuring high precision, they must also possess characteristics such as miniaturization, low power consumption, high reliability, low cost, and resistance to vibration and shock. The development of gyroscopes directly impacts the key performance of inertial navigation and guidance systems, playing an irreplaceable role in various fields.

[0003] As an all-solid-state inertial instrument, optical gyroscopes based on the Sagnac effect offer advantages such as high reliability, long life, fast startup, and a large dynamic range. Interferometric fiber-optic gyroscopes (IFOGs) are relatively mature and widely used. The accuracy of an IFOG is related to the length of the internal fiber loop. High-precision IFOGs require loops several kilometers long, making them difficult to miniaturize. In contrast, resonant optical gyroscopes detect angular rate by detecting the resonant frequency difference between the oppositely propagating light beams within a cavity caused by the Sagnac effect. With a resonant cavity as its core sensitive component, IFOGs can be as small as sub-millimeter microcavities, aligning with the trend toward device miniaturization. They also offer high processing repeatability, device integration capabilities, and sensitivity.

[0004] The existing resonant fiber gyroscope driven by a wide-spectrum light source has significantly better accuracy than traditional interferometric and narrow-linewidth resonant fiber gyroscopes of the same size. However, its accuracy is limited by relative intensity noise. The existing technology based on the micro-whispering gallery resonator requires applying a high modulation frequency to suppress this noise, which increases the crosstalk of high-frequency signals and the load pressure on the gyroscope signal processing. Summary of the Invention

[0005] The present invention provides a chip-level wide-spectrum resonant optical gyroscope based on differential detection and a working method thereof, which are used to solve the problems of high modulation frequency and obvious RIN noise when suppressing relative intensity noise in resonant fiber gyroscopes driven by wide-spectrum light sources in the prior art.

[0006] The present invention is achieved through the following technical solutions: A chip-level wide-spectrum resonant optical gyroscope based on differential detection, comprising a working light source (ASE), a polarizer, a coupler, a straight waveguide (PM), an optical whispering gallery micro-resonator, a photodetector (PDI), a photodetector (PDII), an amplitude modulation signal processing circuit structure (AMSP), a lock-in amplifier (LIA), and a low-pass filter (LPF); The working light source ASE is connected to the coupler through a polarizer; the coupler is also connected to the photodetector PDⅠ, the photodetector PDⅡ, the straight waveguide PM and the optical whispering gallery microresonator, The photodetector PDⅠ and the photodetector PDⅡ output the detection signals to the signal processing circuit structure AMSP. The amplitude modulation signal circuit structure AMSP transmits the AC signal with the speed information to the phase-locked amplifier LIA. After passing through the low-pass filter LPF, the high-frequency useless signal is filtered out, thereby outputting a useful DC gyroscope speed signal.

[0007] Furthermore, the working light source ASE is used to generate a stable rectangular light field; The coupler is used to split the working light source ASE and generate a differential speed signal; The straight waveguide PM is used to modulate the gyro signal to generate a light intensity AC signal with the first harmonic carrying the rotation speed information; The optical whispering gallery micro-resonator is used to sense and amplify the Sagnac effect generated by rotation; The photodetector PD is used to receive the differential optical signal emitted from the coupler and convert the light intensity signal into a voltage signal; The amplitude modulation signal processing circuit structure AMSP is used to differentiate the two received PD electrical signals and perform full-wave rectification on the modulated signals; The lock-in amplifier LIA is used to extract the first harmonic component carrying the speed information from the AC signal; The low-pass filter LPF is used to filter out high-frequency useless interference signals, thereby obtaining a gyro output value that meets the required bandwidth of navigation.

[0008] Furthermore, the coupler is a 3×3 coupler; The couplers adopt a coupling mode of mutual coupling between two pairs; The working light source ASE is a broad-spectrum ASE driven light source.

[0009] Furthermore, the working light source ASE is a broadband laser with a spectral linewidth greater than 30 nm and a power greater than 10 mW; The splitting ratio of the coupler is 1:1:1; The diameter of the whispering gallery microcavity is 3 cm.

[0010] A working method of a chip-level wide-spectrum resonant optical gyroscope based on differential detection, wherein the working method uses the chip-level wide-spectrum resonant optical gyroscope based on differential detection as described above, and the working method is as follows: The driving light source emitted by the working light source ASE enters the coupler through the polarizer and port 2 of the coupler. The driving light source performs laser beam splitting in the coupler. The 120-degree coupling phase shift of the coupler causes the optical signal carrying the rotation speed information passing through the coupler to produce a zero point offset. When the gyroscope rotates, the intensities of the two paths change in opposite directions and form a pair of differential signals. The micro-whispering gallery cavity controls the light wave to propagate periodically in a clockwise or counterclockwise direction for several circles before outputting it. The light wave then interferes through the coupler port, and the interfered light wave is output from port 1 and port 3 of the coupler. The interference light wave signal carrying the phase shift is detected by the photodetector PDⅠ and the photodetector PDⅡ.

[0011] Furthermore, the light intensity output from port 1 and port 3 of the coupler passes through the photodetector PDⅠ and the photodetector PDⅡ, and the light fields output from port 1 and port 3 of the coupler along the CW and CCW directions are respectively:

[0012]

[0013] in is the output light field of the ASE light source, and are the transfer functions of light with frequency f when it is transmitted in the whispering gallery resonator along the CW and CCW directions, and They are the splitting ratios of the coupler from port 2 to port 4 and from port 2 to port 6, and They are the phase delays of the coupler from port 2 to port 4 and from port 2 to port 6, respectively, which is a coupled phase shift of 120 degrees.

[0014] Furthermore, the light field transfer function expression is:

[0015]

[0016] in is the Sagnac frequency shift caused by rotation, is the frequency shift produced by the PM phase modulator, and The parameters of the whispering gallery resonator:

[0017]

[0018] in is the coupling coefficient of the two couplers in the whispering gallery microcavity, is the loss coefficient of the coupler; Given by the following formula,

[0019] Where M is the modulation coefficient, is the modulation frequency.

[0020] Furthermore, after the laser signals are combined and output by the coupler, the light intensities at ports 1 and 3 are:

[0021]

[0022] The superscript * is the complex conjugate, N is the number of FSRs within the spectral width, is the free spectral width of WGMm, is the spectral width of the light source, It is given by:

[0023]

[0024] in These are the phase shifts caused by light coupling from port 6 to port 1 and from port 4 to port 3 of the coupler.

[0025] Furthermore, the PD converts the two-way modulated light intensity sinusoidal fluctuation into a voltage signal, and after AMSP, flips the negative half axis of the fluctuation voltage to positive. It can be expressed as follows:

[0026] The signal Do a fast Fourier transform (FFT), the frequency in the frequency domain is The amplitude of the signal component at is the gyroscope speed; the signal The signal is input into the lock-in amplifier LIA and passes through the low-pass filter LPF to obtain a gyro speed signal output under a corresponding bandwidth.

[0027] Furthermore, the signal The differential processing is specifically to enter the lock-in amplifier LIA to demodulate the useful information, that is, the first harmonic component carrying the rotation speed, to obtain the gyroscope output. This process greatly suppresses the common-mode signal and high-frequency noise, reduces the proportion of electrical noise in the useful signal, and improves the gyroscope output signal-to-noise ratio.

[0028] The beneficial effects of the present invention are: The present invention utilizes differential signal detection technology and amplitude modulation rectification (AMSP) technology implemented by a 3×3 coupler to solve the problems of high modulation frequency and obvious RIN noise when suppressing relative intensity noise in resonant fiber gyros driven by wide-spectrum light sources in the prior art, thereby improving the angular random walk accuracy of resonant fiber gyros driven by wide-spectrum light sources.

[0029] The present invention uses a broadband ASE laser as its working light source and a miniature whispering gallery WGMm as its resonant cavity, reducing the size of the gyro's sensitive components and improving the sensitivity of the resonant gyroscope driven by the broadband light source. Furthermore, a 3×3 coupler is used to perform differential processing of differential signals, eliminating the common-mode noise generated by relative intensity noise. Full-wave rectification technology is used to extract useful signals, further suppressing high-frequency noise. Compared with traditional solutions, this method can achieve lower relative intensity noise at a lower modulation frequency, thereby reducing the impact of relative intensity noise on the resonant gyroscope. This shows that while improving the gyroscope's sensitivity, the present invention also achieves miniaturization of the core sensitive components, improves the gyroscope's signal-to-noise ratio at a lower modulation frequency, and reduces the impact of relative intensity noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the working principle of the 3×3 coupler of the present invention.

[0031] Figure 2 It is a schematic diagram of the optical circuit structure of the present invention.

[0032] Figure 3 It is a schematic diagram comparing the transmission spectrum lines of the optical gyroscope of the present invention.

[0033] Figure 4 It is a schematic diagram of the PD acquisition signal and the AMSP processed signal of the present invention. DETAILED DESCRIPTION

[0034] In the following description, specific details such as specific system structures and technologies are provided for illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present application with unnecessary details.

[0035] It will be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0036] It should also be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0037] The following is a clear and complete description of the technical solutions in the embodiments of this application in conjunction with the drawings in the specification of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0039] Implementation Method 1 This embodiment provides a chip-level wide-spectrum resonant optical gyroscope based on differential detection. The gyroscope includes a working light source ASE, a polarizer, a coupler, a straight waveguide PM, an optical whispering gallery microresonator, a photodetector PDⅠ, a photodetector PDⅡ, an amplitude modulation signal processing circuit structure AMSP, a lock-in amplifier LIA, and a low-pass filter LPF. The working light source ASE is connected to the coupler through a polarizer; the coupler is also connected to the photodetector PDⅠ, the photodetector PDⅡ, the straight waveguide PM and the optical whispering gallery microresonator, The photodetector PDⅠ and the photodetector PDⅡ output the detection signals to the signal processing circuit structure AMSP. The amplitude modulation signal circuit structure AMSP transmits the AC signal with the speed information to the phase-locked amplifier LIA. After passing through the low-pass filter LPF, the high-frequency useless signal is filtered out, thereby outputting a useful DC gyroscope speed signal.

[0040] The optical whispering gallery microresonator is connected to ports 4 and 6 of the coupler respectively, and a straight waveguide PM is arranged between port 4 of the coupler and the whispering gallery microresonator; the photodetector PDⅠ and the photodetector PDⅡ are connected to ports 1 and 3 of the coupler respectively.

[0041] Furthermore, the working light source ASE is a wide-spectrum ASE driven light source for generating a stable rectangular light field; The coupler adopts a two-to-two coupling mode to split the working light source ASE and generate a differential speed signal; The straight waveguide PM is used to modulate the gyro signal to generate a light intensity AC signal with the first harmonic carrying the rotation speed information; The optical whispering gallery micro-resonator serves as the core sensor of the resonant optical gyroscope, detecting and amplifying the Sagnac effect generated by rotation. Its ultra-high quality factor and ultra-small mode volume facilitate the miniaturization and integration of optical gyroscopes. The photodetector PD is used to receive the differential optical signal emitted from the coupler and convert the light intensity signal into a voltage signal; The amplitude modulation signal processing circuit structure AMSP is used to differentiate the two received PD electrical signals and perform full-wave rectification on the modulated signals; The lock-in amplifier LIA is used to extract the first harmonic component carrying the speed information from the AC signal; The low-pass filter LPF is used to filter out high-frequency useless interference signals, thereby obtaining a gyro output value that meets the required bandwidth of navigation.

[0042] An optical whispering gallery micro-resonator that can be integrated on a chip and miniaturized is used as the core sensitive element of the gyroscope; The optical whispering gallery micro-resonator is made of calcium fluoride material and has an ultra-high quality factor, which gives the whispering gallery micro-resonator a better light-binding capability. Using it as a core sensitive element can greatly improve the sensitivity of the chip-level optical gyroscope.

[0043] Furthermore, the coupler is a 3×3 coupler; The couplers adopt a coupling mode of mutual coupling between two pairs; The working light source ASE is a broad-spectrum ASE driven light source.

[0044] Furthermore, the working light source ASE is a broadband laser with a spectral linewidth greater than 30 nm and a power greater than 10 mW; The splitting ratio of the 3×3 coupler is 1:1:1; The diameter of the whispering gallery microcavity is 3 cm.

[0045] Conventional approaches to 3×3 coupler resonant gyroscopes driven by a wide-spectrum light source employ unmodulated DC detection, leveraging the linear relationship between the rotational frequency difference generated by the 120° coupling phase shift of the 3×3 coupler and the change in the dual-path light intensity. However, while reducing the number of optical components, these conventional approaches largely forgo the noise filtering of the lock-in amplifier, significantly degrading the ARW accuracy of DC detection. The solution employed in this invention addresses this issue by innovatively employing an amplitude modulated signal processing (AMSP) architecture. This architecture modulates the signal based on the 3×3 coupler and processes the differential PD signal. This method significantly improves ARW accuracy by approximately 10 times. Furthermore, compared to high-frequency modulated gyroscopes using Y-waveguides, this approach achieves superior ARW accuracy using an extremely low modulation frequency, significantly reducing the offset crosstalk associated with high-frequency signal processing.

[0046]

[0047] Implementation Method 2 This embodiment provides a working method of a chip-level wide-spectrum resonant optical gyroscope based on differential detection. The working method uses the chip-level wide-spectrum resonant optical gyroscope based on differential detection as described in Embodiment 1. The working method is as follows: The driving light source emitted by the working light source ASE enters the coupler through the polarizer and port 2 of the coupler. The driving light source performs laser beam splitting in the coupler. The 120-degree coupling phase shift of the coupler causes the optical signal carrying the rotational speed information passing through the coupler to produce a zero-point offset. When the gyroscope rotates, the intensities of the two paths change in opposite directions and form a pair of differential signals. The use of the coupler can also increase the slope of the gyroscope operating point on the transmission spectrum, improve the gyroscope's angular rate sensitivity, and thus improve the gyroscope's operating signal-to-noise ratio. The micro whispering gallery cavity WGMm controls the light wave to propagate periodically in a clockwise or counterclockwise direction for several turns before outputting the interference light wave. The interference light wave is then output from ports 1 and 3 of the coupler, and the interference light wave signal carrying the Sagnac phase shift is detected by photodetectors PDⅠ and PDⅡ.

[0048] A 3×3 coupler is used as the laser beam splitter. Its unique 120-degree coupling phase shift causes a zero-point offset in the optical signal carrying rotational speed information passing through the 3×3 coupler. As the gyroscope rotates, the intensities of the two beams change in opposite directions, forming a pair of differential signals.

[0049] Furthermore, the use of the 3×3 coupler can improve the slope of the gyro operating point on the transmission spectrum line, increase the gyro angular rate sensitivity, and thus improve the gyro operating signal-to-noise ratio.

[0050] The characteristic of noise reduction through differential processing is that the short-term angular random walk accuracy of a wide-spectrum resonant optical gyroscope is primarily affected by the relative intensity noise (RIN) of the light source. In the optical signals received by photodetectors PD I and PD II, the common-mode signal is primarily the relative intensity noise (RIN) caused by light source intensity fluctuations. Differential processing of the detection signals can significantly suppress this relative intensity noise (RIN).

[0051] Amplitude modulation signal processing (AMSP) is used to rectify the differential PD signal and flip the negative half-axis of the fluctuating voltage to positive. The rectified signal is used as the signal source for demodulation by the lock-in amplifier (LIA). Only the required first harmonic component carrying the speed signal is extracted, which can filter out other high-frequency noise to a large extent.

[0052] Furthermore, the light intensity output from port 1 and port 3 of the coupler passes through the photodetector PDⅠ and the photodetector PDⅡ, and the light fields output from port 1 and port 3 of the coupler along the CW and CCW directions are respectively:

[0053]

[0054] in is the output light field of the ASE light source, and are the transfer functions of light with frequency f when it is transmitted in the whispering gallery resonator along the CW and CCW directions, and These are the splitting ratios of the 3×3 coupler from port 2 to port 4 and from port 2 to port 6, and They are the phase delays from port 2 to port 4 and from port 2 to port 6 of the 3×3 coupler, respectively, which is a coupled phase shift of 120 degrees.

[0055] Furthermore, the light field transfer function expression is:

[0056]

[0057] in is the Sagnac frequency shift caused by rotation, is the frequency shift produced by the PM phase modulator, and Related to the parameters of the whispering gallery resonant cavity itself:

[0058]

[0059] in is the coupling coefficient of the two couplers in the whispering gallery microcavity, is the loss coefficient of the coupler; It can be given by the following formula,

[0060] Where M is the modulation coefficient, is the modulation frequency.

[0061] Furthermore, after the laser signals are combined and output by the 3×3 coupler, the light intensities at ports 1 and 3 are:

[0062]

[0063] The superscript * indicates taking the complex conjugate, N is the number of FSRs within the spectral width, represents the free spectral width of WGMm, is the spectral width of the light source, It is given by:

[0064]

[0065] These are the phase shifts caused by light coupling from port 6 to port 1 and from port 4 to port 3 of the 3×3 coupler.

[0066] Furthermore, the PD converts the two-way modulated light intensity sinusoidal fluctuation into a voltage signal, and after AMSP, flips the negative half axis of the fluctuation voltage to positive. It can be expressed by the following formula:

[0067] The signal Do a fast Fourier transform (FFT), the frequency in the frequency domain is The amplitude of the signal component at is the gyroscope speed; the signal The signal is input into the lock-in amplifier LIA and passes through the low-pass filter LPF to obtain a gyro speed signal output under a corresponding bandwidth.

[0068] Furthermore, the signal The differential processing is specifically to enter the lock-in amplifier (LIA) to demodulate the useful information, that is, the first harmonic component carrying the rotational speed, to obtain the gyroscope output. This process can significantly suppress common-mode signals and high-frequency noise, such as light source intensity fluctuation noise. Properly increasing the light source intensity can reduce the proportion of electrical noise in the useful signal and improve the gyroscope output signal-to-noise ratio.

Claims

1. A chip-level wide-spectrum resonant optical gyroscope based on differential detection, characterized in that: The gyroscope includes a working light source ASE, a polarizer, a coupler, a straight waveguide PM, an optical whispering gallery micro-resonator, a photodetector PDⅠ, a photodetector PDⅡ, an amplitude modulation signal processing circuit structure AMSP, a lock-in amplifier LIA and a low-pass filter LPF; The working light source ASE is connected to the coupler through a polarizer; the coupler is also connected to the photodetector PDⅠ, the photodetector PDⅡ, the straight waveguide PM and the optical whispering gallery microresonator, The photodetector PDⅠ and the photodetector PDⅡ output the detection signals to the signal processing circuit structure AMSP. The amplitude modulation signal circuit structure AMSP transmits the AC signal with the speed information to the phase-locked amplifier LIA. After passing through the low-pass filter LPF, the high-frequency useless signal is filtered out, thereby outputting a useful DC gyroscope speed signal.

2. The chip-level wide-spectrum resonant optical gyroscope according to claim 1, characterized in that: The working light source ASE is used to generate a stable rectangular light field; The coupler is used to split the working light source ASE and generate a differential speed signal; The straight waveguide PM is used to modulate the gyro signal to generate a light intensity AC signal with the first harmonic carrying the rotation speed information; The optical whispering gallery micro-resonator is used to sense and amplify the Sagnac effect generated by rotation; The photodetector PD is used to receive the differential optical signal emitted from the coupler and convert the light intensity signal into a voltage signal; The amplitude modulation signal processing circuit structure AMSP is used to differentiate the two received PD electrical signals and perform full-wave rectification on the modulated signals; The lock-in amplifier LIA is used to extract the first harmonic component carrying the speed information from the AC signal; The low-pass filter LPF is used to filter out high-frequency useless interference signals, thereby obtaining a gyro output value that meets the required bandwidth of navigation.

3. The chip-level wide-spectrum resonant optical gyroscope according to claim 1, characterized in that: The coupler is a 3×3 coupler; The couplers adopt a coupling mode of mutual coupling between two pairs; The working light source ASE is a broad-spectrum ASE driven light source.

4. The chip-level wide-spectrum resonant optical gyroscope according to claim 1, characterized in that: The working light source ASE is a broadband laser with a spectral line width greater than 30nm and a power greater than 10mW; The splitting ratio of the coupler is 1:1:1; The diameter of the whispering gallery microcavity is 3 cm.

5. A working method of a chip-level wide-spectrum resonant optical gyroscope based on differential detection, characterized in that: The working method uses a chip-level wide-spectrum resonant optical gyroscope based on differential detection as described in any one of claims 1 to 3, and the working method is: The driving light source emitted by the working light source ASE enters the coupler through the polarizer and port 2 of the coupler. The driving light source performs laser beam splitting in the coupler. The 120-degree coupling phase shift of the coupler causes the optical signal carrying the rotation speed information passing through the coupler to produce a zero point offset. When the gyroscope rotates, the intensities of the two paths change in opposite directions and form a pair of differential signals. The micro-whispering gallery cavity controls the light wave to propagate periodically in a clockwise or counterclockwise direction for several circles before outputting it. The light wave then interferes through the coupler port, and the interfered light wave is output from port 1 and port 3 of the coupler. The interference light wave signal carrying the phase shift is detected by the photodetector PDⅠ and the photodetector PDⅡ.

6. The working method according to claim 5, characterized in that: The light intensity output from port 1 and port 3 of the coupler passes through the photodetector PDⅠ and the photodetector PDⅡ. The light fields output from port 1 and port 3 of the coupler along the CW and CCW directions are: in is the output light field of the ASE light source, and are the transfer functions of light with frequency f when it is transmitted in the whispering gallery resonator along the CW and CCW directions, and They are the splitting ratios of the coupler from port 2 to port 4 and from port 2 to port 6, and They are the phase delays of the coupler from port 2 to port 4 and from port 2 to port 6, respectively, which is a coupled phase shift of 120 degrees.

7. The working method according to claim 6, characterized in that: The light field transfer function expression is: in is the Sagnac frequency shift caused by rotation, is the frequency shift produced by the PM phase modulator, and The parameters of the whispering gallery resonator: in is the coupling coefficient of the two couplers in the whispering gallery microcavity, is the loss coefficient of the coupler; Given by the following formula, Where M is the modulation coefficient, is the modulation frequency.

8. The working method according to claim 7, characterized in that: After the laser signals are combined and output by the coupler, the light intensities at ports 1 and 3 are: The superscript * is the complex conjugate, N is the number of FSRs within the spectrum width, is the free spectral width of WGMm, is the spectral width of the light source, It is given by: in These are the phase shifts caused by light coupling from port 6 to port 1 and from port 4 to port 3 of the coupler.

9. The working method according to claim 8, characterized in that: The PD converts the two-way modulated light intensity sinusoidal fluctuation into a voltage signal, and then processes the amplitude modulation signal AMSP to flip the negative half axis of the fluctuation voltage to positive. It can be expressed as follows: The signal Perform fast Fourier transform, the frequency in the frequency domain is The amplitude of the signal component at is the gyroscope speed; the signal The signal is input into the lock-in amplifier LIA and passes through the low-pass filter LPF to obtain a gyro speed signal output under a corresponding bandwidth.

10. The working method according to claim 9, characterized in that: The signal The differential processing is specifically to enter the lock-in amplifier LIA to demodulate the useful information, that is, the first harmonic component carrying the rotation speed, to obtain the gyroscope output. This process greatly suppresses the common-mode signal and high-frequency noise, reduces the proportion of electrical noise in the useful signal, and improves the gyroscope output signal-to-noise ratio.

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