Integrated chip for silicon nitride-based optical gyroscope, optical gyroscope and working method of optical gyroscope

Abstract

The invention discloses an integrated chip for a silicon nitride-based optical gyroscope, the optical gyroscope and a working method of the optical gyroscope, and belongs to the field of photoelectric integration, and the integrated chip comprises a wide-spectrum light source tube core, a polarizer, a beam splitter, a phase modulator, a spot size converter and a photoelectric detector which are integrated on the same S < O2 > substrate and are sequentially arranged along the light propagation direction, the beam splitter, the polarizer, the phase modulator and the spot-size converter are all composed of S N waveguides, so that the beam splitter, the polarizer, the phase modulator and the spot-size converter are sequentially and optically interconnected through the S N waveguides. By adopting the integrated chip for the silicon nitride-based optical gyroscope, the optical gyroscope and the working method of the optical gyroscope, the performance of the optical gyroscope is remarkably improved and the application range of the optical gyroscope is remarkably expanded through highly-integrated, multi-band compatible and high-performance components, three-axis synchronous measurement and reliable system design; the design has important value in the key fields of inertial navigation, aircraft attitude control and the like due to high integration level, high precision and high reliability.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic integration technology, and in particular to an integrated chip for a silicon nitride-based optical gyroscope, an optical gyroscope and a working method thereof. Background Art

[0002] Traditional fiber-optic gyroscopes (FOGs), particularly interferometric FOGs based on the Sagnac effect, are widely used in defense, aviation, and aerospace applications both domestically and internationally due to their high stability, low energy consumption, and ability to cover the full navigation range (0.1° / h-0.001° / h). Furthermore, with the rapid development of drone and autonomous driving technologies, optical gyroscopes, core navigation components, require further technological upgrades. The key to these upgrades lies in reducing the size and weight of FOGs while maintaining gyro accuracy to meet the assembly requirements of unmanned systems.

[0003] The existing fiber optic gyroscope structure is as follows:

[0004] CN202410260215.0 discloses a chip, preparation method, and operating method for a composite integrated optical gyroscope. The chip includes a beam splitter, polarizer, modulator, and waveguide ring arranged in the transmission order of the input light. The beam splitter, polarizer, and modulator are all thin-film lithium niobate devices, and the beam splitter, polarizer, and modulator are optically interconnected via a thin-film lithium niobate waveguide. The waveguide ring is a silicon nitride material device, and the waveguide ring and modulator are optically interconnected via an interlayer coupling structure.

[0005] Existing optical gyros are mostly made of lithium niobate (LNbO), which exhibits excellent electro-optical effects and high-precision phase control capabilities, demonstrating unique advantages in high-end scientific research and aerospace. However, its temperature sensitivity and low mechanical strength limit its widespread application. Summary of the Invention

[0006] The purpose of the present invention is to provide an integrated chip for a silicon nitride-based optical gyroscope, an optical gyroscope and a working method thereof, so as to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention provides an integrated chip for a silicon nitride-based optical gyroscope, comprising a broadband light source die, a polarizer, a beam splitter, a phase modulator, a spot size converter, and a photodetector, which are integrated on a single SiO2 substrate and sequentially arranged along the direction of light propagation. The beam splitter, polarizer, phase modulator, and spot size converter are all constructed from SiN waveguides, thereby achieving optical interconnection between the beam splitter, polarizer, phase modulator, and spot size converter via the SiN waveguides.

[0008] Preferably, in the three wavelength bands of 850 nm, 1310 nm and 1550 nm used in optical gyroscope applications, the thickness of the Si N waveguide is in the range of 100 nm to 150 nm, and the width is in the range of 0.9 μm to 1.2 μm.

[0009] Preferably, the broadband light source die is a superluminescent diode die, which is coupled to one of the ports of the beam splitter via a waveguide for photon wire bonding, wherein the bending radius of the waveguide for photon wire bonding is greater than 100 μm and the coupling loss is ≤ 2 dB.

[0010] Preferably, the polarizer is a structure combining bending polarization and mode coupling polarization, and the extinction ratio of the polarizer is 60dB;

[0011] The structure combining bend polarization and mode coupling polarization includes a bend polarization waveguide and a dissipative waveguide. The bend polarization waveguide includes a horizontal straight waveguide for inputting fundamental mode light, a first outer bend waveguide, a first vertical straight waveguide, a first inner bend waveguide, a coupling horizontal straight waveguide, a second inner bend waveguide, a second vertical straight waveguide, a second outer bend waveguide, and an output horizontal straight waveguide for outputting the TE0 mode, which are connected in sequence. The first outer bend waveguide and the second outer bend waveguide are symmetrically arranged with respect to the coupling horizontal straight waveguide, and opposite sides of the first outer bend waveguide and the second outer bend waveguide are opposite to each other. The first inner bend waveguide and the second inner bend waveguide are symmetrically arranged with respect to the coupling horizontal straight waveguide, and opposite sides of the first inner bend waveguide and the second inner bend waveguide are opposite to each other.

[0012] The coupling horizontal straight waveguide is coupled with the dissipative waveguide to convert the TE0 mode into the TE1 mode by using the dissipative waveguide and then output it;

[0013] The radii of the first outer curved waveguide, the second outer curved waveguide, the first inner curved waveguide and the second inner curved waveguide are the same and range from 50 μm to 80 μm. The width of the coupled horizontal straight waveguide ranges from 1.8 μm to 2.1 μm, and the width of the dissipative waveguide ranges from 2 μm to 2.3 μm.

[0014] Preferably, the phase modulator is a thermo-optical modulator or a piezoelectric modulator, wherein the thermo-optical modulator includes electrodes arranged on the upper and lower claddings of the SiN waveguide, and the piezoelectric modulator includes a piezoelectric film and electrodes sequentially arranged above the SiN waveguide, and the material of the piezoelectric film is AlN, PZT or HfO2;

[0015] The SiN waveguide constituting the phase modulator is a rectangular waveguide.

[0016] Preferably, the photodetector is made of a III-V group material, and the photodetector is transferred to the beam splitter by a method of material growth-structure release-micro transfer printing;

[0017] The III-V group material is InP or InGaAs, and the photodetector is heterogeneously integrated on-chip via interlayer coupling between the InP tapered waveguide and the SiN waveguide constituting the beam splitter. The SiN waveguide constituting the beam splitter is a tapered waveguide.

[0018] The spot converter is a three-section tapered waveguide structure.

[0019] An optical gyroscope is a single-axis optical gyroscope, comprising an integrated chip for a silicon nitride-based optical gyroscope. A mode spot converter of the integrated chip for the silicon nitride-based optical gyroscope is fused between a polarization-maintaining pigtail and a sensitive optical fiber ring.

[0020] An operating method for an optical gyroscope comprises the following steps: light emitted from a broad-spectrum light source die enters a polarizer via a waveguide for photon wire bonding; the polarized light is split by a beam splitter and then enters a phase modulator for phase modulation; after mode field conversion by a mode spot converter, the two beams pass through polarization-maintaining pigtails and enter a sensitive element optical fiber ring along two ports, respectively; the two beams are transmitted within the sensitive element optical fiber ring, and after a Sagnac effect occurs, they return to the phase modulator to complete beam combining interference; finally, the optical power information is transmitted to a photodetector via a beam splitter, and then transmitted to an external circuit system for resolution, thereby realizing the rotation speed detection function of the single-axis optical gyroscope.

[0021] An optical gyroscope is a three-axis optical gyroscope, comprising an integrated chip for a silicon nitride-based optical gyroscope and a 1×3 beam splitter. The input end of the 1×3 beam splitter is optically interconnected with a wide-spectrum light source tube core. The three output ends of the 1×3 beam splitter are optically interconnected with polarizers of the integrated chip for measuring the X-axis, Y-axis, and Z-axis, respectively. Moreover, the pattern spot converters of the three integrated chips for the silicon nitride-based optical gyroscope are respectively fused with three sensitive optical fiber rings through polarization-maintaining pigtails.

[0022] An optical gyroscope operating method includes the following steps: light emitted from a wide-spectrum light source tube core is split by a 1×3 beam splitter and then synchronously enters polarizers of three silicon nitride-based optical gyroscope integrated chips for measuring the X-axis, Y-axis, and Z-axis, respectively; the polarized light is split by the beam splitter and then enters a phase modulator for phase modulation; after mode field conversion by a mode spot converter, the two beams pass through polarization-maintaining pigtails and enter a sensitive element optical fiber ring along two ports, respectively; the two beams are transmitted within the sensitive element optical fiber ring, and after the Sagnac effect occurs, they return to the phase modulator to complete beam combining interference; finally, the optical power information is transmitted to a photodetector through the beam splitter, and then transmitted to an external circuit system for resolution, thereby realizing the rotation speed detection function of the three-axis optical gyroscope.

[0023] Therefore, the present invention uses the above-mentioned silicon nitride-based optical gyroscope integrated chip, optical gyroscope and operating method, which have the following beneficial effects:

[0024] 1. High integration and miniaturization: By integrating the broadband light source die, polarizer, beam splitter, phase modulator, spot size converter and photodetector on the same SiO2 substrate, a highly integrated chip design is achieved, which not only reduces the size and weight of the system, but also improves the reliability and stability of the system;

[0025] Application of SiN waveguides: Beam splitters, polarizers, phase modulators, and spot converters are all made of SiN waveguides, making the optical interconnection between these components more efficient and stable, further improving the system's integration.

[0026] 2. Multi-band compatibility: Supports multiple bands: The integrated chip can operate in three bands: 850nm, 1310nm and 1550nm, suitable for different application scenarios and technical requirements;

[0027] 3. High-performance components: Using superluminescent diodes as the broadband light source core, it has broadband characteristics, low coupling loss (≤2dB), and a large bending radius (>100μm), ensuring high-quality light source output;

[0028] High extinction ratio polarizer: adopts a combined structure of bending polarization and mode coupling polarization, with an extinction ratio of 60dB, providing efficient polarization control capability;

[0029] Multiple phase modulator options: The phase modulator can be selected from thermo-optical modulators or piezoelectric modulators to meet different application requirements. The designs of thermo-optical modulators and piezoelectric modulators are optimized for different modulation mechanisms, ensuring high-precision phase modulation.

[0030] High-performance photodetectors: Photodetectors are made of III-V materials (such as InP or InGaAs) and are integrated on-chip using micro-transfer printing technology, ensuring high photoelectric conversion efficiency and low noise characteristics.

[0031] 4. Three-axis synchronous measurement: The light source beam is divided into three paths through a 1×3 beam splitter, used to measure the X-axis, Y-axis, and Z-axis respectively. The integrated chip on each axis works independently but is driven synchronously by the same light source, ensuring the consistency and synchronization of the three-axis data;

[0032] Multi-axis data fusion: Data from three axes is transmitted to an external circuit system for analysis. Through complex algorithm processing and error correction, comprehensive attitude information is output, suitable for high-precision applications such as inertial navigation and aircraft attitude control.

[0033] 5. Reliability and robustness: The mode spot converter adopts a three-section tapered waveguide structure, which effectively reduces the transmission loss caused by mode field mismatch and improves the overall performance of the system;

[0034] At the same time, the mode spot converter is fused with the sensitive fiber ring through the polarization-maintaining pigtail to ensure the stable transmission of the optical signal and improve the reliability and robustness of the system;

[0035] 6. Broad application prospects: It can provide all-round, high-precision attitude information, suitable for aviation, aerospace, navigation and other fields, especially in application scenarios with extremely high requirements for attitude accuracy.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a layout diagram of an integrated chip for a silicon nitride-based optical gyroscope according to the present invention;

[0038] Figure 2 This is a schematic diagram of the coupling between a broadband light source die and a polarizer of an integrated chip for a silicon nitride-based optical gyroscope of the present invention;

[0039] Figure 3 This is a cross-sectional view of a polarizer of an integrated chip for a silicon nitride-based optical gyroscope according to the present invention;

[0040] Figure 4 Schematic diagram of the phase modulator structure of an integrated chip for a silicon nitride-based optical gyroscope of the present invention, wherein (a) is a schematic diagram of the pyroelectric modulator structure, and (b) is a schematic diagram of the pyroelectric modulator structure;

[0041] Figure 5 This is a schematic structural diagram of a pattern spot converter of an integrated chip for a silicon nitride-based optical gyroscope according to the present invention;

[0042] Figure 6 Schematic diagram of the structure of a photodetector integrated chip for a silicon nitride-based optical gyroscope according to the present invention, wherein (a) is a coupling diagram and (b) is a layout diagram;

[0043] Figure 7 Schematic diagram of the structure of a single-axis fiber optic gyroscope of the present invention;

[0044] Figure 8 Schematic diagram of the structure of the three-axis fiber optic gyroscope of the present invention.

[0045] Reference numerals

[0046] 1. Broad-spectrum light source die; 2. Waveguide for photonic wire bonding; 3. Photodetector; 31. InP tapered waveguide; 4. Polarizer; 40. Dissipative waveguide; 41. Input horizontal straight waveguide; 42. First outer curvature waveguide; 43. First vertical straight waveguide; 44. First inner curvature waveguide; 45. Coupling horizontal straight waveguide; 46. Second inner curvature waveguide; 47. Second vertical straight waveguide; 48. Second outer curvature waveguide; 49. Output horizontal straight waveguide; 5. Beam splitter; 6. Phase modulator; 61. Electrode; 62. Piezoelectric film; 7. Mode spot converter; 8. SiO2 substrate; 9. SiN waveguide; 10. Polarization-maintaining pigtail; 11. Sensitive element fiber ring; 12. 1×3 beam splitter. DETAILED DESCRIPTION

[0047] In order to make the purposes, technical solutions and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0048] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0049] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] With the continuous development and improvement of micro-nanofabrication technology and the growing demand for high-efficiency, low-loss optical transmission in the photonic integrated chip field, SiN (silicon nitride) materials capable of producing optical waveguides that meet these requirements are becoming a growing trend. Furthermore, since optical gyros also have certain requirements for device loss, using SiN materials to create passive structures that meet these requirements and applying them to optical gyroscope systems is a viable path to miniaturization.

[0051] As the core components of the fiber optic gyroscope, the beam splitter and the overall light transmission structure can be replaced by an on-chip SiN waveguide structure; the phase modulator can be realized through heterogeneous integration or bonding with other materials based on the material compatibility of SiN; the broadband light source and photodetector can be integrated with the SiN-based chip through the optical method of tube core bonding; and the sensitive ring structure is connected through polarization-maintaining fiber to form an overall integrated optical gyroscope system. While maintaining the same accuracy, the volume and energy consumption of the optical gyroscope are greatly reduced, thus realizing the morphological upgrade of the optical gyroscope.

[0052] Based on the above analysis, the present invention is designed as follows: Figures 1-6 As shown, a silicon nitride-based integrated chip for an optical gyroscope includes a broadband light source die 1, a polarizer 4, a beam splitter 5, a phase modulator 6, a spot size converter 7, and a photodetector 3, all integrated on a single SiO2 substrate 8 and arranged sequentially along the direction of light propagation. The beam splitter 5, polarizer 4, phase modulator 6, and spot size converter 7 are all formed by a SiN waveguide 9, thereby optically interconnecting the beam splitter 5, polarizer 4, phase modulator 6, and spot size converter 7 via the SiN waveguide 9. In the three wavelength bands of 850 nm, 1310 nm, and 1550 nm used in optical gyroscopes, the SiN waveguide 9 has a thickness ranging from 100 nm to 150 nm and a width ranging from 0.9 μm to 1.2 μm.

[0053] The broadband light source die 1 is a superluminescent diode die, which is coupled to one of the ports of the beam splitter 5 via a waveguide 2 for photon wire bonding. Photon wire bonding refers to the use of micro-nano processing methods to form a waveguide structure for light transmission between chips or between optical fibers and chips. This waveguide structure avoids traditional optical methods such as end-to-end docking and spatial optical coupling that require constant adjustment, and achieves efficient coupling and mode matching between chips made of different materials. The bending radius of the waveguide 2 for photon wire bonding is greater than 100μm, and the coupling loss is ≤2dB.

[0054] The polarizer 4 is a combined structure of bend polarization and mode coupling polarization, which achieves a high extinction ratio through the difference in TE / TM mode bending loss and the filtering characteristics of mode coupling conversion between waveguides, and realizes an extinction ratio of 60dB for the polarizer 4; the combined structure of bend polarization and mode coupling polarization includes a bend polarizing waveguide and a dissipative waveguide 40, the bend polarizing waveguide includes a horizontal straight waveguide 41 connected in sequence and used to input fundamental mode light, a first outer curved waveguide 42, a first vertical straight waveguide 43, a first inner curved waveguide 44, a coupled horizontal straight waveguide 45, a second inner curved waveguide 46, a second vertical straight waveguide 47, a second outer curved waveguide 48 and an output horizontal straight waveguide 49 for outputting the TE0 mode, the first outer curved waveguide 42 and the second outer curved waveguide 48 are connected in sequence with respect to the coupling horizontal straight waveguide. The straight waveguides 45 are arranged symmetrically, and the first outer curved waveguide 42 and the second outer curved waveguide 48 are opposite to each other; the first inner curved waveguide 44 and the second inner curved waveguide 46 are arranged symmetrically about the coupled horizontal straight waveguide 45, and the first inner curved waveguide 44 and the second inner curved waveguide 46 are opposite to each other; the coupled horizontal straight waveguide 45 is coupled with the dissipative waveguide 40, and is used to use the dissipative waveguide 40 to convert the TE0 mode into the TE1 mode and then output it; the first outer curved waveguide 42, the second outer curved waveguide 48, the first inner curved waveguide 44 and the second inner curved waveguide 46 have the same radius, and the radius range is 50μm-80μm, the width range of the coupled horizontal straight waveguide 45 is 1.8μm-2.1μm, and the width range of the dissipative waveguide 40 is 2μm-2.3μm.

[0055] The phase modulator 6 is a thermo-optic modulator or a piezoelectric modulator, wherein the thermo-optic modulator includes electrodes 61 arranged on the upper and lower claddings of the SiN waveguide 9. The thermoelectric modulator is based on the thermo-optical properties of SiN itself. By applying power to the electrode 61, the heat released causes the SiN waveguide 9 to produce a thermo-optical effect, thereby introducing an additional phase difference to achieve phase modulation; the piezoelectric modulator includes a piezoelectric film 62 and an electrode 61 sequentially arranged above the SiN waveguide 9, and the material of the piezoelectric film 62 is AlN, PZT or HfO2; the SiN waveguide 9 constituting the phase modulator 6 is a rectangular waveguide, and the piezoelectric modulator is based on the photoelastic effect of the piezoelectric film 62. By applying power to the electrode 61, the piezoelectric film 62 is caused to vibrate, thereby causing the SiN waveguide 9 to resonate, generating a photoelastic effect, changing the refractive index periodicity of the SiN waveguide 9, that is, stress birefringence, introducing different phases between the two arms of the phase modulator 6, generating a phase difference, thereby achieving phase modulation.

[0056] The photodetector 3 is made of a III-V material and is transferred to the beam splitter 5 via a material growth-structure release-micro-transfer method (i.e., a grid structure is reserved during the material growth process for stress release and separation, and multiple individual detector dies are then transferred via an elastic mold). The III-V material is InP or InGaAs. The photodetector 3 is heterogeneously integrated on-chip via interlayer coupling between the InP tapered waveguide 31 and the SiN waveguide 9 constituting the beam splitter 5. The SiN waveguide 9 constituting the beam splitter 5 is a tapered waveguide.

[0057] The mode spot converter 7 is a three-section tapered waveguide structure, which achieves a large mode broadening to improve the coupling efficiency with the polarization-maintaining pigtail 10. The converted mode field size is 4.5μm, and the coupling efficiency with the 6μm mode field fiber can reach 90%.

[0058] like Figure 7 As shown, an optical gyroscope is a single-axis optical gyroscope, which includes an integrated chip for a silicon nitride-based optical gyroscope. The mode spot converter 7 of the integrated chip for the silicon nitride-based optical gyroscope is fused with a sensitive optical fiber ring through a polarization-maintaining pigtail 10.

[0059] An optical gyroscope operating method includes the following steps: light emitted from a broadband light source die 1 enters a polarizer 4 via a waveguide 2 for photon wire bonding; the polarized light is split by a beam splitter 5 and then enters a phase modulator 6 for phase modulation; after mode field conversion by a mode spot converter 7, the two beams pass through a polarization-maintaining pigtail 10 and enter a sensitive element optical fiber ring 11 along two ports, respectively; the two beams are transmitted within the sensitive element optical fiber ring 11, and after a Sagnac effect occurs, the light returns to the phase modulator 6 to complete beam combining interference; finally, the optical power information is transmitted to a photodetector 3 via the beam splitter 5, and then transmitted to an external circuit system for resolution, thereby realizing the rotation speed detection function of the single-axis optical gyroscope.

[0060] like Figure 8 As shown, an optical gyroscope is a three-axis optical gyroscope, comprising a silicon nitride-based optical gyroscope integrated chip and a 1×3 beam splitter 5. The input end of the 1×3 beam splitter 5 is optically interconnected with a broadband light source tube core 1. The three output ends of the 1×3 beam splitter 5 are optically interconnected with polarizers 4 of three silicon nitride-based optical gyroscope integrated chips for measuring the X-axis, Y-axis, and Z-axis, respectively. In addition, the pattern converters 7 of the three silicon nitride-based optical gyroscope integrated chips are fused to three sensitive optical fiber rings respectively through polarization-maintaining pigtails 10.

[0061] A method for operating an optical gyroscope includes the following steps: light emitted from a broadband light source tube core 1 is split by a 1×3 beam splitter 5 and then synchronously enters a polarizer 4 of three silicon nitride-based optical gyroscope integrated chips for measuring the X-axis, Y-axis, and Z-axis, respectively; the polarized light is split by the beam splitter 5 and then enters a phase modulator 6 for phase modulation; after mode field conversion by a mode spot converter 7, the two beams pass through a polarization-maintaining pigtail 10 and enter a sensitive element optical fiber ring 11 along two ports, respectively; the two beams are transmitted within the sensitive element optical fiber ring 11, and after a Sagnac effect occurs, they return to the phase modulator 6 to complete beam combining interference; finally, the optical power information is transmitted to a photodetector 3 through the beam splitter 5, and then transmitted to an external circuit system for resolution, thereby realizing the rotation speed detection function of the three-axis optical gyroscope.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An integrated chip for a silicon nitride-based optical gyroscope, comprising a broadband light source die, a polarizer, a beam splitter, a phase modulator, a spot size converter, and a photodetector, integrated on a single SiO2 substrate and arranged sequentially along the direction of light propagation, characterized in that: The beam splitter, polarizer, phase modulator and spot size converter are all composed of SiN waveguides, thereby realizing optical interconnection between the beam splitter, polarizer, phase modulator and spot size converter via SiN waveguides in sequence.

2. The integrated chip for a silicon nitride-based optical gyroscope according to claim 1, characterized in that: In the three wavelength bands of 850nm, 1310nm, and 1550nm for optical gyroscope applications, the thickness of the SiN waveguide ranges from 100nm to 150nm, and the width ranges from 0.9μm to 1.2μm.

3. The integrated chip for a silicon nitride-based optical gyroscope according to claim 1, characterized in that: The wide-spectrum light source tube core is a superluminescent diode tube core, which is coupled to one of the ports of the beam splitter via a waveguide for photon wire bonding, and the bending radius of the waveguide for photon wire bonding is greater than 100 μm, and the coupling loss is ≤2 dB.

4. The integrated chip for a silicon nitride-based optical gyroscope according to claim 1, characterized in that: The polarizer is a combination of bending polarization and mode coupling polarization, and the extinction ratio of the polarizer is 60dB; The structure combining bend polarization and mode coupling polarization includes a bend polarization waveguide and a dissipative waveguide. The bend polarization waveguide includes a horizontal straight waveguide for inputting fundamental mode light, a first outer bend waveguide, a first vertical straight waveguide, a first inner bend waveguide, a coupling horizontal straight waveguide, a second inner bend waveguide, a second vertical straight waveguide, a second outer bend waveguide, and an output horizontal straight waveguide for outputting the TE0 mode, which are connected in sequence. The first outer bend waveguide and the second outer bend waveguide are symmetrically arranged with respect to the coupling horizontal straight waveguide, and opposite sides of the first outer bend waveguide and the second outer bend waveguide are opposite to each other. The first inner bend waveguide and the second inner bend waveguide are symmetrically arranged with respect to the coupling horizontal straight waveguide, and opposite sides of the first inner bend waveguide and the second inner bend waveguide are opposite to each other. The coupling horizontal straight waveguide is coupled with the dissipative waveguide to convert the TE0 mode into the TE1 mode by using the dissipative waveguide and then output it; The radii of the first outer curved waveguide, the second outer curved waveguide, the first inner curved waveguide and the second inner curved waveguide are the same and range from 50 μm to 80 μm. The width of the coupled horizontal straight waveguide ranges from 1.8 μm to 2.1 μm, and the width of the dissipative waveguide ranges from 2 μm to 2.3 μm.

5. The integrated chip for a silicon nitride-based optical gyroscope according to claim 1, characterized in that: The phase modulator is a thermo-optic modulator or a piezoelectric modulator. The thermo-optic modulator includes electrodes arranged on the upper and lower claddings of the SiN waveguide. The piezoelectric modulator includes a piezoelectric film and electrodes sequentially arranged above the SiN waveguide. The material of the piezoelectric film is AlN, PZT or HfO2. The SiN waveguide constituting the phase modulator is a rectangular waveguide.

6. The integrated chip for a silicon nitride-based optical gyroscope according to claim 1, characterized in that: The photodetector is made of III-V materials and is transferred to the beam splitter through the method of material growth-structure release-micro transfer printing; The III-V group material is InP or InGaAs, and the photodetector is heterogeneously integrated on-chip via interlayer coupling between the InP tapered waveguide and the SiN waveguide constituting the beam splitter. The SiN waveguide constituting the beam splitter is a tapered waveguide. The spot converter is a three-section tapered waveguide structure.

7. An optical gyroscope, wherein the optical gyroscope is a single-axis optical gyroscope, characterized in that: The integrated chip for silicon nitride-based optical gyroscope comprises the integrated chip for silicon nitride-based optical gyroscope according to any one of claims 1 to 6, wherein the mode spot converter of the integrated chip for silicon nitride-based optical gyroscope is fused between the polarization-maintaining pigtail and the sensitive optical fiber ring.

8. The method for operating an optical gyroscope according to claim 7, wherein: The following steps are involved: The light emitted from the wide-spectrum light source tube core enters the polarizer through the waveguide used for photon wire bonding. The polarized light is split by the beam splitter and enters the phase modulator for phase modulation. After mode field conversion by the mode spot converter, the two beams of light pass through the polarization-maintaining fiber pigtail and enter the optical fiber ring of the sensitive element along the two ports respectively. After being transmitted within the ring of the optical fiber ring of the sensitive element and the Sagnac effect occurs, they return to the phase modulator to complete beam combining interference. Finally, the optical power information is transmitted to the photodetector through the beam splitter, and then transmitted to the external circuit system for solution, realizing the speed detection function of the single-axis optical gyroscope.

9. An optical gyroscope, wherein the optical gyroscope is a three-axis optical gyroscope, characterized in that: The invention comprises an integrated chip for a silicon nitride-based optical gyroscope and a 1×3 beam splitter according to any one of claims 1 to 6, wherein the input end of the 1×3 beam splitter is optically interconnected with a broadband light source tube core, and the three output ends of the 1×3 beam splitter are optically interconnected with the polarizers of the three integrated chips for silicon nitride-based optical gyroscopes for measuring the X-axis, Y-axis and Z-axis, respectively, and the pattern spot converters of the three integrated chips for silicon nitride-based optical gyroscopes are respectively fused with three sensitive optical fiber rings through polarization-maintaining pigtails.

10. The operating method of an optical gyroscope according to claim 9, characterized in that: The following steps are involved: The light emitted from the wide-spectrum light source tube core is split by a 1×3 beam splitter and synchronously enters the polarizers of the three integrated chips for measuring the X-axis, Y-axis, and Z-axis respectively. The polarized light is split by the beam splitter and enters the phase modulator for phase modulation. After mode field conversion by the mode spot converter, the two beams pass through the polarization-maintaining fiber pigtail and enter the optical fiber ring of the sensitive element along the two ports respectively. After being transmitted within the ring of the optical fiber ring of the sensitive element and the Sagnac effect occurs, they return to the phase modulator to complete beam combining interference. Finally, the optical power information is transmitted to the photodetector through the beam splitter, and then transmitted to the external circuit system for solution, realizing the speed detection function of the three-axis optical gyroscope.

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