Accurate modulation depth evaluation method for optical path noise reduction technology of fiber-optic gyroscope

Abstract

A modulation depth precise evaluation method for a fiber-optic gyroscope light path noise reduction technology is characterized in that a precise matching model of a light intensity signal of a main light path and a light intensity signal of a reference light path is established by using a fiber-optic gyroscope detector signal, so that precise evaluation of the optimal modulation depth of the fiber-optic gyroscope light path noise reduction technology is realized, and the determination of the optimal state of a gyroscope is efficiently completed. Meanwhile, the voltage signal is used for replacing the optical power signal to achieve evaluation of the optimal modulation depth, the influence of optical power measurement errors can be avoided, and accurate control independent of optical path fusion point loss or accurate matching of optical device parameters is achieved.

Description

Technical Field

[0001] This invention relates to a method for accurately evaluating the modulation depth of optical path noise reduction technology for fiber optic gyroscopes, belonging to the field of fiber optic gyroscope technology. Background Technology

[0002] Fiber optic gyroscopes are all-solid-state angular velocity sensors based on the Sagnac effect, and are widely used in inertial navigation systems. With the continuous development of the inertial navigation field, the requirements for the measurement accuracy of fiber optic gyroscopes are constantly increasing.

[0003] One of the key differences between high-precision fiber optic gyroscopes and traditional high-precision gyroscopes is the presence of relatively high noise, primarily including thermal noise, relative intensity noise, and shot noise generated by the photoelectric conversion of the detector. Relative intensity noise of the light source is a major factor affecting the random walk of high-precision fiber optic gyroscopes; in high-precision fiber optic gyroscopes, relative intensity noise accounts for more than 90% of the total noise in the optical path. Reducing the relative intensity noise of the light source can significantly improve the signal-to-noise ratio of the gyroscope.

[0004] Currently, the most widely used high-precision fiber optic gyroscope optical path noise reduction technology is the relative intensity noise suppression method of dual-path delay subtraction. The dual-path delay subtraction method is a method that achieves relative intensity noise suppression without requiring additional acquisition circuitry, simply by subtracting optical paths. By replacing the couplers in a typical fiber optic gyroscope system with a fully polarization-maintaining intensity noise compensation optical path (including polarizers, polarization-maintaining couplers, polarization-maintaining isolators, etc.), and applying a corresponding 90° polarization-maintaining fusion splice, relative intensity noise can be achieved through dual-path optical path subtraction.

[0005] For dual-path delay-subtraction optical path noise reduction technology, the core is to achieve precise matching of the optical power of the main optical path signal and the reference optical path signal. Only in this way can the subtraction of relative intensity noise between the two optical paths be maximized; otherwise, the suppression effect will be affected, or even have the opposite effect, reducing gyroscope accuracy. Regarding this core point, existing techniques typically involve measuring the optical power of the main optical path signal and the optical power of the reference optical path signal before the optical path assembly is completed. Based on the ratio of the main and reference optical path signals, a gyroscope program with an appropriate modulation depth is selected to achieve optical power matching between the main and reference optical path signals. However, this method has drawbacks: firstly, the main / reference optical path power measurement is performed before the optical path assembly is complete, and the back-end optical path loss will also affect the main / reference optical path power; secondly, the optical power measurement is strongly correlated with the fiber end-face cutting quality, and measurement errors will also affect the main / reference optical path power measurement results. Therefore, the actual effect of this method is not ideal, seriously affecting the technical specifications of fiber optic gyroscopes used in optical path noise reduction technology. Summary of the Invention

[0006] The technical problem solved by this invention is that, in the existing technology, the dual-path delay subtraction optical path noise reduction technology is prone to affecting optical power and measurement errors. Therefore, this invention proposes a method for accurately evaluating the modulation depth of fiber optic gyroscope optical path noise reduction technology.

[0007] The present invention solves the above-mentioned technical problem through the following technical solution:

[0008] A method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology includes:

[0009] Construct and assemble a dual-path delay-subtraction noise reduction optical path and its corresponding circuitry.

[0010] Power on the fiber optic gyroscope, measure the detector voltage in the dual-optical-path delay-subtraction noise reduction optical path when no modulation signal is applied, and then power off after the measurement is completed.

[0011] Power on the fiber optic gyroscope, write the preset gyroscope program into the fiber optic gyroscope, and power off after writing is complete;

[0012] Power on the fiber optic gyroscope, preset the modulation signal, measure the detector voltage value of the dual-path delay subtraction noise reduction optical path after inputting the modulation signal, and then power off after the measurement is completed.

[0013] A noise reduction modulation depth evaluation model for fiber optic gyroscopes is established. The optimal modulation depth for engineering applications is determined using this model, and the preset gyroscope program is adjusted according to the optimal modulation depth for engineering applications.

[0014] The dual-path delay-subtraction noise reduction optical path includes an erbium source, a polarization-maintaining circulator, a first polarization-maintaining beam splitter, a second polarization-maintaining beam splitter, a Y-waveguide, an optical fiber ring, and a detector, wherein:

[0015] The output of the bait source is connected to the input of the polarization-maintaining circulator. The output of the polarization-maintaining circulator is connected to the inputs of the first polarization-maintaining beam splitter and the second polarization-maintaining beam splitter, respectively. The output of the first polarization-maintaining beam splitter is connected to one end of the Y-waveguide. The other end of the Y-waveguide is connected to the fiber optic ring for signal splitting and modulation, and then the signal is returned to the output of the first polarization-maintaining beam splitter via the Y-waveguide. The output of the first polarization-maintaining beam splitter is also connected to the input of the second polarization-maintaining beam splitter. The second polarization-maintaining beam splitter receives the output signals returned from the polarization-maintaining circulator and the first polarization-maintaining beam splitter, and then combines them to connect to the detector.

[0016] The first and second polarization-maintaining beam splitters are used for beam splitting. The erbium source outputs an arbitrary polarization state light signal. The polarization state light signal enters the first polarization-maintaining beam splitter and is converted into linearly polarized light. The first polarization-maintaining beam splitter then performs beam splitting to obtain the main optical path signal and the reference optical path signal. The main optical path signal is processed as follows: the first polarization-maintaining beam splitter outputs the main optical path signal to the Y waveguide for beam splitting and modulation, and then propagates into the fiber ring. The signal returns to the first polarization-maintaining beam splitter via the fiber ring and is combined and interfered to form a return signal. The first polarization-maintaining beam splitter outputs the return signal to the second polarization-maintaining beam splitter.

[0017] The reference optical path signal is output from the first polarization-maintaining beam splitter to the second polarization-maintaining beam splitter for axis switching processing, and then combined with the returned signal. The combined signal is output from the second polarization-maintaining beam splitter to the detector to complete the photoelectric conversion.

[0018] In this process, the main optical path signal propagates clockwise and counterclockwise around the fiber optic loop and then enters the Y waveguide where it is combined and interferes. When the reference optical path signal is output to the second polarization-maintaining beam splitter via the first polarization-maintaining beam splitter, the port fusion of the first and second polarization-maintaining beam splitters enables the reference optical path signal to switch axes.

[0019] The splitting settings of the first and second polarization-maintaining beam splitters are both 90:10 for the ratio of the main optical path signal to the reference optical path signal. After the second polarization-maintaining beam splitter performs light combining, the light intensity of the main optical path signal and the light intensity of the reference optical path signal are the same. When the light intensities of the two signals are the same, the fiber optic gyroscope has the highest accuracy, and the corresponding modulation depth is the theoretically optimal modulation depth.

[0020] The method for determining the optimal modulation depth at the engineering application level using the fiber optic gyroscope optical path noise reduction modulation depth evaluation model is as follows:

[0021] Based on the measured detector voltage values ​​when no modulation signal is applied and the detector voltage values ​​when a preset modulation signal is applied, determine the expression for the relationship between the light intensity of the two optical paths and the expression for the ratio of the light power of the two optical paths in the detector signal at the current actual modulation depth;

[0022] Determine the expression for the ratio of optical power of the main optical path to optical power of the reference optical path at the theoretically optimal modulation depth;

[0023] The theoretically optimal modulation depth is determined based on the obtained expression;

[0024] Based on the theoretical optimal modulation depth and the engineering application environment, the optimal modulation depth at the engineering application level is determined.

[0025] The relationship between the main optical path signal and the reference optical path signal at the current actual modulation depth is expressed as follows:

[0026]

[0027] The expression for the ratio of the optical signal power in the main optical path to the optical signal power in the reference optical path is:

[0028]

[0029] In the formula, P 主 The optical power of the main optical path signal, P 参 The optical power of the reference optical signal is denoted as n, and the voltage responsivity of the detector is denoted as n.

[0030] The preset gyroscope program is used to achieve the optimal signal modulation depth between the optical power of the main optical path and the optical power of the reference optical path. Under the theoretically optimal modulation depth, the ratio between the optical power of the main optical path and the optical power of the reference optical path is expressed as follows:

[0031]

[0032] In the formula, S Y This represents the optimal modulation depth for high-precision fiber optic gyroscope optical path noise reduction technology.

[0033] When the preset modulation program satisfies the theoretical optimal modulation depth, the theoretical optimal modulation depth is determined. The expression for the theoretical optimal modulation depth is:

[0034]

[0035] In the formula, the theoretical optimal modulation depth S Y The digital signal output under the preset modulation program is converted into an analog signal by a DA converter to drive the Y waveguide.

[0036] The optimal modulation depth S at the engineering application level YG The expression is:

[0037]

[0038] In the formula, N is the number of bits in the fiber optic gyroscope DA digital-to-analog converter, and M is 2. N ·S Y / π is rounded to the nearest integer.

[0039] The advantages of this invention compared to the prior art are:

[0040] (1) The present invention provides a method for accurately evaluating the modulation depth of fiber optic gyroscope optical path noise reduction technology. It uses the fiber optic gyroscope detector signal to establish an accurate matching model between the main optical path light intensity signal and the reference optical path light intensity signal, thereby achieving accurate evaluation of the optimal modulation depth of fiber optic gyroscope optical path noise reduction technology. It effectively removes the error caused by optical power measurement. The operation method is simple, the debugging results are highly accurate, and it is easy to apply in engineering batches.

[0041] (2) This invention can efficiently and accurately evaluate the optimal modulation depth of the fiber optic gyroscope in the dual-path delay subtraction optical path noise reduction state, improve product debugging efficiency, and at the same time use the measurement of the fiber optic gyroscope detector signal instead of the measurement of optical power to evaluate the optimal modulation depth of the fiber optic gyroscope in the optical path noise reduction state, which can avoid the problem of inaccurate modulation depth prediction caused by optical power measurement error and ensure the achievement rate of product design indicators.

[0042] (3) This invention provides an accurate evaluation of the optimal modulation depth based on the complete state of the fiber optic gyroscope. It is simple to apply, produces accurate results, and avoids related errors introduced by subsequent operations. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a typical optical path scheme for noise reduction based on dual-optical-path delay subtraction optical path technology provided by the present invention;

[0044] Figure 2 The flowchart of the optimal modulation depth accurate evaluation model for the high-precision fiber optic gyroscope optical path noise reduction technology provided by this invention is shown. Detailed Implementation

[0045] A method for accurately evaluating the modulation depth of fiber optic gyroscope optical path noise reduction technology is proposed. This method utilizes the fiber optic gyroscope detector signal to establish a precise matching model between the main optical path intensity signal and the reference optical path intensity signal, thereby achieving accurate evaluation of the optimal modulation depth for fiber optic gyroscope optical path noise reduction technology. This efficiently determines the optimal state of the gyroscope. Furthermore, by using a voltage signal instead of an optical power signal to evaluate the optimal modulation depth, the influence of optical power measurement errors can be avoided, enabling precise control or precise matching of optical device parameters independent of optical path fusion splice loss.

[0046] The method for accurately evaluating modulation depth includes the following steps:

[0047] Construct and assemble a dual-path delay-subtraction noise reduction optical path and its corresponding circuitry.

[0048] Power on the fiber optic gyroscope, measure the detector voltage in the dual-optical-path delay-subtraction noise reduction optical path when no modulation signal is applied, and then power off after the measurement is completed.

[0049] Power on the fiber optic gyroscope, write the preset gyroscope program into the fiber optic gyroscope, and power off after writing is complete;

[0050] Power on the fiber optic gyroscope, preset the modulation signal, measure the detector voltage value of the dual-path delay subtraction noise reduction optical path after inputting the modulation signal, and then power off after the measurement is completed.

[0051] A noise reduction modulation depth evaluation model for fiber optic gyroscopes is established. The optimal modulation depth for engineering applications is determined using this model, and the preset gyroscope program is adjusted according to the optimal modulation depth for engineering applications.

[0052] The dual-path delay-subtraction noise reduction optical path includes an erbium source, a polarization-maintaining circulator, a first polarization-maintaining beam splitter, a second polarization-maintaining beam splitter, a Y-waveguide, an optical fiber ring, and a detector, wherein:

[0053] The output of the bait source is connected to the input of the polarization-maintaining circulator. The output of the polarization-maintaining circulator is connected to the inputs of the first polarization-maintaining beam splitter and the second polarization-maintaining beam splitter, respectively. The output of the first polarization-maintaining beam splitter is connected to one end of the Y-waveguide. The other end of the Y-waveguide is connected to the fiber optic ring for signal splitting and modulation, and then the signal is returned to the output of the first polarization-maintaining beam splitter via the Y-waveguide. The output of the first polarization-maintaining beam splitter is also connected to the input of the second polarization-maintaining beam splitter. The second polarization-maintaining beam splitter receives the output signals returned from the polarization-maintaining circulator and the first polarization-maintaining beam splitter, and then combines them to connect to the detector.

[0054] The first and second polarization-maintaining beam splitters are used for beam splitting. The erbium source outputs an arbitrary polarization state light signal. The polarization state light signal enters the first polarization-maintaining beam splitter and is converted into linearly polarized light. The first polarization-maintaining beam splitter then performs beam splitting to obtain the main optical path signal and the reference optical path signal. The main optical path signal is processed as follows: the main optical path signal output by the first polarization-maintaining beam splitter is sent to the Y-waveguide for beam splitting and modulation, and then enters the fiber ring for propagation. The signal returns to the first polarization-maintaining beam splitter via the fiber ring and is combined and interfered to form a return signal. The first polarization-maintaining beam splitter outputs the return signal to the second polarization-maintaining beam splitter.

[0055] The reference optical path signal is output from the first polarization-maintaining beam splitter to the second polarization-maintaining beam splitter for axis switching processing, and then combined with the returned signal. The combined signal is output from the second polarization-maintaining beam splitter to the detector to complete the photoelectric conversion.

[0056] In this process, the main optical path signal propagates clockwise and counterclockwise around the fiber optic loop and then enters the Y waveguide where it is combined and interferes. When the reference optical path signal is output to the second polarization-maintaining beam splitter via the first polarization-maintaining beam splitter, the port fusion of the first and second polarization-maintaining beam splitters enables the reference optical path signal to switch axes.

[0057] The splitting settings of the first and second polarization-maintaining beam splitters are both 90:10 for the main optical path signal and the reference optical path signal. After the second polarization-maintaining beam splitter combines the light, the light intensity of the main optical path signal and the light intensity of the reference optical path signal are the same. When the light intensities of the two signals are the same, the fiber optic gyroscope has the highest accuracy, and the corresponding modulation depth is the theoretically optimal modulation depth.

[0058] The method for determining the optimal modulation depth for engineering applications using the fiber optic gyroscope optical path noise reduction modulation depth evaluation model is as follows:

[0059] Based on the measured detector voltage values ​​when no modulation signal is applied and the detector voltage values ​​when a preset modulation signal is applied, determine the expression for the relationship between the light intensity of the two optical paths and the expression for the ratio of the light power of the two optical paths in the detector signal at the current actual modulation depth;

[0060] Determine the expression for the ratio of optical power of the main optical path to optical power of the reference optical path at the theoretically optimal modulation depth;

[0061] The theoretically optimal modulation depth is determined based on the obtained expression;

[0062] Based on the theoretical optimal modulation depth and the engineering application environment, the optimal modulation depth at the engineering application level is determined.

[0063] The preset gyroscope program is used to achieve the optimal signal modulation depth between the optical power of the main optical path signal and the optical power of the reference optical path signal. Under the theoretically optimal modulation depth, the expression for the ratio of the optical power of the main optical path signal to the optical power of the reference optical path signal should be consistent with the power ratio of the main optical path signal and the reference optical path signal under the actual modulation depth.

[0064] When the theoretical optimal modulation depth S Y The digital modulation signal output under the preset modulation program is converted into an analog signal by a DA converter to drive the Y waveguide. Therefore, according to the theoretical optimal modulation depth S Y Determine the optimal modulation depth S for engineering applications YG .

[0065] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0066] In the current embodiment, fiber optic gyroscope detector signal measurements are used to achieve the optimal modulation depth S at the engineering application level. YG The specific examples confirmed are as follows:

[0067] The signal measurement steps for a fiber optic gyroscope detector are as follows:

[0068] Step 1: Based on the fiber optic gyroscope dual-path delay subtraction optical path noise reduction technology, complete the fiber optic gyroscope assembly, including optical path assembly and circuit assembly.

[0069] Step 2: Power on the fiber optic gyroscope and measure the voltage V0 of the fiber optic gyroscope detector when no modulation signal is applied. Then power off the fiber optic gyroscope.

[0070] Step 3: Power on the fiber optic gyroscope, program the gyroscope with an arbitrary modulation depth of S1 in the fiber optic gyroscope FPGA, and then power off the fiber optic gyroscope.

[0071] Step 4: Power on the fiber optic gyroscope and measure the voltage of the fiber optic gyroscope detector after applying the modulation signal. The fiber optic gyroscope lost power.

[0072] After the measurement is completed, the light intensity signals of the main optical path and the reference optical path satisfy the following relationship:

[0073]

[0074] Among them, P 主 Optical power (μW) of the main optical path optical signal, P 参 denoted as , where is the optical power (μW) of the reference optical path signal, and n is the detector voltage responsivity (V / μW).

[0075] The ratio of the optical signal power in the main optical path to the optical signal power in the reference optical path is as follows:

[0076]

[0077] In the precise evaluation model of optimal modulation depth for high-precision fiber optic gyroscope optical path noise reduction technology, the optical power of the main optical path and the optical power of the reference optical path satisfy the following relationship at the optimal modulation depth:

[0078]

[0079] Among them, S Y The optimal modulation depth is evaluated by the precise evaluation model for the optimal modulation depth of high-precision fiber optic gyroscope optical path noise reduction technology.

[0080] Theoretical optimal modulation depth S Y for:

[0081]

[0082] Based on the theoretically optimal modulation depth S Y The final digital modulation signal is converted into an analog signal by a DA converter to drive the Y waveguide. Therefore, the optimal modulation depth S for engineering applications is... YG for:

[0083]

[0084] Where N is the number of bits in the fiber optic gyroscope DA digital-to-analog converter, and M is 2... N ·S Y / π is rounded to the nearest integer.

[0085] Example 1:

[0086] The dual-optical-path design is as follows:

[0087] like Figure 1As shown, an erbium source emits an arbitrary polarization light signal, which enters the polarization-maintaining circulator through port 1. The polarization-maintaining circulator converts the arbitrary polarization light into linearly polarized light, and outputs it through port 2 to port 1 of the polarization-maintaining beam splitter I. The light signal is split in the polarization-maintaining beam splitter I according to a 90:10 ratio; 90% of the signal is output through port 2 to the Y-waveguide, which is the main optical path signal, and 10% is output through port 3, which is the reference optical path signal. After being split and modulated by the Y-waveguide, the main optical path signal propagates clockwise and counterclockwise around the fiber optic loop, and then recombines at the Y-waveguide. Interference occurs; the light returning from the Y-waveguide enters polarization-maintaining beamsplitter I via port 2, and is output from port 1 to port 2 of the polarization-maintaining circulator, and then from port 3 to port 2 of polarization-maintaining beamsplitter II; the reference optical signal, after being output from port 3 of polarization-maintaining beamsplitter I, is fused 90° with port 3 of polarization-maintaining beamsplitter II, completing a 90° axis change, and is input to polarization-maintaining beamsplitter II; within polarization-maintaining beamsplitter II, the main optical signal and the reference optical signal are combined, and output from port 1 of polarization-maintaining beamsplitter II to the detector, completing the photoelectric conversion. The above is... Figure 1 The basic principle of the typical optical path scheme of the dual-optical-path delay-subtraction optical path noise reduction technology is shown. The core of this optical path scheme is to control the intensity of the main optical path optical signal and the reference optical path optical signal in the polarization-maintaining beam splitter II to maximize the gyroscope accuracy.

[0088] Using the fiber optic gyroscope detector signal, a precise matching model between the main optical path intensity signal and the reference optical path intensity signal is established, thereby enabling accurate evaluation of the optimal modulation depth for fiber optic gyroscope optical path noise reduction technology. The process is as follows: Figure 2 As shown.

[0089] When the fiber optic gyroscope is powered on, the detector voltage V0 is measured when no modulation signal is applied. A gyroscope program with an arbitrary modulation depth of S1 = π / 2 is programmed into the fiber optic gyroscope FPGA. After the fiber optic gyroscope is powered on, the detector voltage V0 is measured when a modulation signal is applied. π / 2 The fiber optic gyroscope lost power.

[0090] The optical signal power of the main optical path and the optical signal power of the reference optical path satisfy the following relationship:

[0091]

[0092] Among them, P 主 Optical power (μW) of the main optical path optical signal, P 参 denoted as , where is the optical power (μW) of the reference optical path signal, and n is the detector voltage responsivity (V / μW).

[0093] In the high-precision fiber optic gyroscope optical path noise reduction technology optimal modulation depth accurate evaluation model, the ratio of the optical signal power of the main optical path to the optical signal power of the reference optical path is as follows:

[0094]

[0095] At the optimal modulation depth, the optical power of the main optical path and the optical power of the reference optical path satisfy the following relationship:

[0096]

[0097] S Y The optimal modulation depth is evaluated by the precise evaluation model for the optimal modulation depth of high-precision fiber optic gyroscope optical path noise reduction technology.

[0098] In the high-precision fiber optic gyroscope optical path noise reduction technology optimal modulation depth accurate evaluation model, the theoretical optimal modulation depth S Y for:

[0099]

[0100] Optimal modulation depth S in engineering applications YG for:

[0101]

[0102] This embodiment can efficiently and accurately evaluate the optimal modulation depth of a fiber optic gyroscope in a dual-path delay-subtraction denoising state, improving product debugging efficiency. This invention uses detector voltage measurement instead of optical power measurement to evaluate the optimal modulation depth of the fiber optic gyroscope in a denoising state, avoiding inaccurate modulation depth prediction caused by optical power measurement errors and ensuring the achievement rate of product design specifications. This invention provides accurate evaluation of the optimal modulation depth based on the complete state of the fiber optic gyroscope; it is simple to apply, yields accurate results, and avoids related errors introduced by subsequent operations.

[0103] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0104] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology, characterized in that... include: Construct and assemble a dual-path delay-subtraction noise reduction optical path and its corresponding circuitry. Power on the fiber optic gyroscope, measure the detector voltage in the dual-optical-path delay-subtraction noise reduction optical path when no modulation signal is applied, and then power off after the measurement is completed. Power on the fiber optic gyroscope, write the preset gyroscope program into the fiber optic gyroscope, and power off after writing is complete; Power on the fiber optic gyroscope, preset the modulation signal, measure the detector voltage value of the dual-path delay subtraction noise reduction optical path after inputting the modulation signal, and then power off after the measurement is completed. A noise reduction modulation depth evaluation model for fiber optic gyroscopes is established. The optimal modulation depth for engineering applications is determined using this model, and the preset gyroscope program is adjusted according to the optimal modulation depth for engineering applications.

2. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 1, characterized in that: The dual-path delay-subtraction noise reduction optical path includes an erbium source, a polarization-maintaining circulator, a first polarization-maintaining beam splitter, a second polarization-maintaining beam splitter, a Y-waveguide, an optical fiber ring, and a detector, wherein: The output of the bait source is connected to the input of the polarization-maintaining circulator. The output of the polarization-maintaining circulator is connected to the inputs of the first polarization-maintaining beam splitter and the second polarization-maintaining beam splitter, respectively. The output of the first polarization-maintaining beam splitter is connected to one end of the Y-waveguide. The other end of the Y-waveguide is connected to the fiber optic ring for signal splitting and modulation, and then the signal is returned to the output of the first polarization-maintaining beam splitter via the Y-waveguide. The output of the first polarization-maintaining beam splitter is also connected to the input of the second polarization-maintaining beam splitter. The second polarization-maintaining beam splitter receives the output signals returned from the polarization-maintaining circulator and the first polarization-maintaining beam splitter, and then combines them to connect to the detector.

3. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 2, characterized in that: The first and second polarization-maintaining beam splitters are used for beam splitting. The erbium source outputs an arbitrary polarization state light signal. The polarization state light signal enters the first polarization-maintaining beam splitter and is converted into linearly polarized light. The first polarization-maintaining beam splitter then performs beam splitting to obtain the main optical path signal and the reference optical path signal. The main optical path signal is processed as follows: the first polarization-maintaining beam splitter outputs the main optical path signal to the Y waveguide for beam splitting and modulation, and then propagates into the fiber ring. The signal returns to the first polarization-maintaining beam splitter via the fiber ring and is combined and interfered to form a return signal. The first polarization-maintaining beam splitter outputs the return signal to the second polarization-maintaining beam splitter.

4. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 3, characterized in that: The reference optical path signal is output from the first polarization-maintaining beam splitter to the second polarization-maintaining beam splitter for axis switching processing, and then combined with the returned signal. The combined signal is output from the second polarization-maintaining beam splitter to the detector to complete the photoelectric conversion. In this process, the main optical path signal propagates clockwise and counterclockwise around the fiber optic loop and then enters the Y waveguide where it is combined and interferes. When the reference optical path signal is output to the second polarization-maintaining beam splitter via the first polarization-maintaining beam splitter, the port fusion of the first and second polarization-maintaining beam splitters enables the reference optical path signal to switch axes.

5. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 4, characterized in that: The splitting settings of the first and second polarization-maintaining beam splitters are both 90:10 for the ratio of the main optical path signal to the reference optical path signal. After the second polarization-maintaining beam splitter performs light combining, the light intensity of the main optical path signal and the light intensity of the reference optical path signal are the same. When the light intensities of the two signals are the same, the fiber optic gyroscope has the highest accuracy, and the corresponding modulation depth is the theoretically optimal modulation depth.

6. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 5, characterized in that: The method for determining the optimal modulation depth at the engineering application level using the fiber optic gyroscope optical path noise reduction modulation depth evaluation model is as follows: Based on the measured detector voltage values ​​when no modulation signal is applied and the detector voltage values ​​when a preset modulation signal is applied, determine the expression for the relationship between the light intensity of the two optical paths and the expression for the ratio of the light power of the two optical paths in the detector signal at the current actual modulation depth; Determine the expression for the ratio of optical power of the main optical path to optical power of the reference optical path at the theoretically optimal modulation depth; The theoretically optimal modulation depth is determined based on the obtained expression; Based on the theoretical optimal modulation depth and the engineering application environment, the optimal modulation depth at the engineering application level is determined.

7. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 6, characterized in that: The relationship between the main optical path signal and the reference optical path signal at the current actual modulation depth is expressed as follows: The expression for the ratio of the optical signal power in the main optical path to the optical signal power in the reference optical path is: In the formula, P 主 The optical power of the main optical path signal, P 参 denoted as the optical power of the reference optical signal, and n as the detector voltage responsivity.

8. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 7, characterized in that: The preset gyroscope program is used to achieve the optimal signal modulation depth between the optical power of the main optical path and the optical power of the reference optical path. Under the theoretically optimal modulation depth, the ratio between the optical power of the main optical path and the optical power of the reference optical path is expressed as follows: In the formula, S Y This represents the optimal modulation depth for high-precision fiber optic gyroscope optical path noise reduction technology.

9. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 8, characterized in that: When the preset modulation program satisfies the theoretical optimal modulation depth, the theoretical optimal modulation depth is determined. The expression for the theoretical optimal modulation depth is: In the formula, the theoretical optimal modulation depth S Y The digital signal output under the preset modulation program is converted into an analog signal by a DA converter to drive the Y waveguide.

10. The method for accurately evaluating modulation depth in fiber optic gyroscope optical path noise reduction technology according to claim 9, characterized in that: The optimal modulation depth S at the engineering application level YG The expression is: In the formula, N is the number of bits in the fiber optic gyroscope DA digital-to-analog converter, and M is 2. N ·S Y / π is rounded to the nearest integer.

Images