Fiber-optic gyroscope, method and apparatus for perturbation control

Abstract

The application discloses an optical fiber gyroscope, a disturbance control method and equipment, relates to the technical field of circuit detection, and the optical fiber gyroscope comprises a wide-spectrum light source, a polarization controller, a polarization maintaining coupler, a polarization beam splitter, a second detector, a third detector and a gyro drive demodulation circuit; the polarization maintaining coupler is connected with the polarization beam splitter in an optical path, and the gyro drive demodulation circuit is electrically connected with the polarization controller; the polarization beam splitter is used for receiving first light waves emitted by the wide-spectrum light source and split by the polarization maintaining coupler, splitting the first light waves again, and sending second light waves split again to the gyro drive demodulation circuit; the gyro drive demodulation circuit is used for generating an adjusting signal based on the second light waves and sending the adjusting signal to the polarization controller; and the polarization controller is used for adjusting the polarization state of incident light based on the adjusting signal. The measurement precision and stability of the gyroscope can be improved.

Description

Technical Field

[0001] This application relates to the field of circuit testing technology, and in particular to a fiber optic gyroscope, a polarization control method and device. Background Technology

[0002] In related technologies, fiber optic gyroscopes generally use Lyot depolarizers to achieve depolarization. These depolarizers are usually made using the polarization-maintaining input pigtail of a Y-waveguide modulator. The pigtail is cut into two polarization-maintaining fiber segments with a length ratio of 1:2, and the stress principal axes of the two fiber segments are fused together at 45°. However, the above method is a passive elimination method and cannot dynamically compensate for fluctuations in environmental conditions, which seriously affects the measurement accuracy and stability of the gyroscope. Summary of the Invention

[0003] The main purpose of this application is to provide a fiber optic gyroscope, a polarization control method and device, which aims to solve the technical problem that passive elimination cannot dynamically compensate for fluctuations in environmental conditions, seriously affecting the measurement accuracy and stability of the gyroscope.

[0004] To achieve the above objectives, this application proposes a fiber optic gyroscope, which includes a broadband light source, a polarization controller, a polarization-maintaining coupler, a polarization beam splitter, a second detector, a third detector, and a gyroscope drive demodulation circuit.

[0005] The polarization-maintaining coupler is optically connected to the polarization beam splitter, and the gyroscope drive demodulation circuit is electrically connected to the polarization controller.

[0006] The polarization beam splitter is used to receive the first light wave emitted by the broadband light source and split by the polarization-maintaining coupler, and to split the first light wave again, and to send the second light wave after splitting to the gyroscope drive demodulation circuit.

[0007] The gyroscope drive demodulation circuit is used to generate an adjustment signal based on the second light wave and send it to the polarization controller;

[0008] The polarization controller is used to adjust the polarization state of the incident light based on the adjustment signal.

[0009] In one embodiment, the second optical wave includes a first optical signal and a second optical signal, and the fiber optic gyroscope further includes a second detector and a third detector;

[0010] The polarization beam splitter is connected to the optical paths of the second detector and the third detector respectively, and the gyroscope drive demodulation circuit is electrically connected to the second detector and the third detector respectively;

[0011] The polarization beam splitter is used to receive the first light wave emitted by the broadband light source and split by the polarization-maintaining coupler, and to split the first light wave again, and to send the first light signal and the second light signal after the second split to the second detector and the third detector, respectively.

[0012] The second detector and the third detector are used to convert the first optical signal and the second optical signal into corresponding electrical signals, respectively, and send the electrical signals to the gyroscope drive demodulation circuit;

[0013] The gyroscope drive demodulation circuit is used to compare the intensity difference between the electrical signals. If the intensity difference is greater than a threshold, an adjustment signal is generated and sent to the polarization controller.

[0014] In one embodiment, the fiber optic gyroscope further includes a fusion splice, a first polarization-maintaining fiber, a second polarization-maintaining fiber, a third polarization-maintaining fiber, and a fourth polarization-maintaining fiber;

[0015] The fusion splice is connected to the optical paths of the first polarization-maintaining fiber and the second polarization-maintaining fiber, respectively, and the polarization-maintaining coupler is connected to the optical paths of the second polarization-maintaining fiber, the third polarization-maintaining fiber and the fourth polarization-maintaining fiber, respectively.

[0016] The sum of the lengths of the second polarization-maintaining fiber and the third polarization-maintaining fiber is a preset multiple of the length of the first polarization-maintaining fiber, and the lengths of the third polarization-maintaining fiber and the fourth polarization-maintaining fiber are equal.

[0017] In one embodiment, the first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the third polarization-maintaining fiber constitute a first depolarization optical path;

[0018] The first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the fourth polarization-maintaining fiber constitute the second depolarization optical path, and the depolarization characteristics of the first depolarization optical path and the second depolarization optical path are the same.

[0019] In one embodiment, the fiber optic gyroscope further includes a first detector, a fiber optic circulator, and a waveguide modulator;

[0020] The first detector is electrically connected to the gyroscope drive demodulation circuit, and the feedback end of the waveguide modulator is connected to the optical path of the first detector via the fiber optic circulator.

[0021] The waveguide modulator is used to generate an interference light signal based on the light wave after being depolarized by the first depolarized optical path under the control of the gyroscope drive demodulation circuit, and then transmit the interference light signal to the first detector through the fiber optic circulator.

[0022] The first detector is used to convert the interference optical signal into an electrical signal and transmit the electrical signal to the gyroscope drive demodulation circuit;

[0023] The gyroscope drive demodulation circuit is used to perform phase demodulation on the electrical signal and calculate the angular velocity measurement value of the fiber optic gyroscope.

[0024] Furthermore, to achieve the above objectives, this application also proposes a scrambling control method, which includes:

[0025] The system receives an adjustment signal from the gyroscope-driven demodulation circuit and adjusts the polarization state of the incident light based on the adjustment signal. The adjustment signal is generated by the gyroscope-driven demodulation circuit based on the second light wave, which is obtained by splitting the first light wave using the polarization beam splitter. The first light wave is emitted by the broadband light source and split by the polarization-maintaining coupler.

[0026] In one embodiment, the step of adjusting the polarization state of the incident light based on the adjustment signal includes:

[0027] Based on the adjustment signal, the polarization state of the fourth light wave transmitted again by the broadband light source is adjusted until the intensity of the light signals obtained by the polarization beam splitter is consistent.

[0028] In one embodiment, the step of adjusting the polarization state of the fourth light wave retransmitted by the broadband light source based on the adjustment signal until the intensity of the light signals obtained by the polarization beam splitter is consistent includes:

[0029] Based on the adjustment signal, the polarization state of the third light wave transmitted again by the fiber optic circulator is adjusted to obtain the fourth light wave;

[0030] The fourth light wave is transmitted to the polarization beam splitter through the second depolarization optical path, so that the second detector and the third detector respectively receive the polarized light decomposed by the polarization beam splitter, and convert the polarized light into an electrical signal, which is sent to the gyroscope drive demodulation circuit for intensity comparison until the light intensity of the electrical signal is consistent.

[0031] In one embodiment, the step of receiving the adjustment signal sent by the gyroscope drive demodulation circuit and adjusting the polarization state of the incident light based on the adjustment signal includes:

[0032] The adjusted incident light is transmitted to the waveguide modulator through the first depolarization optical path, so that the waveguide modulator generates interference light based on the adjusted incident light and sends the interference light to the first detector. Based on the gyroscope-driven demodulation circuit, the first detector calculates the angular velocity value of the electrical signal output by the first detector based on the interference light.

[0033] In addition, to achieve the above objectives, this application also proposes an anti-bias control device, the device comprising: a fiber optic gyroscope for implementing the scrambling control method described above.

[0034] One or more technical solutions proposed in this application have at least the following technical effects:

[0035] In related technologies, fiber optic gyroscopes commonly employ Lyot depolarizers to achieve depolarization. These depolarizers are typically made using the polarization-maintaining input pigtail of a Y-waveguide modulator. The pigtail is cut into two segments of polarization-maintaining fiber with a length ratio of 1:2, ensuring that the principal stress axes of the two segments are at 45°. While the above methods involve fusion splicing, they are passive elimination methods and cannot dynamically compensate for fluctuations in environmental conditions, severely affecting the measurement accuracy and stability of the gyroscope. In contrast, this application constructs a fiber optic gyroscope comprising a broadband light source, a polarization controller, a polarization-maintaining coupler, a polarization beamsplitter, a second detector, a third detector, and a gyroscope drive demodulation circuit. The polarization-maintaining coupler is optically connected to the polarization beamsplitter, and the gyroscope drive demodulation circuit is electrically connected to the polarization controller. This allows the polarization beamsplitter to receive the first light wave emitted by the broadband light source under the current environment, after being split by the polarization-maintaining coupler, and then split the first light wave again. The second light wave, resulting from this second split, is then sent to the gyroscope drive demodulation circuit. The gyroscope drive demodulation circuit can then generate an adjustment signal based on the second light wave and send it to the polarization controller. The polarization controller will then adjust the polarization state of the incident light based on the adjustment signal to adapt to fluctuations in environmental conditions, thereby improving the measurement accuracy and stability of the gyroscope. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the fiber optic gyroscope of this application;

[0039] Figure 2 This is a schematic diagram of the device structure of the hardware operating environment involved in the scrambling control method in the embodiments of this application.

[0040] Label:

[0041] Explanation of icon numbers:

[0042] (1) Broadband light source; (2) Fiber circulator; (3) Polarization controller; (4) 45° fusion splice; (5) 1×2 polarization-maintaining coupler; (7) Fiber circulator; (8) Detector 1; (9) Detector 2; (10) Detector 3; (11) Polarization beam splitter; (12) Gyroscope drive demodulation circuit.

[0043] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0044] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0045] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0046] The main solution of this application embodiment is as follows: The fiber optic gyroscope includes a broadband light source, a polarization controller, a polarization-maintaining coupler, a polarization beam splitter, a second detector, a third detector, and a gyroscope drive demodulation circuit; the polarization-maintaining coupler is optically connected to the polarization beam splitter, and the gyroscope drive demodulation circuit is electrically connected to the polarization controller; the polarization beam splitter is used to receive a first light wave emitted by the broadband light source and split by the polarization-maintaining coupler, and then splits the first light wave again, sending the second light wave after further splitting to the gyroscope drive demodulation circuit; the gyroscope drive demodulation circuit is used to generate an adjustment signal based on the second light wave and send it to the polarization controller; the polarization controller is used to adjust the polarization state of the incident light based on the adjustment signal.

[0047] Based on this, this application provides a fiber optic gyroscope including a broadband light source, a polarization controller, a polarization-maintaining coupler, a polarization beam splitter, a second detector, a third detector, and a gyroscope driving demodulation circuit. The polarization-maintaining coupler is optically connected to the polarization beam splitter, and the gyroscope driving demodulation circuit is electrically connected to the polarization controller. The polarization beam splitter receives a first light wave emitted by the broadband light source and split by the polarization-maintaining coupler, further splits the first light wave, and sends a second light wave after further splitting to the gyroscope driving demodulation circuit. The gyroscope driving demodulation circuit generates an adjustment signal based on the second light wave and sends it to the polarization controller. The polarization controller adjusts the polarization state of the incident light based on the adjustment signal.

[0048] Specifically, in mixed-polarity fiber optic gyroscopes, polarization noise is the key error source affecting zero-polarity stability. Components in the optical path, such as the Y-waveguide modulator and fiber optic ring, are polarization sensitive: the Y-waveguide modulator operates based on a specific polarization state (usually the TE mode), and polarization state fluctuations lead to unstable modulation efficiency; the fiber optic ring undergoes birefringence changes under temperature variations and mechanical stress, amplifying the non-reciprocal phase shift caused by polarization fluctuations. Therefore, depolarization processing of the light source output is necessary to reduce gyroscope drift introduced by polarization.

[0049] It should be noted that the broadband light source uses either an SLD or ASE light source, with a working wavelength of 1310nm or 1550nm, and an output optical power stability of ≤±2% (full temperature range). The polarization controller is an electro-optic polarization controller with a response speed ≥1kHz, enabling continuous adjustment of the polarization state from 0° to 360° with an adjustment accuracy ≤0.5°. The polarization-maintaining coupler is a 1×2 polarization-maintaining coupler with a splitting ratio of 50:50±5%, a polarization-dependent loss ≤0.1dB, and a working bandwidth covering the output wavelength of the broadband light source. The polarization extinction ratio of the polarization beamsplitter is ≥30dB, with an insertion loss ≤0.3dB, and it can decompose the incident light wave into a horizontally polarized state (p-light) and a vertically polarized state (s-light). The gyroscope drive demodulation circuit integrates signal acquisition, comparison, feedback control, and angular velocity demodulation functions, with a closed-loop control period ≤10ms. The first light wave refers to the depolarized light transmitted to the polarization beamsplitter via the first depolarized optical path. The second light wave is the optical signal corresponding to the two orthogonally polarized components.

[0050] The entire process constitutes a polarization state closed-loop control flow: After the broadband light source is initially adjusted by the polarization controller, it is sent to the Y-waveguide modulator and the polarization beam splitter respectively through the dual depolarization optical path structure. The latter decomposes the light into orthogonal polarization components, which are detected by two detectors. The gyroscope-driven demodulation circuit determines the polarization balance state accordingly and outputs an adjustment signal to the polarization controller when there is an imbalance, thereby realizing real-time correction of the incident polarization state and ensuring that the polarization degree of the light wave entering the Y-waveguide modulator is ≤0.03.

[0051] The second optical wave includes a first optical signal and a second optical signal. The fiber optic gyroscope further includes a second detector and a third detector. The polarization beam splitter is optically connected to the second detector and the third detector, respectively. The gyroscope drive demodulation circuit is electrically connected to the second detector and the third detector, respectively. The polarization beam splitter is used to receive the first optical wave emitted by the broadband light source and split by the polarization-maintaining coupler, and then splits the first optical wave again. The first optical signal and the second optical signal after the second split are sent to the second detector and the third detector, respectively. The second detector and the third detector are used to convert the first optical signal and the second optical signal into corresponding electrical signals, respectively, and send the electrical signals to the gyroscope drive demodulation circuit. The gyroscope drive demodulation circuit is used to compare the intensity difference between the electrical signals. If the intensity difference is greater than a threshold, an adjustment signal is generated and sent to the polarization controller.

[0052] It is understood that the first and second optical signals refer to the horizontally polarized state (p-light) and the vertically polarized state (s-light). Both the second and third detectors are PIN photodetectors with a responsivity ≥0.9A / W and dark current ≤1nA, ensuring high-sensitivity detection of the optical signals. The threshold is a preset light intensity imbalance tolerance, typically set so that the deviation of the two light intensity ratios from 1:1 does not exceed ±1% (corresponding to an electrical signal difference ≤20 mV). This threshold can be dynamically configured according to the system's zero-bias stability requirements.

[0053] After initial polarization control, the emitted light from the broadband light source is split into a main interference path and a polarization monitoring path via a polarization-maintaining coupler. The light wave in the latter enters a polarization beamsplitter and is decomposed into two orthogonal polarization components, which are converted into electrical signals by the second and third detectors and sent to the gyroscope-driven demodulation circuit. The circuit continuously checks whether the two signals meet the polarization balance condition. If imbalance is found, an adjustment signal is generated to drive the polarization controller until the intensity of the two light paths becomes consistent, thus ensuring that the light entering the main interference path (such as a Y-waveguide) has high depolarization characteristics. By introducing dual detectors to independently detect the orthogonal polarization components and constructing a high-sensitivity polarization balance criterion based on their intensity difference, precise closed-loop control of the incident light's polarization state is achieved. Compared to the background technology that relies solely on fixed-structure depolarizers (such as Lyot depolarizers) and cannot cope with dynamic disturbances such as light source polarization drift and birefringence changes caused by temperature stress, this scheme utilizes a polarization monitoring branch that shares a common source and path with the main optical path, combined with a high-speed electronically controlled polarization adjustment mechanism, significantly improving the system's polarization stability across the entire temperature range and during long-term operation.

[0054] The fiber optic gyroscope further includes a fusion splice, a first polarization-maintaining fiber, a second polarization-maintaining fiber, a third polarization-maintaining fiber, and a fourth polarization-maintaining fiber; the fusion splice is connected to the optical paths of the first polarization-maintaining fiber and the second polarization-maintaining fiber, respectively, and the polarization-maintaining coupler is connected to the optical paths of the second polarization-maintaining fiber, the third polarization-maintaining fiber, and the fourth polarization-maintaining fiber, respectively; the sum of the lengths of the second polarization-maintaining fiber and the third polarization-maintaining fiber is a preset multiple of the length of the first polarization-maintaining fiber, and the lengths of the third polarization-maintaining fiber and the fourth polarization-maintaining fiber are equal.

[0055] It should be noted that the fusion splice is a 45° fusion splice, fabricated using a high-precision polarization-maintaining fusion splicer. The stress principal axis angle between the two polarization-maintaining fiber segments is 45°±0.5°, and the fusion loss is ≤0.1dB. The first polarization-maintaining fiber L1 is the polarization-maintaining fiber segment from the broadband light source output end to the fusion splice. The second polarization-maintaining fiber L2 connects the fusion splice to one input port of the polarization-maintaining coupler. The third polarization-maintaining fiber L3 and the fourth polarization-maintaining fiber L4 constitute the output arms of the main interference optical path and the polarization monitoring optical path, respectively. Both are connected to the two output ports of the polarization-maintaining coupler and lead to the Y-waveguide modulator (or sensing ring) and the polarization beam splitter, respectively. The preset multiplier is usually 2, i.e., L2+L3=2*L1, to ensure that the accumulated birefringence phase difference between the two polarization-maintaining fiber segments exactly cancels the polarization-dependent noise within the coherence length of the light source, achieving effective depolarization. Furthermore, L3=L4 is used to ensure that the main optical path and the polarization monitoring optical path have the same optical path length and temperature-stress response characteristics, so that the light energy received by the polarization beam splitter can truly reflect the polarization state in the main interference optical path.

[0056] Specifically, the entire optical path structure constitutes a symmetrical dual depolarization architecture: the light emitted from the broadband light source passes sequentially through the first polarization-maintaining fiber, the 45° fusion splice, and the second polarization-maintaining fiber into the polarization-maintaining coupler. After being equally split, it is sent to the main interference branch and the polarization monitoring branch through the third and fourth polarization-maintaining fibers of equal length. The polarization monitoring branch realizes polarization state feedback through a polarization beam splitter and dual detectors, while the main interference branch is used for Sagnac effect detection. The two share the front-end depolarization path to ensure the effectiveness and consistency of polarization control.

[0057] The first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the third polarization-maintaining fiber constitute a first depolarization optical path; the first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the fourth polarization-maintaining fiber constitute a second depolarization optical path, and the depolarization characteristics of the first depolarization optical path and the second depolarization optical path are the same.

[0058] It is understandable that the first and second depolarization paths follow the exact same front-end path (first polarization-maintaining fiber → fusion splice → second polarization-maintaining fiber → polarization-maintaining coupler). They share the same Lyot depolarization structure (composed of L1, fusion splice, and L2) and satisfy the length constraints L2+L3=2*L1 and L3=L4. This ensures that the additional birefringence introduced by the third and fourth polarization-maintaining fibers is exactly the same, thereby guaranteeing that the polarization state statistical distribution, residual polarization degree, and response characteristics to temperature / stress of the two output lights are highly consistent. This design ensures that the polarization state detected by the polarization monitoring branch can truly and without distortion represent the actual polarization state of the main interference branch, providing a reliable basis for subsequent closed-loop feedback control.

[0059] Compared to the problems of limited depolarization efficiency due to splicing errors, inability to adapt to temperature changes, and high residual polarization degree (≥0.05) caused by passive Lyot depolarizers in the background technology, this solution utilizes a second depolarization optical path that is completely symmetrical with the main optical path for indirect monitoring of polarization state. Millisecond-level feedback adjustment is achieved through a high-speed electro-optic polarization controller, effectively suppressing polarization noise caused by environmental disturbances such as light source polarization drift and changes in fiber birefringence, significantly improving zero-polarization stability across the entire temperature range (-40℃~85℃). This technology not only solves the bottleneck problem of large zero-polarization drift in traditional mixed-polarity fiber optic gyroscopes in high-precision scenarios (such as inertial navigation and satellite attitude control), but also avoids structural modifications to core components such as Y-waveguides or fiber rings, possessing good engineering compatibility and cost controllability.

[0060] Specifically, refer to Figure 1 , Figure 1 A structural diagram of a fiber optic gyroscope is provided. A broadband light source (1) outputs 1550nm SLD light, which enters the polarization controller (3) through the fiber optic circulator (2), and then enters the 1×2 polarization coupler (5) through the L1=1.5m polarization-maintaining fiber, the 45° fusion splice (4), and the L2=1m polarization-maintaining fiber. One beam of light enters the Y-waveguide modulator (6) through the L3=2m polarization-maintaining fiber for Sagnac interferometry, and the other beam of light enters the polarization beam splitter (11) through the L4=2m polarization-maintaining fiber (satisfying L3=L4 and L2+L3=2L1), and is decomposed into p-light and s-light, which are received by detector 2 (9) and detector 3 (10) respectively. The gyroscope drive demodulation circuit (12) compares the intensity of the two electrical signals in real time. When the difference exceeds 1%, it immediately sends an adjustment command to the polarization controller (3) to fine-tune the polarization axis angle until the intensity of the two light signals is consistent.

[0061] The first detector is electrically connected to the gyroscope drive demodulation circuit, and the feedback terminal of the waveguide modulator is optically connected to the first detector via the fiber optic circulator. The waveguide modulator, under the control of the gyroscope drive demodulation circuit, generates an interference light signal based on the light wave depolarized by the first depolarized optical path, and then transmits the interference light signal to the first detector via the fiber optic circulator. The first detector converts the interference light signal into an electrical signal and transmits the electrical signal to the gyroscope drive demodulation circuit. The gyroscope drive demodulation circuit performs phase demodulation on the electrical signal and calculates the angular velocity measurement value of the fiber optic gyroscope.

[0062] It should be noted that the first detector is a high-bandwidth, low-noise PIN or APD photodetector, used to receive the Sagnac interference optical signal returned from the waveguide modulator and convert it into an analog current / voltage signal. The waveguide modulator, specifically the Y-waveguide modulator, is used, under the control of the gyroscope-driven demodulation circuit, to split the depolarized light wave after passing through the first depolarization optical path into two opposing optical signals (clockwise and counterclockwise). The two optical signals propagate along the fiber optic loop, and a Sagnac phase shift is generated when the fiber rotates around the sensitive axis. After the two optical signals reach the end of the fiber optic loop, they are combined by the Y-waveguide modulator to form an interference optical signal, which is then transmitted to the first detector via the fiber optic circulator. The first detector converts the interference optical signal into an electrical signal, which is transmitted to the gyroscope-driven demodulation circuit. The gyroscope-driven demodulation circuit performs phase demodulation on this electrical signal and calculates the angular velocity measurement value of the fiber optic gyroscope.

[0063] Furthermore, the light wave after depolarization by the first depolarization optical path refers to the broadband light that has undergone Lyot depolarization processing through the L1–45° fusion point–L2–L3 path, with a residual polarization degree ≤0.03, ensuring that the two beams entering the waveguide modulator have high polarization consistency, thereby suppressing non-reciprocal phase noise caused by polarization crosstalk.

[0064] This implementation achieves efficient suppression of the polarization characteristics of broadband light sources by constructing a polarization-maintaining fiber length relationship that satisfies L2+L3=2*L1 and L3=L4, and forming a Lyot depolarization structure by combining a 45° fusion splice. At the same time, by using a common path and equal length main / monitoring optical path design, the polarization monitoring results can accurately map the actual polarization state of the main interference optical path.

[0065] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description and will not be repeated hereafter. Based on this, the deviation control method includes step S01:

[0066] Step S01: Receive the adjustment signal sent by the gyroscope drive demodulation circuit, and adjust the polarization state of the incident light based on the adjustment signal. The adjustment signal is generated by the gyroscope drive demodulation circuit based on the second light wave. The second light wave is obtained by splitting the first light wave by the polarization beam splitter. The first light wave is emitted by the broadband light source and obtained by splitting the beam by the polarization-maintaining coupler.

[0067] It should be noted that the execution entity in this embodiment is a polarization controller. The incident light refers to the optical signal originating from the broadband light source and entering the polarization controller. The polarization controller first receives an adjustment signal from the gyroscope-driven demodulation circuit. This adjustment signal is generated by the gyroscope-driven demodulation circuit based on the polarization information contained in the second light wave. The second light wave itself is obtained by orthogonally polarizing the first light wave using a polarization beamsplitter, resulting in two optical components. The first light wave is the original broadband light emitted from the broadband light source, which is guided to the polarization monitoring branch after being split by the polarization-maintaining coupler. The polarization controller dynamically adjusts the operating state of its internal phase delay unit according to this adjustment signal, thereby changing the polarization ellipticity and azimuth angle of the incident light, causing the polarization state of its output light to tend towards the optimal direction required by the system. This ensures that the light processed by the subsequent depolarization structure achieves intensity balance between the s-ray and p-ray at the polarization beamsplitter, providing high-quality depolarization input light for the main interference optical path.

[0068] Furthermore, when the intensity difference between the second light waves exceeds a preset tolerance threshold, the adjustment signal sent by the gyroscope drive demodulation circuit is received;

[0069] It should be noted that the second light wave consists of two orthogonally polarized components formed after being split by a polarization beamsplitter: the first optical signal (e.g., s-polarized light) and the second optical signal (e.g., p-polarized light). The preset tolerance threshold is the upper limit of polarization imbalance set by the system according to the design accuracy requirements. A typical value is that the intensity ratio of the two light sources deviates from 1:1 by no more than ±1% (corresponding to an electrical signal difference of approximately 10–20 mV). The adjustment signal is a feedback control command generated by the gyroscope-driven demodulation circuit after it detects in real-time that the intensity difference exceeds the tolerance threshold. It is usually an analog voltage or serial communication signal, used to drive the electro-optic or liquid crystal phase modulation unit inside the polarization controller to adjust the polarization ellipticity and azimuth angle of the incident light. After the gyroscope-driven demodulation circuit detects in real-time that the intensity difference exceeds the tolerance threshold, the polarization controller receives the adjustment signal sent by the circuit and drives the electro-optic or liquid crystal phase modulation unit inside the polarization controller to adjust the polarization ellipticity and azimuth angle of the incident light.

[0070] Optionally, after the gyroscope drive demodulation circuit generates the adjustment signal, the adjustment signal is sent to the polarization controller after a preset light propagation delay, wherein the preset light propagation delay is equal to the time required for the incident light to propagate from the polarization controller through the second depolarization optical path to the polarization beam splitter.

[0071] Understandably, because the adjustment signal in this application waits for the same amount of time as the light propagates in the monitoring branch before acting on the polarization controller, the adjustment action is precisely applied to the light wave about to enter the monitoring branch in the next round. Instead of using iterative polarization correction for light that is not currently in transit, and because the main / monitoring optical paths have a fixed transmission delay, the timing of the synchronous adjustment and the position of the light wave can actually avoid control misalignment and oscillation. Furthermore, this approach is only meaningful in closed-loop polarization systems with a defined optical path length, measurable propagation delay, and discrete periodic adjustment. Since this delay time precisely matches the transmission time of light from the polarization controller to the polarization beam splitter, when the adjustment takes effect, it coincides with the arrival of the third light wave emitted by the broadband light source and transmitted through the fiber optic circulator at the polarization controller. This third light wave is then adjusted to a new polarization state (becoming the fourth light wave) and enters the second depolarization optical path in subsequent cycles, its polarization state accurately reflecting the effect of this adjustment.

[0072] Optionally, after the gyroscope drive demodulation circuit generates an adjustment signal and delays the preset light propagation delay, the adjustment signal is applied to the polarization controller in the form of a differential increment, wherein the differential increment is the difference between the current adjustment signal and the reference polarization configuration of the previous cycle, and an update is performed only when the difference exceeds the set minimum effective step size.

[0073] It should be noted that the differential increment form means that the adjustment signal is not output as an absolute control parameter (such as "voltage = 3.2V"), ​​but as a correction amount relative to the previous effective polarization state (such as "voltage change ΔV = +0.05V"). The polarization controller internally accumulates this increment to update the current output state. The previous cycle reference polarization configuration refers to the polarization controller control parameters stored at the time of the most recent determination of polarization balance (i.e., the light intensities of the second and third detectors are consistent), serving as the reference starting point for the current adjustment. The minimum effective step size refers to the control quantity threshold corresponding to the smallest polarization state change that the polarization controller can resolve; adjustments below this value are considered noise disturbances. After generating a new adjustment signal, the gyroscope-driven demodulation circuit first calculates the difference between the signal and the reference polarization configuration of the previous cycle to obtain the differential increment. Then, the circuit determines whether the absolute value of the differential increment exceeds the preset minimum effective step size. If it does not exceed the limit, the current polarization controller output remains unchanged. If it does exceed the limit, the differential increment is temporarily stored, and after a delay equal to the time required for light to propagate from the polarization controller through the second depolarization optical path to the polarization beam splitter, the increment is applied to the polarization controller to fine-tune it based on the original reference configuration. The adjusted polarization state acts on the next round of incident light, is transmitted through the second depolarization optical path, and is decomposed by the polarization beam splitter. The effect is verified by feedback from the dual detectors, and the reference configuration is updated or maintained accordingly.

[0074] In one feasible implementation, the step of adjusting the polarization state of the incident light based on the adjustment signal includes:

[0075] Based on the adjustment signal, the polarization state of the third light wave transmitted again by the broadband light source is adjusted until the intensity of the light signals obtained by the polarization beam splitter is consistent.

[0076] It is understandable that the third light wave refers to the broadband optical signal emitted by the broadband light source after receiving feedback adjustment and transmitted to the polarization controller. It is used to replace or update the previous incident light, and its polarization state can be corrected by the polarization controller according to the adjustment signal. The polarization controller dynamically adjusts the polarization state of the third light wave subsequently emitted by the broadband light source based on the adjustment signal sent by the gyroscope-driven demodulation circuit. This adjustment is achieved by changing the parameters (such as voltage or stress) of the phase delay unit inside the polarization controller, so that the polarization ellipticity and azimuth angle of the third light wave gradually approach the optimal polarization direction required by the circuit. The adjusted third light wave is transmitted to the polarization beam splitter through the front-end depolarization structure (including the first polarization-maintaining fiber, fusion splice, second polarization-maintaining fiber, etc.) and the polarization-maintaining coupler, and is decomposed into two orthogonal polarization components. The gyroscope-driven demodulation circuit continuously monitors the light intensity of these two components and uses the consistency of intensity as the convergence criterion to iteratively update the adjustment signal until the intensity of the two optical signals output by the polarization beam splitter reaches a preset equilibrium state. This ensures that the light entering the main interference optical path has extremely low residual polarization, providing a stable polarization environment for high-precision interferometric measurements in the main optical path.

[0077] In one feasible implementation, the step of adjusting the polarization state of the third light wave retransmitted by the broadband light source based on the adjustment signal until the intensity of the light signals obtained by the polarization beam splitter is consistent includes:

[0078] Based on the adjustment signal, the polarization state of the third light wave transmitted again by the fiber optic circulator is adjusted to obtain the fourth light wave;

[0079] It should be noted that the fiber optic circulator is used to guide the light from the broadband light source to the polarization controller and can route the reflected or returned light to the detector. The fourth light wave refers to the optical signal output after the polarization state of the third light wave is adjusted by the polarization controller according to the adjustment signal. Its polarization direction and ellipticity have been optimized according to the system feedback requirements and are used for subsequent depolarization optical path transmission. The polarization controller receives the adjustment signal sent by the gyroscope-driven demodulation circuit and acts on the third light wave transmitted again by the fiber optic circulator. Specifically, the polarization controller dynamically changes the working state of its internal phase delay unit (such as liquid crystal layer voltage or piezoelectric structure) according to the adjustment signal to precisely control the polarization ellipticity and azimuth angle of the third light wave, thereby generating a fourth light wave with an optimized polarization state. This fourth light wave is then sent to the front-end depolarization structure (including the first polarization-maintaining fiber, the 45° fusion splice, the second polarization-maintaining fiber, etc.) as the input light for the next round of polarization monitoring and main interferometry.

[0080] The fourth light wave is transmitted to the polarization beam splitter through the second depolarization optical path, so that the second detector and the third detector respectively receive the polarized light decomposed by the polarization beam splitter, and convert the polarized light into an electrical signal, which is sent to the gyroscope drive demodulation circuit for intensity comparison until the light intensity of the electrical signal is consistent.

[0081] Understandably, the polarization controller processes the fourth light wave through the second depolarization optical path and outputs it to the polarization beam splitter. The polarization beam splitter decomposes the first light wave into two light signals according to the orthogonal polarization direction. These signals are then converted into electrical signals by the second and third detectors and sent to the gyroscope drive demodulation circuit. This circuit determines the current polarization balance state by comparing the intensity difference between the two electrical signals. If the deviation exceeds a preset threshold, an adjustment signal is generated and fed back to the polarization controller to dynamically adjust its output polarization state. This enables real-time anti-polarization compensation for polarization mismatch caused by environmental disturbances (such as temperature drift and stress changes) in the first depolarization optical path.

[0082] Specifically, since a polarization beam splitter (PBS) is an optical device that completely separates incident light according to orthogonal polarization states, if the incident light is completely randomly polarized (i.e., natural light or ideal depolarized light), and its polarization state is uniformly distributed in all directions in time or wavelength, then after passing through the PBS, the average power of the s component and the p component are equal, that is, the ratio of the two output light intensities is 1:1. Therefore, the two output light intensities are equal, which indicates that effective depolarization has been achieved. Furthermore, since the polarization monitoring branch (second depolarization optical path) and the main interference branch (first depolarization optical path) are structurally completely symmetrical, when the two light intensities output by the PBS in the monitoring optical path are equal, it indicates that the output light of this branch has been highly depolarized. Since the main optical path is completely consistent with it, the light entering the Y waveguide or fiber ring in the main optical path must also be in the same depolarization state.

[0083] In one feasible implementation, the step of receiving the adjustment signal sent by the gyroscope drive demodulation circuit and adjusting the polarization state of the incident light based on the adjustment signal includes:

[0084] The adjusted incident light is transmitted to the waveguide modulator through the first depolarization optical path, so that the waveguide modulator generates interference light based on the adjusted incident light and sends the interference light to the first detector. Based on the gyroscope-driven demodulation circuit, the first detector calculates the angular velocity value of the electrical signal output by the first detector based on the interference light.

[0085] It should be noted that the interference light refers to the intensity-modulated light formed by the coherent superposition of two depolarized beams propagating clockwise (CW) and counterclockwise (CCW) in the waveguide modulator at the output end. Its intensity varies with the Sagnac phase shift caused by rotation. The incident light, after its polarization state is adjusted by the polarization controller, is sent to the first depolarization optical path, and passes sequentially through the first polarization-maintaining fiber, the 45° fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the third polarization-maintaining fiber to complete high-precision Lyot depolarization processing and output broadband light with low polarization degree. After entering the waveguide modulator, the light is split into two beams, clockwise and counterclockwise, which propagate in opposite directions in the fiber optic sensing loop and generate a non-reciprocal phase shift proportional to the angular velocity due to the Sagnac effect. The two beams return to the waveguide modulator and are recombined to form the interference light. The interference light is transmitted to the first detector through the fiber optic circulator (or directly) and converted into a corresponding electrical signal. The electrical signal is sent to the gyroscope drive demodulation circuit, which executes the phase demodulation algorithm to calculate the angular velocity measurement value under the current rotation state. This enables a complete sensing link from polarization-optimized input to high-precision angular velocity output, ensuring that measurement results are not affected by polarization noise.

[0086] Furthermore, before the adjusted incident light is transmitted to the waveguide modulator through the first depolarized optical path, the fourth light wave is simultaneously transmitted to the polarization beam splitter through the second depolarized optical path. Only after the gyroscope drive demodulation circuit determines that the electrical signal light intensity output by the second detector and the third detector is consistent is the light in the first depolarized optical path allowed to enter the waveguide modulator for interference.

[0087] Furthermore, referring to Figure 1 When the polarization degree of the light wave input to the Y-waveguide modulator (6) is close to 0, the Y-waveguide modulator (6), under the control of the gyroscope drive demodulation circuit (12), splits the light wave after depolarization through the first depolarization optical path into two beams of optical signals that are transmitted in opposite directions (clockwise and counterclockwise). The two beams of optical signals are transmitted along the fiber loop (7). When the fiber rotates around the sensitive axis, a Sagnac phase shift is generated. After the two beams of optical signals are transmitted to the end of the fiber loop (7), they are combined by the Y-waveguide modulator (6) to form an interference light signal, and then transmitted to the detector 1 (8) through the fiber circulator. The detector 1 (8) converts the interference light signal into an electrical signal and transmits it to the gyroscope drive demodulation circuit (12). The gyroscope drive demodulation circuit (12) performs phase demodulation on the electrical signal and calculates the angular velocity measurement value of the fiber optic gyroscope.

[0088] In this embodiment, a closed-loop iterative adjustment mechanism is used to enable the fiber optic gyroscope to have self-calibration and self-adaptation capabilities. Since the second depolarization optical path and the main interference optical path have the same depolarization structure and environmental response characteristics, when the intensity of the two optical paths output by the polarization beam splitter is consistent, it can be confirmed that the polarization disturbance in the main optical path has been effectively suppressed, thereby fundamentally eliminating the non-reciprocal phase error caused by residual polarization.

[0089] This application provides an anti-bias control device, which includes a fiber optic gyroscope capable of performing the functions described in Embodiment 1 above.

[0090] The following is for reference. Figure 2 The diagram illustrates a structural schematic suitable for implementing the anti-bias control device in the embodiments of this application. The anti-bias control device in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, tablets, digital broadcast receivers, PDAs (Personal Digital Assistants), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 2 The anti-bias control device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0091] like Figure 2 As shown, the anti-bias control device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the anti-bias control device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touchscreen, touchpad, keyboard, mouse, image sensor, microphone, accelerometer, gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; storage devices 1003 including, for example, magnetic tape, hard disk, etc.; and communication devices 1009. Communication device 1009 allows the anti-bias control device to communicate wirelessly or wiredly with other devices to exchange data. Although the figures show anti-bias control devices with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0092] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0093] The anti-bias control device provided in this application, employing the disturbance control method in the above embodiments, can solve the technical problem of anti-bias control. Compared with the prior art, the beneficial effects of the anti-bias control device provided in this application are the same as those of the disturbance control method provided in the above embodiments, and other technical features of the anti-bias control device are the same as those disclosed in the method of the previous embodiment, and will not be repeated here.

[0094] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0095] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0096] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described scrambling control method.

[0097] The computer program product provided in this application can solve the technical problem of anti-bias control. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as the beneficial effects of the scrambling control method provided in the above embodiments, and will not be repeated here.

[0098] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the scope of protection of this application.

Claims

1. A fiber optic gyroscope, characterized in that, The fiber optic gyroscope includes a broadband light source, a polarization controller, a polarization-maintaining coupler, a polarization beam splitter, a second detector, a third detector, and a gyroscope drive demodulation circuit. The polarization-maintaining coupler is connected to the optical path of the polarization beam splitter, and the gyroscope drive demodulation circuit is electrically connected to the polarization controller; the polarization beam splitter is connected to the optical paths of the second detector and the third detector respectively, and the gyroscope drive demodulation circuit is electrically connected to the second detector and the third detector respectively. The polarization beam splitter is used to receive the first light wave emitted by the broadband light source and split by the polarization-maintaining coupler, and to split the first light wave again, and to send the first optical signal and the second optical signal after the second split to the second detector and the third detector, respectively. The second detector and the third detector are used to convert the first optical signal and the second optical signal into corresponding electrical signals, respectively, and send the electrical signals to the gyroscope drive demodulation circuit; The gyroscope drive demodulation circuit is used to compare the intensity difference between the electrical signals. If the intensity difference is greater than a threshold, an adjustment signal is generated and sent to the polarization controller. The polarization controller is used to adjust the polarization state of the incident light based on the adjustment signal.

2. The fiber optic gyroscope as described in claim 1, characterized in that, The fiber optic gyroscope also includes a fusion splice, a first polarization-maintaining fiber, a second polarization-maintaining fiber, a third polarization-maintaining fiber, and a fourth polarization-maintaining fiber. The fusion splice is connected to the optical paths of the first polarization-maintaining fiber and the second polarization-maintaining fiber, respectively, and the polarization-maintaining coupler is connected to the optical paths of the second polarization-maintaining fiber, the third polarization-maintaining fiber and the fourth polarization-maintaining fiber, respectively. The sum of the lengths of the second polarization-maintaining fiber and the third polarization-maintaining fiber is a preset multiple of the length of the first polarization-maintaining fiber, and the lengths of the third polarization-maintaining fiber and the fourth polarization-maintaining fiber are equal.

3. The fiber optic gyroscope as described in claim 2, characterized in that, The first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the third polarization-maintaining fiber constitute the first depolarization optical path; The first polarization-maintaining fiber, the fusion splice, the second polarization-maintaining fiber, the polarization-maintaining coupler, and the fourth polarization-maintaining fiber constitute the second depolarization optical path, and the depolarization characteristics of the first depolarization optical path and the second depolarization optical path are the same.

4. The fiber optic gyroscope as described in claim 3, characterized in that, The fiber optic gyroscope also includes a first detector, a fiber optic circulator, and a waveguide modulator; The first detector is electrically connected to the gyroscope drive demodulation circuit, and the feedback end of the waveguide modulator is connected to the optical path of the first detector via the fiber optic circulator. The waveguide modulator is used to generate an interference light signal based on the light wave after being depolarized by the first depolarized optical path under the control of the gyroscope drive demodulation circuit, and then transmit the interference light signal to the first detector through the fiber optic circulator. The first detector is used to convert the interference optical signal into an electrical signal and transmit the electrical signal to the gyroscope drive demodulation circuit; The gyroscope drive demodulation circuit is used to perform phase demodulation on the electrical signal and calculate the angular velocity measurement value of the fiber optic gyroscope.

5. A polarization scrambling control method, wherein the polarization scrambling control method is applied to the polarization controller in the fiber optic gyroscope according to any one of claims 1 to 4, characterized in that, The perturbation control method includes: The system receives an adjustment signal sent by the gyroscope drive demodulation circuit and adjusts the polarization state of the incident light based on the adjustment signal. The adjustment signal is generated by the gyroscope drive demodulation circuit when the intensity difference between electrical signals is greater than a threshold. The electrical signals are obtained by the second detector and the third detector converting the first optical signal and the second optical signal, respectively. The first optical signal and the second optical signal are obtained by the polarization beam splitter splitting the first light wave. The first light wave is emitted by the broadband light source and obtained by the polarization-maintaining coupler splitting the beam.

6. The swerve control method as described in claim 5, characterized in that, The step of adjusting the polarization state of the incident light based on the adjustment signal includes: Based on the adjustment signal, the polarization state of the third light wave transmitted again by the broadband light source is adjusted until the intensity of the light signals obtained by the polarization beam splitter is consistent.

7. The stalking control method as described in claim 6, characterized in that, The step of adjusting the polarization state of the third light wave transmitted again by the broadband light source based on the adjustment signal until the intensity of the light signals obtained by the polarization beam splitter is consistent includes: Based on the adjustment signal, the polarization state of the third light wave transmitted again by the fiber optic circulator is adjusted to obtain the fourth light wave; The fourth light wave is transmitted to the polarization beam splitter through the second depolarization optical path, so that the second detector and the third detector respectively receive the polarized light decomposed by the polarization beam splitter, and convert the polarized light into an electrical signal, which is sent to the gyroscope drive demodulation circuit for intensity comparison until the light intensity of the electrical signal is consistent.

8. The stalking control method as described in claim 6, characterized in that, The step of receiving the adjustment signal sent by the gyroscope drive demodulation circuit and adjusting the polarization state of the incident light based on the adjustment signal includes: The adjusted incident light is transmitted to the waveguide modulator through the first depolarization optical path, so that the waveguide modulator generates interference light based on the adjusted incident light and sends the interference light to the first detector. Based on the gyroscope drive demodulation circuit, the first detector calculates the angular velocity value of the electrical signal output by the first detector based on the interference light.

9. An anti-bias control device, characterized in that, The device includes: a fiber optic gyroscope as described in any one of claims 1 to 4.

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