Optical fiber gyroscope

Abstract

The invention discloses an optical fiber gyroscope, which is suitable for the technical field of sensors and comprises a first substrate, a first planar optical waveguide coupler, a second planar optical waveguide coupler, at least one optical fiber resonant cavity and a first optical fiber. The first substrate comprises a first surface and a second surface which are opposite. The first planar optical waveguide coupler and the second planar optical waveguide coupler are arranged on the first surface. The at least one optical fiber resonant cavity is arranged on the first surface and extends into the first substrate from the first surface, and the at least one optical fiber resonant cavity is located between the first planar optical waveguide coupler and the second planar optical waveguide coupler in the direction parallel to the second surface. And the orthographic projection of the at least one optical fiber resonant cavity on the second surface is annular. The first optical fiber is arranged in the at least one optical fiber resonant cavity. According to the technical scheme, the test precision and the integration degree of the optical fiber gyroscope are improved.

Description

Technical Field

[0001] The present application belongs to the field of sensor technology, and in particular relates to a fiber optic gyroscope. Background Art

[0002] An optical gyroscope is an inertial sensor device that senses and detects angular velocity and attitude, and is essential for applications that require precise navigation and attitude control. At present, compared with traditional electromechanical gyroscopes and ring laser gyroscopes, interferometric fiber gyroscopes (IFOGs) and resonant optical gyroscopes (RFOGs) have greater potential in achieving high integration, high stability, low cost, and low power consumption.

[0003] However, the interferometric fiber gyroscope has problems with miniaturized integrated design, and the resonant fiber gyroscope has problems with back noise, which means that the test accuracy and integration of optical gyroscopes need to be improved. Summary of the invention

[0004] The present application provides a fiber optic gyroscope, aiming to improve the integration of the fiber optic gyroscope.

[0005] To achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0006] Provided is a fiber optic gyroscope, comprising a first substrate, a first planar optical waveguide coupler, a second planar optical waveguide coupler, at least one fiber resonant cavity and a first optical fiber. The first substrate comprises a first surface and a second surface opposite to each other. The first planar optical waveguide coupler and the second planar optical waveguide coupler are arranged on the first surface. At least one fiber resonant cavity is arranged on the first surface and extends from the first surface into the first substrate. Along a direction parallel to the second surface, at least one fiber resonant cavity is located between the first planar optical waveguide coupler and the second planar optical waveguide coupler, and the shape of the orthographic projection of at least one fiber resonant cavity on the second surface is annular. The first optical fiber is arranged in at least one fiber resonant cavity.

[0007] The fiber optic gyroscope provided in the present application includes a first planar optical waveguide coupler and a second planar optical waveguide coupler arranged on a first surface of a first substrate, and at least one fiber optic resonant cavity located between the first planar optical waveguide coupler and the second planar optical waveguide coupler. The fiber optic gyroscope combines the optical waveguide coupler with the at least one fiber optic resonant cavity, thereby improving the test accuracy and integration of the fiber optic gyroscope. The orthographic projection of the at least one fiber optic resonant cavity on the second surface of the first substrate is in the shape of a ring, and a first optical fiber is arranged in the fiber optic resonant cavity. This arrangement realizes the miniaturization of the fiber optic resonant cavity in terms of structure and assembly, thereby further improving the integration of the fiber optic gyroscope.

[0008] In some embodiments, the fiber optic gyroscope further includes a curing glue disposed in the fiber optic resonance cavity, and the first optical fiber is connected to the fiber optic resonance cavity via the curing glue.

[0009] In some embodiments, the cross-section of the optical fiber resonant cavity is V-shaped.

[0010] In some embodiments, the fiber optic gyroscope includes at least two fiber optic resonant cavities, and the at least two fiber optic resonant cavities are both located between the first planar optical waveguide coupler and the second planar optical waveguide coupler. The first optical fiber is disposed in the at least two fiber optic resonant cavities.

[0011] In some embodiments, the first planar optical waveguide coupler and the second planar optical waveguide coupler are both integrally provided with the first substrate.

[0012] In some embodiments, the fiber optic gyroscope further comprises a Y-branch waveguide, a polarizer and a broadband phase modulator disposed on the first surface. The Y-branch waveguide comprises an input arm, a first output arm and a second output arm, the first output arm is connected to the first planar optical waveguide coupler, and the second output arm is connected to the second planar optical waveguide coupler. The polarizer and the broadband phase modulator are both connected to the first output arm, and the polarizer and the broadband phase modulator are both connected to the second output arm.

[0013] In some embodiments, the material of the first substrate includes lithium niobate. The first output arm and the first planar optical waveguide coupler are both integrally arranged with the first substrate, and the second output arm and the second planar optical waveguide coupler are both integrally arranged with the first substrate.

[0014] In some embodiments, the fiber optic gyroscope further comprises a second substrate, and a Y-branch waveguide, a polarizer and a broadband phase modulator disposed on the second substrate. The Y-branch waveguide comprises an input arm, a first output arm and a second output arm, the first output arm is connected to the first planar optical waveguide coupler, and the second output arm is connected to the second planar optical waveguide coupler. The polarizer and the broadband phase modulator are both connected to the first output arm, and the polarizer and the broadband phase modulator are both connected to the second output arm.

[0015] In some embodiments, the first output arm is directly connected to the first planar optical waveguide coupler, and the second output arm is directly connected to the second planar optical waveguide coupler. Alternatively, the first output arm is connected to the first planar optical waveguide coupler via a second optical fiber, and the second output arm is connected to the second planar optical waveguide coupler via a third optical fiber.

[0016] In some embodiments, the fiber optic gyroscope further includes a third substrate, and a light source chip, a photodetector, and an optical circulator disposed on the third substrate. The light source chip and the photodetector are respectively connected to the optical circulator, and the optical circulator is connected to the input arm of the Y-branch waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0018] Figure 1 A schematic diagram of the structure of the fiber optic gyroscope provided in the embodiment of the present application;

[0019] Figure 2 for Figure 1 A local enlarged view of the fiber optic gyroscope at position M;

[0020] Figure 3 for Figure 2 The cross-sectional view of the fiber optic gyroscope along the A-A' direction;

[0021] Figure 4 for Figure 3 Schematic diagram of the cross section of the structure along plane XZ;

[0022] Figure 5 A schematic diagram of an optical fiber resonant cavity provided in an embodiment of the present application;

[0023] Figure 6 for Figure 1 Another partial enlarged view of the fiber optic gyroscope at position M. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0025] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0026] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0027] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0028] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0029] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0030] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0031] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0032] With the development of micro-nano technology and integrated circuit technology, miniaturized and integrated optical gyroscopes have gradually become the first choice for more emerging applications. Traditional discrete optical devices inevitably have problems such as optical path alignment, large size and high system complexity, and small and micro optical gyroscopes (Micro-optical gyroscope, MOG) with strong resistance to mechanical vibration, high stability, small size, low power consumption and easy to carry have emerged. Optical gyroscopes are widely used in navigation, inertial navigation systems, aerospace, self-driving cars, drones, robotics, earthquake monitoring, geological exploration and scientific research.

[0033] However, the traditional interferometric three-axis optical gyroscope transceiver consists of a light-emitting chip, a beam splitter coupler, a phase modulator, and a detector module. Since the modulation principle of the interferometric optical gyroscope is based on time non-reciprocity, the shorter the fiber loop, the higher the frequency of the modulation signal, and the difficulty of modulation and demodulation increases accordingly. A high-frequency modulation signal is required to match the intrinsic frequency, which will undoubtedly increase the volume or circuit load of the fiber gyroscope. The longer fiber loop hinders the lightweight and integrated application of high-precision integrated optical gyroscopes.

[0034] Moreover, the optical resonant cavity is one of the core components of the resonant optical gyroscope. The main optical noise in the resonant optical gyroscope exists in the optical resonant cavity, which directly determines the performance of the resonant optical gyroscope. Commonly used resonant cavities generally use polarization-maintaining fiber and optical waveguide as resonant cavities. The resonant cavity based on polarization-maintaining fiber cannot avoid the problem of polarization crosstalk. The existence of intrinsic birefringence and directional coupling greatly destroy the stability of resonance. In addition, the polarization-maintaining fiber is easily affected by ambient temperature and vibration, and its fixed assembly problem has been difficult to solve. Although the resonant cavity based on optical waveguide has the advantages of small size and integration, the optical waveguide has large loss, causing large backscattered noise in the cavity, and the structure of the cavity is not flexible, and the polarization noise cannot be effectively suppressed.

[0035] To solve at least one of the above problems, an embodiment of the present application provides a fiber optic gyroscope as a Sagnac sensor of a gyroscope system, wherein the Sagnac effect refers to the change in the propagation speed of light when a light beam in a closed light path (usually a circular light path) is rotated in one direction, and this change can be measured. The rotation speed of light is proportional to the angular velocity of the object. Figure 1 A schematic diagram of the structure of the fiber optic gyroscope provided in the embodiment of the present application; Figure 2 for Figure 1 A local enlarged view of the fiber optic gyroscope at M.

[0036] like Figure 1 As shown, the fiber optic gyroscope 1 includes a first substrate 10, a first planar optical waveguide coupler 11, a second planar optical waveguide coupler 12, at least one optical fiber resonant cavity 13 and a first optical fiber 14. Figure 2 As shown, the first substrate 10 includes a first surface 101 and a second surface 102 opposite to each other. The first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are arranged on the first surface 101. Exemplarily, the structural layout of the optical waveguide coupler can be designed in the optical waveguide design software according to the application requirements and the selected substrate material, and the simulated optical waveguide shape and parameters are optimized, and then the optical waveguide coupler is designed and taped out. Specifically, the optical waveguide layout is transferred through thin film deposition and photolithography technology, and the corresponding waveguide structure is formed on the first surface 101 after exposure and etching.

[0037] At least one optical fiber resonant cavity 13 is disposed on the first surface 101 and extends from the first surface 101 into the first substrate 10. In a direction parallel to the second surface 102, at least one optical fiber resonant cavity 13 is located between the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12. The shape of the orthographic projection of at least one optical fiber resonant cavity 13 on the second surface 102 is annular. Exemplarily, the structural layout of the annular optical fiber resonant cavity 13 can be designed in the optical waveguide design software according to the application requirements and the selected substrate material, and the shape and parameters of the simulated resonant cavity structure can be optimized, and then the optical fiber resonant cavity 13 can be designed and taped out. Specifically, the resonant cavity structure layout is transferred by thin film deposition and photolithography technology, and the corresponding resonant cavity structure is formed on the first surface 101 after exposure and etching.

[0038] The first optical fiber 14 is arranged in at least one annular optical fiber resonant cavity 13. Exemplarily, the first optical fiber 14 is a polarization-maintaining optical fiber. The polarization-maintaining optical fiber can keep the polarization state of the optical signal unchanged during the transmission of the optical signal. The embodiment provided in the present application combines the planar optical waveguide coupler with the first optical fiber 14 arranged in an annular shape. The high-precision optical fiber gyroscope 1 requires a longer optical fiber length, and the long optical fiber length will inevitably increase the stability requirements under ambient temperature, vibration and other conditions. The first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are miniaturized and highly reliable. The effective combination of the two can realize the miniaturization, high stability and high reliability assembly and high-precision testing requirements of the optical fiber gyroscope 1. Compared with the traditional interferometric gyroscope, the size of the optical fiber resonant cavity 13 of the optical fiber gyroscope 1 provided in the present application is greatly reduced, and sufficient transit time can be guaranteed, that is, the requirements of medium or even high precision for optical devices can be guaranteed, and there is no problem of sensitivity and zero bias stability of the optical fiber gyroscope 1 caused by too small radius.

[0039] The fiber optic gyroscope 1 provided in the present application includes a first planar optical waveguide coupler 11 and a second planar optical waveguide coupler 12 arranged on a first surface 101 of a first substrate 10, and at least one optical fiber resonant cavity 13 located between the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12. The fiber optic gyroscope 1 combines the optical waveguide coupler with the at least one optical fiber resonant cavity 13, thereby improving the test accuracy and integration of the fiber optic gyroscope 1. The orthographic projection of the at least one optical fiber resonant cavity 13 on the second surface 102 of the first substrate 10 is in the shape of a ring, and a first optical fiber 14 is arranged in the optical fiber resonant cavity 13. This arrangement realizes the miniaturization of the optical fiber resonant cavity 13 in terms of structure and assembly, thereby further improving the integration of the fiber optic gyroscope 1.

[0040] Figure 3 for Figure 2 The cross-sectional view of the fiber optic gyroscope along the A-A' direction; Figure 4 for Figure 3 Schematic diagram of the cross section of the structure along plane XZ.

[0041] In some embodiments, Figure 3 As shown, the cross-section of the optical fiber resonant cavity 13 is V-shaped. It can be understood that the optical fiber resonant cavity 13 is provided with a V-shaped groove, so that the first optical fiber 14 is arranged more stably in the groove. Among them, when the optical fiber resonant cavity 13 is formed, a V-shaped groove structure is simultaneously etched as a fixing device for the first optical fiber 14. This setting can realize the miniaturization of the optical fiber resonant cavity 13 in terms of structure and assembly, and realize the high integration of the optical fiber gyroscope 1.

[0042] In some embodiments, Figure 4 As shown, the fiber optic gyroscope 1 also includes a curing glue 130 disposed in the fiber optic resonant cavity 13, and the first optical fiber 14 is connected to the fiber optic resonant cavity 13 through the curing glue 130. Optionally, the curing glue 130 is selected from a high-refractive and high-transmittance curing glue such as ultraviolet curing glue to fix the first optical fiber 14 to form the fiber optic resonant cavity 13. Among them, the first optical fiber 14 is coiled at the V-groove, and the coiling method can be selected as parallel coiling or non-parallel coiling. In addition, by fixing the first optical fiber 14 located in the fiber optic resonant cavity 13 with the curing glue 130, the influence of temperature on the fiber optic resonant cavity 13 can be reduced.

[0043] Figure 5 A schematic diagram of an optical fiber resonant cavity provided in an embodiment of the present application.

[0044] In some embodiments, Figure 5 As shown, the fiber optic gyroscope 1 includes at least two fiber optic resonant cavities 13, namely a first fiber optic resonant cavity 131 and a second fiber optic resonant cavity 132. The at least two fiber optic resonant cavities 13 constitute a dual-ring resonant cavity structure (Microring), which can be used as a sensitive unit of the gyroscope system. The at least two fiber optic resonant cavities 13 are located between the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12, have the same size, and share the input optical signal. Exemplarily, along the direction Y, the first planar optical waveguide coupler 11 located above includes a first port P, and the second planar optical waveguide coupler 12 located below includes a second port Q. V-grooves are etched at at least two fiber optic resonant cavities 13, and the first optical fiber 14 is arranged in the V-grooves of the at least two fiber optic resonant cavities 13 and fixed by curing glue.

[0045] It can be understood that, when the optical signal enters from the first port P of the first planar optical waveguide coupler 11, the optical signal is divided into two beams along the direction X, respectively entering the first optical fiber resonant cavity 131 and the second optical fiber resonant cavity 132, and after rotating a certain number of times along the first optical fiber 14, it enters the second planar optical waveguide coupler 12 and exits from the second port Q. When the optical signal enters from the second port Q of the second planar optical waveguide coupler 12, the optical signal is divided into two beams along the direction X, respectively entering the first optical fiber resonant cavity 131 and the second optical fiber resonant cavity 132, and after rotating a certain number of times along the first optical fiber 14, it enters the first planar optical waveguide coupler 11 and exits from the first port P. After the resonant signals converge at the exit port, interference signals are generated, and the intensity of the interference signals changes with the change of the angular velocity of the micro-ring rotation. The change of the angular velocity of rotation can be obtained by detecting the change of the intensity of the interference signals.

[0046] In some embodiments, Figure 2 As shown, the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are both integrally provided with the first substrate 10. It can be understood that the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are made of the same material as the first substrate 10, and the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 can be formed on the first substrate 10 by a photolithography process.

[0047] In some embodiments, Figure 2 As shown, the fiber optic gyroscope 1 also includes a Y-branch waveguide 15, a polarizer 16 and a broadband phase modulator 17 arranged on the first surface. The Y-branch waveguide 15 includes an input arm 150, a first output arm 151 and a second output arm 152. The first output arm 151 is connected to the first planar optical waveguide coupler 11, and the second output arm 152 is connected to the second planar optical waveguide coupler 12. The polarizer 16 and the broadband phase modulator 17 are both connected to the first output arm 151, and the polarizer 16 and the broadband phase modulator 17 are both connected to the second output arm 152.

[0048] In some embodiments, Figure 2As shown, the material of the first substrate 10 includes lithium niobate (LiNbO3). The first output arm 151 and the first planar optical waveguide coupler 11 are both integrally arranged with the first substrate 10, and the second output arm 152 and the second planar optical waveguide coupler 12 are both integrally arranged with the first substrate 10. It can be understood that the Y-branch waveguide 15, the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are integrated on the first substrate 10. Since lithium niobate as a waveguide material has a wide optical window and a high refractive index, and has a strong electro-optical effect and a high nonlinear coefficient, it is an ideal material for optical modulation and photon integrated substrates. Therefore, lithium niobate material can be used as the material of the first substrate 10 to prepare the Y-branch waveguide 15, the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12.

[0049] Exemplarily, the Y-branch waveguide 15 and the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 can be integrally arranged with the first substrate 10, that is, the first substrate 10 of lithium niobate material is exposed and etched along the positions where the Y-branch waveguide 15, the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are arranged to form a corresponding structural pattern.

[0050] In some embodiments, Figure 2 As shown, the material of the first substrate 10 can also be silicon (Si), silicon nitride (Si3N4) or other high refractive index materials, the first planar optical waveguide coupler 11 and the second planar optical waveguide coupler 12 are integrally arranged with the first substrate 10, and the Y-branch waveguide 15 is arranged on the first substrate 10, but is arranged separately. Optionally, the Y-branch waveguide 15 can be made of lithium niobate material with a strong electro-optical effect to enhance the refractive index and optical window of the optical signal.

[0051] Figure 6 for Figure 1 Another partial enlarged view of the fiber optic gyroscope at position M.

[0052] In some embodiments, Figure 6 As shown, the optical fiber gyroscope 1 further includes a second substrate 20, and a Y-branch waveguide 15, a polarizer 16, and a broadband phase modulator 17 disposed on the second substrate 20, that is, the Y-branch waveguide 15, the polarizer 16, and the broadband phase modulator 17 are not disposed on the first substrate 10. The Y-branch waveguide 15 includes an input arm 150, a first output arm 151, and a second output arm 152, the first output arm 151 is connected to the first planar optical waveguide coupler 11, and the second output arm 152 is connected to the second planar optical waveguide coupler 12. The polarizer 16 and the broadband phase modulator 17 are both connected to the first output arm 151, and the polarizer 16 and the broadband phase modulator 17 are both connected to the second output arm 152.

[0053] It can be understood that the Y-branch waveguide 15 , the polarizer 16 and the broadband phase modulator 17 are integrally arranged with the second substrate 20 , and the second substrate 20 can be set to lithium niobate material to ensure a higher refractive index and a larger optical window of the Y-branch waveguide 15 .

[0054] In some embodiments, Figure 6 As shown, the first output arm 151 is directly connected to the first planar optical waveguide coupler 11, and the second output arm 152 is directly connected to the second planar optical waveguide coupler 12, so that the loss of the optical signal is lower and it is more conducive to the integration of the optical fiber gyroscope 1. Alternatively, the first output arm 151 is connected to the first planar optical waveguide coupler 11 through the second optical fiber, and the second output arm 152 is connected to the second planar optical waveguide coupler 12 through the third optical fiber, and the second optical fiber and the third optical fiber and the first optical fiber 14 are all polarization-maintaining optical fibers. The first output arm 151 and the second output arm 152 are connected to the corresponding planar optical waveguide couplers through the polarization-maintaining optical fiber, which can keep the polarization state of the optical signal stable and improve the reliability of the data finally obtained.

[0055] In some embodiments, Figure 1 As shown, the fiber optic gyroscope 1 also includes a third substrate 30, and a light source chip 2, a photodetector 3, and an optical circulator 4 arranged on the third substrate 30. The light source chip 2 and the photodetector 3 are respectively connected to the optical circulator 4, and the optical circulator 4 is connected to the input arm 150 of the Y-branch waveguide 15. Compared with the traditional interferometric fiber optic gyroscope, the light source chip 2, the photodetector 3, and the optical circulator 4 selected in the fiber optic gyroscope 1 provided in the present application can further improve the integration, and the spatial alignment coupling reduces the requirements for the gyroscope optical path assembly and reduces the difficulty of the preparation process.

[0056] like Figure 1 , Figure 2 and Figure 6 As shown, the optical signal output by the light source chip 2 enters the Y-branch waveguide 15 through the optical circulator 4, and the optical signal is divided into two optical signals. One optical signal goes along the first output arm 151, is phase-modulated by the broadband phase modulator 17, and then enters the first planar optical waveguide coupler 11 in a clockwise direction, and enters the optical fiber resonant cavity 13 at the position where the first planar optical waveguide coupler 11 and the optical fiber resonant cavity 13 are closest. The other optical signal goes along the second output arm 152, is phase-modulated by the broadband phase modulator 17, and then enters the second planar optical waveguide coupler 12 in a counterclockwise direction, and enters the optical fiber resonant cavity 13 at the position where the second planar optical waveguide coupler 12 and the optical fiber resonant cavity 13 are closest.

[0057] The two beams of light are transmitted through multiple turns of the first optical fiber 14 in the cavity, and the light in two directions is returned to the confluence point of the Y-branch waveguide 15 through the optical waveguide coupler again and interferes. The interference light passes through the optical circulator 4 and is received by the photodetector module. After amplification and other signal processing processes, the gyro rotation signal is obtained, thereby obtaining the basic performance parameters at different angular velocities, including zero bias and zero drift, scale factor, random walk coefficient, threshold and resolution, and maximum input angular velocity.

[0058] Furthermore, by calculating the random noise of the embodiments and comparative examples, such as quantization noise, angular random walk, angular rate random walk noise, zero bias instability, and rate ramp noise, the noise data of the fiber optic gyroscope 1 provided by the present application can be obtained. Compared with the conventional waveguide-based resonant fiber optic gyroscope, the fiber optic gyroscope 1 provided by the present application has lower backscatter noise, and the structure of the fiber resonant cavity 13 is more flexible, which can effectively suppress polarization drift noise.

[0059] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A fiber optic gyroscope, characterized in that: include: a first substrate including a first surface and a second surface opposite to each other; A first planar optical waveguide coupler and a second planar optical waveguide coupler are disposed on the first surface; at least one optical fiber resonant cavity, disposed on the first surface and extending from the first surface into the first substrate; Along a direction parallel to the second surface, the at least one optical fiber resonant cavity is located between the first planar optical waveguide coupler and the second planar optical waveguide coupler; the orthographic projection of the at least one optical fiber resonant cavity on the second surface is in the shape of a ring; The first optical fiber is arranged in the at least one optical fiber resonant cavity.

2. The fiber optic gyroscope according to claim 1, characterized in that: The fiber optic gyroscope further includes a curing glue disposed in the fiber optic resonant cavity; The first optical fiber is connected to the optical fiber resonant cavity through the curing glue.

3. The fiber optic gyroscope according to claim 1, characterized in that: The cross section of the optical fiber resonant cavity is in a V-shape.

4. The fiber optic gyroscope according to claim 1, characterized in that: The fiber optic gyroscope comprises at least two fiber optic resonant cavities, and at least two fiber optic resonant cavities are both located between the first planar optical waveguide coupler and the second planar optical waveguide coupler; The first optical fiber is disposed in at least two of the optical fiber resonant cavities.

5. The fiber optic gyroscope according to claim 1, characterized in that: The first planar optical waveguide coupler and the second planar optical waveguide coupler are both integrally provided with the first substrate.

6. The fiber optic gyroscope according to claim 1, characterized in that: The fiber optic gyroscope further includes a Y-branch waveguide, a polarizer, and a broadband phase modulator disposed on the first surface; The Y-branch waveguide includes an input arm, a first output arm and a second output arm, the first output arm is connected to the first planar optical waveguide coupler, and the second output arm is connected to the second planar optical waveguide coupler; The polarizer and the broadband phase modulator are both connected to the first output arm, and the polarizer and the broadband phase modulator are both connected to the second output arm.

7. The fiber optic gyroscope according to claim 6, characterized in that: The material of the first substrate includes lithium niobate; The first output arm and the first planar optical waveguide coupler are both integrally provided with the first substrate, and the second output arm and the second planar optical waveguide coupler are both integrally provided with the first substrate.

8. The fiber optic gyroscope according to claim 1, characterized in that: The optical fiber gyroscope further includes a second substrate, and a Y-branch waveguide, a polarizer, and a broadband phase modulator disposed on the second substrate; The Y-branch waveguide includes an input arm, a first output arm and a second output arm, the first output arm is connected to the first planar optical waveguide coupler, and the second output arm is connected to the second planar optical waveguide coupler; The polarizer and the broadband phase modulator are both connected to the first output arm, and the polarizer and the broadband phase modulator are both connected to the second output arm.

9. The fiber optic gyroscope according to claim 8, characterized in that: The first output arm is directly connected to the first planar optical waveguide coupler, and the second output arm is directly connected to the second planar optical waveguide coupler; or, The first output arm is connected to the first planar optical waveguide coupler via a second optical fiber, and the second output arm is connected to the second planar optical waveguide coupler via a third optical fiber.

10. The fiber optic gyroscope according to any one of claims 6 to 9, characterized in that: The fiber optic gyroscope further includes a third substrate, and a light source chip, a photodetector and an optical circulator arranged on the third substrate; The light source chip and the photodetector are respectively connected to the optical circulator, and the optical circulator is connected to the input arm of the Y-branch waveguide.

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