Method and device for detecting angular velocity

Abstract

The present application provides a method and device for detecting an angular velocity. A polarization maintaining function is implemented by means of polarization rotators and a single-mode fiber, so that an input polarization state is aligned with a polarization principal state of the single-mode fiber, and meanwhile, phase modulation is performed by means of a 3*3 coupler or a phase modulator, thereby achieving the purpose of cost reduction and ensuring the detection performance of the device.

Description

A method and apparatus for detecting angular velocity

[0001] This application claims priority to Chinese Patent Application No. 202411526598.8, filed on October 29, 2024, entitled "A Method and Apparatus for Detecting Angular Velocity", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical gyroscope technology, and more specifically, to a method and apparatus for detecting angular velocity. Background Technology

[0003] As a high-precision sensor, the fiber optic gyroscope (FOG) can support long-endurance, high-precision fiber optic inertial navigation to achieve long-term autonomous and covert navigation, which is of great strategic significance.

[0004] The high cost of current fiber optic gyroscopes is primarily due to the cost constraints of polarization-maintaining fiber and lithium niobate modulators. Polarization-maintaining fiber is a crucial component in fiber optic gyroscopes, ensuring that the polarization direction of the outgoing light matches that of the incident light through enhanced birefringence. Its manufacturing process is relatively complex, requiring precise control of the fiber's geometry and material properties to ensure excellent matched birefringence and good geometric uniformity. The characteristics of polarization-maintaining fiber are critical to the accuracy and stability of fiber optic gyroscopes, but the complex fabrication process correspondingly increases costs. Lithium niobate modulators are used in fiber optic gyroscopes for phase modulation of light. This material exhibits a strong photoelectric effect, allowing for effective phase modulation at very low voltages without affecting amplitude, making it a key component for Sagnac effect measurements. However, the processing difficulty of lithium niobate crystals contributes to the high cost of lithium niobate modulators.

[0005] Therefore, reducing costs while ensuring the performance of fiber optic gyroscopes is an urgent problem to be solved. Summary of the Invention

[0006] This application provides a method and apparatus for detecting angular velocity. The polarization-maintaining function is achieved through an on-chip polarization rotator and a single-mode fiber, so that the input polarization state is consistent with the dominant polarization state of the single-mode fiber, avoiding polarization fluctuations, thereby reducing costs and ensuring the detection performance of the apparatus.

[0007] In a first aspect, a communication device is provided, comprising: a first coupler, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a third photodetector, and a fourth photodetector, and a single-mode fiber loop; a second port of the first coupler is coupled to a first port of the first polarization rotator, the first port of the first polarization rotator is connected to the first photodetector, the second port of the first polarization rotator is coupled to a first port of the single-mode fiber loop, the third port of the first coupler is coupled to a first port of the second polarization rotator, the first port of the second polarization rotator is connected to the second photodetector, and the second port of the second polarization rotator is connected to the first photodetector. The first coupler is coupled at its second port, with its fourth port connected to the third photodetector and its fifth port connected to the fourth photodetector. The first coupler receives a light beam through its first port, processes the beam, outputs a first optical signal through its second port, outputs a second optical signal through its third port, and outputs a third optical signal through its sixth port. The first optical signal is transmitted to the single-mode fiber loop via the first polarization rotator, outputs from the single-mode fiber loop via the second polarization rotator, and then enters the first coupler again through its third port. After processing by the first coupler, a fourth optical signal is output from the fourth port and the fifth port. The second optical signal is transmitted to the single-mode fiber loop via the second polarizer, and output from the single-mode fiber loop via the first polarization rotator. It then enters the first coupler through the second port, is processed by the first coupler, and outputs a fifth optical signal from the fourth port and the fifth port. The first photodetector is used to detect the second optical signal. The first polarization rotator is used to adjust the polarization state of the first optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the first photodetector. The polarization state of the adjusted signal is consistent with the polarization state of the second optical signal input from the second port of the first polarization rotator; the second photodetector is used to detect the first optical signal; the second polarization rotator is used to adjust the polarization state of the second optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the second photodetector, and the polarization state of the adjusted second optical signal is consistent with the polarization state of the first optical signal input from the second port of the second polarization rotator; the third photodetector is used to detect the fourth optical signal and the fifth optical signal; the fourth photodetector is used to detect the fourth optical signal and the fifth optical signal.

[0008] In this technical solution, polarization maintenance is achieved through a polarization rotator and a single-mode fiber, aligning the input polarization state with the dominant polarization state of the single-mode fiber. Simultaneously, phase modulation is performed through a first coupler, thereby reducing costs and ensuring the detection performance of the device.

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the first coupler is a 3*3 coupler.

[0010] In this technical solution, the gyroscope with a 3*3 coupler structure does not require a bias phase modulator and can automatically operate near the operating point with the highest sensitivity, thereby improving measurement accuracy and stability.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the device further includes a data processing unit for calculating the angular velocity based on the detection results of the third photodetector and the fourth photodetector.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the fiber length of the single-mode fiber loop is greater than or equal to 700m, and the diameter of the single-mode fiber loop is greater than or equal to 6cm.

[0013] In this technical solution, the fiber length of the single-mode fiber loop is greater than or equal to 700m, thereby improving sensitivity; the diameter of the single-mode fiber loop is greater than or equal to 6cm, which reduces noise and improves system performance.

[0014] In a second aspect, a communication device is provided, comprising: a second coupler, a phase modulator, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a fifth photodetector, and a single-mode fiber loop; a second port of the second coupler is coupled to a first port of the phase modulator, a second port of the phase modulator is coupled to a first port of the first polarization rotator, a first port of the first polarization rotator is connected to the first photodetector, a second port of the first polarization rotator is coupled to a first port of the single-mode fiber loop, a third port of the phase modulator is coupled to a first port of the second polarization rotator, a first port of the second polarization rotator is connected to the second photodetector, a second port of the second polarization rotator is coupled to a second port of the single-mode fiber loop, and a fourth port of the second coupler is connected to the fifth photodetector; the second coupler is used to receive a light beam through its first port, process the light beam, output a sixth optical signal through its second port, and output a seventh optical signal through its third port; the phase modulator is used to perform phase modulation on the sixth optical signal, output an eighth optical signal through its second port, and output an eighth optical signal through its third port. The system outputs a ninth optical signal; wherein, the eighth optical signal is transmitted to the single-mode fiber loop through the first polarization rotator, and output from the single-mode fiber loop through the second polarization rotator, then enters the phase adjuster through the third port of the phase modulator; the ninth optical signal is transmitted to the single-mode fiber loop through the second polarization rotator, and output from the single-mode fiber loop through the first polarization rotator, then enters the phase adjuster after passing through the second port of the phase modulator; the phase adjuster processes the eighth and ninth optical signals and outputs a tenth optical signal from the first port of the phase adjuster; the tenth optical signal... The signal enters the second coupler through the second port, is processed by the second coupler, and is output as an eleventh optical signal from the fourth port of the second coupler; the first photodetector is used to detect the ninth optical signal; the first polarization rotator is used to adjust the polarization state of the eighth optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the first photodetector, and the adjusted polarization state of the eighth optical signal is consistent with the polarization state of the ninth optical signal input from the second port of the first polarization rotator; the second photodetector is used to detect the eighth optical signal;The second polarization rotator is used to adjust the polarization state of the ninth optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the second photodetector. The adjusted polarization state of the ninth optical signal is consistent with the polarization state of the eighth optical signal input from the second port of the second polarization rotator. The fifth photodetector is used to detect the eleventh optical signal.

[0015] In this technical solution, polarization maintenance is achieved through a polarization rotator and a single-mode fiber, aligning the input polarization state with the dominant polarization state of the single-mode fiber. Simultaneously, phase modulation is performed through a second coupler and a phase modulator, thereby reducing costs and ensuring the detection performance of the device.

[0016] In conjunction with the second aspect, in some implementations of the second aspect, the second coupler is a 2*2 coupler.

[0017] In this technical solution, the angular velocity measurement device with a 2*2 coupler structure requires a bias phase modulator, for example, a lithium niobate modulator can be used for phase modulation. This angular velocity measurement device with this structure is suitable for dynamic measurement.

[0018] In conjunction with the second aspect, in some implementations of the second aspect, the device further includes a data processing unit for calculating the angular velocity based on the detection result of the fifth photodetector.

[0019] In conjunction with the second aspect, in some implementations of the second aspect, the fiber length of the single-mode fiber loop is greater than or equal to 700m, and the diameter of the single-mode fiber loop is greater than or equal to 6cm.

[0020] In this technical solution, the fiber length of the single-mode fiber loop is greater than or equal to 700m, thereby improving sensitivity; the diameter of the single-mode fiber loop is greater than or equal to 6cm, which reduces noise and improves system performance.

[0021] Thirdly, a method for detecting angular velocity is provided. This method can be applied to a device for detecting angular velocity, that is, the device can be a communication device (such as a terminal device, a network device, or an artificial intelligence (AI) node), or the device can be a component of a communication device (such as a chip, a chip system, a circuit, or a communication module).

[0022] The method may include: processing a received light beam to obtain a first optical signal, a second optical signal, and a third optical signal; detecting the second optical signal; adjusting the polarization state of the first optical signal to the dominant polarization state of a single-mode fiber loop based on the detection result of the second optical signal, wherein the adjusted polarization state of the first optical signal is consistent with the adjusted polarization state of the second optical signal; detecting the first optical signal; adjusting the polarization state of the second optical signal to the dominant polarization state of a single-mode fiber loop based on the detection result of the first optical signal, wherein the adjusted polarization state of the second optical signal is consistent with the adjusted polarization state of the first optical signal; processing the first optical signal after it is output from the single-mode fiber loop to obtain a fourth optical signal; processing the second optical signal after it is output from the single-mode fiber loop to obtain a fifth optical signal; and detecting the fourth optical signal and the fifth optical signal.

[0023] In this technical solution, when performing angular velocity detection, the polarization rotator at the input and output ends of the single-mode fiber can detect and adjust the input polarization state to align with the dominant polarization state of the single-mode fiber, avoiding polarization fluctuations. At the same time, phase modulation is achieved through a 3*3 coupler, thereby ensuring detection performance.

[0024] In conjunction with the third aspect, in some implementations of the third aspect, the angular velocity is calculated based on the detection results of the fourth optical signal and the fifth optical signal.

[0025] Fourthly, a method for detecting angular velocity is provided. This method can be applied to a device for detecting angular velocity, that is, the device can be a communication device (such as a terminal device, a network device, or an artificial intelligence (AI) node), or the device can be a component of a communication device (such as a chip, a chip system, a circuit, or a communication module).

[0026] The method may include: processing a received light beam to obtain a sixth optical signal and a seventh optical signal; performing phase modulation on the sixth optical signal to obtain an eighth optical signal and a ninth optical signal; detecting the ninth optical signal; adjusting the polarization state of the eighth optical signal to the dominant polarization state of a single-mode fiber loop based on the detection result of the ninth optical signal, wherein the adjusted polarization state of the eighth optical signal is consistent with the adjusted polarization state of the ninth optical signal; detecting the eighth optical signal; adjusting the polarization state of the ninth optical signal to the dominant polarization state of a single-mode fiber loop based on the detection result of the eighth optical signal, wherein the adjusted polarization state of the ninth optical signal is consistent with the adjusted polarization state of the eighth optical signal; after the eighth and ninth optical signals are output from the single-mode fiber loop, performing phase modulation on the eighth and ninth optical signals to obtain a tenth optical signal; processing the tenth optical signal to obtain an eleventh optical signal; and detecting the eleventh optical signal.

[0027] In this technical solution, when performing angular velocity detection, the polarization rotator at the input and output ends of the single-mode fiber can detect and adjust the input polarization state to align with the dominant polarization state of the single-mode fiber, avoiding polarization fluctuations. At the same time, phase modulation is achieved through a 2*2 coupler and a phase modulator, thereby ensuring detection performance.

[0028] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the angular velocity is calculated based on the detection result of the eleventh optical signal. Attached Figure Description

[0029] Figure 1 is a schematic diagram of a device 100 for detecting angular velocity applicable to an embodiment of this application.

[0030] Figure 2 is a schematic diagram of a device 200 for detecting angular velocity applicable to an embodiment of this application.

[0031] Figure 3 is a schematic diagram of a method 100 for detecting angular velocity provided in an embodiment of this application.

[0032] Figure 4 is a schematic diagram of a method 200 for detecting angular velocity provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0034] The technical solutions of this application can be applied to communication systems. For example, in communication sensing active antenna unit (AAU) scenarios, the accuracy requirements for target sensing over a larger area are higher. Current mobile measurement solutions can provide some effective geospatial data acquisition terminals, but they have obvious limitations, such as site limitations and accuracy limitations. They cannot meet the accuracy requirements for target sensing. The technical solutions of this application can provide stable and high-precision angular velocity and attitude information while reducing the cost of fiber optic gyroscopes.

[0035] Before introducing the embodiments of this application, the technical terms involved in this application will be explained first.

[0036] 1. Fiber optic gyroscope: It is an inertial sensor based on fiber optic technology, used to measure and detect rotation speed and direction. It has the characteristics of high precision, high stability, anti-electromagnetic interference and anti-vibration shock, and is widely used in aerospace, marine, military, machinery, automotive and other fields.

[0037] Basic structure:

[0038] A fiber optic gyroscope mainly consists of a laser source, a fiber optic ring, a beam splitter, a detector, and a signal processing system. Among these components, the fiber optic ring is a key component, consisting of a section of optical fiber arranged in a loop, used for light transmission and the generation of phase difference.

[0039] Working principle:

[0040] The working principle of a fiber optic gyroscope is based on the Sagnac effect, which states that when a beam of light travels in a circular channel, if the channel itself has a rotational speed, the time required for the light to travel along the direction of rotation is longer than the time required to travel along the opposite direction. Specifically, light emitted from the source is split into two beams by a beam splitter, which propagate in opposite directions along the fiber optic ring. Due to the rotation of the fiber optic ring, a phase difference is formed between the two beams as they propagate within the ring; this phase difference is proportional to the rotational speed of the fiber optic ring. By detecting this phase difference and processing it through a signal processing system, the detector can obtain the rotational speed and direction information of the fiber optic ring.

[0041] Performance parameters:

[0042] The main performance parameters of a fiber optic gyroscope include zero bias, zero drift, scaling factor, random walk coefficient, threshold, and resolution. Zero bias is the gyroscope's output when the input angular velocity is zero. Zero drift is an important indicator of gyroscope accuracy, representing the degree of dispersion of the gyroscope's output around its zero bias mean when the input angular velocity is zero. The scaling factor is the ratio of the gyroscope's output to the input angular velocity, reflecting the gyroscope's sensitivity. The random walk coefficient reflects the uncertainty of the integral of the gyroscope's output angular velocity over time. The threshold and resolution characterize the gyroscope's sensitivity.

[0043] 2. Polarization-maintaining fiber (PMF): This is a key component in fiber optic gyroscopes that maintains the polarization state. Its enhanced birefringence ensures that the polarization direction of the outgoing light is consistent with that of the incident light. PMF typically consists of a central core, a cladding layer surrounding the core, and sometimes one or more additional protective layers. Its internal structure differs from ordinary optical fibers, maintaining the polarization state of the optical signal by introducing asymmetry and birefringence. Its manufacturing process is relatively complex, requiring precise control of the fiber's geometry and material properties to ensure excellent matched birefringence performance and good geometric uniformity. The characteristics of PMF are crucial to the accuracy and stability of fiber optic gyroscopes, but the complex manufacturing process correspondingly increases the cost, for example, reaching 7 yuan / meter (m). To ensure high precision, the length is usually over 1000m, resulting in high costs.

[0044] 3. Single-mode fiber (SMF): Single-mode fiber is a type of optical fiber with a very thin core (typically 9 or 10 μm in diameter), capable of transmitting only a single mode of light beam. While also composed of a core and cladding, the smaller core diameter allows the optical signal to propagate in only one mode. SMF has lower transmission loss, enabling signals to travel longer distances. It also exhibits lower transmission dispersion, beneficial for high-speed, high-capacity data transmission. Furthermore, SMF offers a wide bandwidth, supporting higher data transmission rates. Due to its small core diameter, a laser is required as the light source to ensure signal stability and clarity. The cost of SMF is relatively low, for example, as low as 0.1 yuan per meter (m).

[0045] 4. Y-waveguide modulator: Currently, partial integration of the light source, coupler, Y-waveguide modulator, and photodetector for closed-loop interferometric FOGs has been achieved both domestically and internationally. The Y-waveguide modulator primarily uses lithium niobate. Lithium niobate possesses excellent electro-optic effects and stable chemical properties, making it an ideal material for fabricating waveguide modulators. However, the availability of this material is relatively limited, and its processing is challenging, resulting in high manufacturing costs for Y-waveguide modulators.

[0046] Furthermore, the high technical requirements of heterogeneous integration are also a key factor restricting the large-scale mass production of Y-waveguide modulators. Heterogeneous integration requires integrating devices made of different materials and using different processes, which necessitates high-precision processing and packaging technologies, increasing manufacturing complexity and cost.

[0047] In summary, the high cost of current fiber optic gyroscopes is primarily due to the cost constraints of polarization-maintaining fiber and lithium niobate modulators. Polarization-maintaining fiber is a crucial component in fiber optic gyroscopes, ensuring that the polarization direction of the outgoing light matches that of the incident light through enhanced birefringence. Its manufacturing process is relatively complex, requiring precise control of the fiber's geometry and material properties to ensure excellent matched birefringence and good geometric uniformity. The characteristics of polarization-maintaining fiber are critical to the accuracy and stability of fiber optic gyroscopes, but the complex fabrication process correspondingly increases the cost. Lithium niobate modulators are used in fiber optic gyroscopes for phase modulation of light. This material exhibits a strong photoelectric effect, allowing for effective phase modulation at very low voltages without affecting amplitude, making it a key component for Sagnac effect measurements. However, the processing difficulty of lithium niobate crystals leads to the high cost of lithium niobate modulators.

[0048] In view of this, this application proposes a technical solution that can achieve polarization maintaining function through an on-chip polarization rotator and a single-mode fiber: the polarization rotator at the input and output ends of the single-mode fiber detects and adjusts the input polarization state to align with the dominant polarization state of the single-mode fiber, avoiding polarization fluctuations, thereby achieving the purpose of replacing the polarization maintaining fiber, reducing costs, and ensuring the detection performance of the device.

[0049] The following description is provided to facilitate understanding of the embodiments of this application.

[0050] First, in the embodiments of this application shown below, the terms "first," "second," "third," "fourth," and various numerical designations are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. For example, distinguishing different states of optical signals after different steps, etc.

[0051] Second, in the embodiments of this application shown below, "and / or" can be used to describe three relationships between associated objects. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0052] Third, in the embodiments of this application shown below, a module can also be understood as an element. For example, a signal conversion module can also refer to a signal conversion element, etc.

[0053] Third, the modules in the embodiments of this application may include multiple devices or functional units to achieve more complex system functions. Each module has an independent function and can be used alone or in combination with other modules.

[0054] Maintaining the polarization state in a fiber optic gyroscope is crucial for its accuracy and stability. In this embodiment, polarization maintenance can be achieved using an on-chip polarization rotator and a single-mode fiber. The polarization rotator at the input and output ends of the single-mode fiber detects and adjusts the input polarization state to align with the dominant polarization state of the single-mode fiber, thus keeping the polarization state unchanged. This fiber optic gyroscope also includes other components, such as couplers for processing optical signals and photodetectors for detecting optical signals; however, this embodiment does not limit the inclusion of these components. The following embodiments provide two examples of fiber optic gyroscope structures.

[0055] The embodiments provided in this application are described below with reference to the accompanying drawings.

[0056] Referring to Figure 1, as an example, Figure 1 is a schematic diagram of a device 100 for detecting angular velocity provided in an embodiment of this application.

[0057] In this application embodiment, the device for detecting angular velocity can be replaced with other terms, such as detection device, angular velocity detection device, gyroscope, angular velocity detection device, angular velocity detection module, etc. In this application embodiment, the device for detecting angular velocity is used as an example for description, and the name of this term does not limit the embodiments of this application.

[0058] As shown in Figure 1, the device 100 may include a first coupler, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a third photodetector, and a fourth photodetector, as well as a single-mode fiber loop.

[0059] For example, the first coupler includes six interfaces (e.g., A1, A2, A3, A4, A5, A6 shown in Figure 1), the first polarization rotator includes two ports (e.g., B1, B2 shown in Figure 1), the second polarization rotator includes two ports (e.g., C1, C2 shown in Figure 1), and the single-mode fiber loop includes two ports (e.g., D1, D2 shown in Figure 1).

[0060] Specifically, the second port of the first coupler (A2 as shown in Figure 1) is coupled to the first port of the first polarization rotator (B1 as shown in Figure 1), the first port of the first polarization rotator (B1 as shown in Figure 1) is connected to the first photodetector, the second port of the first polarization rotator (B2 as shown in Figure 1) is coupled to the first port of the single-mode fiber loop (D1 as shown in Figure 1), the third port of the first coupler (A3 as shown in Figure 1) is coupled to the first port of the second polarization rotator (C1 as shown in Figure 1), the first port of the second polarization rotator (C1 as shown in Figure 1) is connected to the second photodetector, the second port of the second polarization rotator (C2 as shown in Figure 1) is coupled to the second port of the single-mode fiber loop (D2 as shown in Figure 1), the fourth port of the first coupler (A4 as shown in Figure 1) is connected to the third photodetector, and the fifth port of the first coupler (A5 as shown in Figure 1) is connected to the fourth photodetector.

[0061] In one possible implementation, the coupling relationship in this application embodiment refers to the close cooperation and mutual influence between the inputs and outputs of two devices, and the realization of functions such as information transmission, energy transfer, or signal control through interaction. This application embodiment does not limit the specific coupling method. For example, it can be physical coupling (such as connection through physical media such as wires or cables), electromagnetic coupling (such as energy or signal transmission through electromagnetic waves), optical coupling (such as optical signal transmission through optical fibers), etc.

[0062] The first coupler is used to receive the light beam through the first port (A1 as shown in Figure 1), process the light beam, output the first optical signal through the second port (A2 as shown in Figure 1), output the second optical signal through the third port (A3 as shown in Figure 1), and output the third optical signal through the sixth port (A6 as shown in Figure 1).

[0063] In one possible implementation, the input port of the first coupler (A1 as shown in Figure 1) is coupled to the output port of the light source, and the first coupler can receive the light beam from the light source through the A1 port.

[0064] For example, the light source can be a light emitting device, such as a super luminescent diode (SLD), but this application embodiment does not limit it to this.

[0065] For example, the light source can be a SLD with a broad emission spectrum and a short coherence length. This can improve accuracy, make passive devices more stable, and reduce costs.

[0066] For example, the first coupler is a 3*3 coupler, and the light beam is split into three beams (a first optical signal, a second optical signal, and a third optical signal) after passing through the first coupler.

[0067] For example, the first coupler is an MMI coupler.

[0068] In one possible implementation, the 3x3 coupler has more input and output ports. In fiber optic gyroscopes, 3x3 couplers are commonly used to construct open-loop fiber optic gyroscopes with a non-reciprocal structure. This type of gyroscope does not require a bias phase modulator and can automatically operate near its most sensitive operating point, thus improving measurement accuracy and stability. The 3x3 coupler has unique input-output characteristics: when an optical signal is input from one port, it is distributed to three output ports. For example, in this embodiment, the light beam is distributed to three output ports (A2, D3, and A6) after passing through the first coupler, and the optical signal intensity at each output port has a constant ratio. This characteristic enables the 3x3 coupler to achieve reversible direction determination and high-sensitivity measurements in fiber optic gyroscopes.

[0069] The propagation paths of the three beams of light (the first optical signal, the second optical signal, and the third optical signal) output by the first coupler will be explained next.

[0070] In this process, the first optical signal at the second port of the first coupler (A2 as shown in Figure 1) propagates in the CW (clockwise) direction in the single-mode fiber loop. The first optical signal is transmitted to the single-mode fiber loop through the first polarization rotator, and is output from the single-mode fiber loop through the second polarization rotator. It then enters the first coupler through the third port (A3 as shown in Figure 1), and after being processed by the first coupler, the fourth optical signal is output from the fourth port (A4 as shown in Figure 1) and the fifth port (A5 as shown in Figure 1).

[0071] The first photodetector is used to detect the second optical signal.

[0072] For example, a first photodetector is used to detect the illumination intensity of the second optical signal transmitted in the CCW direction.

[0073] The first polarization rotator is used to adjust the polarization state of the first optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the first photodetector. The polarization state of the first optical signal after adjustment is consistent with the polarization state of the second optical signal input from the second port of the first polarization rotator.

[0074] In one possible implementation, the first polarization rotator detects and adjusts the polarization state of the first optical signal input to the single-mode fiber loop, ensuring that the polarization state of the first optical signal entering the single-mode fiber loop from the second port of the first polarization rotator (e.g., port B2 in Figure 1) is consistent with the polarization state of the second optical signal input from the second port of the first polarization rotator (e.g., port B2 in Figure 1), both being the dominant polarization state of the single-mode fiber loop. Alternatively, the first photodetector assists the first polarization rotator in adjusting the polarization state of the passing optical signal. Based on the detection result of the second optical signal transmitted in the CCW direction detected by the first photodetector, the first polarization rotator adjusts the polarization state of the first optical signal transmitted in the CW direction, aligning it with the dominant polarization state of the single-mode fiber loop. In other words, the first photodetector and the first polarization rotator can achieve polarization-maintaining functionality.

[0075] The optical signal transmitted in the CW direction is output from the single-mode fiber loop, processed by the first coupler, and then output from the two ports of the first coupler (ports A4 and A5 in Figure 1) as the fourth optical signal, which is detected by the third and fourth photodetectors.

[0076] For example, the third and fourth photodetectors are used to detect the illumination intensity of the fourth light signal.

[0077] The second optical signal output from the third port of the first coupler (A3 as shown in Figure 1) propagates in the single-mode fiber loop along the CCW (counterclockwise) direction. The second optical signal is transmitted to the single-mode fiber loop through the second polarizer, and is output from the single-mode fiber loop through the first polarization rotator. It then enters the first coupler through the second port of the first coupler (A2 as shown in Figure 1), and is processed by the first coupler before being output from the fourth port (A4 as shown in Figure 1) and the fifth port (A5 as shown in Figure 1).

[0078] The second photodetector is used to detect the first optical signal.

[0079] For example, a first photodetector is used to detect the illumination intensity of a first optical signal transmitted in the CW direction.

[0080] The second polarization rotator is used to adjust the polarization state of the second optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the second photodetector. The polarization state of the second optical signal after adjustment is consistent with the polarization state of the first optical signal input from the second port of the second polarization rotator.

[0081] In one possible implementation, the second polarization rotator detects and adjusts the polarization state of the second optical signal input to the single-mode fiber loop, ensuring that the polarization state of the second optical signal entering the single-mode fiber loop from the second port of the second polarization rotator (e.g., port C2 in Figure 1) is consistent with the polarization state of the first optical signal input from the second port of the second polarization rotator (e.g., port C2 in Figure 1), both being the dominant polarization state of the single-mode fiber loop. Alternatively, the second photodetector assists the second polarization rotator in adjusting the polarization state of the passing optical signal. Based on the detection result of the first optical signal transmitted in the CW direction detected by the second photodetector, the second polarization rotator adjusts the polarization state of the second optical signal transmitted in the CCW direction, aligning it with the dominant polarization state of the single-mode fiber loop. In other words, the second photodetector and the second polarization rotator can achieve polarization-maintaining functionality.

[0082] The optical signal transmitted in the CCW direction is output from the single-mode fiber loop, processed by the first coupler, and then output from the two ports of the first coupler (ports A4 and A5 in Figure 1) as the fifth optical signal, which is detected by the third and fourth photodetectors.

[0083] For example, the third and fourth photodetectors are used to detect the illumination intensity of the fifth light signal.

[0084] For example, the detection results of the illumination intensity of the fourth light signal and the detection results of the illumination intensity of the fifth light signal are used to calculate the rotation speed and direction.

[0085] For example, the first polarization rotator and the second polarization rotator described above can be on-chip polarization rotators.

[0086] The third optical signal output from the sixth port of the first coupler (A6 as shown in Figure 1) can be used for optical signal detection or left unused; this embodiment does not limit this.

[0087] In the above scheme, the first optical signal at port A2 propagates in the single-mode fiber loop along the CW (clockwise) direction, while the second optical signal at port A3 propagates in the single-mode fiber loop along the CCW (counterclockwise) direction. The light propagating in the CW and CCW directions passes through on-chip polarization rotators (first and second polarization rotators) at input and output. The polarization rotators adjust the polarization state to the dominant polarization state by measuring the received light intensity detected by photodetectors (first and second photodetectors), achieving a stable output polarization state. The optical signal output from the fiber loop passes through the first coupler again and is finally detected by photodetectors (third and fourth photodetectors). Based on the Sagnac effect, the two optical signals propagating in the CW and CCW directions will have a phase difference due to the rotation of the gyroscope as they propagate in the single-mode fiber loop. By converting the optical signals detected by the detectors into electrical signals and measuring the intensity changes of the two beams, the rotation speed and direction can be calculated.

[0088] In one possible implementation, the aforementioned photodetector and polarization rotator can achieve polarization maintenance.

[0089] In one possible implementation, the above-mentioned single-mode fiber loop has a polarization mode dominant state theory, that is, random birefringent fiber, like polarization-maintaining fiber, has a set of input orthogonal polarization states, which keeps the output polarization state stable.

[0090] In one possible implementation, the device 100 further includes a data processing unit for calculating angular velocity based on the detection results of the third and fourth photodetectors.

[0091] For example, the fiber length of the aforementioned single-mode fiber loop is greater than or equal to 700m. This can improve sensitivity.

[0092] For example, the diameter of the single-mode fiber loop is greater than or equal to 6 cm. This can reduce noise and improve system performance.

[0093] In the above technical solution, polarization maintenance is achieved by using a polarization rotator and a single-mode fiber, so that the input polarization state is aligned with the dominant polarization state of the single-mode fiber. At the same time, phase modulation is performed by a 3*3 coupler, which reduces costs and ensures the detection performance of the device.

[0094] In one possible implementation, the aforementioned device 100 can be integrated based on a silicon photonics platform.

[0095] In the above technical solutions, phase modulation using a 3x3 coupler is only one example; phase modulation can also be achieved in other ways. As an example, phase control can also be achieved using a 2x2 coupler and a lithium niobate modulator, allowing the FOG to operate in the linear region.

[0096] The following describes in detail the device 200 for detecting angular velocity by phase modulation using a 2*2 coupler and a lithium niobate modulator, with reference to Figure 2.

[0097] Referring to Figure 2, as an example, Figure 2 is a schematic diagram of a device 200 for detecting angular velocity provided in an embodiment of this application.

[0098] In this application embodiment, the device for detecting angular velocity can be replaced with other terms, such as detection device, angular velocity detection device, gyroscope or fiber optic gyroscope, angular velocity detection device, angular velocity detection module, etc. In this application embodiment, the device for detecting angular velocity is used as an example for description, and the name of this term does not limit the embodiments of this application.

[0099] As shown in Figure 2, the device 200 may include a second coupler, a phase modulator, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a fifth photodetector, and a single-mode fiber loop.

[0100] For example, the second coupler includes four interfaces (e.g., E1, E2, E3, E4 shown in Figure 2), the phase modulator includes three interfaces (e.g., F1, F2, F3 shown in Figure 2), the first polarization rotator includes two ports (e.g., B1, B2 shown in Figure 1), the second polarization rotator includes two ports (e.g., C1, C2 shown in Figure 1), and the single-mode fiber loop includes two ports (e.g., D1, D2 shown in Figure 1).

[0101] Specifically, the second port of the second coupler (E2 as shown in Figure 2) is coupled to the first port of the phase modulator (F1 as shown in Figure 2), the second port of the phase modulator (F2 as shown in Figure 2) is coupled to the first port of the first polarization rotator (B1 as shown in Figure 2), the first port of the first polarization rotator (B1 as shown in Figure 2) is connected to the first photodetector, the second port of the first polarization rotator (B2 as shown in Figure 2) is coupled to the first port of the single-mode fiber loop (D1 as shown in Figure 2), the third port of the phase modulator (F3 as shown in Figure 2) is coupled to the first port of the second polarization rotator (C1 as shown in Figure 2), the first port of the second polarization rotator (C1 as shown in Figure 2) is connected to the second photodetector, the second port of the second polarization rotator (C2 as shown in Figure 2) is coupled to the second port of the single-mode fiber loop (D2 as shown in Figure 2), and the fourth port of the second coupler (E4 as shown in Figure 2) is connected to the fifth photodetector.

[0102] In one possible implementation, the coupling relationship in this application embodiment refers to the close cooperation and mutual influence between the inputs and outputs of two devices, and the realization of functions such as information transmission, energy transfer, or signal control through interaction. This application embodiment does not limit the specific coupling method. For example, it can be physical coupling (such as connection through physical media such as wires or cables), electromagnetic coupling (such as energy or signal transmission through electromagnetic waves), optical coupling (such as optical signal transmission through optical fibers), etc.

[0103] The second coupler is used to receive the light beam through the first port (E1 as shown in Figure 2), process the light beam, output the sixth optical signal through the second port (E2 as shown in Figure 2), and output the seventh optical signal through the third port (E3 as shown in Figure 2).

[0104] In one possible implementation, the input port of the second coupler (E1 as shown in Figure 2) is coupled to the output port of the light source, and the first coupler can receive the light beam from the light source through the E1 port.

[0105] For example, the light source can be a light emitting device, such as a super luminescent diode (SLD), but this application embodiment does not limit it to this.

[0106] For example, the light source can be a SLD with a broad emission spectrum and a short coherence length. This can improve accuracy, make passive devices more stable, and reduce costs.

[0107] For example, the first coupler is a 2*2 coupler, and after the light beam passes through the first coupler, it is split into two beams (the sixth optical signal and the seventh optical signal).

[0108] For example, the first coupler is an MMI coupler.

[0109] In one possible implementation, a 2x2 coupler is an optical element capable of distributing an input optical signal to two output ports or mixing two input optical signals to a single output port. In fiber optic gyroscopes, 2x2 couplers are typically used as beam splitters, distributing optical signals emitted from a light source into two fiber optic loops in opposite directions. After propagating through the fiber optic loops, the optical signals in these two directions return to the coupler and interfere, thereby measuring the rotational speed of the fiber optic loops. For example, in this embodiment, the light beam is distributed to two output ports (E2 port, E3 port) after passing through this second coupler. The 2x2 coupler has bidirectional coupling characteristics, meaning either port can be used as an input or output. Furthermore, it features a high extinction ratio and a stable coupling ratio, ensuring high accuracy and stability of the optical signal during distribution and mixing.

[0110] The phase modulator is used to phase-modulate the sixth optical signal, outputs the eighth optical signal through the second port of the phase modulator (F2 as shown in Figure 2), and outputs the ninth optical signal through the third port of the phase modulator (F3 as shown in Figure 2).

[0111] For example, the phase modulator is a lithium niobate modulator. This phase modulator allows for phase control, enabling it to operate in the linear region.

[0112] The propagation paths of the two beams of light (the eighth and ninth optical signals) output by the phase modulator will be explained next.

[0113] In this circuit, the eighth optical signal output from the second port of the phase modulator (F2 as shown in Figure 2) propagates in the single-mode fiber loop along the CW (clockwise) direction. The eighth optical signal is transmitted to the single-mode fiber loop via the first polarization rotator, and then output from the single-mode fiber loop via the second polarization rotator. It then enters the phase adjuster via the third port of the phase modulator (F3 as shown in Figure 2). The ninth optical signal output from the third port of the phase modulator (F3 as shown in Figure 2) propagates in the single-mode fiber loop along the CCW (counterclockwise) direction. The ninth optical signal is transmitted to the single-mode fiber loop via the second polarization rotator. The fiber loop is output from the single-mode fiber loop through the first polarization rotator, passes through the second port of the phase modulator (F2 as shown in Figure 2), and enters the phase adjuster. The phase adjuster processes the eighth and ninth optical signals and outputs the tenth optical signal from the first port of the phase adjuster (F1 as shown in Figure 2). The tenth optical signal enters the second coupler through the second port of the second coupler (E2 as shown in Figure 2), is processed by the second coupler, and outputs the eleventh optical signal from the fourth port of the second coupler (E4 as shown in Figure 2).

[0114] The first photodetector is used to detect the ninth optical signal.

[0115] For example, the first photodetector is used to detect the illumination intensity of the ninth optical signal transmitted in the CCW direction.

[0116] The first polarization rotator is used to adjust the polarization state of the eighth optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the first photodetector. The polarization state of the eighth optical signal after adjustment is consistent with the polarization state of the ninth optical signal input from the second port of the first polarization rotator.

[0117] In one possible implementation, the first polarization rotator detects and adjusts the polarization state of the eighth optical signal input to the single-mode fiber loop, ensuring that the polarization state of the eighth optical signal entering the single-mode fiber loop from the second port of the first polarization rotator (e.g., port B2 in Figure 1) is consistent with the polarization state of the ninth optical signal input from the second port of the first polarization rotator (e.g., port B2 in Figure 1), both being the dominant polarization state of the single-mode fiber loop. Alternatively, the first photodetector assists the first polarization rotator in adjusting the polarization state of the passing optical signal. Based on the detection result of the ninth optical signal transmitted in the CCW direction detected by the first photodetector, the first polarization rotator adjusts the polarization state of the eighth optical signal transmitted in the CW direction, aligning it with the dominant polarization state of the single-mode fiber loop. In other words, the first photodetector and the first polarization rotator can achieve polarization-maintaining functionality.

[0118] The second photodetector is used to detect the eighth optical signal.

[0119] For example, the second photodetector is used to detect the illumination intensity of the eighth optical signal transmitted in the CW direction.

[0120] The second polarization rotator is used to adjust the polarization state of the ninth optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop based on the detection result of the second photodetector. The polarization state of the ninth optical signal after adjustment is consistent with the polarization state of the eighth optical signal input from the second port of the second polarization rotator.

[0121] In one possible implementation, the second polarization rotator detects and adjusts the polarization state of the ninth optical signal input to the single-mode fiber loop, ensuring that the polarization state of the ninth optical signal entering the single-mode fiber loop from the second port of the second polarization rotator (e.g., port C2 in Figure 1) is consistent with the polarization state of the eighth optical signal input from the second port of the second polarization rotator (e.g., port C2 in Figure 1), both being the dominant polarization state of the single-mode fiber loop. Alternatively, the second photodetector assists the second polarization rotator in adjusting the polarization state of the passing optical signal. Based on the detection result of the eighth optical signal transmitted in the CW direction detected by the second photodetector, the second polarization rotator adjusts the polarization state of the ninth optical signal transmitted in the CCW direction, aligning it with the dominant polarization state of the single-mode fiber loop. In other words, the second photodetector and the second polarization rotator can achieve polarization-maintaining functionality.

[0122] The optical signal transmitted in the CW direction is output from the single-mode fiber loop and then re-enters the phase modulator from the third port (F3 as shown in Figure 2). The optical signal transmitted in the CCW direction is output from the single-mode fiber loop and then re-enters the phase modulator from the second port (F2 as shown in Figure 2). The phase modulator processes these two optical signals and outputs the tenth optical signal from the first port (F1 as shown in Figure 2). The tenth optical signal enters the second coupler through the second port (E2 as shown in Figure 2), and after being processed by the second coupler, the eleventh optical signal is output from the fourth port (E4 as shown in Figure 2).

[0123] The fifth photodetector is used to detect the eleventh optical signal.

[0124] For example, the fifth photodetector is used to detect the illumination intensity of the eleventh light signal.

[0125] For example, the detection result of the illumination intensity of the eleventh light signal is used to calculate the rotation speed and direction.

[0126] For example, the first polarization rotator and the second polarization rotator described above can be on-chip polarization rotators.

[0127] The seventh optical signal output from the third port of the second coupler (E3 as shown in Figure 2) can be used for optical signal detection or left unused; this embodiment does not limit this.

[0128] In the above scheme, the eighth optical signal propagates in the single-mode fiber loop along the CW (clockwise) direction, and the ninth optical signal propagates in the single-mode fiber loop along the CCW (counterclockwise) direction. The light propagating in the CW and CCW directions passes through on-chip polarization rotators (first and second polarization rotators) at input and output. The polarization rotators adjust the polarization state to the dominant polarization state by measuring the received light intensity detected by photodetectors (first and second photodetectors), achieving a stable output polarization state. The optical signal output from the fiber loop passes again through a phase modulator and a second coupler, and is finally detected by a photodetector (fifth photodetector). Based on the Sagnac effect, the two optical signals propagating in the CW and CCW directions will have a phase difference due to the rotation of the gyroscope when propagating in the single-mode fiber loop. By converting the optical signals detected by the detectors into electrical signals and measuring the intensity changes of the two beams, the rotation speed and direction can be calculated.

[0129] In one possible implementation, the aforementioned photodetector and polarization rotator can achieve polarization maintenance.

[0130] In one possible implementation, the above-mentioned single-mode fiber loop has a polarization mode dominant state theory, that is, random birefringent fiber, like polarization-maintaining fiber, has a set of input orthogonal polarization states, which keeps the output polarization state stable.

[0131] The verification process of the polarization dominant state theory of a single-mode fiber loop can be referred to the description in Figure 1, and will not be repeated here.

[0132] In one possible implementation, the device 200 further includes a data processing unit for calculating angular velocity based on the detection results of the third and fourth photodetectors.

[0133] For example, the fiber length of the aforementioned single-mode fiber loop is greater than or equal to 700m. This can improve sensitivity.

[0134] For example, the diameter of the single-mode fiber loop is greater than or equal to 6 cm. This can reduce noise and improve system performance.

[0135] In the above technical solution, polarization maintenance is achieved by using a polarization rotator and a single-mode fiber, so that the input polarization state is aligned with the dominant polarization state of the single-mode fiber. At the same time, phase modulation is performed by using a 2*2 coupler and a lithium niobate modulator, which reduces costs and ensures the detection performance of the device.

[0136] It should be noted that the phase modulation method shown in Figure 2 above, which uses a 2*2 coupler and a lithium niobate modulator, is only an exemplary method. This application does not limit the method of phase modulation.

[0137] According to the technical solution provided in this application, the polarization rotator at the input and output ends of the single-mode fiber can detect and adjust the input polarization state to align with the dominant polarization state of the single-mode fiber, thereby avoiding polarization fluctuations, achieving the purpose of replacing the polarization-maintaining fiber, reducing costs, and ensuring the detection performance of the device.

[0138] It should be noted that the structures shown in Figures 1 and 2 above are merely illustrative examples. For instance, the coupler used for processing optical signals can be a 3x3 coupler, a 2x2 coupler, or other types of couplers; phase modulation can be achieved through a 3x3 coupler, a phase modulator, or other phase modulation methods. Accordingly, the connection relationships between the structures shown in Figures 1 and 2 are only examples. Different structural components may be used, and the connection relationships can be changed accordingly. This application does not limit the scope of the embodiments in this regard.

[0139] The apparatus provided in the embodiments of this application has been described in detail above with reference to Figures 1 and 2. The above apparatus can be used to implement the method provided in the embodiments of this application. The method provided in the embodiments of this application will now be described with reference to Figures 3 and 4.

[0140] Figure 3 is a schematic flowchart of a method 100 for detecting angular velocity provided in an embodiment of this application. As shown in Figure 3, the method may include at least the following steps.

[0141] S110 processes the received light beam to obtain a first optical signal, a second optical signal, and a third optical signal.

[0142] Optionally, prior to step S110, the method may further include: receiving a light beam emitted from a light source.

[0143] For example, the light source can be a light emitting device, such as a super luminescent diode (SLD), but this application embodiment does not limit it to this.

[0144] For example, the first coupler processes the received light beam to obtain a first optical signal, a second optical signal, and a third optical signal.

[0145] For example, the first coupler is a 3*3 coupler, and the light beam is split into three beams (a first optical signal, a second optical signal, and a third optical signal) after passing through the first coupler.

[0146] The description of the first coupler can be found in the description of device 100 above, and will not be repeated here.

[0147] The third optical signal can be used for optical signal detection or left unused; this application does not limit this.

[0148] S120, detects the second optical signal.

[0149] The second optical signal propagates in the single-mode fiber loop along the CCW (counterclockwise) direction.

[0150] The first photodetector detects the second optical signal, that is, it detects the illumination intensity of the second optical signal transmitted in the CCW direction.

[0151] S130, based on the detection result of the second optical signal, adjust the polarization state of the first optical signal to the dominant polarization state of the single-mode fiber loop.

[0152] The polarization state of the first optical signal after adjustment is consistent with the polarization state of the second optical signal propagating in the CCW (counterclockwise) direction in the single-mode fiber loop.

[0153] The first polarization rotator detects and adjusts the polarization state of the first optical signal input to the single-mode fiber loop, so that the polarization state of the first optical signal is consistent with the polarization state of the second optical signal, thus aligning with the dominant polarization state of the single-mode fiber loop.

[0154] S140, the first optical signal is detected.

[0155] The first optical signal propagates in the CW (clockwise) direction within the single-mode fiber loop.

[0156] The second photodetector detects the first optical signal, that is, it detects the illumination intensity of the first optical signal transmitted in the CW direction.

[0157] S150, based on the detection result of the first optical signal, adjust the polarization state of the second optical signal to the dominant polarization state of the mode fiber loop.

[0158] The polarization state of the second optical signal after adjustment is consistent with the polarization state of the first optical signal propagating in the CW (clockwise) direction in the single-mode fiber loop.

[0159] The second polarization rotator detects and adjusts the polarization state of the second optical signal input to the single-mode fiber loop, so that the polarization state of the second optical signal is consistent with the polarization state of the first optical signal, thus aligning with the dominant polarization state of the single-mode fiber loop.

[0160] S160, after the first optical signal is output from the single-mode fiber loop, the first optical signal is processed to obtain the fourth optical signal.

[0161] After the first optical signal passes through the second polarization rotator and is output from the single-mode fiber loop, it re-enters the first coupler, where it is processed and outputs the fourth optical signal.

[0162] S170, after the second optical signal is output from the single-mode fiber loop, the second optical signal is processed to obtain the fifth optical signal.

[0163] After the second optical signal passes through the first polarization rotator and is output from the single-mode fiber loop, it re-enters the first coupler, where it is processed and outputs the fifth optical signal.

[0164] S180, the fourth optical signal and the fifth optical signal are detected.

[0165] For example, the third photodetector and the fourth photodetector detect the illumination intensity of the fourth optical signal.

[0166] For example, the third and fourth photodetectors detect the illumination intensity of the fifth light signal.

[0167] For example, the detection results of the illumination intensity of the fourth light signal and the detection results of the illumination intensity of the fifth light signal are used to calculate the rotation speed and direction.

[0168] Optionally, the method further includes calculating the angular velocity based on the detection results of the fourth optical signal and the fifth optical signal.

[0169] It should be understood that the above steps are merely illustrative, and the execution order is not limited in the embodiments of this application.

[0170] Figure 4 is a schematic flowchart of a method 200 for detecting angular velocity provided in an embodiment of this application. As shown in Figure 4, the method may include at least the following steps.

[0171] S210 processes the received light beam to obtain the sixth and seventh optical signals.

[0172] Optionally, prior to step S210, the method may further include receiving a light beam emitted from a light source.

[0173] For example, the light source can be a light emitting device, such as a super luminescent diode (SLD), but this application embodiment does not limit it to this.

[0174] For example, the second coupler processes the received light beam to obtain a sixth optical signal and a seventh optical signal.

[0175] For example, the second coupler is a 2*2 coupler, and the beam is split into two beams (the sixth optical signal and the seventh optical signal) after passing through the first coupler.

[0176] The description of the second coupler can be found in the description of device 200 above, and will not be repeated here.

[0177] The seventh optical signal can be used for optical signal detection or left unused; this application does not limit this.

[0178] S220, Phase modulation is performed on the sixth optical signal to obtain the eighth and ninth optical signals.

[0179] For example, a phase modulator is used to phase-modulate the sixth optical signal so that it operates in the linear region.

[0180] For example, the phase modulator is a lithium niobate modulator. Refer to the description of device 200 above; further details are omitted here.

[0181] S230, detects the ninth optical signal.

[0182] The ninth optical signal propagates in the single-mode fiber loop in the CCW (counterclockwise) direction.

[0183] The first photodetector detects the ninth optical signal, that is, it detects the illumination intensity of the ninth optical signal transmitted in the CCW direction.

[0184] S240, based on the detection result of the ninth optical signal, adjust the polarization state of the eighth optical signal to the dominant polarization state of a single-mode fiber loop.

[0185] Among them, the polarization state of the eighth optical signal after adjustment is consistent with the polarization state of the ninth optical signal propagating in the CCW (counterclockwise) direction in the single-mode fiber loop.

[0186] The first polarization rotator detects and adjusts the polarization state of the eighth optical signal input to the single-mode fiber loop, so that the polarization state of the eighth optical signal is consistent with the polarization state of the ninth optical signal, thus aligning with the dominant polarization state of the single-mode fiber loop.

[0187] S250, the eighth optical signal is detected.

[0188] The eighth optical signal propagates in the CW (clockwise) direction within the single-mode fiber loop.

[0189] The second photodetector detects the eighth optical signal, that is, it detects the illumination intensity of the eighth optical signal transmitted in the CW direction.

[0190] S260, based on the detection result of the eighth optical signal, adjust the polarization state of the ninth optical signal to the dominant polarization state of the mode fiber loop.

[0191] Among them, the polarization state of the ninth optical signal after adjustment is consistent with the polarization state of the eighth optical signal propagating in the CW (clockwise) direction in the single-mode fiber loop.

[0192] The second polarization rotator detects and adjusts the polarization state of the ninth optical signal input to the single-mode fiber loop, so that the polarization state of the ninth optical signal is consistent with the polarization state of the eighth optical signal, thus aligning with the dominant polarization state of the single-mode fiber loop.

[0193] S270, after the eighth optical signal and the ninth optical signal are output from the single-mode fiber loop, the phase of the eighth optical signal and the ninth optical signal is adjusted to obtain the tenth optical signal.

[0194] The optical signal transmitted in the CW direction (eighth optical signal) is output from the single-mode fiber loop and then re-enters the phase modulator. The optical signal transmitted in the CCW direction (ninth optical signal) is output from the single-mode fiber loop and then re-enters the phase modulator. The phase modulator processes these two optical signals and then outputs the tenth optical signal.

[0195] S280, the tenth optical signal is processed to obtain the eleventh optical signal.

[0196] After the phase adjuster outputs the tenth optical signal, it enters the second coupler again, and after processing by the second coupler, the eleventh optical signal is output.

[0197] S290, the eleventh optical signal is detected.

[0198] For example, the fifth photodetector is used to detect the illumination intensity of the eleventh light signal.

[0199] For example, the detection result of the illumination intensity of the eleventh light signal is used to calculate the rotation speed and direction.

[0200] Optionally, the method further includes calculating the angular velocity based on the detection result of the eleventh optical signal.

[0201] It should be understood that the above steps are merely illustrative, and the execution order is not limited in the embodiments of this application.

[0202] According to the technical solution provided in this application, the polarization rotator at the input and output ends of the single-mode fiber can detect and adjust the input polarization state to align with the dominant polarization state of the single-mode fiber, thereby avoiding polarization fluctuations, achieving the purpose of replacing the polarization-maintaining fiber, reducing costs, and ensuring the detection performance of the device.

[0203] It should be noted that the methods shown in Figures 3 and 4 above are merely illustrative. For example, the coupler used to process optical signals can be a 3*3 coupler, a 2*2 coupler, or other types of couplers; phase modulation can be achieved through a 3*3 coupler, a phase modulator, or other phase modulation methods. This application does not limit these methods.

[0204] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0205] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0206] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0207] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0208] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0209] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0210] 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.

Claims

1. A device for detecting angular velocity, characterized in that, It includes a first coupler, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a third photodetector, and a fourth photodetector, as well as a single-mode fiber loop; The second port of the first coupler is coupled to the first port of the first polarization rotator, the first port of the first polarization rotator is connected to the first photodetector, the second port of the first polarization rotator is coupled to the first port of the single-mode fiber loop, the third port of the first coupler is coupled to the first port of the second polarization rotator, the first port of the second polarization rotator is connected to the second photodetector, the second port of the second polarization rotator is coupled to the second port of the single-mode fiber loop, the fourth port of the first coupler is connected to the third photodetector, and the fifth port of the first coupler is connected to the fourth photodetector. The first coupler is used to receive a light beam through a first port, process the light beam, output a first optical signal through a second port of the first coupler, output a second optical signal through a third port of the first coupler, and output a third optical signal through a sixth port of the first coupler. The first optical signal is transmitted to the single-mode fiber loop via the first polarization rotator, and output from the single-mode fiber loop via the second polarization rotator. It then enters the first coupler through the third port, is processed by the first coupler, and outputs a fourth optical signal from the fourth and fifth ports. The second optical signal is transmitted to the single-mode fiber loop via the second polarization rotator, and output from the single-mode fiber loop via the first polarization rotator. It then enters the first coupler through the second port, is processed by the first coupler, and outputs a fifth optical signal from the fourth and fifth ports. The first photodetector is used to detect the second optical signal; The first polarization rotator is used to adjust the polarization state of the first optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the first photodetector. The polarization state of the first optical signal after adjustment is consistent with the polarization state of the second optical signal input from the second port of the first polarization rotator. The second photodetector is used to detect the first optical signal; The second polarization rotator is used to adjust the polarization state of the second optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the second photodetector. The polarization state of the second optical signal after adjustment is consistent with the polarization state of the first optical signal input from the second port of the second polarization rotator. The third photodetector is used to detect the fourth optical signal and the fifth optical signal; The fourth photodetector is used to detect the fourth optical signal and the fifth optical signal.

2. The apparatus according to claim 1, characterized in that, The first coupler is a 3*3 coupler.

3. The apparatus according to claim 1 or 2, characterized in that, The device also includes a data processing unit. The data processing unit is used to calculate the angular velocity based on the detection results of the third photodetector and the fourth photodetector.

4. The apparatus according to any one of claims 1-3, characterized in that, The single-mode fiber loop has a fiber length greater than or equal to 700m and a diameter greater than or equal to 6cm.

5. A device for detecting angular velocity, characterized in that, It includes a second coupler, a phase modulator, a first polarization rotator, a first photodetector, a second polarization rotator, a second photodetector, a fifth photodetector, and a single-mode fiber loop; The second port of the second coupler is coupled to the first port of the phase modulator, the second port of the phase modulator is coupled to the first port of the first polarization rotator, the first port of the first polarization rotator is connected to the first photodetector, the second port of the first polarization rotator is coupled to the first port of the single-mode fiber loop, the third port of the phase modulator is coupled to the first port of the second polarization rotator, the first port of the second polarization rotator is connected to the second photodetector, the second port of the second polarization rotator is coupled to the second port of the single-mode fiber loop, and the fourth port of the second coupler is connected to the fifth photodetector. The second coupler is used to receive the light beam through the first port, process the light beam, output a sixth optical signal through the second port of the second coupler, and output a seventh optical signal through the third port of the second coupler; The phase modulator is used to perform phase modulation on the sixth optical signal, outputs the eighth optical signal through the second port of the phase modulator, and outputs the ninth optical signal through the third port of the phase modulator; The eighth optical signal is transmitted to the single-mode fiber loop through the first polarization rotator and output from the single-mode fiber loop through the second polarization rotator. It then enters the phase adjuster through the third port of the phase modulator. The ninth optical signal is transmitted to the single-mode fiber loop through the second polarization rotator and output from the single-mode fiber loop through the first polarization rotator. It then enters the phase adjuster through the second port of the phase modulator. The phase adjuster processes the eighth and ninth optical signals and outputs the tenth optical signal from the first port of the phase adjuster. The tenth optical signal enters the second coupler through the second port of the second coupler and, after being processed by the second coupler, outputs the eleventh optical signal from the fourth port of the second coupler. The first photodetector is used to detect the ninth optical signal; The first polarization rotator is used to adjust the polarization state of the eighth optical signal input from the first port of the first polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the first photodetector. The adjusted polarization state of the eighth optical signal is consistent with the polarization state of the ninth optical signal input from the second port of the first polarization rotator. The second photodetector is used to detect the eighth optical signal; The second polarization rotator is used to adjust the polarization state of the ninth optical signal input from the first port of the second polarization rotator to the dominant polarization state of the single-mode fiber loop according to the detection result of the second photodetector. The adjusted polarization state of the ninth optical signal is consistent with the polarization state of the eighth optical signal input from the second port of the second polarization rotator. The fifth photodetector is used to detect the eleventh optical signal.

6. The apparatus according to claim 5, characterized in that, The second coupler is a 2*2 coupler.

7. The apparatus according to claim 5 or 6, characterized in that, The device also includes a data processing unit. The data processing unit is used to calculate the angular velocity based on the detection result of the fifth photodetector.

8. The apparatus according to any one of claims 5-7, characterized in that, The single-mode fiber loop has a fiber length greater than or equal to 700m and a diameter greater than or equal to 6cm.

9. A method for detecting angular velocity, characterized in that, include: The received light beam is processed to obtain a first optical signal, a second optical signal, and a third optical signal; The second optical signal is detected; Based on the detection result of the second optical signal, the polarization state of the first optical signal is adjusted to the dominant polarization state of the single-mode fiber loop, and the adjusted polarization state of the first optical signal is consistent with the adjusted polarization state of the second optical signal. The first optical signal is detected; Based on the detection result of the first optical signal, the polarization state of the second optical signal is adjusted to the dominant polarization state of the mode fiber loop, and the adjusted polarization state of the second optical signal is consistent with the adjusted polarization state of the first optical signal. After the first optical signal is output from the single-mode fiber loop, the first optical signal is processed to obtain the fourth optical signal; After the second optical signal is output from the single-mode fiber loop, the second optical signal is processed to obtain the fifth optical signal; The fourth and fifth optical signals are detected.

10. The method according to claim 9, characterized in that, The method further includes: The angular velocity is calculated based on the detection results of the fourth and fifth optical signals.

11. A method for detecting angular velocity, characterized in that, include: The received light beam is processed to obtain the sixth and seventh optical signals; Phase modulation of the sixth optical signal yields the eighth and ninth optical signals; The ninth optical signal is detected; Based on the detection result of the ninth optical signal, the polarization state of the eighth optical signal is adjusted to the dominant polarization state of a single-mode fiber loop, and the adjusted polarization state of the eighth optical signal is consistent with the adjusted polarization state of the ninth optical signal. The eighth optical signal is detected; Based on the detection result of the eighth optical signal, the polarization state of the ninth optical signal is adjusted to the dominant polarization state of the mode fiber loop, and the adjusted polarization state of the ninth optical signal is consistent with the adjusted polarization state of the eighth optical signal. After the eighth and ninth optical signals are output from the single-mode fiber loop, the phase of the eighth and ninth optical signals is adjusted to obtain the tenth optical signal. The eleventh optical signal is obtained by processing the tenth optical signal; The eleventh optical signal is detected.

12. The method according to claim 11, characterized in that, The method further includes: The angular velocity is calculated based on the detection result of the eleventh optical signal.

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