Fiber-optic gyroscope capable of suppressing relative intensity noise of light path and noise suppression method of fiber-optic gyroscope

Abstract

The invention relates to the technical field of high-precision fiber-optic gyroscopes, and provides a fiber-optic gyroscope capable of suppressing relative intensity noise of a light path and a noise suppression method of the fiber-optic gyroscope in order to solve the problems that an existing method for suppressing the relative intensity noise is complex in operation process, poor in applicability and the like. The optical fiber ring module comprises a polarization beam splitter / combiner, a Y waveguide integrated modulator, a polarization-maintaining optical fiber ring and a polarization-maintaining optical fiber reflector; an input end of the polarization beam splitter / combiner is welded with a polarization light source, a polarization-maintaining tail fiber of a first output end is welded with an input tail fiber fast axis of the Y waveguide integrated modulator in a 0-degree alignment manner, a polarization-maintaining tail fiber of a second output end is welded with a tail fiber slow axis of the polarization-maintaining fiber reflector in a 0-degree alignment manner, and a polarization-maintaining tail fiber of a third output end is welded with the photoelectric detector; and two output tail fibers of the Y waveguide integrated modulator are welded with two input tail fibers of the polarization maintaining fiber ring in a fast axis 0-degree alignment manner.

Description

Technical Field

[0001] The invention belongs to the technical field of high-precision fiber optic gyroscopes, and in particular relates to a fiber optic gyroscope capable of suppressing relative intensity noise of an optical path and a noise suppression method thereof. Background Art

[0002] Fiber optic gyroscope is an optical angular velocity sensor and a core component of the inertial navigation system. Its accuracy determines the navigation alignment accuracy. Improving the angular velocity measurement accuracy of the fiber optic gyroscope is an unremitting goal in the inertial field and is of great significance to the development of industry technology.

[0003] Fiber optic gyroscopes are widely used as angular velocity sensors in the fields of aviation, navigation, and defense industry. High-precision fiber optic gyroscopes are based on fiber optic gyroscopes. By increasing the size of the fiber ring, the Sagnac effect is enhanced to improve the measurement accuracy and sensitivity, making the zero bias stability of the super-large ring fiber optic gyroscope better than 0.001° / h. It can be used in high-precision positioning and orientation, inertial navigation and guidance, geodesy, earthquake monitoring, world time, deep space exploration and other precision measurement fields.

[0004] High-precision fiber gyroscopes usually use wide-spectrum light sources to suppress optical path noise such as back-Rayleigh scattering and polarization error. Erbium-doped fiber light sources have the advantages of good wavelength stability, high power, and wide spectrum. The high output power of the light source is conducive to improving the signal-to-noise ratio of the gyroscope signal, thereby reducing the angular random walk coefficient of the fiber gyroscope. When the light intensity increases to a certain level, the gyroscope signal-to-noise ratio is mainly determined by the light source intensity noise and no longer increases with the increase of light power. In order to further improve the signal-to-noise ratio of the fiber gyroscope, enhance the accuracy of the fiber gyroscope, and reduce the angular random walk coefficient of the fiber gyroscope, the light source intensity noise must be suppressed.

[0005] The relative intensity noise of the light source is an additional noise caused by the random beat frequency between all irrelevant frequency components of the wide spectrum. It reflects the characteristics of the light source amplitude and has nothing to do with the detection process. The relative intensity noise (RIN) of the light source is white noise and is characterized by the random walk coefficient. In addition to using high-power wide-spectrum light sources and overmodulation technology to reduce the amplitude of the relative intensity noise, the relative intensity noise can also be cancelled by taking advantage of the fact that the light signals emitted by the same wide-spectrum light source have the same relative intensity noise.

[0006] Currently, there are various technical solutions for relative intensity noise suppression, mainly including dual-detector circuit cancellation solutions, software solutions using FPGA for noise cancellation, and relative intensity noise cancellation solutions based on optical paths. However, the dual-detector circuit cancellation solutions and software solutions using FPGA for noise cancellation have complex operation processes, make significant changes to the overall system framework, and have relatively harsh application conditions. The relative intensity noise cancellation solution based on the optical path does not increase the complexity of the system much and can be implemented without changing the existing hardware and software status framework, with minimal changes to the gyroscope's hardware and software status. Therefore, high-precision fiber optic gyroscope relative intensity noise suppression technology based on optical path design is one of the most engineered solutions. Summary of the invention

[0007] The purpose of the present invention is to solve the problems of the existing high-precision fiber optic gyroscope method for suppressing relative intensity noise, such as complex operation process, large changes to the overall system framework, harsh application conditions, and poor suppression effect, and to propose a fiber optic gyroscope that can suppress the relative intensity noise of the optical path and a noise suppression method thereof.

[0008] To achieve the above objectives, the technical solution proposed by the present invention is:

[0009] A fiber optic gyroscope capable of suppressing relative intensity noise of an optical path comprises a polarized light source, a photodetector and a fiber optic ring module, and the special features thereof are:

[0010] The optical fiber ring module includes a polarization splitter / combiner, a Y-waveguide integrated modulator, a polarization-maintaining optical fiber ring and a polarization-maintaining optical fiber reflector;

[0011] The input end of the polarization beam splitter / combiner is fused with a polarized light source, the polarization-maintaining pigtail at the first output end is fused with the input pigtail of the Y-waveguide integrated modulator at 0° alignment of the fast axis, the polarization-maintaining pigtail at the second output end is fused with the pigtail slow axis of the polarization-maintaining fiber reflector at 0° alignment, and the polarization-maintaining pigtail at the third output end is fused with the input pigtail of the photodetector;

[0012] The polarization beam splitter / combiner is used to split the input light of the polarization light source into orthogonal linear polarized lights with an optical power of 1:1, one of which is used as signal light to sequentially enter the Y-waveguide integrated modulator and the polarization-maintaining fiber ring to form an interference light signal carrying angular velocity information and return to the polarization beam splitter / combiner, and the other is used as reference light to enter the polarization-maintaining fiber reflector to attenuate, and the attenuated reference light is reflected to the polarization beam splitter / combiner; the interference light signal carrying angular velocity information and the attenuated reference light are combined by the polarization beam splitter / combiner and enter the photodetector for superposition output;

[0013] The two output pigtails of the Y-waveguide integrated modulator are fused with the two input pigtails of the polarization-maintaining optical fiber ring with their fast axes aligned at 0°.

[0014] Furthermore, the polarized light source is a low polarization degree ASE light source.

[0015] Furthermore, the reflection ratio of the polarization-maintaining optical fiber reflector is 1%-5%.

[0016] Furthermore, the pigtails between the polarization beam splitter / combiner and the polarization light source, and between the polarization beam splitter / combiner and the photodetector are all single-mode-polarization-maintaining fusion spliced;

[0017] The pigtails between the polarization beam splitter / combiner and the Y-waveguide integrated modulator, the polarization beam splitter / combiner and the polarization-maintaining fiber reflector, and the Y-waveguide integrated modulator and the polarization-maintaining fiber ring are all polarization-maintaining fusion-spliced.

[0018] Furthermore, the polarization beam splitter / combiner is a 2x2 polarization beam splitter / combiner.

[0019] The present invention also proposes a noise suppression method for the fiber optic gyroscope capable of suppressing the relative intensity noise of the optical path, which is special in that it comprises the following steps:

[0020] Step 1: Input the light from the polarized light source into the polarization beam splitter / combiner, and split the incident light into o light and e light by the polarization beam splitter / combiner, wherein the o light and the e light are orthogonal linear polarized lights with an optical power of 1:1;

[0021] Step 2: The e-light is input as signal light into the Y-waveguide integrated modulator through the first output end of the polarization beam splitter / combiner, and the two output pigtails of the Y-waveguide integrated modulator are input into the polarization-maintaining fiber ring to form an interference light signal carrying angular velocity information;

[0022] The o light is used as a reference light and is input into the polarization-maintaining fiber reflector through the polarization-maintaining fiber pigtail at the second output end of the polarization beam splitter / combiner. The o light is attenuated and reflected by the polarization-maintaining fiber reflector to form an attenuated reference light.

[0023] The polarization states of the attenuated reference light and the interference light signal carrying the angular velocity information are perpendicular to each other and have equal amplitudes;

[0024] Step 3: After combining the interference light signal carrying the angular velocity information and the attenuated reference light through a polarization beam splitter / combiner, the interference light signal enters a photodetector through a third output end of the polarization beam splitter / combiner;

[0025] Step 4: Use a photoelectric detector to perform intensity superposition on the interference light signal carrying the angular velocity information and the attenuated reference light, eliminate the light intensity fluctuation on the photoelectric detector and then output it, thereby completing the suppression of the relative intensity noise of the light source.

[0026] Furthermore, in step 2, it also includes applying a voltage modulation signal through a Y-waveguide integrated modulator to adjust the light intensity amplitude of the interference light signal, so that the light intensity amplitude of the interference light signal carrying the angular velocity information is the same as that of the attenuated reference light;

[0027] The applied voltage modulation signal adjusts the light intensity amplitude of the interference light signal to satisfy the following formula:

[0028]

[0029] Among them, α1 is the optical path loss of the signal light, α2 is the optical path loss of the reference light, is the modulated phase shift of the forward propagating light wave at time t, is the modulation phase shift produced on the counter-propagating light wave after a delay of τ.

[0030] Furthermore, in step 4, when the interference light signal and the attenuated light are subjected to intensity superposition by the photoelectric detector, the calculation formula for superposition of the interference light signal and the attenuated light is:

[0031] I(t)=I N1 (t)+I N2 (t) = α2[I N (t-τ)+I N (t)];

[0032] The conversion formula from the time domain to the frequency domain output is:

[0033]

[0034] Where I(t) is the total light field intensity after superposition, I N is the random fluctuation of light intensity over time, I N1 is the intensity of interference light signal, I N2 is the reference light intensity, ω τ is the fiber ring oscillation frequency;

[0035] When τ =π and When , the light intensity fluctuation on the photodetector is eliminated, achieving the suppression of the relative intensity noise of the light source.

[0036] Beneficial effects of the present invention:

[0037] (1) The fiber optic gyroscope capable of suppressing the relative intensity noise of the optical path of the present invention has a simple structure and does not require major changes to the overall frame of the fiber optic gyroscope. The input polarized light source light field can be split into two light beams with equal light intensity and perpendicular polarization directions through a polarization beam splitter / combiner. Linear polarized light can be obtained without adding a polarizer separately. Then, an optical path structure that suppresses the relative intensity noise is formed with a Y-guide integrated modulator, a polarization-maintaining fiber ring, and a polarization-maintaining fiber reflector. The interference light signal carrying the angular velocity information and the attenuated reference light are intensity-superimposed in a photodetector to eliminate the fluctuation of the light intensity on the detector, thereby achieving the suppression of the relative intensity noise of the light source.

[0038] (2) The present invention achieves light intensity attenuation and light reflection through a polarization-maintaining fiber reflector with a reflection ratio of 1%-5%, wherein the reflection ratio of the polarization-maintaining fiber reflector can be controlled according to the multi-layer dielectric film process, thereby ensuring the precise attenuation and light reflection of the light signal intensity, so that the polarization of the attenuated reference light and the modulated interference light signal carrying angular velocity information are perpendicular to each other and have equal amplitudes, thereby avoiding interference between the two beams of light and eliminating the fluctuation of the light intensity on the photodetector, thereby suppressing the relative intensity noise of the light source.

[0039] (3) In the present invention, single-mode-polarization-maintaining welding is adopted between the polarization splitter / combiner and the polarization light source and between the polarization splitter / combiner and the photodetector, and there is no need for axis alignment; polarization-polarization-maintaining welding is adopted between the polarization splitter / combiner and the Y-waveguide integrated modulator, between the polarization splitter / combiner and the polarization-maintaining fiber reflector, and between the Y-waveguide integrated modulator and the polarization-maintaining fiber ring, which can effectively reduce the number of welding points, reduce the difficulty of the welding process of the internal optical path of the fiber optic gyroscope, make it convenient for engineering mass production, effectively reduce the processing cost and production cost of the fiber optic gyroscope, and improve the product production efficiency.

[0040] (4) The noise suppression method of the fiber optic gyroscope capable of suppressing the relative intensity noise of the optical path of the present invention has a simple operation process and is easy to implement. The polarization states of the interference light signal carrying the angular velocity information and the attenuated reference light are kept perpendicular to each other through the polarization splitter / combiner and the Y-waveguide integrated modulator. Then, the interference light signal carrying the angular velocity information and the attenuated reference light are intensity-superimposed in the photoelectric detector to eliminate the fluctuation of the light intensity on the detector and suppress the relative intensity noise of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of a fiber optic gyroscope capable of suppressing relative intensity noise of an optical path according to the present invention;

[0042] Figure 2 Schematic diagram of the polarization beam splitter / combiner in an embodiment of the present invention;

[0043] Figure 3Schematic diagram of light combining by a polarization beam splitter / combiner in an embodiment of the present invention;

[0044] Reference numerals:

[0045] 1-polarized light source, 2-polarized beam splitter / combiner, 3-Y waveguide integrated modulator, 4-polarization-maintaining fiber ring, 5-polarization-maintaining fiber reflector, 6-photodetector, 7-first output end, 8-second output end, 9-third output end. DETAILED DESCRIPTION

[0046] like Figure 1 As shown, a fiber optic gyroscope capable of suppressing relative intensity noise of an optical path comprises a low-polarization ASE light source, a 2x2 polarization beam splitter / combiner 2, a Y-waveguide integrated modulator 3, a polarization-maintaining fiber ring 4, a polarization-maintaining fiber reflector 5 with a reflection ratio of 1%-5%, and a photodetector 6.

[0047] The 2x2 polarization beam splitter / combiner 2 is a 4-port optical fiber device, the input end of the polarization beam splitter / combiner 2 is fused with the polarization light source 1, and no axis alignment is required; the polarization-maintaining pigtail of the first output end 7 is fused with the input pigtail of the Y-waveguide integrated modulator 3 at a 0° alignment with the fast axis, the polarization-maintaining pigtail of the second output end 8 is fused with the pigtail slow axis of the polarization-maintaining optical fiber reflector 5 at a 0° alignment, and the polarization-maintaining pigtail of the third output end 9 is fused with the photodetector 6, and no axis alignment is required; the two output pigtails of the Y-waveguide integrated modulator 3 are fused with the two input pigtails of the polarization-maintaining optical fiber ring 4 at a 0° alignment with the fast axis;

[0048] The light from the low polarization ASE light source is input into the 2x2 polarization beam splitter / combiner 2 and is divided into orthogonal linear polarized light with an optical power of 1:1, namely, o light and e light; the e light enters the Y branch of the Y waveguide integrated modulator 3 as signal light and is divided into two linear polarized light beams with an optical power of 1:1 and transmitted in opposite directions along the polarization-maintaining fiber ring 4, and is combined at the Y branch to form an interference light signal carrying angular velocity information, and then returns to the polarization beam splitter / combiner 2;

[0049] The o light enters the polarization-maintaining fiber reflector 5 as the reference light, and the light intensity attenuation and light reflection are completed in the polarization-maintaining fiber reflector 5, and the attenuated reference light is reflected to the polarization beam splitter / combiner 2. The interference light signal carrying the angular velocity information and the attenuated reference light keep the polarization states perpendicular to each other, and enter the photodetector 6 in sequence after being combined by the 2x2 polarization beam splitter / combiner 2. The interference light signal carrying the angular velocity information and the attenuated reference light are superimposed in intensity in the photodetector 6, thereby eliminating the fluctuation of the light intensity on the photodetector 6 and suppressing the relative intensity noise of the light source.

[0050] The signal light link carrying angular velocity information and relative intensity noise of the light source composed of the first output end 7 of the polarization splitter / combiner 2 and the Y waveguide and the polarization-maintaining fiber ring 4 is all on the fast axis, and the reference light link carrying relative intensity noise of the light source composed of the second output end 8 and the polarization-maintaining fiber reflector 5 with a reflection ratio of 5% is all on the slow axis; the polarization states of the signal light and the reference light are orthogonal and perpendicular, and are delayed in time by a sensitive loop light signal passing time τ. Only square-law intensity signal superposition is performed in the photodetector, which can eliminate the light intensity fluctuation of the photodetector 6 and suppress the relative intensity noise of the light source.

[0051] This embodiment also proposes a noise suppression method for a fiber optic gyroscope that can suppress relative intensity noise of an optical path, comprising the following steps:

[0052] Step 1: input the light of the polarized light source 1 into the polarization beam splitter / combiner 2, and the polarization beam splitter / combiner 2 splits the incident light into o light and e light, wherein the o light and the e light are orthogonal linear polarized lights with an optical power of 1:1;

[0053] The light emitted by polarized light source 1 is expressed as:

[0054] I(t0)=I0+I N (t)

[0055] Where: I(t0) is the light source output power, I0 is the average light power, I N is the random fluctuation of light intensity over time, and its mean is zero;

[0056] Step 2: Figure 2 As shown, the e-light is input as signal light into the Y-waveguide integrated modulator 3 through the first output end 7 of the polarization beam splitter / combiner 2, and the two output pigtails of the Y-waveguide integrated modulator 3 are input into the polarization-maintaining fiber ring 4 to form an interference light signal carrying angular velocity information;

[0057] like Figure 3 As shown, the o light is used as a reference light and is input into the polarization-maintaining fiber reflector 5 through the polarization-maintaining fiber pigtail at the second output end 8 of the polarization beam splitter / combiner 2. The o light is subjected to light intensity attenuation and light reflection by the polarization-maintaining fiber reflector 5 to form an attenuated reference light.

[0058] The polarization states of the attenuated reference light and the interference light signal carrying the angular velocity information are perpendicular to each other and have equal amplitudes;

[0059] The partial intensity noise contained in the interference light can be expressed as follows:

[0060]

[0061] The partial intensity noise contained in the reference light can be expressed as follows:

[0062] I N1 (t) = α2I N (t)

[0063] Among them, α1 is the optical path loss of the signal light, α2 is the optical path loss of the reference light, is the modulated phase shift of the forward propagating light wave at time t, is the modulation phase shift of the reverse propagating light wave after a delay of τ;

[0064] I N is the random fluctuation of light intensity over time, I N1 is the intensity of interference light signal, I N2 is the reference light intensity;

[0065] Due to the closed-loop feedback Feedback Phase Shift vs. Sagnac Phase Shift Equal in magnitude and opposite in sign, that is So the formula can be simplified to

[0066]

[0067] After the interference light and the reference light intensity are superimposed, the light intensity of the photodetector (6) is:

[0068]

[0069] In order to ensure that the signal light carrying the angular rate information and the relative intensity noise of the light source is consistent with the reference light intensity amplitude carrying the relative intensity noise of the light source, a precise voltage modulation signal needs to be applied to the Y-waveguide integrated modulator 3; from the above formula, it can be seen that in order to achieve the best matching effect of the relative intensity noise suppression, the modulation phase of the voltage modulation signal on the optical phase needs to meet the following conditions:

[0070]

[0071] Step 3: After the interference light signal carrying the angular velocity information and the attenuated reference light are combined by the polarization beam splitter / combiner 2, the interference light signal enters the photodetector 6 from the third output terminal 9 of the polarization beam splitter / combiner 2;

[0072] Step 4: The interference light signal carrying the angular velocity information and the attenuated reference light are subjected to intensity superposition through the photodetector 6. When the matching condition in step 2 is met, the light intensity entering the photodetector 6 is superimposed to satisfy the following formula:

[0073] I(t)=I N1 (t)+I N2 (t) = α2[I N (t-τ)+I N (t)]

[0074] Convert the above formula from time domain to frequency domain output

[0075]

[0076] Among them, I(t) is the total light field intensity after superposition, ω τ is the fiber ring oscillation frequency;

[0077] When the fiber optic gyroscope is modulated by its eigenfrequency, there is ω τ =π and When the light intensity fluctuation on the photodetector 6 is eliminated, the relative intensity noise of the light source is suppressed, thereby completing the suppression of the relative intensity noise of the light source.

Claims

1. A fiber optic gyroscope capable of suppressing relative intensity noise of an optical path, comprising a polarized light source (1), a photodetector (6) and a fiber optic ring module, characterized in that: The optical fiber ring module comprises a polarization splitter / combiner (2), a Y-waveguide integrated modulator (3), a polarization-maintaining optical fiber ring (4) and a polarization-maintaining optical fiber reflector (5); The input end of the polarization beam splitter / combiner (2) is fused to the polarization light source (1), the polarization-maintaining pigtail of the first output end (7) is fused to the input pigtail of the Y-waveguide integrated modulator (3) with its fast axis aligned at 0°, the polarization-maintaining pigtail of the second output end (8) is fused to the pigtail slow axis of the polarization-maintaining optical fiber reflector (5) with its slow axis aligned at 0°, and the polarization-maintaining pigtail of the third output end (9) is fused to the input pigtail of the photodetector (6); The polarization beam splitter / combiner (2) is used to split the input light of the polarization light source (1) into orthogonal linear polarized light with an optical power of 1:1, wherein one beam as signal light sequentially enters a Y-waveguide integrated modulator (3) and a polarization-maintaining optical fiber ring (4) to form an interference light signal carrying angular velocity information and returns to the polarization beam splitter / combiner (2), and the other beam as reference light enters a polarization-maintaining optical fiber reflector (5) to be attenuated, and the attenuated reference light is reflected to the polarization beam splitter / combiner (2); the interference light signal carrying angular velocity information and the attenuated reference light are combined by the polarization beam splitter / combiner (2) and enter the photodetector (6) for superposition and output; The two output pigtails of the Y-waveguide integrated modulator (3) and the two input pigtails of the polarization-maintaining optical fiber ring (4) are fused with their fast axes aligned at 0°.

2. The fiber optic gyroscope capable of suppressing relative intensity noise of an optical path according to claim 1, characterized in that: The polarized light source (1) is a low polarization degree ASE light source.

3. The fiber optic gyroscope capable of suppressing relative intensity noise of an optical path according to claim 2, characterized in that: The reflection ratio of the polarization-maintaining optical fiber reflector (5) is 1%-5%.

4. The fiber optic gyroscope capable of suppressing relative intensity noise of an optical path according to claim 3, characterized in that: The pigtails between the polarization beam splitter / combiner (2) and the polarization light source (1), and between the polarization beam splitter / combiner (2) and the photodetector (6) are all single-mode-polarization-maintaining fusion spliced; The pigtails between the polarization beam splitter / combiner (2) and the Y-waveguide integrated modulator (3), the polarization beam splitter / combiner (2) and the polarization-maintaining optical fiber reflector (5), and the Y-waveguide integrated modulator (3) and the polarization-maintaining optical fiber ring (4) are all polarization-maintaining fusion-spliced.

5. The fiber optic gyroscope capable of suppressing relative intensity noise of an optical path according to claim 4, characterized in that: The polarization beam splitter / combiner (2) is a 2x2 polarization beam splitter / combiner.

6. A noise suppression method for an optical fiber gyroscope capable of suppressing relative intensity noise of an optical path according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: inputting light from a polarized light source (1) into a polarization beam splitter / combiner (2), and splitting the incident light into o light and e light by the polarization beam splitter / combiner (2), wherein the o light and the e light are orthogonal linearly polarized lights with an optical power of 1:1; Step 2: inputting the e-light as signal light into the Y-waveguide integrated modulator (3) through the first output end (7) of the polarization beam splitter / combiner (2), and inputting the two output pigtails of the Y-waveguide integrated modulator (3) into the polarization-maintaining fiber ring (4), thereby forming an interference light signal carrying angular velocity information; The o light is used as reference light and is input into the polarization-maintaining fiber reflector (5) through the polarization-maintaining fiber pigtail at the second output end (8) of the polarization beam splitter / combiner (2); the o light is subjected to light intensity attenuation and light reflection by the polarization-maintaining fiber reflector (5) to form attenuated reference light; The polarization states of the attenuated reference light and the interference light signal carrying the angular velocity information are perpendicular to each other and have equal amplitudes; Step 3: After the interference light signal carrying the angular velocity information and the attenuated reference light are combined by the polarization beam splitter / combiner (2), the interference light signal enters the photodetector (6) through the third output end (9) of the polarization beam splitter / combiner (2); Step 4: The interference light signal carrying the angular velocity information and the attenuated reference light are subjected to intensity superposition by the photoelectric detector (6), and the light intensity fluctuation on the photoelectric detector (6) is eliminated before output, thereby completing the suppression of the relative intensity noise of the light source.

7. A noise suppression method for an optical fiber gyroscope capable of suppressing relative intensity noise of an optical path according to claim 6, characterized in that: The second step further includes applying a voltage modulation signal through a Y-waveguide integrated modulator (3) to adjust the light intensity amplitude of the interference light signal, so that the light intensity amplitude of the interference light signal carrying the angular velocity information is the same as that of the attenuated reference light; The applied voltage modulation signal adjusts the light intensity amplitude of the interference light signal to satisfy the following formula: Among them, α1 is the optical path loss of the signal light, α2 is the optical path loss of the reference light, is the modulated phase shift of the forward propagating light wave at time t, is the modulation phase shift produced on the counter-propagating light wave after a delay of τ.

8. A noise suppression method for an optical fiber gyroscope capable of suppressing relative intensity noise of an optical path according to claim 7, characterized in that: In step 4, when the interference light signal and the attenuated light are subjected to intensity superposition by the photoelectric detector (6), the calculation formula for the superposition of the interference light signal and the attenuated light is: I(t)=I N1 (t)+I N2 (t)=α2[I N (t-τ)+I N (t)]; The conversion formula from the time domain to the frequency domain output is: Where I(t) is the total light field intensity after superposition, I N is the random fluctuation of light intensity over time, I N1 is the intensity of interference light signal, I N2 is the reference light intensity, ω τ is the fiber ring oscillation frequency; When τ =π and When , the light intensity fluctuation on the photoelectric detector (6) is eliminated, thereby achieving the suppression of the relative intensity noise of the light source.

Images