A Brillouin fiber gyroscope frequency stabilizing device and method

Abstract

The present application relates to a kind of Brillouin optical fiber gyro frequency stabilizing device and method, belong to the technical field of optical fiber gyro, solve the robustness of the prior art in optical fiber gyro for environmental noise is poor, cannot adapt to the temperature, noise change in environment Problem.Published a kind of Brillouin optical fiber gyro frequency stabilizing device, including semiconductor laser, waveguide, voltage-controlled current source, waveguide drive, photodetector and controller.The unused PZT of the present application and other larger devices have small size, all solid state;The frequency stabilization part of the present application is separated from the composite filter, avoids introducing noise itself.The frequency stabilization part of the present application is realized based on waveguide, has larger dynamic range and is easy to integrate.

Description

Technical Field

[0001] This invention belongs to the technical field of fiber optic gyroscopes, specifically relating to a Brillouin fiber optic gyroscope frequency stabilization device and method. Background Technology

[0002] Fiber optic gyroscopes are angular rate sensors based on the SAGNAC effect. They are one of the core sensors for motion control and inertial navigation, and are widely used in the aerospace field. They have advantages such as high precision, no moving parts, and strong anti-interference ability.

[0003] Existing Brillouin fiber optic gyroscopes primarily employ a dual-resonance method, simultaneously controlling the pump light and Brillouin laser resonance, to reduce the pump light power threshold for exciting the Brillouin laser. The dual-resonance method requires the system's Brillouin frequency shift to be strictly equal to an integer multiple of the fiber resonator's free spectral range. It also necessitates strictly maintaining the initial resonator length and using PZT to control the cavity length, increasing the system's manufacturing complexity, size, and reducing its immunity to noise from temperature, vibration, and other factors. Furthermore, this significantly increases the difficulty of stabilizing the Brillouin laser frequency, impacting its frequency stability.

[0004] To address the poor frequency stability of Brillouin lasers, a bidirectional Brillouin laser based on an asymmetric Mach-Zehnder interferometer-resonant cavity composite filter (hereinafter referred to as the composite filter) was developed. Fiber gyroscopes using this novel Brillouin laser, such as... Figure 1 As shown, the composite filter is formed by connecting two couplers O2 and O3. First, the two ports 5 and 6 of coupler O2 are connected to the two ports 7 and 8 of coupler O3 respectively, ensuring that the two arms have a specific length difference, thus obtaining an asymmetric Mach-Zehnder interferometer. Then, the two ports 3 and 9 of the asymmetric Mach-Zehnder interferometer are connected to form a resonant cavity, thus obtaining the asymmetric Mach-Zehnder interferometer-resonant cavity composite filter. Figure 2To normalize the transmission power of the asymmetric Mach-Zehnder interferometer in the composite filter at port 2 input and port 9 output, the transmission spectrum period of the composite filter is made twice the Brillouin frequency shift by setting the difference in fiber lengths between the two arms of the composite filter (5-7, 6-8). The pump light frequency is selected so that the pump light transmission power is close to 1. This allows most of the pump light to pass through the composite filter once, while most of the Brillouin scattering circulates within the composite filter. By adjusting the cavity length of the composite filter, the Brillouin laser can be generated by controlling its resonance within the composite filter. The Brillouin laser resonance condition can be met simply by adjusting the pump light frequency, greatly reducing the difficulty of Brillouin laser frequency stabilization and improving the system's resistance to temperature and stress interference. Since the Brillouin laser still resonates within the composite filter, the threshold of this scheme is also relatively low. However, the difficulties and disadvantages of this type of Brillouin fiber optic gyroscope are: simultaneously achieving pump light frequency adjustment at the GHz level and Brillouin laser tuning control at the MHz level; poor robustness to environmental noise, unable to adapt to changes in temperature and noise in the environment; requiring high-precision temperature control, resulting in high cost, complex structure, and inability to miniaturize. Summary of the Invention

[0005] In view of the above problems, the present invention provides a Brillouin fiber optic gyroscope frequency stabilization device and method, which solves the problem that the existing fiber optic gyroscopes have poor robustness to environmental noise and cannot adapt to changes in temperature and noise in the environment.

[0006] This invention provides a Brillouin fiber optic gyroscope frequency stabilization device, comprising a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide driver, a photodetector, and a controller;

[0007] A semiconductor laser is used to output pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter.

[0008] Waveguides are used to modulate the pump light frequency into a square wave shape, and to fine-tune the frequency reference value of the pump light in the square wave shape.

[0009] A photodetector is used to convert the power of the Brillouin laser into a voltage signal and send it to the analog-to-digital converter of the controller;

[0010] The controller is used to scan the pump light frequency to obtain the pump light excitation frequency that can excite the Brillouin laser and adjust the pump light frequency to that excitation frequency; it is used to convert the voltage signal of the Brillouin laser power into a digital signal and demodulate the digital signal to obtain the comprehensive frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter; it is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonant peak of the composite filter and send it to the voltage-controlled current source and the waveguide driver respectively.

[0011] A voltage-controlled current source and waveguide drive are used to change the pump light frequency emitted by the semiconductor laser according to the control input of the controller, so as to ensure that the Brillouin laser frequency remains stable under the influence of the external environment.

[0012] Optionally, the controller includes a control algorithm module, a modulation and demodulation module, a first digital-to-analog converter, a second digital-to-analog converter, and an analog-to-digital converter.

[0013] Optionally, the control algorithm module includes a Brillouin laser frequency positioning module and a Brillouin laser resonance module; the Brillouin laser frequency positioning module is used to scan the pump light frequency, find the pump light frequency that excites the Brillouin laser, and adjust the pump light frequency to the excitation frequency; the Brillouin laser resonance control module is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonance peak of the composite filter, and send it to the voltage-controlled current source and waveguide drive respectively.

[0014] Optionally, the modulation and demodulation module is used to apply a modulation signal to the pump light frequency to obtain a pump light in the form of a square wave, and to demodulate the digital signal of the Brillouin laser power to obtain the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter.

[0015] Optionally, the control quantities include pump light coarse adjustment control quantities and pump light fine adjustment control quantities; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine adjustment control quantity is added to the pump light frequency modulation signal to obtain the waveguide control quantity.

[0016] Optionally, the first digital-to-analog converter is used to convert the current control quantity into a current control electrical signal and apply it to the voltage-controlled current source.

[0017] Optionally, a second digital-to-analog converter is used to convert waveguide control quantities into waveguide control electrical signals and apply them to the waveguide drive.

[0018] Optionally, an analog-to-digital converter is used to convert Brillouin laser power in the form of a voltage signal into Brillouin laser power in the form of a digital quantity.

[0019] Alternatively, the semiconductor laser is an electric current tunable semiconductor laser.

[0020] In another aspect, the present invention also provides a method for frequency stabilization of a Brillouin fiber optic gyroscope, the specific steps of which are as follows:

[0021] Step 1: The semiconductor laser outputs pump light, which enters the composite filter through a waveguide to excite the Brillouin laser; the Brillouin laser power is converted into a voltage signal by a photodetector and input into the controller; the pump light frequency positioning module of the controller is activated.

[0022] Step 2: The pump light frequency positioning module steps and scans the current of the semiconductor laser; after the step scanning is completed, the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser are obtained.

[0023] Step 3: Trace the current of the semiconductor laser back to the current value of the semiconductor laser corresponding to the maximum power of the Brillouin laser to obtain the pump light frequency that can excite the Brillouin laser, and start the Brillouin laser resonant module of the controller.

[0024] Step 4: The control algorithm module uses the frequency difference between the Brillouin laser frequency obtained by demodulation in the previous control cycle and the resonant peak of the composite filter as feedback to calculate the control quantity.

[0025] Step 5: Convert the control quantity into the sawtooth wave accumulation of the waveguide driving voltage to control the Brillouin laser to resonate stably within the composite filter.

[0026] Step 6: The waveguide performs triangular wave phase modulation on the pump light output by the semiconductor laser in the current control cycle, and superimposes it with the sawtooth wave accumulation obtained in Step 5 to obtain the pump light frequency in the square wave form of the current control cycle.

[0027] Step 7: Obtain the Brillouin laser power of the current control period based on the pump light frequency of the square wave shape of the current control period; The modulation and demodulation module distinguishes the Brillouin laser power of the current control period according to the high-frequency and low-frequency bands of the pump light corresponding to its time, and demodulates to obtain the frequency difference between the Brillouin laser frequency of the current control period and the resonant peak of the composite filter.

[0028] Step 8: Increment the control cycle by 1, then return to step 4 until the Brillouin fiber optic gyroscope is no longer in use.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) The stabilizing device of the present invention does not use larger devices such as PZT, and has the advantages of small size and all solid state.

[0031] (2) The frequency stabilization part of the stabilization device of the present invention is separated from the composite filter, thus avoiding the introduction of noise itself.

[0032] (3) The frequency stabilization part of the stabilization device of the present invention is based on waveguide, which has a large dynamic range and is easy to integrate. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] Figure 1 This is a schematic diagram of a composite filter in the prior art;

[0035] Figure 2 The transmission characteristics of an unbalanced Mach-Zehnder interferometer for composite filters in the prior art are shown.

[0036] Figure 3 This is a schematic diagram of the frequency stabilization device of the present invention;

[0037] Figure 4 This is a schematic diagram of the triangular wave phase modulation of the present invention;

[0038] Figure 5 This is the synchronous demodulation curve of the present invention;

[0039] Figure 6 This is a flowchart of the control method of the present invention. Detailed Implementation

[0040] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0041] A specific embodiment of the present invention, such as Figure 1-6 A frequency stabilization device for a Brillouin fiber optic gyroscope is disclosed. This device is used to stabilize the Brillouin laser frequency of a Brillouin fiber optic gyroscope based on an asymmetric Mach-Zehnder interferometer-resonant cavity composite filter, such as... Figure 3 As shown, it includes a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide driver, a photodetector, and a controller;

[0042] A semiconductor laser is used to output pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter.

[0043] A waveguide is used to modulate the pump light frequency into a square wave shape, and to fine-tune the frequency reference value of the pump light in the square wave shape; and to input the pump light into a composite filter.

[0044] A photodetector is used to convert the power of the Brillouin laser input from the composite filter into a voltage signal and send it to the analog-to-digital converter of the controller.

[0045] The controller is used to scan the pump light frequency to obtain the pump light excitation frequency that can excite the Brillouin laser and adjust the pump light frequency to that excitation frequency; it is used to convert the voltage signal of the Brillouin laser power into a digital signal and demodulate the digital signal to obtain the comprehensive frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter; it is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonant peak of the composite filter and send it to the voltage-controlled current source and the waveguide driver respectively.

[0046] A voltage-controlled current source and waveguide drive are used to change the pump light frequency emitted by the semiconductor laser according to the control input of the controller, so as to ensure that the Brillouin laser frequency based on the asymmetric Mach-Zehnder interferometer-resonant cavity composite filter remains stable under the influence of the external environment.

[0047] Furthermore, the controller includes a control algorithm module, a modulation and demodulation module, a first digital-to-analog converter, a second digital-to-analog converter, and an analog-to-digital converter.

[0048] The control algorithm module includes a Brillouin laser frequency positioning module and a Brillouin laser resonance module; the Brillouin laser frequency positioning module is used to scan the pump light frequency, find the pump light frequency that excites the Brillouin laser, and adjust the pump light frequency to that excitation frequency.

[0049] The Brillouin laser resonant control module is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonant peak of the composite filter, and send it to the voltage-controlled current source and waveguide driver respectively.

[0050] Preferably, the control quantities include pump light coarse adjustment control quantities and pump light fine adjustment control quantities; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine adjustment control quantity is added to the pump light frequency modulation signal to obtain the waveguide control quantity.

[0051] The modulation and demodulation module is used to apply a modulation signal to the pump light frequency to obtain a pump light in the form of a square wave, and to demodulate the digital signal of the Brillouin laser power to obtain the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter.

[0052] The first digital-to-analog converter is used to convert the current control quantity into a current control electrical signal and apply it to the voltage-controlled current source.

[0053] The second digital-to-analog converter is used to convert waveguide control quantities into waveguide control electrical signals and apply them to the waveguide drive.

[0054] An analog-to-digital converter is used to convert Brillouin laser power in the form of a voltage signal into Brillouin laser power in the form of a digital quantity.

[0055] Optionally, the waveguide is a lithium niobate waveguide; the bandwidth of the lithium niobate waveguide is a low-frequency bandwidth, and the half-wave voltage is a low half-wave voltage. Preferably, the bandwidth is less than 1 GHz, and the half-wave voltage is less than 4 V. This ensures that the waveguide can operate normally within the working frequency band, and reduces the performance requirements of the waveguide driver, resulting in low cost and small size.

[0056] In operation, the semiconductor laser outputs pump light into the waveguide, which finely tunes the pump light frequency and modulates it into a square wave. This square wave pump light enters the composite filter through the pump light input port to excite the Brillouin laser. The Brillouin laser output port then enters the photodetector. In the circuit, the photodetector converts the Brillouin laser power signal into a voltage-based signal. This voltage-based signal is then input to the controller's analog-to-digital converter (ADC). The ADC converts this voltage-based signal into a digital signal. The ADC then inputs the digital signal to the modulation / demodulation module. The ADC demodulates the digital signal from the ADC to obtain a demodulated value (the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter). This demodulated value is then input to the control algorithm module to obtain the current. The system includes control quantities and waveguide control quantities. The current control quantity is input to a first digital-to-analog converter (DAC) to obtain a current control signal. The DAC is connected to a voltage-controlled current source (VDC), which converts the current control quantity into a current control signal. This VDC is connected to a semiconductor laser, and the current control signal is used to drive the semiconductor laser. The waveguide control quantity is input to a second DAC to obtain a waveguide control signal. The second DAC is connected to a waveguide driver, which amplifies the waveguide control signal. The waveguide driver is connected to the waveguide, and the amplified waveguide control voltage signal is sent to the waveguide to drive it.

[0057] Optionally, the semiconductor laser is a current-tunable semiconductor laser, the tuning range of which is the transmission spectrum period of the Mach-Zehnder interferometer in the composite filter (see Appendix). Figure 3 The frequency of the pump light is 1-3 times that of the composite filter to ensure that the frequency of the pump light can be adjusted to any frequency within one transmission spectrum period of the composite filter. In addition, for the same digital-to-analog converter, the tuning resolution decreases as the tuning range increases.

[0058] In this invention, the reference voltage of the voltage-controlled current source is added to the output voltage of the digital-to-analog converter 2, and the added voltage is linearly converted into a high-power current, giving the voltage-controlled current source high current driving capability and fast dynamic response characteristics. The waveguide drive amplifies the voltage signal and outputs it to the waveguide, enabling the waveguide to continuously and rapidly change the phase and frequency of the pump light.

[0059] Another embodiment of the present invention discloses a frequency stabilization method for a Brillouin fiber optic gyroscope, using the aforementioned Brillouin fiber optic gyroscope frequency stabilization device, with the following specific steps:

[0060] Step 1: The semiconductor laser outputs pump light, which enters the composite filter through a waveguide to excite the Brillouin laser; the Brillouin laser power is converted into a voltage signal by a photodetector and input into the controller; the pump light frequency positioning module of the controller is activated.

[0061] Step 2: The pump light frequency positioning module steps and scans the current of the semiconductor laser; after the step scanning is completed, the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser are obtained.

[0062] Optionally, the frequency tuning range corresponding to the current scanning range is the transmission spectrum period of the Mach-Zehnder interferometer in the composite filter.

[0063] Step 3: The current of the semiconductor laser is traced back to the current value of the semiconductor laser corresponding to the maximum power of the Brillouin laser to obtain the pump light excitation frequency that can excite the Brillouin laser, and the Brillouin laser resonant module of the controller is started.

[0064] Step 4: The control algorithm module calculates the control quantity by using the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter obtained from the demodulation of the previous control cycle (one pump light frequency square wave modulation cycle).

[0065] Optionally, the control algorithm module is a PI algorithm module, based on the synchronous demodulation curve, see [link / reference]. Figure 5 The digital form of the Brillouin laser power of the previous control cycle is demodulated to obtain the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter in the previous control cycle, and the control quantity is calculated. The frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter in the first control cycle is initially set to 0.

[0066] Step 5: Convert the control quantity into the sawtooth wave accumulation of the waveguide driving voltage to control the Brillouin laser to resonate stably within the composite filter.

[0067] Further, it is determined whether the control quantity obtained in step 4 exceeds the waveguide drive output range. If it does not exceed the range, all control quantities are converted into a sawtooth wave accumulation of the waveguide drive voltage. The sawtooth wave accumulation is used to change the waveguide drive voltage, so that the pump light produces continuous phase changes and constant frequency shifts. If it exceeds the range, it indicates that the waveguide output is close to saturation and cannot achieve the required frequency. Most of the frequency adjustment required by the control quantity is used as the current control quantity to fine-tune the drive current of the semiconductor laser. The remaining small portion of the control quantity is output by the waveguide drive to adjust the waveguide output to a lower level, thereby releasing the waveguide control range.

[0068] Optionally, when the control quantity exceeds the waveguide drive output range, the current control quantity is taken as an integer multiple of a fixed current. The frequency change caused by this fixed current value is an integer multiple of the free spectral range of the composite filter. Using this fine-tuning quantity effectively reduces the oscillation caused by the fine-tuning current. Control quantities that are not integer multiples are used as waveguide control quantities and are implemented by the waveguide drive in the form of sawtooth wave accumulation.

[0069] Optionally, determine whether the waveguide control quantity obtained in step 4 exceeds the waveguide drive output range.

[0070] Step 6: The waveguide performs triangular wave phase modulation on the pump light output by the semiconductor laser in the current control cycle, and superimposes it with the sawtooth wave accumulation obtained in Step 5 to obtain the pump light frequency in the square wave form of the current control cycle.

[0071] Optionally, during triangular wave phase modulation, a high-frequency stepped triangular wave is obtained by alternately accumulating and subtracting the pump light using a high-frequency clock signal as a reference. The expression is as follows:

[0072]

[0073] Among them, f M f is the pump light frequency in square wave form; f0 is the pump light frequency without triangular wave phase modulation; f tri The slope of the rising segment of the high-frequency stepped triangular wave is preferably taken as less than half of the frequency corresponding to the free spectral region of the composite filter; K represents the Kth high-frequency clock signal, T0 is the clock period, T is the period of the square wave shape of the high-frequency stepped triangular wave signal, i.e., the pump light frequency, i.e., the control period; n is a positive integer.

[0074] like Figure 4 As shown, this invention uses phase triangular wave modulation to achieve an approximately constant Brillouin frequency shift within a relatively fast modulation period. As a result, the Brillouin laser frequency changes with the pump light frequency, thus obtaining a square wave Brillouin laser frequency. The processing is simple and convenient, and the modulation effect is excellent.

[0075] Step 7: Obtain and record the Brillouin laser power of the current control period based on the pump light frequency of the current control period square wave shape; the modulation and demodulation module distinguishes and demodulates the Brillouin laser power of the current control period according to the high-frequency and low-frequency bands of the pump light corresponding to its time, that is, the average Brillouin laser power corresponding to the high-frequency band of the pump light minus the average Brillouin laser power corresponding to the low-frequency band of the pump light to obtain the frequency difference between the Brillouin laser frequency of the current control period and the resonant peak of the composite filter, expressed as:

[0076]

[0077] Where dem represents the demodulation value of the current control cycle (i.e., the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter), and KT0 is the demodulation value obtained when demodulation is performed at T, 1.5T, 2T, 2.5T...; express The cumulative value of digital quantities over a period of time; express The cumulative value of digital quantities within a time period; express The cumulative value of numbers within a time period.

[0078] Preferably, when obtaining the average Brillouin laser power corresponding to the high-frequency and low-frequency bands of the pump light, low-pass filtering is used to suppress noise generated by waveguide modulation, Brillouin laser excitation, and analog-to-digital conversion processes.

[0079] Step 8: Increment the control cycle by 1, then return to step 4 until the Brillouin fiber optic gyroscope is no longer in use.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A frequency stabilization method for a Brillouin fiber optic gyroscope, comprising using a Brillouin fiber optic gyroscope frequency stabilization device for frequency stabilization, characterized in that... The Brillouin fiber optic gyroscope frequency stabilization device includes a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide driver, a photodetector, and a controller. A semiconductor laser is used to output pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter. Waveguides are used to modulate the pump light frequency into a square wave shape, and to fine-tune the frequency reference value of the pump light in the square wave shape. A photodetector is used to convert the power of the Brillouin laser into a voltage signal and send it to the analog-to-digital converter of the controller; The controller is used to scan the pump light frequency to obtain the pump light excitation frequency that can excite the Brillouin laser and adjust the pump light frequency to that excitation frequency; it is used to convert the voltage signal of the Brillouin laser power into a digital signal and demodulate the digital signal to obtain the comprehensive frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter; it is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonant peak of the composite filter and send it to the voltage-controlled current source and the waveguide driver respectively. A voltage-controlled current source and waveguide drive are used to change the pump light frequency emitted by the semiconductor laser according to the control input of the controller in order to ensure that the Brillouin laser frequency remains stable under the influence of the external environment. The specific steps are as follows: Step 1: The semiconductor laser outputs pump light, which enters the composite filter through a waveguide to excite the Brillouin laser; the Brillouin laser power is converted into a voltage signal by a photodetector and input into the controller; the pump light frequency positioning module of the controller is activated. Step 2: The pump light frequency positioning module steps and scans the current of the semiconductor laser; after the step scanning is completed, the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser are obtained. Step 3: Trace the current of the semiconductor laser back to the current value of the semiconductor laser corresponding to the maximum power of the Brillouin laser to obtain the pump light frequency that can excite the Brillouin laser, and start the Brillouin laser resonant module of the controller. Step 4: The control algorithm module uses the frequency difference between the Brillouin laser frequency obtained by demodulation in the previous control cycle and the resonant peak of the composite filter as feedback to calculate the control quantity. Step 5: Convert the control quantity into the sawtooth wave accumulation of the waveguide driving voltage to control the Brillouin laser to resonate stably within the composite filter. Step 6: The waveguide performs triangular wave phase modulation on the pump light output by the semiconductor laser in the current control cycle, and superimposes it with the sawtooth wave accumulation obtained in Step 5 to obtain the pump light frequency in the square wave form of the current control cycle. Step 7: Obtain the Brillouin laser power of the current control period based on the pump light frequency of the square wave shape of the current control period; The modulation and demodulation module distinguishes the Brillouin laser power of the current control period according to the high-frequency and low-frequency bands of the pump light corresponding to its time, and demodulates to obtain the frequency difference between the Brillouin laser frequency of the current control period and the resonant peak of the composite filter. Step 8: Increment the control cycle by 1, then return to step 4 until the Brillouin fiber optic gyroscope is no longer in use.

2. The frequency stabilization method according to claim 1, characterized in that, The controller includes a control algorithm module, a modulation and demodulation module, a first digital-to-analog converter, a second digital-to-analog converter, and an analog-to-digital converter.

3. The frequency stabilization method according to claim 2, characterized in that, The control algorithm module includes a Brillouin laser frequency positioning module and a Brillouin laser resonance module. The Brillouin laser frequency positioning module is used to scan the pump light frequency, find the pump light frequency that excites the Brillouin laser, and adjust the pump light frequency to the excitation frequency. The Brillouin laser resonance control module is used to calculate the control quantity based on the comprehensive frequency difference between the demodulated Brillouin laser frequency and the resonance peak of the composite filter, and send it to the voltage-controlled current source and waveguide drive respectively.

4. The frequency stabilization method according to claim 2, characterized in that, The modulation and demodulation module is used to apply a modulation signal to the pump light frequency to obtain a pump light in the form of a square wave, and to demodulate the digital signal of the Brillouin laser power to obtain the frequency difference between the Brillouin laser frequency and the resonant peak of the composite filter.

5. The frequency stabilization method according to claim 2, characterized in that, The control quantities include pump light coarse adjustment control quantities and pump light fine adjustment control quantities; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine adjustment control quantity is added to the pump light frequency modulation signal to obtain the waveguide control quantity.

6. The frequency stabilization method according to claim 5, characterized in that, The first digital-to-analog converter is used to convert the current control quantity into a current control electrical signal and apply it to the voltage-controlled current source.

7. The frequency stabilization method according to claim 5, characterized in that, The second digital-to-analog converter is used to convert waveguide control quantities into waveguide control electrical signals and apply them to the waveguide drive.

8. The frequency stabilization method according to claim 2, characterized in that, An analog-to-digital converter is used to convert Brillouin laser power in the form of a voltage signal into Brillouin laser power in the form of a digital quantity.

9. The frequency stabilization method according to claim 1, characterized in that, The semiconductor laser is a current-tunable semiconductor laser.

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