Film lithium niobate heterogeneous integrated chip configuration for fiber-optic gyroscope

Abstract

The invention belongs to the technical field of integrated optics and inertial sensing, and particularly relates to a thin-film lithium niobate heterogeneous integrated chip configuration for a fiber-optic gyroscope. The thin-film lithium niobate hybrid photon integrated chip is utilized to realize on-chip heterogeneous integration of functional devices of the fiber-optic gyroscope. The discrete optical path device of the gyroscope is monolithic integrated and integrally packaged, the size and cost of the optical path are greatly reduced, optical fiber interconnection is reduced, the complexity of the assembly process is obviously reduced, and the long-term reliability of the performance of the gyroscope is effectively improved. By means of the CMOS technology with mature silicon photons, low-cost and large-scale batch production of the miniature fiber-optic gyroscope can be achieved, and the requirements for miniaturization and light weight of a future weapon system are met.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated optics and inertial sensing, and in particular relates to a thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope. Background Art

[0002] As the core component of the inertial navigation system, fiber optic gyroscopes are widely used in aviation navigation, ammunition guidance, industrial automation and other fields. As modern warfare increasingly presents significant characteristics such as full space and three-dimensionality, the demand for information-based, unmanned and intelligent operations is increasing. UAV clusters, tactical missiles, guided ammunition and unmanned driving are developing in a blowout manner. As the core technology support, small-sized, low-cost, and scalable fiber optic gyroscopes have become an urgent need. However, traditional fiber optic gyroscopes are composed of discrete optical fiber devices, which leads to large gyroscope size and requires complex fiber winding processes, with many manufacturing processes and long manufacturing time. In addition, the production process requires more manpower participation, and the consistency of the process, long-term reliability, and stability of different batches cannot be guaranteed. At the same time, the production scale and production capacity are small, and the manufacturing cost is high. These defects have become bottlenecks that restrict the large-scale promotion and application of fiber optic gyroscopes. Summary of the invention

[0003] Technical problem solved by the present invention: In view of the problems of large size, high power consumption and poor long-term consistency of current fiber optic gyroscopes, the present invention proposes a solution for implementing a thin-film lithium niobate heterogeneous integrated chip for fiber optic gyroscopes.

[0004] The technical solution of the present invention:

[0005] A thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope, wherein the heterogeneous integrated chip is realized by directly etching thin-film lithium niobate, and the heterogeneous integrated chip configuration comprises: an SLD chip 1-1, an isolator 1-2, a light source-waveguide mode converter 1-3, a coupler I1-5, a polarizer 1-7, a coupler II1-9, a stray light absorption structure II1-10, an electro-optic modulator 1-11, a metal electrode 1-12, an inclined output waveguide I1-13, an optical fiber-waveguide mode converter I1-14, an inclined output waveguide II1-15, an optical fiber-waveguide mode converter II1-16, a coupling grating 1-19, and a detector chip 1-20;

[0006] The output light of the SLD chip 1-1 is coupled into the light source-waveguide mode converter 1-3 through the isolator 1-2, and then connected to the first input end of the coupler I1-5; the through end of the coupler I1-5 is connected to the input end of the polarizer 1-7; the output end of the polarizer 1-7 is connected to one input end of the coupler II1-9, and the other input end of the coupler II1-9 is connected to the stray light absorption structure II1-10, and the two arms of the output end of the coupler II1-9 are connected to the two arms of the input end of the electro-optic modulator 1-11; after the light is modulated by the electric field applied by the metal electrode 1-12, it is output from the two arms of the output end of the electro-optic modulator 1-11 respectively; the two arms of the output end of the electro-optic modulator 1-11 are respectively connected to the optical fiber-waveguide mode converter I1-14 and the optical fiber-waveguide mode converter II1-16 through the inclined output waveguide I1-13 and the inclined output waveguide II1-15, and then connected to the polarization-maintaining optical fiber array of the two channels. The second input end of the coupler I1-5 is connected to the detector chip 1-20 via the coupling grating 1-19.

[0007] Furthermore, the heterogeneous integrated chip configuration also includes: a stray light isolation structure I1-4, a stray light absorption structure I1-6, a stray light isolation structure II1-8, a stray light isolation structure III1-17, and a stray light isolation structure IV1-18;

[0008] The stray light isolation structure I1-4 is arranged on both sides of the light source-waveguide mode converter 1-3;

[0009] The stray light absorption structure I1-6 is disposed on the surface of the coupler I1-5;

[0010] The stray light isolation structure II1-8 is arranged on the periphery of the polarizer 1-7;

[0011] The stray light isolation structure III1-17 is arranged at the periphery of the curved waveguide of the electro-optic modulator 1-11;

[0012] The stray light isolation structure IV1-18 is arranged on both sides of the coupling grating 1-19.

[0013] Furthermore, the stray light isolation structure I1-4, the stray light isolation structure II1-8, the stray light isolation structure III1-17, the stray light isolation structure IV1-18 and the stray light absorption structure I1-6, the stray light isolation structure II1-10 are realized by filling and covering the light damping material on the thin film lithium niobate chip;

[0014] The SLD chip (1-1) and the isolator (1-2) are formed by deeply etching grooves on the surface of the thin-film lithium niobate, and the SLD chip (1-1) and the light source-waveguide mode converter (1-3) are aligned and surface-bonded by using a flip-chip packaging method; the detector chip (1-20) is coupled to the thin-film lithium niobate chip through a coupling grating (1-19);

[0015] The electro-optic modulator (1-11) realizes the electro-optic modulation effect by preparing a patterned ridge waveguide and a gold electrode through shallow etching.

[0016] Furthermore, the coupler I1-5 is a 1×2 Y-branch structure, and the surface of the Y-branch is covered with a light-damping material film; the coupler II1-9 is a 2×2 multi-mode interference coupling MMI structure, one of the input ends is connected to the light-damping material, and the central operating wavelengths of the two couplers are 850nm, 1310nm and 1550nm;

[0017] The polarizers 1-7 are cascaded bent waveguide polarizers, using flat waveguides with a large aspect ratio greater than 10, multi-stage bent cascades, and central operating wavelengths of 850nm, 1310nm and 1550nm.

[0018] Furthermore, the electro-optic modulator 1-11 is realized by directly etching a lithium niobate film, and light is confined by the lithium niobate waveguide and mainly transmitted in the lithium niobate film;

[0019] The light confined in the lithium niobate film in the two arms of the electro-optic modulator 1-11 interacts with the electric field applied by the metal electrode 1-12; the modulation area of ​​the electro-optic modulator 1-11 is bent twice, and the central operating wavelengths are 850nm, 1310nm and 1550nm.

[0020] Furthermore, the light source-waveguide mode converter 1-3 adopts an inverted cone structure, with one end close to the light source being narrower than the transmission waveguide and the other end having the same width as the transmission waveguide;

[0021] The optical fiber-waveguide mode converter I1-14 and the optical fiber-waveguide mode converter II1-16 adopt an inverted cone structure, where one end close to the optical fiber is narrower than the transmission waveguide, and the other end has the same width as the transmission waveguide;

[0022] The coupling grating (1-19) has a duty cycle of 50%, and central operating wavelengths are 850nm, 1310nm and 1550nm.

[0023] Furthermore, the light damping material is metal, polymer or ferromagnetic material.

[0024] Furthermore, the inclined output waveguide I1-13 and the inclined output waveguide II1-15 are double-layer inverted cone structures;

[0025] The inclined output waveguide I1-13 and the inclined output waveguide II1-15 form an angle of 82 degrees with the end face of the heterogeneous integrated chip, and the spacings are 250 μm, 300 μm, and 500 μm.

[0026] Furthermore, an 8-degree inclined grinding with a width at the top and a narrowness at the bottom is performed on the end faces of the heterogeneous integrated chip near the fiber-waveguide mode converter I1-14 and the fiber-waveguide mode converter II1-16.

[0027] In view of the current problems of large size, high power consumption, and poor long-term consistency of fiber optic gyroscopes, the present invention proposes a solution for implementing a thin-film lithium niobate heterogeneous integrated chip for fiber optic gyroscopes. This solution uses a thin-film lithium niobate hybrid photonic integrated chip to achieve full on-chip heterogeneous integration of fiber optic gyroscope functional devices. The gyroscope discrete optical path devices are monolithically integrated and packaged as a whole, which greatly reduces the size and cost of the optical path, reduces optical fiber interconnections, and significantly reduces the complexity of the assembly process, effectively improving the long-term reliability of the gyroscope performance. With the help of the mature CMOS process of silicon photonics, low-cost, large-scale mass production of miniature fiber optic gyroscopes can be achieved to meet the miniaturization and lightweight requirements of future weapon systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a thin-film lithium niobate heterogeneous integrated chip for a fiber optic gyroscope of the present invention;

[0029] Figure 2 (a) is the Y-branch structure coupler structure; (b) is the schematic diagram of the 2×2 MMI coupler structure;

[0030] Figure 3 It is the top view and cross-sectional view of the inverted cone-shaped mold spot conversion structure;

[0031] Figure 4 It is a schematic diagram of the structure of the stray light isolator for the light source and the detector;

[0032] Figure 5 is a schematic cross-sectional view of an electro-optic modulator;

[0033] Figure 6 Schematic diagram of the end face inclined grinding structure. DETAILED DESCRIPTION

[0034] In order to make the technical solutions and advantages of the solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and completely in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0036] Aiming at the shortcomings of current fiber optic gyroscopes, such as large size, complex process, and poor long-term consistency caused by the use of discrete optical path devices, a heterogeneous integrated optical chip based on thin-film lithium niobate is provided.

[0037] The present invention is further described in detail with reference to the accompanying drawings.

[0038] See also Figure 1 The thin-film lithium niobate heterogeneous integrated chip for the optical fiber gyroscope described in the present invention comprises: an SLD chip 1-1, an isolator 1-2, a light source-waveguide mode converter 1-3, a stray light isolation structure I1-4, a coupler I1-5, a stray light absorption structure I1-6, a polarizer 1-7, a stray light isolation structure II1-8, a coupler II1-9, a stray light absorption structure II1-10, an electro-optic modulator 1-11, a metal electrode 1-12, an inclined output waveguide I1-13, an optical fiber-waveguide mode converter I1-14, an inclined output waveguide II1-15, an optical fiber-waveguide mode converter II1-16, a stray light isolation structure III1-17, a stray light isolation structure IV1-18, a coupling grating 1-19, and a detector chip 1-20.

[0039] The output light of the SLD chip 1-1 is coupled into the light source-waveguide mode converter 1-3 through the isolator 1-2, and then connected to the first input end of the coupler I1-5; the through end of the coupler I1-5 is connected to the input end of the polarizer 1-7; the output end of the polarizer 1-7 is connected to one input end of the coupler II1-9, and the other input end of the coupler II1-9 is connected to the stray light absorption structure II1-10, and the two arms of the output end of the coupler II1-9 are connected to the two arms of the input end of the electro-optic modulator 1-11; after the light is modulated by the electric field applied by the metal electrode 1-12, it is output from the two arms of the output end of the electro-optic modulator 1-11 respectively; the two arms of the output end of the electro-optic modulator 1-11 are respectively connected to the optical fiber-waveguide mode converter I1-14 and the optical fiber-waveguide mode converter II1-16 through the inclined output waveguide I1-13 and the inclined output waveguide II1-15, and then connected to the polarization-maintaining optical fiber array of the two channels. The second input end of the coupler I1-5 is connected to the detector chip 1-20 via the coupling grating 1-19.

[0040] Passive devices in the optical path include: light source-waveguide mode converter 1-3, coupler I1-5, polarizer 1-7, coupler II1-9, tilted output waveguide I1-13, tilted output waveguide II1-15, fiber-waveguide mode converter I1-14, fiber-waveguide mode converter II1-16, coupled grating 1-19, which are monolithically integrated on a thin-film lithium niobate chip; stray light isolation structure I1-4, stray light isolation structure II1-8, stray light isolation structure III1-17 , stray light isolation structure IV1-18 and stray light absorption structure I1-6, stray light absorption structure II1-10 are realized by filling and covering light damping materials on the thin film lithium niobate chip; the SLD chip 1-1 and isolator 1-2 are integrated with the thin film lithium niobate chip by surface bonding in deep etching grooves; the detector chip 1-20 is integrated with the thin film lithium niobate chip by vertical coupling of gratings; the electro-optic modulator 1-11 realizes the electro-optic modulation effect by preparing a patterned ridge waveguide and gold electrode by shallow etching.

[0041] The SLD chip 1-1 and the isolator 1-2 are formed by deeply etching grooves on the surface of the thin-film lithium niobate, and using a flip-chip packaging method to align the SLD chip 1-1 with the light source-waveguide mode converter 1-3 and bond the surface. The output light of the SLD chip 1-1 enters the isolator 1-2 through spatial light; the detector chip 1-20 is integrated with the thin-film lithium niobate chip by vertical coupling and surface mounting through the coupling grating 1-19.

[0042] The coupler I1-5 is a 1×2 Y-branch structure, and the surface of the Y branch is covered with a light damping material film; the coupler II1-9 is a 2×2 multi-mode interference coupling MMI structure, one of the input ends is connected to the light damping material, and the central operating wavelengths of the two couplers are 850nm, 1310nm and 1550nm.

[0043] The polarizers 1-7 are cascaded bent waveguide polarizers, using flat waveguides with a large aspect ratio greater than 10, multi-stage bent cascades, and central operating wavelengths of 850nm, 1310nm and 1550nm.

[0044] The electro-optic modulator 1-11 is realized by directly etching the lithium niobate film, and the light is confined by the lithium niobate waveguide and mainly transmitted in the lithium niobate film; the metal electrode 1-12 is made of gold and a traveling wave electrode is used; the light in the two arms of the electro-optic modulator 1-11 confined in the lithium niobate film interacts with the electric field applied by the metal electrode 1-12; the modulation area of ​​the electro-optic modulator 1-11 is bent twice, and the central working wavelengths are 850nm, 1310nm and 1550nm.

[0045] The light source-waveguide mode converter 1-3 adopts an inverted cone structure, with one end close to the light source being narrower than the transmission waveguide, and the other end having the same width as the transmission waveguide; the optical fiber-waveguide mode converter I1-14 and the optical fiber-waveguide mode converter II1-16 adopt an inverted cone structure, with one end close to the optical fiber being narrower than the transmission waveguide, and the other end having the same width as the transmission waveguide; the central operating wavelengths of the coupling grating 1-19 are 850nm, 1310nm and 1550nm.

[0046] The stray light isolation structure I1-4, the stray light isolation structure II1-8, the stray light isolation structure III1-17, and the stray light isolation structure IV1-18 are realized by deep etching on the surface of the thin film lithium niobate chip and filling it with light damping material.

[0047] The stray light absorption structure I1-6 is realized by covering and patterning a thin film of light damping material on the surface of the coupler I1-5; the stray light absorption structure II1-10 is realized by deep etching on the surface of the thin film lithium niobate chip and filling it with light damping material, and is connected to an input end of the coupler II1-9 through a waveguide.

[0048] The stray light isolation structure and the absorption structure are made of metal, polymer, ferromagnetic material and the like.

[0049] The inclined output waveguide I1-13 and the inclined output waveguide II1-15 form an angle of 82 degrees with the end face of the heterogeneous integrated chip, and the spacings are 250μm, 300μm, and 500μm.

[0050] On the heterogeneous integrated chip, an 8-degree inclined grinding with a width at the top and a narrowness at the bottom is performed near the end faces of the optical fiber-waveguide mode converter I1-14 and the optical fiber-waveguide mode converter II1-16.

[0051] See also Figure 1 The thin-film lithium niobate heterogeneous integrated chip for the optical fiber gyroscope of the present invention mainly includes: an SLD chip 1-1, an isolator 1-2, a light source-waveguide mode converter 1-3, a stray light isolation structure I1-4, a coupler I1-5, a stray light absorption structure I1-6, a polarizer 1-7, a stray light isolation structure II1-8, a coupler II1-9, a stray light absorption structure II1-10, an electro-optic modulator 1-11, a metal electrode 1-12, an inclined output waveguide I1-13, an optical fiber-waveguide mode converter I1-14, an inclined output waveguide II1-15, an optical fiber-waveguide mode converter II1-16, a stray light isolation structure III1-17, a stray light isolation structure IV1-18, a coupling grating 1-19, and a detector chip 1-20.

[0052] The wide-spectrum light emitted by the SLD chip 1-1 includes two different polarization modes, TE and TM, which are efficiently coupled into the coupler I1-5 through the isolator 1-2 and the light source-waveguide mode converter 1-3; the mode size of the light spot is effectively enlarged by the light source-waveguide mode converter 1-3, and the light not coupled into the coupler I1-5 is absorbed and isolated and suppressed by the stray light isolation structure I1-4 after the mode size is enlarged; the 3dB stray light generated during the light transmission in the coupler I1-5 is fully absorbed by the stray light absorption structure I1-6 of the optical damping film covered on the surface. The transmitted light enters the polarizer 1-7. Since the two different polarization mode lights, TE and TM, have different effective refractive indices and mode spot sizes during the transmission process, the TM mode will be gradually absorbed and attenuated during the transmission process, and finally the TE mode light will be mainly left to be transmitted in the waveguide. The dissipated light is isolated by the curved stray light isolation structure II1-8. Then the light enters the coupler II1-9. The 3dB stray light generated during the light transmission process is absorbed by the stray light absorption structure II1-10 after being transmitted through the waveguide. The light at the output end of the coupler II1-9 is divided into two beams and enters The two arms of the electro-optic modulator 1-11, the transmitted light is bounded by the SiN waveguide, and the light concentrated in the lithium niobate film passes through the metal electrode 1-12 to apply an electric field and add a phase difference, and then the two arms of the output end of the electro-optic modulator 1-11 are connected to the inclined output waveguide I1-13 and the inclined output waveguide II1-15 respectively. The stray light generated at the bend inside the modulator is absorbed and attenuated by the bent stray light isolation structure III1-17 and effectively isolated; the transmitted light passes through the fiber-waveguide mode converter I1-14 and the fiber-waveguide mode converter II1-16 and the 2-channel The polarization-maintaining fiber array realizes efficient end-face coupling with low backscatter and low back reflection; after the two beams of light propagate in the fiber ring in clockwise and counterclockwise directions respectively and meet the coherence condition, when the fiber rotates around its central axis, a Sagnac effect is generated, resulting in a change in the interference light intensity after the two beams of light are coupled; when the interference light returns to the coupler I1-5 along the optical path, it is output from the other input end, vertically coupled into the detector chip 1-20 through the coupling grating 1-19, and the light that is not coupled in is absorbed and effectively isolated after mode field amplification by the stray light isolation structure IV1-18.

[0053] As an implementation method, coupler I1-5 adopts a 1×2 Y-branch structure, and coupler II1-9 adopts a 2×2 MMI structure, and the central operating wavelengths are 850nm, 1310nm and 1550nm. The Y-branch structure can achieve a splitting ratio of 1:1, and the 3dB stray light generated by the transmission of light in it is absorbed by the thin film of light damping material covered on the surface and converted into heat energy to prevent the stray light from crosstalking on the chip and interfering with normal gyroscope signal detection; the 2×2 MMI structure can achieve a splitting ratio of 1:1, and the 3dB stray light can be transmitted through the waveguide to the stray light absorption structure for absorption processing. In order to reduce device loss and improve the splitting ratio, the embodiment of the present invention optimizes the design of the Y-branch structure and the MMI coupler, see Figure 2 In the present invention, the thin-film lithium niobate waveguide has a width of 1 μm, a height of 300 nm, and a device center wavelength of 1310 nm; the designed MMI coupler interference zone has a width of 12 μm and a length of 68 μm, the input and output positive cone structures have a width of 3 μm and a length of 300 μm, and the splitting ratio is 1:1; the designed Y-branch structure has a branch spacing of 300 nm, the input positive cone structure length is 300 μm, the output two arms are spaced 300 μm apart, the bending waveguide length is 800 μm, the bending radius is about 1000 μm, and the splitting ratio is 1:1.

[0054] As an implementation mode, the light source-waveguide mode converter 1-3, the optical fiber-waveguide mode converter I1-14, and the optical fiber-waveguide mode converter II1-16 all adopt an inverted cone structure, the coupling grating 1-19 has a duty cycle of 50%, and the central operating wavelengths are 850nm, 1310nm, and 1550nm. Figure 3 The light spot diameter in the 300nm thick SiN waveguide is about 6.5μm. By designing a conical coupling structure, the end face coupling efficiency can be effectively improved. Among them, the inverted cone area is 400μm long and 300nm wide; the positive cone area is 500μm long and 2.5μm wide. Both can achieve a coupling efficiency of more than 90%.

[0055] As an implementation mode, the polarizer 1-7 adopts a cascaded curved waveguide. The polarization principle is: in the waveguide, different polarization states of TE and TM mode light have different mode field distributions and effective refractive indices, and the difference between different modes will lead to different polarization-related losses and mode dispersions. By designing a specific bending radius of the waveguide, the effective refractive index of the TM mode is lower and its transmission loss is increased, and the TE mode is transmitted with extremely low loss. After passing through the polarizer 1-7, a high polarization extinction ratio can be achieved. The cascaded curved waveguide has a bending radius of 100μm and a multi-stage cascade, which can achieve an extinction ratio of>80dB. At the same time, the input and output ports can be staggered to reduce optical signal crosstalk.

[0056] As an implementation method, Figure 4As shown, the stray light isolation structure I1-4, the stray light isolation structure II1-8, the stray light isolation structure III1-17, and the stray light isolation structure IV1-18 are realized by deeply etching the surface of the thin-film lithium niobate chip and filling it with light damping material. The stray light absorption structure I1-6 is realized by covering the surface of the coupler I1-5 with a thin film of light damping material and patterning it; the stray light absorption structure II1-10 is realized by deeply etching the surface of the thin-film lithium niobate chip and filling it with light damping material, and is connected to an input end of the coupler II1-9 through a waveguide. The stray light isolation and absorption structure can effectively suppress the crosstalk of stray light on the chip surface, effectively improve the gyro signal-to-noise ratio, and improve the detection accuracy.

[0057] As an implementation method, the electro-optic modulator 1-11 is realized by directly etching a lithium niobate film, light is confined by a lithium niobate waveguide and is mainly transmitted in the lithium niobate film, and a metal electrode 1-12 is evaporated on the lithium niobate film, and finally covered with a layer of SiO2, see Figure 5 . This method realizes the modulation function by applying an electric field through the electrode to interact with the light in the lithium niobate film, thereby realizing the on-chip modulator; covered with SiO2, compared with being exposed to the air, SiO2 has a larger relative dielectric constant, which is conducive to enhancing the effect of the electric field on the light in the lithium niobate to enhance the modulation effect. The thickness of SiO2 is 800nm. In addition, the width of the gold electrode is selected to be 80μm and the thickness is 1μm. After size optimization, the traveling wave loss in the metal can be effectively reduced, and the impedance and refractive index can be better matched.

[0058] As an implementation scheme, the inclined output waveguide I1-13 and the inclined output waveguide II1-15 are at an angle of 82 degrees to the right end face of the chip, with spacings of 250 μm, 300 μm, and 500 μm; in addition, the chip grinding end face 1-21 is subjected to 8-degree end face grinding with a width at the top and a narrowness at the bottom, see Figure 6 The two methods of waveguide tilted output and end face tilted grinding can effectively reduce the back reflection and back scattering between the chip and the optical fiber array, and effectively suppress the stray light from entering the chip surface to generate crosstalk.

Claims

1. A thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope, characterized in that: The heterogeneous integrated chip is realized by directly etching thin-film lithium niobate. The heterogeneous integrated chip configuration includes: an SLD chip (1-1), an isolator (1-2), a light source-waveguide mode converter (1-3), a coupler I (1-5), a polarizer (1-7), a coupler II (1-9), a stray light absorption structure II (1-10), an electro-optic modulator (1-11), a metal electrode (1-12), an inclined output waveguide I (1-13), an optical fiber-waveguide mode converter I (1-14), an inclined output waveguide II (1-15), an optical fiber-waveguide mode converter II (1-16), a coupling grating (1-19), and a detector chip (1-20); The output light of the SLD chip (1-1) is coupled into the light source-waveguide mode converter (1-3) through the isolator (1-2), and then connected to the first input end of the coupler I (1-5); the through end of the coupler I (1-5) is connected to the input end of the polarizer (1-7); the output end of the polarizer (1-7) is connected to an input end of the coupler II (1-9); the other input end of the coupler II (1-9) is connected to the stray light absorption structure II (1-10); the output end of the coupler II (1-9) is connected to the input end of the coupler II (1-9); The two arms are connected to the two arms of the input end of the electro-optic modulator (1-11); after the light is modulated by applying an electric field through the metal electrode (1-12), it is outputted from the two arms of the output end of the electro-optic modulator (1-11); the two arms of the output end of the electro-optic modulator (1-11) are connected to the fiber-waveguide mode converter I (1-14) and the fiber-waveguide mode converter II (1-16) through the inclined output waveguide I (1-13) and the inclined output waveguide II (1-15), respectively, and then connected to the polarization-maintaining fiber array of the two channels. The second input end of the coupler I (1-5) is connected to the detector chip (1-20) through the coupling grating (1-19).

2. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The heterogeneous integrated chip configuration also includes: a stray light isolation structure I (1-4), a stray light absorption structure I (1-6), a stray light isolation structure II (1-8), a stray light isolation structure III (1-17), and a stray light isolation structure IV (1-18); The stray light isolation structure I (1-4) is arranged on both sides of the light source-waveguide mode converter (1-3); The stray light absorption structure I (1-6) is arranged on the surface of the coupler I (1-5); The stray light isolation structure II (1-8) is arranged on the periphery of the polarizer (1-7); The stray light isolation structure III (1-17) is arranged on the periphery of the curved waveguide of the electro-optic modulator (1-11); The stray light isolation structure IV (1-18) is arranged on both sides of the coupling grating (1-19).

3. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The stray light isolation structure I (1-4), the stray light isolation structure II (1-8), the stray light isolation structure III (1-17), the stray light isolation structure IV (1-18) and the stray light absorption structure I (1-6), the stray light absorption structure II (1-10) are realized by filling and covering the light damping material on the thin film lithium niobate chip; The SLD chip (1-1) and the isolator (1-2) are formed by deeply etching grooves on the surface of the thin-film lithium niobate, and the SLD chip (1-1) and the light source-waveguide mode converter (1-3) are aligned and surface-bonded by using a flip-chip packaging method; The detector chip (1-20) is coupled to the thin-film lithium niobate chip via a coupling grating (1-19); The electro-optic modulator (1-11) realizes the electro-optic modulation effect by preparing a patterned ridge waveguide and a gold electrode through shallow etching.

4. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The coupler I (1-5) is a 1×2 Y-branch structure, and the surface of the Y-branch is covered with a light-damping material film; the coupler II (1-9) is a 2×2 multi-mode interference coupling MMI structure, one of the input ends is connected to the light-damping material, and the central operating wavelengths of the two couplers are 850nm, 1310nm and 1550nm; The polarizer (1-7) is a cascaded curved waveguide polarizer, using a flat waveguide with a large aspect ratio (greater than 10), multi-stage curved cascade, and central operating wavelengths of 850nm, 1310nm and 1550nm.

5. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The electro-optic modulator (1-11) is realized by directly etching a lithium niobate film, and light is confined by a lithium niobate waveguide and mainly transmitted in the lithium niobate film; The two arms of the electro-optic modulator (1-11) are confined in the lithium niobate film, and the light interacts with the electric field applied by the metal electrode (1-12); the modulation area of ​​the electro-optic modulator (1-11) is bent twice, and the central working wavelength is 850nm, 1310nm and 1550nm.

6. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The light source-waveguide mode converter (1-3) adopts an inverted cone structure, with one end close to the light source being narrower than the transmission waveguide and the other end having the same width as the transmission waveguide; The fiber-waveguide mode converter I (1-14) and the fiber-waveguide mode converter II (1-16) adopt an inverted cone structure, where one end close to the optical fiber is narrower than the transmission waveguide and the other end has the same width as the transmission waveguide; The coupling grating (1-19) has a duty cycle of 50%, and central operating wavelengths are 850nm, 1310nm and 1550nm.

7. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 3, characterized in that: The light damping material is metal, polymer or ferromagnetic material.

8. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: The inclined output waveguide I (1-13) and the inclined output waveguide II (1-15) are double-layer inverted cone structures; The inclined output waveguide I (1-13) and the inclined output waveguide II (1-15) form an angle of 82 degrees with the end face of the heterogeneous integrated chip, and the spacings are 250 μm, 300 μm, and 500 μm.

9. The thin-film lithium niobate heterogeneous integrated chip configuration for an optical fiber gyroscope according to claim 1, characterized in that: An 8-degree inclined grinding with a width at the top and a narrowness at the bottom is performed on the end faces of the heterogeneous integrated chip close to the fiber-waveguide mode converter I (1-14) and the fiber-waveguide mode converter II (1-16).

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