306 results about "Polarization beam splitter" patented technology

The invention discloses a polarization-state-based optical fiber vibration sensing system and application, and relates to the technical field of optical fiber sensing, and the polarization-state-based optical fiber vibration sensing system mainly comprises a transmitting end and a receiving end. The transmitting end comprises a laser diode, a first erbium-doped optical fiber amplifier, a first circulator, a polarization scrambler, a single-mode optical fiber link, a second circulator and a second erbium-doped optical fiber amplifier which are connected in sequence; and the receiving end comprises a polarization beam splitter, a first shunt module, a second shunt module, an optical mixer, a first balanced photoelectric detector, a second balanced photoelectric detector, a third balanced photoelectric detector and a polarization analysis module. According to the optical fiber vibration sensing system based on the polarization state and the application, the vibration monitoring performance and reliability in a long-distance and high-noise environment can be improved.

The invention relates to the technical field of optical element surface shape dynamic measurement scheme design, in particular to an element surface shape dynamic measurement system based on a metasurface. According to the scheme, polarized light emitted by a laser is split into reference light and test light, the test light passes through a quarter-wave plate twice to realize polarization orthogonalization, and the test light is combined with the reference light to form elliptically polarized light; synchronously capturing component intensities of left-handed / right-handed circular polarized light and orthogonal line polarized light by using a detector, and resolving a phase difference delta in real time by combining a Stokes parameter; environmental interference is eliminated based on a common-path design, a polarization beam-splitting element is omitted, and the architecture is simplified; accurate dynamic measurement of the surface shape of the measured piece is realized by deducting the inherent surface shape error of the system. The system provided by the invention has the advantages of strong anti-interference performance, high measurement efficiency, remarkable cost reduction and the like, and is suitable for precise optical manufacturing and on-line detection scenes.

A zero-optical-path-difference double-frequency heterodyne grating ruler comprises a light source, a signal detecting and processing system, a polarization splitting prism, a first quarter-wave plate, a rectangular prism, a second quarter-wave plate, a third quarter-wave plate, a total reflection mirror, a long-strip prism, a reference grating and a 45-degree-placed polaroid. The two measuring light paths of the system always keep zero optical path difference, so that the measuring precision can be ensured, and the environmental stability of the system is also remarkably improved. And a high-precision and high-robustness measurement scheme is provided for precision equipment such as a photoetching machine and a precision motion platform.

The invention discloses a light attenuation assembly, an optical module, an optical device and related equipment. The light attenuation assembly comprises a half-wave plate, a first polarization beam splitter and a second polarization beam splitter which are sequentially arranged along a light path. The half-wave plate is used for converting the first linearly polarized light into second linearly polarized light, and the second linearly polarized light can be decomposed into third linearly polarized light and fourth linearly polarized light of which the polarization directions are perpendicular to each other; the first polarization beam splitter is used for dividing incident second linearly polarized light into third linearly polarized light and fourth linearly polarized light, reflecting the third linearly polarized light to the second polarization beam splitter, and transmitting and filtering the fourth linearly polarized light at the same time; and the second polarization beam splitter is used for reflecting and outputting the third linearly polarized light and transmitting and filtering the residual fourth linearly polarized light. Through the light attenuation assembly, the quality of the output laser beam can be improved.

The present disclosure describes an optical system and method of operating the optical system. The optical system includes a substrate and first and second photonic integrated circuits. The first photonic integrated circuit is positioned on the substrate. The second photonic integrated circuit is positioned on the first photonic integrated circuit. The second photonic integrated circuit receives a first optical signal that includes a first mode and a second mode. The second photonic integrated circuit includes a polarization splitter rotator, a first demultiplexer, and a second demultiplexer. The polarization splitter rotator separates the first optical signal into a second optical with the first mode and a third optical signal with the first mode. The first and second demultiplexers separate the second and third optical signals into first and second pluralities of optical signals. The first and second pluralities of optical signals couple into the first photonic integrated circuit.

The utility model provides a macro-energy laser energy measuring device, which comprises a beam expanding lens, a polarization beam splitter and two wedge-shaped mirrors which are arranged along a light beam propagation path, the polarization beam splitter is matched with the beam expanding lens to divide an expanded light beam into two polarized light beams, and the number of the wedge-shaped mirrors is two. And the two wedge-shaped mirrors are matched with the polarization beam splitter and are used for respectively splitting the two beams of polarized light in proportion and then enabling the two beams of polarized light to enter a light measurement area. According to the utility model, the PBS, namely the polarization beam splitter, is combined with the wedge-shaped mirror, so that the change of the light splitting proportion caused by the thermal depolarization effect of the high-power laser is avoided, and the influence of the polarization state change of the high-power laser under the change of the thermal effect on the measurement is reduced, thereby improving the precision of energy measurement; the light spot area is increased through the beam expanding lens, and the damage threshold is improved; according to the utility model, as the precision of energy measurement is improved, light beams can be prevented from directly hitting on the probe of the energy meter, and after the damage threshold is improved, the damage risk of an instrument is greatly reduced, the service life of the instrument is prolonged, and the measurement cost is reduced.

The application discloses a Stokes parameter encoder, which comprises a fiber optical circulator and an optical path round trip path; a polarization maintaining fiber Faraday rotator is arranged on the optical path round trip path to rotate the polarization of light by 45 degrees; the fiber optical circulator is a polarization maintaining fiber optical circulator; the fiber optical polarization beam splitter is a polarization maintaining fiber optical polarization beam splitter; the delay fiber is a polarization maintaining delay fiber; and the fiber optical phase modulator is a polarization maintaining fiber optical phase modulator. The application further discloses a parameter encoding method of the encoder. The above technical scheme can perfectly offset the rotation angle deviation problem caused by the device, can guarantee the stability of the rotation angle regardless of the angle deviation of the device, is easy to realize the driving circuit, is easy to integrate and small in size due to the pure fiber structure, and can realize the continuous variable quantum key distribution of the complete GG02 protocol based on the Stokes encoder.

This application provides an identification device and method for soybean grain screening equipment in soybean milk production. The device scans and images the soybean surface. A polarization beam splitter in the camera's optical path separates the reflected light from the soybean surface into parallel polarized light and orthogonally polarized light with mutually perpendicular polarization directions, acquiring parallel and orthogonal polarized images. The parallel and orthogonal polarized images are adaptively fused to generate a polarization-fused image that suppresses surface reflection interference and enhances structural information. Texture periodic features characterizing the regularity of the soybean skin texture and distortion energy features characterizing the degree of surface undulation are extracted from the polarization-fused image. The texture periodic features and distortion energy features are input into a pre-constructed feature discrimination model for defect identification. Based on the defect identification results, it is determined whether defects exist on the soybean surface. Using the scheme of this application, polarization-fused imaging can suppress surface reflection interference, thereby improving the accuracy of soybean surface defect detection.

The application discloses a vortex light interference device and method for measuring three-dimensional vibration and sound field rotation characteristics, wherein a helium-neon laser emits laser light, the laser light passes through a half-wave plate and a first polarization beam splitter prism, and is divided into object light and reference light; the object light passes through a first spiral phase plate and becomes vortex object light, the vortex object light passes through a second polarization beam splitter prism, a quarter-wave plate, and a beam expander lens, and is irradiated on a test sample surface, reflected light of the sample surface passes through the beam expander lens, the quarter-wave plate, the second polarization beam splitter prism, a beam splitter prism and a focusing lens, and is irradiated on a photodetector; the reference light passes through an acousto-optic modulator to generate frequency modulation, passes through a mirror and a second spiral phase plate to become frequency-modulated vortex light, and the vortex light passes through a beam splitter prism and a focusing lens and is irradiated on the photodetector; a computer calculates and demodulates frequency-modulated signals of the photodetector and modulation signals of the acousto-optic modulator, and finally obtains three-dimensional vibration information and sound field rotation characteristics of the sample.

This invention discloses a noise reduction method for electromagnetic measurements of Rydberg atoms. This method constructs a 509nm coupled optical closed-loop circulation system comprising a polarization beam splitter, a half-wave plate, and a high-reflection mirror. This enables multiple reciprocating propagations of the laser within the atomic gas chamber. Utilizing the optical path circulation mechanism, the coupling strength between light and atoms is significantly improved without increasing the laser source power, thus greatly enhancing the excitation efficiency of Rydberg states. Simultaneously, this structure allows the intermediate frequency carrier signal to linearly and coherently superimpose with the number of cycles, while the laser background noise accumulates incoherently only according to a square root law, thereby significantly improving the measurement signal-to-noise ratio. This invention solves the problems of low excitation efficiency and difficulty in eliminating laser background noise in existing single-path optical systems, providing a new solution with high excitation efficiency and high signal-to-noise ratio for high-sensitivity microwave electric field measurements.

Embodiments of the present disclosure relate to an optical scanning system, a laser radar and a vehicle. The optical scanning system includes a polarization converter, a polarization beam splitter, a phase delay element, and a scanning element. The polarization converter is configured to receive a first light having a first polarization state and a second light having a second polarization state and emit a third light having the second polarization state. The polarization beam splitter is configured to reflect the third light. The phase delay element is configured to receive the third light and emit a fourth light. The scanning element is configured to receive the fourth light and emit a fifth light. The phase delay element is further configured to convert the fifth light into a scanning light having the first polarization state, and the polarization beam splitter is further configured to transmit the scanning light.

The application provides a distributed optical fiber acoustic wave sensing system and a pattern recognition method. The application relates to the fields of optical fiber sensing and pattern recognition, and the system comprises the following steps: continuous coherent light emitted by a narrow-line-width laser is split into two paths by a beam splitting fiber coupler, one path is used as local reference light, and the other path is used as probe light; the probe light is modulated into optical pulses in an acousto-optic modulator driven by a waveform generator, and the optical pulses are injected into a measured sensing optical fiber through a fiber loop; Rayleigh backscattering light returned through the measured sensing optical fiber is mixed with the local reference light through the fiber loop, and the mixed light is decomposed into two orthogonal polarized light beams in a polarization beam splitter and is transmitted to a first balanced photodetector and a second balanced photodetector respectively to be converted into electrical signals; and the two orthogonal interference electrical signals are synchronously collected by a data acquisition card and are sent to a host computer for demodulation. The application provides a new distributed acoustic wave monitoring method with high reliability and high generalization ability, and has extremely high engineering popularization value.

The invention belongs to the field of photoelectric chips, and provides a low-loss silicon nitride optical engine chip for a triaxial fiber-optic gyroscope. The chip comprises an end face coupling area, a polarization rotation area and a beam splitting area, a low-polarization light beam from a light source is transmitted to the end face coupling area through the single-mode optical fiber and is transmitted to the silicon nitride waveguide through the input end face coupler, a TM0 mode of the silicon nitride waveguide is output and converted into a TE0 mode by the cross end of the polarization beam splitter through the polarization rotator, and the TM0 mode and a TE0 mode output by the straight-through end of the silicon nitride waveguide are combined in the heat insulation beam combiner. And the combined light is transmitted to the beam splitting area and is output through output end face couplers in the beam splitting area and the end face coupling area. Through the mode, efficient conversion from a non-working polarization mode to a main mode and high-efficiency, low-loss and high-stability light path connection are realized, inherent polarization loss of-3dB is avoided fundamentally, and a feasible scheme of an integrated, low-power-consumption and high-performance fiber-optic gyroscope is provided.

Methods and systems for measuring the optical quality of an eye based on laser ray tracing are provided herein. Generally, the method uses the steps of temporally detecting the human eye with one or more laser beams in a set of points within the pupil of the eye, detecting projections of the laser beams reflected and scattered from the retina, and processing an image of the detected laser spots. In one embodiment, the components of the system include, but are not limited to, a laser having a dual-axis acousto-optic deflector and a dual-output generator of a digitally synthesized sinusoidal voltage, a collimating optical system, a conjugate telescope system, a polarizing beam splitter, and first and second photosensitive detectors, each component being in operable communication with a processing unit. Another embodiment uses a multi-laser block that does not require laser beam scanning.

The invention discloses a waveguide-based all-fiber quantum entanglement source and quantum equipment, relates to a quantum information technology, and can realize the stability and miniaturization of the quantum entanglement source. The waveguide-based all-fiber quantum entanglement source comprises a pump light source module used for generating pump light; the polarization beam splitter is used for receiving and outputting the pump light; the Sagnac interference ring is used for generating entangled photon pairs based on the pump light output by the polarization beam splitter and returning the entangled photon pairs to the polarization beam splitter; the polarization beam splitter is also used for receiving the entangled photon pair and outputting the entangled photon pair; and the filtering output module is connected with the polarization beam splitter and is used for filtering residual pump light and outputting entangled photon pairs.

The invention relates to the technical field of optical polarization state measurement, in particular to a laser polarization state real-time measurement analyzer which comprises collimators, a non-polarization beam splitter, a 1 / 4 wave plate, a compensation module and a polaroid. The first non-polarization beam splitter divides two light beams into a second non-polarization beam splitter, a 1 / 2 wave plate and a third non-polarization beam splitter respectively, and the second non-polarization beam splitter divides two light beams into a second collimator and a third collimator respectively through a first polaroid and a second polaroid; the third non-polarization beam splitter divides two paths of light beams into a fourth collimator and a 1 / 4 wave plate through a third polaroid, the fourth polaroid enters a fifth collimator, the second collimator, the third collimator, the fourth collimator and the fifth collimator are connected to an oscilloscope through four photoelectric detectors, and the upper computer collects data of the oscilloscope and calculates the real-time polarization state of the laser. The method is simple, high in precision and low in cost, and realizes real-time measurement of the laser polarization state.

The present application relates to the technical field of welding positioning and machine vision, and particularly relates to a part positioning device for a welding machine tool, which comprises a protection window, an objective lens, a quarter-wave plate, a polarization beam splitter prism and an imaging unit located at the transmission end of the polarization beam splitter prism, which are arranged in sequence along the same main optical axis; further comprising a laser emission unit connected to the side end of the polarization beam splitter prism; further comprising a calculation and output unit electrically connected to the imaging unit; wherein the laser emission unit emits linearly polarized near-infrared laser, which is reflected by the polarization beam splitter prism and then irradiated to the workpiece surface along the main optical axis through the quarter-wave plate and the objective lens in sequence; the return light from the workpiece passes through the objective lens and the quarter-wave plate in sequence along the main optical axis; in the present application, the emission and imaging share the same main optical axis, which is naturally aligned with the movement direction of the machine tool, the shielding and blind area are significantly reduced, and the cross light and ghost image are effectively suppressed, so that the precise positioning of the weld path is completed.

This invention discloses a liquid crystal filter-based lidar chopping device for atmospheric wind and temperature detection, comprising a digitally controlled voltage output module, a liquid crystal module, a light guide module, a timing control module, a polarization beam splitter module, a frequency discriminator module, a reference channel photodetector, a frequency discriminator channel photodetector, a photon counting and acquisition card, a computer, a pulsed laser, a telescope, and a collimation module. This invention also discloses a liquid crystal filter-based lidar chopping method for atmospheric wind and temperature detection. This invention solves the problem of atmospheric wind and temperature detection being limited by the dynamic range of the photodetector; the received signal attenuation amplitude can be adaptively adjusted in real time, better adapting to weather changes. Furthermore, although liquid crystal filtering introduces some signal loss, wind and temperature detection typically uses the ratio of the reference channel and frequency discriminator channel signals for inversion, so the final result is independent of the liquid crystal's transmittance, thus avoiding the negative impact of liquid crystal filtering.

The application discloses an SBS phase conjugation mirror capable of displaying a sound wave field in real time, and belongs to the technical field of nonlinear optics.The application comprises the following steps: pump light passes through a half-wave plate and a polarization beam splitter, passes through an optical isolator, changes a polarization state through a quarter-wave plate, is focused through a focusing lens, and then enters an SBS medium pool, stimulated Brillouin scattering occurs, a periodic density modulation is formed in the medium, and an equivalent acousto-optic grating structure is generated.Through introducing an independent probe light beam, the probe light enters the SBS medium pool at an incident angle satisfying the Bragg diffraction condition, and the probe light will be diffracted on the acousto-optic grating formed by the sound wave field.The intensity of the diffracted light changes with the intensity of the sound wave field, so that the real-time measurement of the sound wave field waveform and the life parameter in the SBS process can be realized by detecting the change of the diffracted light intensity with time.

The application discloses a laser converging system, a laser welding system and a laser welding machine, and relates to the technical field of optical converging. The laser converging system converts the preset S polarization laser beams sent by a laser device into two S polarization beams, and then into two P polarization beams through a plane mirror, an S polarization beam splitter, a first controlled mirror and a second controlled mirror arranged in the same XY plane, and converges the first light path and the second light path corresponding to the two P polarization beams at a preset space point outside the XY plane, so that the imaging light path for observing the converging conditions of the P polarization beams is designed outside the XY plane where the laser transmission light path is located, the mutual interference between the laser transmission light path and the imaging light path is avoided, and the control precision of the laser convergence is improved.

The invention discloses an alignment sensing system of a multi-wavelength vortex light projection photoetching machine. The system is composed of n light sources which are arranged in parallel and have different wavelengths, vortex light generators corresponding to the light sources, a light beam combiner, a reflector, two amplitude gratings, a Dove prism, a quarter-wave plate, a half-wave plate, a polarization beam splitter and detectors corresponding to the light sources. The processed second diffracted light received by the detector interferes with the first diffracted light, and an interference image is formed at the detector. The structure is simple, and high-precision detection of the alignment mark position of the phase silicon wafer can be realized.

The application belongs to a polarization Michelson wind measurement interferometer, and aims at the technical problems of resolution reduction, instrument volume and weight increase caused by internal movement components or aperture division of the existing wind imaging interferometer, and provides a polarization Michelson wind measurement interferometer based on LCVR and a measurement method thereof. Incident light is sequentially divided into transmitted light and reflected light after passing through a front telescope system, a first linear polarizer and a polarization beam splitter. The transmitted light forms first linearly polarized light by passing through a first compensation glass, a second compensation glass and a first achromatic quarter-wave plate. The reflected light forms second linearly polarized light by passing through a third compensation glass and a back surface of a second achromatic quarter-wave plate. The first linearly polarized light and the second linearly polarized light have an optical path difference and orthogonal polarization directions. The first linearly polarized light and the second linearly polarized light are sequentially imaged on a surface array CCD after passing through a first imaging lens, an aperture diaphragm, a second imaging lens, an LCVR and a second linear polarizer.

A dynamic 3D light scattering particle size distribution measurement device includes a polarization splitter for generating an s laser beam with perpendicular polarization and a p laser beam with parallel polarization that travels parallel to and spaced apart from the s laser beam. A lens is used to focus the s laser beam and the p laser beam onto a common focus area inside a sample holder holding a sample whose particle size is to be measured. An s light intensity detector measures a time-resolved s light intensity from s backscattered light from the focus area. An s-polarisation filter allows perpendicularly polarized light to pass, resulting in s measuring light, and includes a light detector for time-resolved intensity measurements of the s measuring light. A p light intensity detector measures a time-resolved p light intensity detects p backscattered light from the focus area, and includes a p polarization filter that allows parallel polarized light to pass. A light detector provides for time-resolved intensity measurement of the p measuring light, and an evaluation unit automatically calculates the particle size distribution from the time-resolved p light intensity and the time-resolved s light intensity.

The application provides an optical lens measuring device and method, which comprises a light source, a half-wave plate, a polarization beam splitter, a 1 / 4 wave plate, a first mirror, a second mirror, a first beam splitter, a rotating module, a transmittance and reflectance detection module and a chirp detection module, the transmittance, reflectance and chirp are measured by constructing a reflection measurement path and a transmission measurement path and setting a detachable light beam shielding module on the mirror, without the need for recalibration and debugging, a large amount of time is saved, and the detection efficiency is improved. In addition, the rotating module is used to rotate the to-be-measured lens and the corresponding mirror lens, so that different optical parameters can be measured according to different optical lenses and different angles, the detection diversity is increased, the detection complexity is simplified, the cost of manpower and material resources is reduced, and the sustainable development of enterprises is beneficial.

The invention discloses a frequency locking and frequency discrimination integrated device of a Doppler laser radar. The frequency locking and frequency discrimination integrated device comprises a pulse light source module, a receiving front light path module and a frequency locking and frequency discrimination module. The pulse light source module emits frequency-tunable pulse laser as a frequency-locked optical signal; receiving an echo optical signal from a detection target collected by the front optical path module; the frequency locking and frequency discrimination module is an integrated optical path, and through cooperation of a 1 / 2 wave plate, a beam splitter, a 1 / 4 wave plate, a polarizing beam splitter, a reflector, a dual-channel Fabry-Perot etalon and other elements, polarization state cooperative regulation and frequency discrimination are carried out on two paths of signals, and cascade multiplexing of echo signals is realized. Through the integrated design, the problem of system complexity caused by separation of a frequency locking link and a frequency discrimination link is solved, the echo signal utilization rate is improved, the receiving efficiency of the system is improved by more than one time through cascade multiplexing of reflected signals, meanwhile, an independent frequency locking channel is omitted, the system architecture is remarkably simplified, and the stability and the wind speed inversion precision are improved.

The application discloses an output light power proportion adjustable fiber coupling system for atomic physics research, comprising a first fiber collimator, and further comprising a second fiber collimator, a first reflector, a second reflector, a liquid crystal variable retarder, a polarization beam splitter prism, a first half-wave plate and a second half-wave plate; the application can work in two modes of proportion adjustable beam splitting and beam combining according to specific requirements; the proportion of laser entering the first fiber collimator and the second fiber collimator can be quickly adjusted; the utilization efficiency of laser in a set of experimental system and the stability of the experimental system are improved; the space occupied by the experimental system is reduced, and a large amount of experimental resources is saved.

The invention discloses a method and device for modulating random polarized light through a liquid crystal spatial light modulator, and relates to the technical field of light field regulation and control. The device comprises a laser, a two-in-one optical fiber, a beam expander, a polarization beam splitter (PBS), a 1 / 2 wave plate, an optical fiber coupler, a polarization maintaining optical fiber, a liquid crystal spatial light modulator and other core components, wherein the liquid crystal spatial light modulator is reflective or transmissive. According to the method, random polarized light is divided into parallel and vertical polarized light components through a PBS, the vertical polarized light is converted by a 45-degree 1 / 2 wave plate and then is transmitted by a polarization maintaining optical fiber and is converged with the original parallel polarized light component, or the vertical polarized light is directly used for preheating a sample to be processed, and the converged single beam of parallel polarized light is modulated by a liquid crystal spatial light modulator. Single-beam modulation is achieved, high-power large light spot application is adapted, the hologram manufacturing difficulty is lowered, the light path structure is simplified, light energy loss is reduced, and the device is suitable for 3D metal printing, laser welding and other scenes.

A biometric recognition device for palm prints and palm veins includes: a light source being used to emit illuminating beams in a near-infrared band; a polarizing unit being used to convert the illuminating beams to polarized beams which are emitted to a palm; an imaging unit receiving retroreflected beams from a palm and being used to converge the retroreflected beams to a focal plane; a polarizing beam splitter forming transmitted beams and reflected beams based on different polarization directions of beams from the imaging unit, wherein the transmitted beams propagate after pass through the polarizing beam splitter, and the reflected beams propagate after reflected by the polarizing beam splitter. An identity authentication method is further provided. Based on the non-contact technical solution, only one light source is used to obtain the palm print images and palm vein images at the same time and in the same space.

The application discloses an optical signal inner circulation delay system based on electro-optic polarization modulation, comprising a signal light source, a first polarization beam splitter prism, a first electro-optic polarization modulator, a second polarization beam splitter prism, a second electro-optic polarization modulator, a third polarization beam splitter prism, a first full reflection mirror, a first lens, a first optical fiber collimator, a single-mode / multi-mode optical fiber, a second lens, a second optical fiber collimator and a second full reflection mirror, forming a ring-shaped light path. The length of the single-mode / multi-mode optical fiber and the high level duration of the modulation electric signal are adjusted, the repetition frequency and the pulse width of the output optical signal can be changed respectively, and therefore the application can also be used for converting continuous light into controllable pulsed light. The number of times that the signal light circulates in the ring-shaped light path can be controlled through the loaded electric signal, the delay time is flexibly adjusted, and the delay time range is expanded.

The invention discloses an optical fiber interferometer, and relates to the technical field of polarization sensitive optical coherence tomography. According to the optical fiber interferometer, through modular structural design and precise parameter limitation, a compact framework formed by sequentially coupling and connecting the polarization unit, the polarization-maintaining coupler, the first polarization light splitting unit and the second polarization light splitting unit is constructed. The input end of the polarization-maintaining coupler is respectively coupled and connected with the input ends of the first polarization-maintaining optical fiber and the first single-mode optical fiber, the output end of the polarization-maintaining coupler is respectively coupled and connected with the input ends of the second polarization-maintaining optical fiber and the third polarization-maintaining optical fiber, and the included angle between the optical axis of the polarization-maintaining coupler and the optical axes of various optical fibers and the light splitting proportion of the polarization-maintaining coupler are strictly limited; the second polarized light and the third polarized light are orthogonal to each other, the fourth polarized light and the fifth polarized light are orthogonal to each other, the physical properties of the second polarized light and the fourth polarized light are consistent, and the physical properties of the third polarized light and the fifth polarized light are consistent.