844 results about "Lithium niobate" patented technology

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.

The invention relates to the field of optical protection materials, and provides a transparent film with laser eavesdropping prevention performance and a preparation method thereof.The transparent film is composed of surface-modified doped tungsten oxide nanosheets, amino-isocyanate bifunctional lithium niobate nanowires, urethane acrylate, an ultraviolet light absorber, a silane coupling agent, a dispersing agent and a flatting agent; the molybdenum-doped tungsten oxide nanosheets are obtained through silane coupling modification after hydrothermal synthesis, and the lithium niobate nanowires are prepared through a gradient modification process of hydrothermal synthesis-silane coupling-isocyanate grafting-phenol end capping. A modified nano material is uniformly dispersed in a resin matrix through an ultrasonic dispersion composite technology, and through blade coating forming, ultraviolet curing and constant-temperature and constant-humidity post-treatment, compared with the prior art, the scheme overcomes the problems that a traditional protective film is insufficient in optical transparency, laser eavesdropping prevention function and dynamic viscoelasticity, and is suitable for the field of high-end security and protection.

A centimeter-resolution integrated photonic millimeter-wave (mmWave) radar chip operating in the mmWave V band based on a 4-inch wafer-scale thin-film lithium niobate (TFLN) technology is provided. The fabricated TFLN photonic mmWave integrated circuit has a first electro-optic modulator (EOM) capable of generating a broadband linear frequency modulated mmWave radar waveform through optical frequency multiplication of a low-frequency input signal, and a second EOM for frequency de-chirp of the reflected echo wave, thereby greatly relieving bandwidth requirements for the digital-to-analog converter in the transmitter and analog-to-digital converter in the receiver. In the absence of optical and electrical filters, the radar chip features continuous on-demand tunability of the center frequency and bandwidth, currently only limited by the bandwidths of electrical amplifiers. The radar chip provides a promising way to achieve high resolution sensing and detection for vehicle radar, airborne radar, and smart home in the 6G era.

The invention discloses a composite modified material for a lithium niobate wafer, and relates to the technical field of nano materials. The material is composed of an anti-corrosion passivation matrix and a function enhancement component, wherein the anti-corrosion matrix adopts a silicon nitride / SiO2 multi-layer composite layer, atomic layer deposition titanium dioxide and magnetron sputtering aluminum oxide to form cascade protection; the functional layer comprises lead sulfide nanoparticles and nano silicon dioxide, and is directionally modified by a silane coupling agent and a perfluoropolyether surfactant. During preparation, PbS nano-particles are synthesized by combining a PECVD-ALD-magnetron sputtering stepped deposition process (200-150 DEG C) with a solvothermal method, and finally, the PbS nano-particles are formed through spin coating-annealing (300-400 DEG C). The optical loss of the material under the wavelength of 1550 nm is smaller than 0.2 dB / cm, the acid and alkali corrosion resistance is larger than 240 h, the lead dissolution rate is smaller than 0.1 ppm, the interface state density is reduced by 2 orders of magnitude, the contradiction between lithium niobate wafer surface degradation, photoelectric property degradation and lead-containing material environment risk is solved, and the material is suitable for 5G optical waveguide and quantum integrated device packaging.

The invention relates to the technical field of optoelectronics, and discloses a compact mixed optical path high-density integration method of a multi-level waveguide composite structure, which comprises the following steps: S1, preparing a multi-material layer: sequentially depositing a silicon layer, a silicon nitride layer and a lithium niobate layer, preparing the silicon layer and the silicon nitride layer through a chemical vapor deposition process, preparing the lithium niobate layer through direct current magnetron sputtering, and preparing the multi-material layer; the refractive indexes of the silicon layer, the silicon nitride layer and the lithium niobate layer meet gradient distribution; s2, designing an interlayer coupling structure: forming a gradient waveguide coupler at an interface of adjacent material layers to realize interlayer light field transmission; and S3, stress regulation and control layer integration: arranging a buffer layer with a matched thermal expansion coefficient between the silicon layer and the silicon nitride layer. According to the invention, the silicon layer, the silicon nitride layer and the lithium niobate layer are sequentially deposited, and the refractive index of each layer satisfies gradient distribution, so that the problems of large light field reflection and scattering loss and low coupling efficiency caused by the fact that most of the traditional multilayer waveguide structures adopt single material layers are solved.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, and at least one lithium niobate layer and first and second principal surfaces opposed to each other, and first and second IDT electrodes respectively on the first and second principal surfaces. Each of the first and second IDT electrodes includes electrode fingers. A duty ratio of each of the first and second IDT electrodes is equal to or greater than about 0.6. Directions of polarization of the piezoelectric layer are inverted in a thickness direction of the piezoelectric layer.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate and a lithium niobate (LN) plate having front and back surfaces and a thickness ts. The back surface is attached to a surface of the substrate. A portion of the LN plate forms a diaphragm spanning a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the LN plate with interleaved fingers of the IDT disposed on the diaphragm. The LN plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic wave in the diaphragm. Euler angles of the LN plate are [0°, β, 0°], where 0≤β≤60°. A thickness of the interleaved fingers of the IDT is greater than or equal to 0.8 ts and less than or equal to 2.0 ts.

The invention discloses an 8 * 8 lithium niobate array optical switch, and belongs to the technical field of integrated photon and optical communication. Comprising twenty switch units of Mach-Zehnder interferometer structures, and each switch unit is provided with a modulation arm composed of an upper bent waveguide and a lower bent waveguide and is provided with a push-pull type loading electrode. The switch units are combined in a multi-stage array mode and are connected through crossed waveguides, and the 8 * 8 array non-blocking optical switch is formed by using twenty switch units. According to the invention, the 2 * 2 optical switch units with small size and high modulation efficiency are designed, the transverse size of a modulation arm is shortened by adopting upper and lower bent waveguides, the driving voltage is reduced by combining a push-pull electrode loading technology, and finally the high-density 8 * 8 array optical switch is constructed by twenty units. By utilizing the electro-optical effect of lithium niobate, through the optimization of a bent waveguide structure and the driving of a push-pull electrode, low-power-consumption and high-speed optical path switching is realized, and a high-integration-level routing solution is provided for a high-speed optical communication system.

An optical device includes a silicon substrate, a waveguide formed of a thin film that is laminated on the silicon substrate and that is made of a perovskite oxide with a large electro-optic effect as compared to lithium niobate, and a cladding layer that covers the waveguide. Further, the optical device includes ground electrode that has a ground potential and a signal electrode that is arranged at a position facing the ground electrode and that applies driving voltage to the waveguide.

An electro-optic device is described. The electro-optic device includes an electro-optic component implemented on an electro-optic material having a slab and a ridge portion. The electro-optic component includes a first portion of the slab and a portion of the ridge portion. The first portion of the slab has a first height. The ridge portion has a second height greater than the first height. A passive functionality component is implemented on a second portion of the slab and is optically coupled with the electro-optic component.

A miniaturized interferometric integrated photonic gyroscope structure with top silicon oxide, middle silicon oxide and bottom silicon oxide deposited on a silicon substrate comprises broadband optical source or a semiconductor optical amplifier with silicon nitride ring resonator wavelength filter, connected with a thin film lithium niobate or piezoelectrically actuated silicon nitride phase modulator vertically coupled with a silicon nitride waveguide spiral loop. The silicon nitride waveguide spiral loop is patterned on thin bottom oxide layer with air trenches below it and connected with a germanium detector either through photonic wire bonding or vertically integrated through reflecting mirror embedded into silicon wafer. Various methods of coupling alternative materials are described and the potential of connecting several spiral waveguides for enhanced sensitivity in a gyroscope application.

A thin film lithium niobate polarizer and a manufacturing method therefor. The thin film lithium niobate polarizer comprises a substrate layer, an optical waveguide layer and an upper cladding layer; the optical waveguide layer comprises a light input port, a light output port, a slab layer and a ridge waveguide layer, the ridge waveguide layer being disposed on the slab layer; the ridge waveguide layer comprises at least one transmission waveguide section, and two ends of the transmission waveguide section are symmetrically connected with connecting waveguide sections; and the transmission waveguide section is used to filter light in a TM mode in a laser signal, and output light in a TE mode in the laser signal by means of the connecting waveguide section at the other end and the light output port, achieving separation of TM and TE components in the input laser signal, to obtain pure TE light, and thereby achieve a polarizing effect. In addition, using a thin film lithium niobate platform helps to reduce the size of a device, facilitating device integration and chip miniaturization. A standard semiconductor process is used, and the process technology is mature, so that costs can be effectively reduced, and the batch production capacity of the device is improved.

The invention relates to a laser radar on-chip integrated chip based on acousto-optic modulation, an on-chip acousto-optic scanning method and a laser radar system. A plurality of groups of interdigital transducers are arranged on the lithium niobate film, two groups of chirp IDTs respectively work at a low-frequency band and a high-frequency band, and sound waves at the low-frequency band correspondingly generate a relatively large Bragg deflection angle; and the high-frequency-band sound waves correspondingly generate a relatively small Bragg deflection angle. The two groups of IDTs work cooperatively, so that two-dimensional vector scanning of a dual-frequency broadband can be realized in a chip plane; the pair of focusing IDTs can form a focusing sound field in an action area, so that the light beam subjected to two-dimensional deflection is controllably deflected in the Z direction, and the chip is endowed with the three-dimensional scanning capability. The device is high in diffraction efficiency and low in power consumption; unification of large-range search and high-precision scanning is realized; z-axis deflection is realized by integrating a special focusing type interdigital transducer, a three-dimensional scanning function is realized on a monolithic integrated acousto-optic chip, and the structure is extremely compact.

A filter device includes first and second acoustic wave resonators each including a support, a piezoelectric layer that has an X-axis, a Y-axis, and a Z-axis that are crystal axes and is made of Y-cut lithium niobate, and an IDT electrode including first and second electrode fingers. When a thickness of the piezoelectric layer is d and a center-to-center distance of the first and second electrode fingers and the second electrode fingers adjacent to each other is p, d / p is less than or equal to 0.5. An absolute value of a first slant angle α1 differs from an absolute value of a second slant angle α2.

According to the Y-type thin-film lithium niobate electro-optical modulator and the manufacturing method provided by the invention, the lithium niobate layer on the electro-optical modulator chip is etched into the corresponding bent waveguide structures, and the two bent waveguide structures are symmetrically arranged on the two sides of the Y-type waveguide structure, so that the height consistency of two optical paths is ensured; according to the bent waveguide structure, the length of the waveguide is guaranteed, meanwhile, the size of the space occupied by the waveguide is reduced, the waveguide with the same length can be carried by adopting a chip with smaller length, and meanwhile, the signal electrode and the ground electrode are arranged on the two sides of each section of straight waveguide in the bent waveguide structure, so that the size of the waveguide is reduced. The optical signal in the waveguide is modulated, and the modulation requirement of the electro-optical modulator is met.

An acoustic wave device includes a silicon single crystal baseplate including a main surface, a piezoelectric layer directly or indirectly on the main surface of the silicon single crystal baseplate, and an IDT electrode on the piezoelectric layer and including electrode fingers. The piezoelectric layer is a lithium niobate layer. In the main surface of the silicon single crystal baseplate, a plane orientation is (111). When Euler angles in the main surface of the silicon single crystal baseplate are (φ, θ, ψ), the ψ in the Euler angles of the silicon single crystal baseplate is about −30 degrees <ψ< about 30 degrees.

The invention discloses an optical frequency comb generation device and method based on lithium niobate film waveguide series connection double micro-rings. The device comprises a first bus waveguide, a first annular waveguide, a second annular waveguide and a second bus waveguide which are etched on a lithium niobate film. Wherein one end of the first bus waveguide is a pump light input end, the other end of the first bus waveguide is an auxiliary light input end, the first bus waveguide and the first annular waveguide are mutually coupled, the first annular waveguide and the second annular waveguide are mutually coupled, the second annular waveguide is a soliton cavity, and a temperature regulation and control device is arranged below the soliton cavity. The temperature of the soliton cavity is regulated and controlled to enable the harmonic peak of the soliton cavity to drift, so that the pump light enters a soliton state, the auxiliary light performs power compensation on the soliton state of the pump light, and a soliton optical frequency comb is generated. In combination with auxiliary photo-thermal modulation, the micro-cavity thermal effect is compensated, the soliton stability is improved, and finally a comb-shaped structure spectrum with stable performance, high coherence and high flatness is output from a soliton cavity port.

This optical modulation element includes a first optical waveguide, a second optical waveguide, a first electrode for applying an electric field to the first optical waveguide, and a second electrode for applying an electric field to the second optical waveguide. The first optical waveguide and the second optical waveguide each include a ridge-shaped portion protruding from a first surface of a lithium niobate film. A first interaction length L1 that is a length of a part of the first electrode overlapping the first optical waveguide in a longitudinal direction is 0.9 mm or more and 20 mm or less. A second interaction length L2 that is a length of a part of the second electrode overlapping the second optical waveguide in the longitudinal direction is 0.9 mm or more and 20 mm or less.

The invention provides a thin-film lithium niobate integrated optical engine for a fiber-optic gyroscope. The thin-film lithium niobate integrated optical engine comprises a substrate, a lower cladding, a lithium niobate thin-film waveguide core layer and an upper cladding, the lithium niobate film waveguide core layer comprises an incident unit, a polarizing unit, a coupling unit, a beam splitting unit, a spot size conversion unit, a phase modulation unit and an emergent unit; the input unit and the polarization unit are gas-phase proton exchange waveguides and naturally have a polarization function; the coupling unit and the beam splitting unit are integrated into a whole, the structure is 2 * 2MMI, and a gas-phase proton exchange process is adopted for preparation; the phase modulation region adopts a lithium niobate film ridge waveguide structure, and coplanar traveling wave electrodes are arranged to realize an electro-optical modulation function; and spot-size conversion structures are additionally arranged between the gas-phase proton exchange waveguide and the ridge waveguide as well as between the ridge waveguide and the output optical fiber, so that mode field matching is realized. According to the embodiment of the invention, the lithium niobate film platform is utilized, and gas-phase proton exchange is combined with a ridge waveguide etching process, so that multiple functions of polarization, coupling, beam splitting, modulation and the like are integrated, the problem of optical coupling loss is solved, and the purposes of miniaturization and low cost of future fiber-optic gyroscopes are achieved.

The invention discloses an optical communication wavelength meter for exciting rubidium atom two-photon transition based on a lithium niobate microcavity optical comb. The optical communication wavelength meter comprises a microcavity optical comb module, a repetition frequency phase-locked loop, an initial frequency phase-locked loop, a rubidium atom gas chamber and a frequency-stabilized light source. The micro-cavity optical comb module is used for generating a fundamental frequency optical comb and a frequency doubling optical comb, rubidium atom two-photon transition is directly excited, the frequency stabilization light source achieves frequency stabilization through rubidium atom saturation absorption, and the repetition frequency phase-locked loop feeds back and adjusts repetition frequency according to error signals of two-photon transition fluorescence intensity. The initial frequency phase-locked loop feeds back and adjusts the initial frequency through beat frequency signals of the frequency multiplication optical comb and the frequency stabilization light source, and the two groups of phase-locked loops stabilize the frequency of the microcavity optical comb to two groups of transition energy levels, so that locking of the repetition frequency and the initial frequency is realized. According to the optical communication wavelength meter based on the lithium niobate microcavity optical comb excitation rubidium atom two-photon transition, the cross modulation effect in a pumping wavelength and pumping power combined adjustment mechanism is avoided, and the size of the optical communication wavelength meter is reduced.

The invention provides an electro-optical modulator and a modulation method thereof, the electro-optical modulator comprises a substrate, a buried oxide layer and a lithium niobate waveguide layer are sequentially stacked on the substrate, and the lithium niobate waveguide layer comprises a first optical waveguide and a second optical waveguide; the electrode layer comprises a composite traveling wave electrode and a direct-current electrode, and the direct-current electrode is arranged on one side, in the signal transmission direction, of the composite traveling wave electrode; wherein the composite traveling wave electrode comprises a metal electrode and a polymer electrode, the metal electrode is embedded into the buried oxide layer, the polymer electrode is arranged on the surface of the buried oxide layer, and the composite traveling wave electrode is arranged between the first optical waveguide and the second optical waveguide and arranged on the side faces of the first optical waveguide and the second optical waveguide respectively; wherein the direct current electrode is arranged between the first optical waveguide and the second optical waveguide. The electro-optical modulator is high in electro-optical conversion efficiency, the plasma effect caused by light field coupling is effectively avoided, and the light loss of the device is remarkably reduced.

The invention belongs to the technical field of integrated optics and inertial sensing, and particularly relates to a full-on-chip integrated photon chip gyroscope. The active devices integrated on the silicon-based heterogeneous integrated chip comprise an SLD light source, a thin film lithium niobate modulator and a detector; the passive device integrated on the silicon-based heterogeneous integrated chip comprises an isolator, a one-to-two coupler, a polarizer, a one-to-two coupler and an on-chip waveguide ring; the silicon-based heterogeneous integrated chip is also integrated with a spot size converter, a bending waveguide, a bending waveguide and a spot size converter.

The invention relates to the technical field of optical fiber communication, in particular to a thin-film lithium niobate electro-optical modulator of a stepped electrode, which comprises a substrate, a buffer layer, an optical waveguide, a metal electrode and a transition layer, the optical waveguide is an X-shaped or Y-shaped cutting LN film, a traditional ridge-shaped structure is adopted, the optical waveguide is bonded to the thick SiO2 buffer layer on the substrate, the film can be prepared through various technologies such as ion implantation, wafer bonding and hot slicing, and in order to improve the electro-optical overlapping coefficient and reduce light absorption loss, a silicon dioxide transition layer is used for connecting the metal electrode and the optical waveguide. The metal electrode is of a stepped structure, the electrode can effectively reduce electrical loss and obtain high bandwidth, and the electrode is used for generating an electric field in the aspect of photoelectric efficiency; the electric field is used for changing the functional characteristics of the thin-film lithium niobate layer and further changing the optical transmission characteristics of the waveguide, so that electro-optical modulation is realized. Therefore, the problem that an existing electro-optical modulator is low in modulation efficiency is solved.

The invention relates to the technical field of industrial detection, and discloses a lithium niobate metasurface defect intelligent identification method based on reactive ion beam etching, which systematically solves the problem of scarcity of experimental data through physical driving simulation and a physics-based rendering algorithm, and provides large-scale field specific training data for a deep learning model. The bidirectional coupling simulation model generates defect morphology prediction data conforming to an etching dynamics law based on real process parameters and material parameters, the prediction data is converted into a synthetic image with real microscopic image statistical characteristics by a physical rendering algorithm, and the quality and consistency of the synthetic data are ensured by an automatic labeling and statistical verification process. According to the method, the number of samples of the ternary association database is multiplied, and extreme process conditions and rare defect modes which are difficult to obtain through experimental collection are covered.

The embodiment of the present disclosure provides an optical transceiver and a manufacturing method thereof. The manufacturing method comprises the following steps: providing a substrate, wherein the substrate comprises a substrate, a buried oxygen layer and a lithium niobate layer which are sequentially stacked; the substrate comprises a light modulation area and a light detection area; etching the lithium niobate layer located in the light modulation area to form a thin film lithium niobate waveguide; removing the lithium niobate layer and part of the buried oxygen layer located in the light detection area to form a groove; the bottom of the groove exposes the substrate; forming a light absorption layer in the groove; wherein the thin film lithium niobate waveguide is used for modulating an optical signal and outputting the modulated optical signal; and the light absorption layer is used for detecting the modulated optical signal and converting the modulated optical signal into an electrical signal.

The invention relates to the technical field of spot-size converters, and discloses a lithium niobate film spot-size converter with an asymmetric trident structure and a preparation method of the lithium niobate film spot-size converter with the asymmetric trident structure. The lithium niobate film waveguide layer is positioned on the insulating layer; the silicon dioxide layer is coated on the lithium niobate film waveguide layer; the silicon nitride waveguide layer is located on the silicon dioxide layer; the silicon nitride waveguide layer comprises a first waveguide part, a second waveguide part and a third waveguide part which are connected in sequence in the direction from the input end to the output end of the lithium niobate film spot size converter, and the first waveguide part, the second waveguide part and the third waveguide part are located on the same plane; in the light wave transmission direction, the transverse size of the second waveguide part is sequentially increased, and the transverse size of the third waveguide part is sequentially reduced; according to the invention, the process preparation difficulty is low, high-efficiency coupling with the coupling efficiency of more than 90% from the silicon nitride waveguide to the lithium niobate waveguide can be realized, and the optical fiber coupling alignment tolerance and overlay tolerance as well as the overall coupling efficiency of the spot size converter are improved.

The invention provides a film lithium niobate chip optical fiber coupling machine vision alignment control method, which comprises the following steps: acquiring a high-resolution image of a waveguide end surface of a film lithium niobate chip, and extracting a multi-structure vision representation set from the high-resolution image; determining an effective action area of the mode field by combining the emergent light intensity distribution and geometric constraint provided by the boundary of the side wall; calculating an energy weighted center based on the light intensity distribution in the effective action area of the mode field, and mapping the energy weighted center to an assembly platform coordinate system to obtain an optical coupling reference center for alignment; with the optical coupling reference center as a target, the position and posture of the optical fiber are adjusted through feedback control, so that the center of an optical fiber core approaches and aligns to the optical coupling reference center; after alignment is completed, the stable optical fiber pose is evaluated and locked, the final coupling pose and performance indexes are output, the problem of decoupling of the visual reference and the real optical reference can be solved, and low-loss and high-stability coupling between the thin-film lithium niobate chip and the optical fiber is achieved.

An electro-optic device is described. The electro-optic device includes a substrate, an insulator on the substrate, an optical structure on the insulator and an electrode proximate to at least a portion of the optical structure. The substrate includes a trench region having a plurality of trenches therein. The trench region has an effective microwave index based on a substrate material and the plurality of trenches. The insulator is on the substrate. The optical structure is on the insulator. The optical structure has a thin film electro-optic layer including lithium. The electrode is proximate to a portion of the optical structure.

To provide an optical waveguide element having a structure in which a proper tolerance is ensured in bonding, an optical connection loss between heterogeneous waveguides is small, and a chip size can be reduced even in the optical waveguide element obtained by bonding a low refractive index substrate and a TFLN.SOLUTION: The optical waveguide element comprises: a low refractive index substrate 1 composed of a material having a lower refractive index than that of lithium niobate (LN); a thin film 2 composed of LN and having a thickness of 1 μm or less, arranged on a part of the substrate 1, wherein an optical waveguide 10 having a higher refractive index than the substrate 1 and composed of materials other than LN is arranged on the substrate 1, at least a part of the optical waveguide 10 is continuously arranged from on the substrate 1 to on the thin film 2, the thin film 2 is shaped in slope in a thickness direction in a region (transition region) where the optical waveguide 10 crosses over an outer peripheral edge of the thin film 2, and an inclination (tanθ) of an edge is set to be 0.189 or less.SELECTED DRAWING: Figure 3

The invention discloses a non-equilibrium Michelson interferometer electric field sensor capable of automatically calibrating temperature influence, which has the characteristics of wide bandwidth, high measurement precision and small interference of distribution of an electric field to be measured, and can also automatically calibrate temperature influence and prevent a working point of the non-equilibrium Michelson interferometer electric field sensor from deviating. The electric field sensor comprises a lithium niobate substrate, the lithium niobate substrate is provided with a non-equilibrium Michelson interferometer, the non-equilibrium Michelson interferometer comprises an input and output waveguide, the input and output waveguide is connected with a first waveguide arm and a second waveguide arm which are different in length, two sides of the first waveguide arm are provided with electrodes, and the second waveguide arm is provided with electrodes. An antenna is arranged on the electrode, a first metal reflecting mirror is arranged at the tail end of the first waveguide arm, a second metal reflecting mirror is arranged at the tail end of the second waveguide arm, the first metal reflecting mirror and the second metal reflecting mirror are both arranged on the lithium niobate substrate, and the thermal expansion coefficients of the first metal reflecting mirror and the second metal reflecting mirror are different.