CN117213460A - Brillouin fiber optic gyroscope frequency stabilizing device and method - Google Patents
Brillouin fiber optic gyroscope frequency stabilizing device and method Download PDFInfo
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Abstract
The invention relates to a Brillouin fiber optic gyro frequency stabilizing device and method, belongs to the technical field of fiber optic gyroscopes, and solves the problems that the fiber optic gyroscopes in the prior art are poor in robustness to environmental noise and cannot adapt to temperature and noise changes in the environment. The utility model discloses a brillouin optical fiber gyro frequency stabilization device, which comprises a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide drive, a photoelectric detector and a controller. The device which does not use PZT and the like has small volume and full solid state; the frequency stabilizing part is separated from the composite filter, so that noise is prevented from being introduced. The frequency stabilization part of the invention is realized based on the waveguide, has a large dynamic range and is easy to integrate.
Description
Technical Field
The invention belongs to the technical field of fiber-optic gyroscopes, and particularly relates to a device and a method for stabilizing the frequency of a Brillouin fiber-optic gyroscope.
Background
The fiber optic gyroscope is an angular rate sensor based on SAGAC effect, is one of core sensors for motion control and inertial navigation, is widely applied to the aerospace field, and has the advantages of high precision, no moving parts, strong anti-interference capability and the like.
The prior Brillouin fiber optic gyroscope mainly adopts a method for simultaneously controlling pumping light and Brillouin laser resonance, namely a double resonance method, so as to reduce the pumping light power threshold of the laser diode Brillouin laser. The dual-resonance method requires that the Brillouin frequency shift of the system is strictly equal to integer times of the free spectral range of the optical fiber resonant cavity, the initial resonant cavity length is strictly ensured, the cavity length of the resonant cavity is controlled by using PZT, the manufacturing difficulty of the system is improved, the volume of the system is increased, and the anti-interference capability of the system to noise such as temperature, vibration and the like is reduced. Meanwhile, the difficulty of stabilizing the frequency of the Brillouin laser is greatly increased, and the frequency stability of the Brillouin laser is affected.
Aiming at the problem of poor frequency stability of the Brillouin laser, a two-way operation type Brillouin laser based on an asymmetric Mach-Zehnder interferometer-resonant cavity composite filter (hereinafter referred to as a composite filter) is developed, and an optical fiber gyro of the novel Brillouin laser is used, as shown in figure 1, the composite filter is formed by connecting two couplers O2 and O3, two ports 5 and 6 of the coupler O2 are firstly connected with two ports 7 and 8 of the coupler O3 respectively, a specific length difference of two arms is ensured, so that the asymmetric Mach-Zehnder interferometer is obtained, and two ports 3 and 9 of the asymmetric Mach-Zehnder interferometer are connected to form a resonant cavity, so that the asymmetric Mach-Zehnder interferometer-resonant cavity composite filter is obtained. FIG. 2 shows normalized transmission power of an asymmetric Mach-Zehnder interferometer in a composite filter, which is input at a port 2 and output at a port 9, wherein the transmission spectrum period of the composite filter is twice as long as the Brillouin frequency shift by setting the difference of the lengths of two arms 5-7 and 6-8 of the composite filter, and the pump light frequency is selected to enable the transmission power of the pump light to be close to 1, so that most of the pump light can pass through the composite filter once and most of the pump light is circularly transmitted in the composite filter, the Brillouin laser can be generated by adjusting the cavity length of the composite filter to control the resonance of the Brillouin laser in the composite filter, the Brillouin laser resonance condition can be met by adjusting the pump light frequency only, the stability difficulty of the Brillouin laser frequency is greatly reduced, and the anti-interference capability of the system on temperature and stress is improved; since the brillouin laser still resonates in the complex filter, the threshold of this scheme is also low. However, the brillouin fiber-optic gyroscope has the following difficulties and disadvantages: meanwhile, brillouin laser tuning control of the GHz-level pump light frequency adjustment and MHz-level Brillouin laser tuning control are realized; the robustness to the environmental noise is poor, and the temperature and noise variation in the environment cannot be adapted; high-precision temperature control is required, the cost is high, the structure is complex, and miniaturization is impossible.
Disclosure of Invention
In view of the above problems, the invention provides a device and a method for stabilizing the frequency of a Brillouin optical fiber gyroscope, which solve the problems that an optical fiber gyroscope in the prior art has poor robustness to environmental noise and cannot adapt to temperature and noise changes in the environment.
The invention provides a Brillouin optical fiber gyro frequency stabilizing device, which comprises a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide drive, a photoelectric detector and a controller, wherein the waveguide drive is connected with the semiconductor laser;
a semiconductor laser for outputting pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter;
a waveguide for modulating the frequency of the pump light into a square wave form and fine-tuning a frequency reference value of the pump light in the square wave form;
the photoelectric detector is used for converting the power of the Brillouin laser into a voltage signal and sending the voltage signal to the analog-to-digital converter of the controller;
the controller is used for scanning the pumping light frequency to obtain pumping light excitation frequency capable of exciting the Brillouin laser and adjusting the pumping light frequency to the excitation frequency; the method comprises the steps of converting a voltage signal of Brillouin laser power into a digital quantity signal, and demodulating the digital signal to obtain a comprehensive frequency difference value between the Brillouin laser frequency and a resonance peak of a composite filter; the method comprises the steps of calculating a control quantity according to a comprehensive frequency difference value between the demodulated Brillouin laser frequency and a resonance peak of a composite filter, and respectively sending the control quantity to a voltage-controlled current source and waveguide driving;
the voltage-controlled current source and the waveguide drive are used for changing the pumping light frequency emitted by the semiconductor laser according to the control quantity of the controller so as to ensure that the Brillouin laser frequency is kept stable under the influence of external environment.
Optionally, the controller includes a control algorithm module, a modem module, a first digital-to-analog converter, a second digital-to-analog converter, and an analog-to-digital converter.
Optionally, the control algorithm module comprises a brillouin laser frequency positioning module and a brillouin laser resonance module; the Brillouin laser frequency positioning module is used for scanning the pumping light frequency, finding the pumping light frequency of the pumping Brillouin laser and adjusting the pumping light frequency to the excitation frequency; the Brillouin laser resonance control module is used for calculating control quantity according to the obtained comprehensive frequency difference value of the Brillouin laser frequency and the resonance peak of the composite filter, and sending the control quantity to the voltage-controlled current source and the waveguide drive respectively.
Optionally, the modulation and demodulation module is configured to apply a modulation signal to the pump light frequency to obtain pump light with a frequency in the form of square wave, and demodulate the digital quantity signal of the brillouin laser power to obtain a frequency difference value between the brillouin laser frequency and a resonance peak of the composite filter.
Optionally, the control amount includes a pump light coarse control amount and a pump light fine control amount; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine tuning control amount is added with the pump light frequency modulation signal to obtain the waveguide control amount.
Optionally, the first digital-to-analog converter is used for converting the current control quantity into a current control electric signal and applying the current control electric signal to the voltage-controlled current source.
Optionally, a second digital-to-analog converter is used to convert the waveguide control quantity into a waveguide control electrical signal and apply to the waveguide drive.
Optionally, the analogue to digital converter is arranged to convert the brillouin laser power in the form of a voltage signal into the brillouin laser power in the form of a digital quantity.
Alternatively, the semiconductor laser is a current tunable semiconductor laser.
On the other hand, the invention also provides a frequency stabilization method of the Brillouin optical fiber gyro, which comprises the following specific steps:
step 1, a semiconductor laser outputs pump light, and the pump light enters a composite filter through a waveguide to excite Brillouin laser; converting the Brillouin laser power into a voltage signal through a photoelectric detector, and inputting the voltage signal into a controller; the pump light frequency positioning module of the controller is started;
step 2, the pump light frequency positioning module scans the current of the semiconductor laser step by step; obtaining the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser after the step scanning is finished;
step 3, backtracking the current of the semiconductor laser to the current value of the semiconductor laser corresponding to the maximum value of the Brillouin laser power to obtain pumping light frequency capable of exciting the Brillouin laser, and starting a Brillouin laser resonance module of the controller;
step 4, the control algorithm module calculates and obtains the control quantity by taking the frequency difference value between the Brillouin laser frequency obtained by demodulation in the previous control period and the resonance peak of the composite filter as the feedback quantity;
step 5, converting the control quantity into a sawtooth wave accumulation quantity of waveguide driving voltage, and controlling stable resonance of the Brillouin laser in the composite filter;
step 6, the waveguide carries out triangular wave phase modulation on the pump light output by the current control period of the semiconductor laser, and overlaps with the sawtooth wave accumulation obtained in the step 5 to obtain the pump light frequency of the square wave form of the current control period;
step 7, acquiring the Brillouin laser power of the current control period based on the pumping light frequency of the square wave form of the current control period; the modulation-demodulation module distinguishes the Brillouin laser power of the current control period according to the pumping light high frequency band and the pumping light low frequency band which correspond to each other in time, and demodulates the Brillouin laser power to obtain a frequency difference value between the Brillouin laser frequency of the current control period and a resonance peak of the composite filter;
and step 8, adding 1 in the control period, and returning to the step 4 until the use of the Brillouin optical fiber gyroscope is finished.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) The stabilizing device does not use larger devices such as PZT and the like, and has the advantages of small volume and full solid state.
(2) The frequency stabilizing part of the stabilizing device is separated from the composite filter, so that noise is prevented from being introduced.
(3) The frequency stabilization part of the stabilizing device is realized based on the waveguide, has a large dynamic range and is easy to integrate.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention.
FIG. 1 is a schematic diagram of a prior art composite filter;
FIG. 2 is a diagram showing transmission characteristics of an unbalanced Mach-Zehnder interferometer of a composite filter according to the prior art;
FIG. 3 is a schematic diagram of a frequency stabilization device according to the present invention;
FIG. 4 is a schematic diagram of triangular wave phase modulation according to the present invention;
FIG. 5 is a plot of synchronous demodulation according to the present invention;
fig. 6 is a flow chart of the control method of the present invention.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, without conflict, the embodiments of the present invention and features in the embodiments may be combined with each other. In addition, the invention may be practiced otherwise than as specifically described and thus the scope of the invention is not limited by the specific embodiments disclosed herein.
1-6, a Brillouin fiber optic gyro frequency stabilization device is disclosed, and is used for stabilizing the Brillouin laser frequency of a Brillouin fiber optic gyro based on an asymmetric Mach-Zehnder interferometer-resonant cavity composite filter, and comprises a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide driver, a photoelectric detector and a controller, as shown in FIG. 3;
a semiconductor laser for outputting pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter;
a waveguide for modulating the frequency of the pump light into a square wave form and fine-tuning a frequency reference value of the pump light in the square wave form; and inputting the pump light into the composite filter;
the photoelectric detector is used for converting the power of the Brillouin laser input from the composite filter into a voltage signal and transmitting the voltage signal to the analog-to-digital converter of the controller;
the controller is used for scanning the pumping light frequency to obtain pumping light excitation frequency capable of exciting the Brillouin laser and adjusting the pumping light frequency to the excitation frequency; the method comprises the steps of converting a voltage signal of Brillouin laser power into a digital quantity signal, and demodulating the digital signal to obtain a comprehensive frequency difference value between the Brillouin laser frequency and a resonance peak of a composite filter; the method comprises the steps of calculating a control quantity according to a comprehensive frequency difference value between the demodulated Brillouin laser frequency and a resonance peak of a composite filter, and respectively sending the control quantity to a voltage-controlled current source and waveguide driving;
the voltage-controlled current source and the waveguide drive are used for changing the frequency of pumping light emitted by the semiconductor laser according to the control quantity of the controller so as to ensure that the Brillouin laser frequency based on the asymmetric Mach-Zehnder interferometer-resonant cavity composite filter is kept stable under the influence of external environment.
Further, the controller comprises 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.
The control algorithm module comprises a Brillouin laser frequency positioning module and a Brillouin laser resonance module; the Brillouin laser frequency positioning module is used for scanning the pumping light frequency, finding the pumping light frequency of the pumping Brillouin laser and adjusting the pumping light frequency to the excitation frequency;
the Brillouin laser resonance control module is used for calculating control quantity according to the obtained comprehensive frequency difference value of the Brillouin laser frequency and the resonance peak of the composite filter, and sending the control quantity to the voltage-controlled current source and the waveguide drive respectively;
preferably, the control amount includes a pump light coarse adjustment control amount and a pump light fine adjustment control amount; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine tuning control amount is added with the pump light frequency modulation signal to obtain the waveguide control amount.
The modulation and demodulation module is used for applying a modulation signal to the pump light frequency to obtain pump light with the frequency in a square wave form, and demodulating the digital quantity signal of the Brillouin laser power to obtain a frequency difference value between the Brillouin laser frequency and a resonance peak of the composite filter.
The first digital-to-analog converter is used for converting the current control quantity into a current control electric signal and applying the current control electric signal to the voltage-controlled current source.
The second digital-to-analog converter is used for converting the waveguide control quantity into a waveguide control electric signal and applying the waveguide control electric signal to the waveguide drive.
The analog-to-digital converter is used for converting the Brillouin laser power in the form of a voltage signal into the Brillouin laser power in the form of a digital quantity.
Optionally, the waveguide is a lithium niobate waveguide; the bandwidth of the lithium niobate waveguide is a low-frequency bandwidth, the half-wave voltage is a low half-wave voltage, preferably the bandwidth is less than 1GHz, and the half-wave voltage is less than 4V. The normal operation of the waveguide in the working frequency band is ensured, and the performance requirement on waveguide driving is low, the cost is low and the volume is small.
When the laser is used, on an optical path, the semiconductor laser outputs pump light, the pump light enters the waveguide, the waveguide finely adjusts the pump light frequency, and the pump light frequency is modulated into a square wave form on the basis; the pumping light frequency in the square wave form enters the composite filter through the pumping light input port to excite the Brillouin laser, and the Brillouin laser is input into the photoelectric detector through the Brillouin laser output port. In the circuit, a photoelectric detector converts a power signal of Brillouin laser into a Brillouin laser power signal in a voltage form, the Brillouin laser power signal in the voltage form is input into an analog-to-digital conversion module of a controller, and the analog-to-digital conversion module converts the Brillouin laser power signal in the voltage form into a Brillouin laser power signal in a digital form; the analog-to-digital converter inputs the digital quantity signal into the modulation-demodulation module; the modulation and demodulation module demodulates the digital quantity signal output by the analog-to-digital converter to obtain a demodulation value (namely, the frequency difference value between the Brillouin laser frequency and the resonance peak of the composite filter), and inputs the demodulation value into the control algorithm module to obtain a current control quantity and a waveguide control quantity; inputting the current control quantity into a first digital-to-analog converter to obtain a current control quantity electric signal, wherein the first digital-to-analog converter is connected with a voltage-controlled current source, the voltage-controlled current source converts the current control quantity into a current control electric signal, the voltage-controlled current source is connected with a semiconductor laser, and the current control electric signal is used for driving the semiconductor laser; the waveguide control quantity is input into a second digital-to-analog converter to obtain a waveguide control electric signal, the second digital-to-analog converter is connected with a waveguide driver, the waveguide driver amplifies the waveguide control quantity electric signal, the waveguide driver is connected with the waveguide, and the amplified waveguide control quantity voltage signal is transmitted to the waveguide to drive the waveguide.
Optionally, the semiconductor laser is a current tunable semiconductor laser, the tuning range of which is 1-3 times of the transmission spectrum period (see fig. 3) of the mach-zehnder interferometer in the composite filter, so as to ensure that the frequency of the pump light can be adjusted to any one frequency in one transmission spectrum period of the composite filter, and in addition, for the same digital-to-analog converter, the tuning resolution decreases with the increase of the tuning range.
The voltage-controlled current source reference voltage is added with the output voltage of the digital-to-analog converter 2, and the added voltage line is converted into high-power current, so that the voltage-controlled current source has high current driving capability and quick dynamic response characteristic. The waveguide drive amplifies the voltage signal and outputs the amplified voltage signal to the waveguide, so that the waveguide can continuously and rapidly change the phase and frequency of the pumping light.
In another embodiment of the present invention, a method for stabilizing the frequency of a brillouin optical fiber gyro is disclosed, and the method for stabilizing the frequency of the brillouin optical fiber gyro includes the following specific steps:
step 1, a semiconductor laser outputs pump light, and the pump light enters a composite filter through a waveguide to excite Brillouin laser; converting the Brillouin laser power into a voltage signal through a photoelectric detector, and inputting the voltage signal into a controller; the pump light frequency positioning module of the controller is started;
step 2, the pump light frequency positioning module scans the current of the semiconductor laser step by step; obtaining the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser after the step scanning is finished;
optionally, the frequency tuning range corresponding to the current scanning range is a transmission spectrum period of the mach-zehnder interferometer in the composite filter.
Step 3, backtracking the current of the semiconductor laser to the current value of the semiconductor laser corresponding to the maximum value of the Brillouin laser power to obtain pumping light excitation frequency capable of exciting the Brillouin laser, and starting a Brillouin laser resonance module of the controller;
and 4, calculating the control quantity by the control algorithm module according to the frequency difference value between the Brillouin laser frequency of the last control period obtained by demodulation in the last control period (one pump light frequency square wave modulation period) and the resonance peak of the composite filter.
Optionally, the control algorithm module is a PI algorithm module, based on a synchronous demodulation curve, referring to fig. 5, demodulating the brillouin laser power in the form of a digital quantity of a previous control period to obtain a frequency difference value between the brillouin laser frequency of the previous control period and a resonance peak of the composite filter, and calculating to obtain a control quantity; the difference between the brillouin laser frequency and the complex filter resonance peak in the first control period is initially set to 0.
Step 5, converting the control quantity into a sawtooth wave accumulation quantity of waveguide driving voltage, and controlling stable resonance of the Brillouin laser in the composite filter;
further, judging whether the control quantity obtained in the step 4 exceeds the waveguide driving output range, if not, converting all the control quantity into a sawtooth wave accumulation quantity of the waveguide driving voltage, and changing the waveguide driving voltage by using the sawtooth wave accumulation quantity to enable the pumping light to generate continuous phase change and constant frequency movement; if the output of the waveguide is more than the current control quantity, the waveguide output is close to saturation, the frequency which needs to be adjusted cannot be achieved, and most of the frequency adjustment quantity required by the control quantity is used as the current control quantity to finely adjust the driving current of the semiconductor laser; the remaining fraction of the control volume is output driven by the waveguide, adjusting the waveguide output to a lower level, thereby freeing the waveguide control range.
Optionally, when the control amount exceeds the waveguide driving output range, the current control amount is an integer multiple of a fixed current, the frequency change amount caused by the fixed current value is an integer multiple of the free spectrum range of the composite filter, and the oscillation caused by the trimming current is effectively reduced by adopting the trimming amount. The control amount less than the integer multiple is realized by the waveguide drive in the form of a sawtooth wave accumulation amount as the waveguide control amount.
Alternatively, it is determined whether the waveguide control amount obtained in step 4 exceeds the waveguide drive output range.
Step 6, the waveguide carries out triangular wave phase modulation on the pump light output by the current control period of the semiconductor laser, and overlaps with the sawtooth wave accumulation obtained in the step 5 to obtain the pump light frequency of the square wave form of the current control period;
optionally, during the phase modulation of the triangular wave, the pump light is alternately accumulated and subtracted by taking the high-frequency clock signal as a reference to obtain a high-frequency stepped triangular wave, where the expression is as follows:
wherein f M Pump light frequency in square wave form; f (f) 0 The frequency of the pump light when the triangular wave phase modulation is not applied; f (f) tri The slope of the rising section of the high-frequency step triangular wave is preferably less than half of the corresponding frequency of the free spectrum region of the composite filter; k represents the Kth high-frequency clock signal, T 0 The clock period is the period of the square wave form of the high-frequency step triangular wave signal, namely the pumping light frequency, namely the control period; n is a positive integer.
As shown in fig. 4, the brillouin frequency shift is approximately constant in a faster modulation period through phase triangular wave modulation, so that the brillouin laser frequency changes along with the frequency change of pumping light, the brillouin laser frequency in a square wave form is obtained, the processing process is simple and convenient, and the modulation effect is excellent.
Step 7, acquiring and recording the Brillouin laser power of the current control period based on the pumping light frequency of the square wave form of the current control period; the modulation-demodulation module distinguishes and demodulates the Brillouin laser power of the current control period according to the pumping light high frequency band and the pumping light low frequency band which correspond to the time of the modulation-demodulation module, namely, the Brillouin laser power average value corresponding to the pumping light high frequency band subtracts the Brillouin laser power average value corresponding to the pumping light low frequency band to obtain the frequency difference value between the Brillouin laser frequency of the current control period and the resonance peak of the composite filter, and the expression is as follows:
wherein dem represents the demodulation value (i.e. the frequency difference between the brillouin laser frequency and the resonance peak of the composite filter) of the current control period, KT 0 Demodulation is carried out when the values are T,1.5T,2T and 2.5T …, and demodulation values are obtained;representation ofA digital quantity accumulation value over time; />Representation ofA digital quantity accumulated value over a period of time; />Representation ofDigital quantity accumulation over a time periodValues.
Preferably, when the average value of the brillouin laser power corresponding to the high-frequency band and the low-frequency band of the pump light is obtained, noise generated in the waveguide modulation, the excitation of the brillouin laser, and the analog-to-digital conversion process is suppressed by using low-pass filtering.
And step 8, adding 1 in the control period, and returning to the step 4 until the use of the Brillouin optical fiber gyroscope is finished.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. The Brillouin optical fiber gyro frequency stabilizing device is characterized by comprising a semiconductor laser, a waveguide, a voltage-controlled current source, a waveguide driver, a photoelectric detector and a controller;
a semiconductor laser for outputting pump light, the frequency of which can be arbitrarily adjusted within one period of the transmission spectrum of the composite filter;
a waveguide for modulating the frequency of the pump light into a square wave form and fine-tuning a frequency reference value of the pump light in the square wave form;
the photoelectric detector is used for converting the power of the Brillouin laser into a voltage signal and sending the voltage signal to the analog-to-digital converter of the controller;
the controller is used for scanning the pumping light frequency to obtain pumping light excitation frequency capable of exciting the Brillouin laser and adjusting the pumping light frequency to the excitation frequency; the method comprises the steps of converting a voltage signal of Brillouin laser power into a digital quantity signal, and demodulating the digital signal to obtain a comprehensive frequency difference value between the Brillouin laser frequency and a resonance peak of a composite filter; the method comprises the steps of calculating a control quantity according to a comprehensive frequency difference value between the demodulated Brillouin laser frequency and a resonance peak of a composite filter, and respectively sending the control quantity to a voltage-controlled current source and waveguide driving;
the voltage-controlled current source and the waveguide drive are used for changing the pumping light frequency emitted by the semiconductor laser according to the control quantity of the controller so as to ensure that the Brillouin laser frequency is kept stable under the influence of external environment.
2. The brillouin optical fiber gyro frequency stabilization device according to claim 1, wherein the controller comprises a control algorithm module, a modem module, a first digital-to-analog converter, a second digital-to-analog converter, and an analog-to-digital converter.
3. The brillouin optical fiber gyro frequency stabilization device according to claim 2, wherein 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 for scanning the pumping light frequency, finding the pumping light frequency of the pumping Brillouin laser and adjusting the pumping light frequency to the excitation frequency; the Brillouin laser resonance control module is used for calculating control quantity according to the obtained comprehensive frequency difference value of the Brillouin laser frequency and the resonance peak of the composite filter, and sending the control quantity to the voltage-controlled current source and the waveguide drive respectively.
4. The device of claim 2, wherein the modulation and demodulation module is configured to apply a modulation signal to the pump light frequency to obtain pump light with a frequency in the form of square wave, and demodulate the digital quantity signal of the brillouin laser power to obtain a frequency difference between the brillouin laser frequency and a resonance peak of the composite filter.
5. The brillouin optical fiber gyro frequency stabilizing apparatus according to claim 2, wherein the control amounts include a pump light coarse adjustment control amount and a pump light fine adjustment control amount; the pump light coarse adjustment control quantity is a current control quantity; the pump light fine tuning control amount is added with the pump light frequency modulation signal to obtain the waveguide control amount.
6. The brillouin optical fiber gyro frequency stabilizing apparatus according to claim 5, wherein the first digital-to-analog converter is configured to convert a current control amount into a current control electric signal and apply the current control electric signal to the voltage-controlled current source.
7. The brillouin optical fiber gyro frequency stabilizing apparatus according to claim 5, wherein the second digital-to-analog converter is configured to convert a waveguide control amount into a waveguide control electric signal and apply to the waveguide drive.
8. The brillouin optical fiber gyro frequency stabilization device according to claim 2, wherein the analog-to-digital converter is configured to convert brillouin laser power in a voltage signal form into brillouin laser power in a digital quantity form.
9. The brillouin optical fiber gyro frequency stabilization device according to claim 1, wherein the semiconductor laser is a current tunable semiconductor laser.
10. The frequency stabilization method of the Brillouin optical fiber gyro is characterized by comprising the following specific steps:
step 1, a semiconductor laser outputs pump light, and the pump light enters a composite filter through a waveguide to excite Brillouin laser; converting the Brillouin laser power into a voltage signal through a photoelectric detector, and inputting the voltage signal into a controller; the pump light frequency positioning module of the controller is started;
step 2, the pump light frequency positioning module scans the current of the semiconductor laser step by step; obtaining the maximum value of the Brillouin laser power and the corresponding current value of the semiconductor laser after the step scanning is finished;
step 3, backtracking the current of the semiconductor laser to the current value of the semiconductor laser corresponding to the maximum value of the Brillouin laser power to obtain pumping light frequency capable of exciting the Brillouin laser, and starting a Brillouin laser resonance module of the controller;
step 4, the control algorithm module calculates and obtains the control quantity by taking the frequency difference value between the Brillouin laser frequency obtained by demodulation in the previous control period and the resonance peak of the composite filter as the feedback quantity;
step 5, converting the control quantity into a sawtooth wave accumulation quantity of waveguide driving voltage, and controlling stable resonance of the Brillouin laser in the composite filter;
step 6, the waveguide carries out triangular wave phase modulation on the pump light output by the current control period of the semiconductor laser, and overlaps with the sawtooth wave accumulation obtained in the step 5 to obtain the pump light frequency of the square wave form of the current control period;
step 7, acquiring the Brillouin laser power of the current control period based on the pumping light frequency of the square wave form of the current control period; the modulation-demodulation module distinguishes the Brillouin laser power of the current control period according to the pumping light high frequency band and the pumping light low frequency band which correspond to each other in time, and demodulates the Brillouin laser power to obtain a frequency difference value between the Brillouin laser frequency of the current control period and a resonance peak of the composite filter;
and step 8, adding 1 in the control period, and returning to the step 4 until the use of the Brillouin optical fiber gyroscope is finished.
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