60 results about "Optical gyroscope" patented technology

The invention provides a method and a system for realizing a weak measurement enhanced chip-level microcavity gyroscope. The method comprises the following steps of: 1, providing a coherent state input by a system by using a single-frequency laser; 2, the output of the single-frequency laser is switched between a first path and a second path through an optical switch, the laser beam is transmitted to the first path in the first half part of the period, and the laser beam is transmitted to the second path in the second half part of the period; 3, the light transmitted along the first path and the second path respectively passes through an optical resonant cavity to sense the rotation angular speed, and a weak value amplification effect is achieved by setting front and back selection states; and step 4, weak measurement enhanced output results transmitted along the first path and the second path are respectively received by a photoelectric detector, and the value of the rotation angular velocity is demodulated according to the obtained output results. According to the invention, the optical microcavity is used as a sensing unit of the gyroscope, the sensing performance of the integrated optical gyroscope is greatly enhanced through a weak measurement technology, and the whole set of system can realize chip-level integration.

The invention relates to a resonant optical gyroscope signal detection method based on an optical switch. The resonant optical gyroscope signal detection method comprises the following steps: step 1, adopting a narrow linewidth laser as a light source; 2, the split light field enters a lithium niobate phase modulator A and a phase modulator B to be modulated by a triangular wave voltage signal, the light field subjected to phase modulation is coupled in opposite directions to enter a waveguide resonant cavity, and a photoelectric detector A and a photoelectric detector B are used at the output end of the resonant cavity to obtain a voltage signal; and voltage signals obtained by the photoelectric detector A and the photoelectric detector B are accessed to a lock-in amplifier. 3, arranging an optical switch A between the waveguide resonant cavity and the photoelectric detector A; and an optical switch b is arranged between the waveguide resonant cavity and the photoelectric detector B, so that the detection of a gyro signal is completed. The interference of polarization noise can be reduced, and the resonant frequency locking precision and the angular velocity detection sensitivity of the gyroscope are improved.

The invention discloses a single-laser self-injection locking resonant optical gyroscope based on light intensity detection and a working method thereof, and belongs to the technical field of optical gyroscopes, a working light source DFB laser is connected with a first port of a circulator, and a second port of the circulator is connected with a beam splitting coupler through an isolator; two output ends of the beam splitting coupler are respectively connected with an input end of the echo wall microcavity and the phase modulator, and the phase modulator is connected with the other input end of the echo wall microcavity; a first port of the output end of the echo wall microcavity is connected with a third port of the circulator, and a second port of the output end of the echo wall microcavity is connected with the frequency locking amplifier through the photoelectric detector. According to the invention, the problems of high cost of double light sources in the self-injection locking resonant optical gyroscope and frequency drift and complex structure of beat frequency detection are solved, so that the measurement precision and economical efficiency of the gyroscope are effectively improved.

The lithium niobate-silicon nitride waveguide structure comprises a silicon substrate layer, a first silicon oxide isolation layer, a second silicon oxide isolation layer, a lithium niobate thin film layer and a silicon oxide dielectric layer which are stacked in sequence, the second silicon oxide isolation layer is wrapped with a silicon nitride layer; the thickness of the second silicon oxide isolation layer between the silicon nitride layer and the lithium niobate thin film layer is 50 + / -10nm; the thickness of the silicon nitride layer is 400 + / -10nm, and the thickness of the lithium niobate film layer is 600 + / -50nm; the silicon oxide dielectric layer is provided with at least two electrodes which are arranged at intervals. According to the lithium niobate-silicon nitride waveguide structure, the preparation method and the optical gyroscope provided by the invention, on the basis of the advantages of silicon nitride and lithium niobate materials, an ultra-low-loss silicon nitride waveguide, an ultra-high-Q-value micro-ring resonator and a high-modulation-rate lithium niobate modulator are obtained at the same time through a lithium niobate and silicon nitride hybrid integration method; and thus, the overall performance of the resonant integrated optical gyroscope is improved.

One or more phase modulators in an optical gyroscope operate on two counter-propagating beams to introduce a phase shift between the beams before the beams are interferometrically combined to generate a rotation signal. A signal generator generates first and second modulation frequencies to drive the phase modulators. The first modulation frequency in isolation biases the rotation signal at an operating point sensitive to rotation, and the second modulation frequency in isolation biases the rotation signal at an operating point insensitive to rotation. One or more control integrated circuits (ICs) isolate a first portion of the rotation signal associated with the first modulation frequency and a second portion of the rotation signal associated with the second modulation frequency. The control ICs determine a difference between the first and second portions of the rotation signal to remove one or more bias instabilities from the first portion of the rotation signal.

Various examples of a closed-loop optical gyroscope are disclosed. The closed-loop optical gyroscope includes a broadband light source configured to generate broadband optical signal(s). The broadband optical signal(s) propagate in an optical resonator and are coupled in and out of the optical resonator by optical couplers. A phase modulator applies phase modulation to the optical signal(s) based on a sawtooth modulation signal. The optical signal(s) repropagate in the optical resonator in a different direction. The optical signal(s) are then received and analyzed to determine parameter(s) of the phase modulator. One or more processors configure the phase modulator based on the determined parameter(s).

An interferometric resonator optical gyroscope includes an optical frequency comb generator configured to generate an optical frequency comb. Optical signals representative of the optical frequency comb pass through an optical resonator in different directions, and a rotation rate is determined based on the extent of interference between the optical signals. Parameters of the optical frequency comb generator can be controlled by a control servo based on an intensity of the optical signals after propagating in the optical resonator. Utilizing an optical frequency comb generator reduces the bias error during gyroscope operation.

The present invention discloses an optical gyroscope integrated chip based on a thin-film lithium niobate photonic integrated platform. The overall structure adopts a hybrid curved waveguide with multiple parts of continuously variable curvature, which reduces the insertion loss caused by the mode field mismatch between the straight waveguide and the curved waveguide at the junction, reduces the excitation of high-order modes, and helps to reduce the overall size of the chip. In addition, the curved waveguide increases the polarization extinction ratio of the chip and filters out quasi-TE 00 The present invention utilizes waveguide mode leakage to achieve single-mode, single-polarization operation of the lithium niobate waveguide. The single-TE mode lithium niobate waveguide on the entire chip, excluding the curved waveguide of the folded modulator and the coupler, forms a waveguide polarizer with a high polarization extinction ratio. This allows on-chip single-mode, single-polarization operation to be achieved without the need for an additional polarizer design, effectively reducing chip complexity, improving chip stability, and reducing chip size.

The present invention provides an integrated interferometric optical gyroscope, assembly, system, and method for calculating rotational speed, the gyroscope comprising a light source module, a first coupling module, a second coupling module, at least two polarization-separated rotation modules, a photoelectric detection module, and a helical waveguide module, the two polarization-separated rotation modules each connected to the distal and proximal ends of the helical waveguide module, each converting two optical beams in a TE polarization state into two polarization states, TE and TM, transmitting them to both ends of the helical waveguide module, transmitting them in opposite directions within the helical waveguide module, receiving the two optical beams after they have passed through the helical waveguide module, and converting both polarization states back to the same TE mode, the gyroscope does not use a circulator or 50 / 50 coupler, avoids reflected light waves to the light source, and eliminates the influence of system errors, drift or disturbances, changes in ambient temperature, etc. on the performance stability of the gyroscope.

The invention discloses a novel reciprocity resonance interference combined type integrated optical gyroscope sensing and detection method, and belongs to the field of integrated optical gyroscopes. Firstly, an integrated optical gyroscope optical path sensing module is built, light emitted by a laser is split and modulated after sequentially passing through a circulator and a phase modulator and is split again after passing through a straight-through end coupler of a resonant cavity, two light beams are output to a photoelectric detector I and a photoelectric detector II after passing through an isolator from a straight-through end, and the other two light beams are output from a transmission end after entering the cavity for resonance; the light returns to the circulator for light combination interference and is output to a photoelectric detector III; generating a laser frequency locking signal by using light output from the straight-through end, and returning the laser frequency locking signal to the laser to form a closed loop so as to complete establishment of a laser frequency locking detection module; after the laser locks the resonant frequency of the resonant cavity, light is output from the transmission end, construction of a differential interference sensitive angular velocity detection module is completed, and the final gyro angular velocity is output. The invention solves the problem that the optical path scheme of the resonant gyroscope is not reciprocal and is easily influenced by environment temperature change.

The invention provides an angular velocity detection system and method based on weak measurement, which can be applied to the technical field of quantum sensing and the technical field of optical gyroscopes. The system comprises a laser emitting initial light; the front selection module performs phase adjustment on two parts of light in the initial light; the first optical resonant cavity transmits the first path of light along an anticlockwise path; the second optical resonant cavity transmits the second path of light along a clockwise path; the post-selection module couples the first path light with a first part of light in the second path light to obtain first interference light; the detection module detects the first interference light to obtain first light intensity; the processor obtains a linear coefficient according to the preset phase, the initial light intensity of the initial light and the transmission coefficient; according to the first light intensity, the linear coefficient and the preset phase, the rotation angular velocity is obtained, the optical microcavity serves as a sensing unit of the gyroscope, the sensing performance of the integrated optical gyroscope is enhanced through the weak measurement technology, and the detection precision of the rotation angular velocity is improved.

The invention discloses an all-normal dispersion super-continuum spectrum driven resonant optical gyroscope and a working method thereof, and belongs to the field of optical gyroscopes. The input end of the mode-locked laser ML is connected to a left port of the full-normal dispersion photonic crystal fiber ANDi-PCF, input ports of the full-normal dispersion photonic crystal fiber ANDi-PCF and the photoelectric detector PD are connected to two left ports of the circulator CIR respectively, and a right port of the circulator CIR is connected with a left port of the multifunctional integrated optical chip MIOC. And two ports on the right side of the multifunctional integrated optical chip MIOC are respectively connected with two ports of the waveguide ring resonator WRR. Based on the resonance mode of the full-normal dispersion super-continuum spectrum excitation waveguide ring resonator, the influence of relative intensity noise and shot noise on the gyroscope performance is further reduced by using the broadband and smooth light source spectrum pattern, and finally the angle random walk of the gyroscope is promoted.

The present invention primarily relates to a compound of formula (I) as defined herein and to a mixture comprising or consisting of one or more compound(s) of formula (I) as defined herein and optionally one or more host material(s). Moreover, the present invention relates to the compounds of formula (II) to (VIII) as defined herein and to further specific compounds as defined herein. The present invention also relates to an electro-optic film and an electro-optic modulator-device as defined herein and to a method for manufacturing an electro-optic modulator-device comprising or consisting of the steps as defined herein. Lastly, the present invention relates to the use of a compound of formula (I) or of a mixture as defined herein or of an electro-optic film as defined herein or of an electro-optic modulator-device as defined or as manufactured herein in a field selected from the group consisting of nonlinear optics, Mach-Zehnder modulators, silicon organic hybrid electro-optic modulators, materials for devices or arrangements for the control of the intensity, color, phase, polarization or direction of light arriving from an independent light source, preferably switching, gating, or modulating, photonic communication networks, optical data transmission, preferably in 6G applications, phased array radars, satellite and fiber telecommunications, cable television (CATV), optical gyroscopes for application in aerial and missile guidance, electronic counter measure (ECM) systems, backplane interconnects for high-speed computation, ultra-quick analog-to-digital conversion, land mine detection, radio frequency photonics, programmable photonics, cryo-communications, quantum computing, spatial light modulation, and all-optical (light-switching-light) signal processing.

The invention discloses an on-chip programmable multiplexing waveguide ring based on thin film lithium niobate, which comprises a thin film lithium niobate chip, a first TE mode straight waveguide, a first polarization beam splitting rotator, a first TE mode bent waveguide, a first polarization independent short waveguide, a first TE / TM mode controllable converter, a second TE mode straight waveguide, a second polarization beam splitting rotator, a second TE mode bent waveguide, a second polarization independent short waveguide and a second TE / TM mode controllable converter are integrated on the thin film lithium niobate chip. Through the structural combination, the programmable multiplexing on-chip integrated waveguide ring function can be realized, so that the functions of adjustable optical delay length, adjustable on-chip integrated waveguide ring and the like can be realized, and the programmable multiplexing on-chip integrated waveguide ring can be widely applied to the fields of microwave photon adjustable optical delay, on-chip optical gyroscopes and the like.

The application belongs to the field of optical gyroscopes, and particularly relates to a wide-spectrum light source driven resonant optical gyroscope based on light intensity fluctuation feedback technology and a RIN suppression method thereof. The light source ASE is connected with a No.1 port of a circulator CIR, the No.2 port of the circulator CIR is connected with a micro integrated optical waveguide modulator MIOC, the tail end of the micro integrated optical waveguide modulator MIOC is connected with one end of a coupler C1 and one end of a coupler C2 respectively, the other end of the coupler C1 and the other end of the coupler C2 are connected with a fiber resonant cavity FRR respectively to realize multi-turn transmission of light in the fiber resonant cavity FRR; the polarization maintaining optical fiber extended from the right transmission end of the coupler C2 is connected with the No.3 output end of the circulator CIR after 90-degree fusion, and then connected with one side of a coupler C3, and the light intensity signal output by the coupler C3 is detected by a photodetector PD, and then output as a rotation value after passing through a lock-in amplifier LIA and a low-pass filter LPF. The application can actively suppress the light intensity fluctuation caused by the light source at a specific frequency.

This invention proposes a resonant micro-optical gyroscope based on a variable fiber beam splitter and its closed-loop control method, belonging to the field of resonant optical gyroscope technology. It includes a laser, a variable fiber beam splitter, phase modulators PMⅠ and PMⅡ, circulator Ⅰ and circulator Ⅱ, a 95% 2×2 coupler, photodetectors PDⅠ and PDⅡ, a whispering-gallery resonator, a digital-to-analog interface, a digital system, and an analog-to-digital interface. This invention achieves a dual-closed-loop structure by designing a Schmitt-type closed-loop switching, a linear region judgment scheme, and an automatic reset operation, thereby improving the linearity and dynamic range of the ROG output.

A technique is provided for reducing angle random walk (ARW) noise in a resonant optical gyroscope (ROG) using a pair of optical frequency combs. The ARW noise is reduced by propagating each optical frequency comb through a dispersive optical component. As a result, at least some of the spectral components, of an optical frequency comb emitted from a dispersive optical component, are no longer phase locked. As a result, ROG rotation rate accuracy is increased.

The present application relates to the technical field of integrated optical gyroscopes, and particularly relates to a method and system for sensing angular velocity based on double silicon-based micro-ring resonance demodulation. The method comprises the following steps: a driving circuit drives broadband light emitted by an on-chip light source to be coupled into an on-chip silicon-based optical waveguide through an input grating; the broadband light is modulated into narrowband light after passing through a first silicon-based micro-ring; the narrowband light enters a silicon-based sensing ring, and the narrowband light generates Sagnac frequency shift when the silicon-based sensing ring rotates; a second silicon-based micro-ring changes a channel frequency band through electrical modulation, and resonance demodulation is achieved when the channel frequency band matches the frequency of the narrowband light signal after frequency shift; the demodulated optical signal enters an on-chip detector through an output grating and is converted into an electrical signal, and the initial angular velocity of a carrier platform is demodulated after being processed by a demodulation circuit. The present application realizes high-sensitivity sensing of angular velocity based on double silicon-based micro-ring resonance demodulation; and provides a theoretical basis and technical support for the development of integrated optical gyroscopes with the advantages of high sensitivity, miniaturization, chipization and low cost.

Embodiments utilize an optical frequency comb generator coupled to an optical resonator of an optical gyroscope. The optical frequency comb generator generates an optical frequency comb having frequency peaks that each correspond to a respective resonance frequency of the optical resonator. A control servo can be coupled to the optical frequency comb generator and controls the optical frequency comb output from the optical frequency comb generator. In doing so, the optical frequency comb remains tuned to the resonance frequencies of the optical resonator during gyroscope operation.

The invention discloses a design method of a lithium niobate film phase modulator with a high polarization extinction ratio, and belongs to the field of integrated optical gyroscopes. The method comprises the following steps: firstly, designing a lithium niobate film phase modulator comprising a silicon substrate, a silicon dioxide cladding, a lithium niobate film optical waveguide core layer and a modulation electrode; the double-layer conical gradient waveguide meeting the TE mode light fundamental mode transmission condition couples light into a chip, and polarization of a transmittable light mode is limited by designing the width and the thickness of the waveguide; the effective refractive index, the bending radius, the waveguide width and the center distance are designed for the directional coupling unit, and polarization is generated through phase matching polarization beam splitting; the multimode interference coupler is polarized by designing the length and width of a multimode interference region; the bending beam splitting unit is polarized by designing bending radius leakage; finally, through an electric field generated by a modulation electrode, the light is subjected to phase change, and two beams of light with phase difference are output; according to the invention, a high polarization extinction ratio is realized on the basis of a basic beam splitting modulation function.

The invention discloses an optical gyroscope based on photon orbital angular momentum, which belongs to the field of photoelectric sensing and comprises a thin-film lithium niobate integrated optical chip, and a distributed feedback laser and a photoelectric detector are integrated on the thin-film lithium niobate integrated optical chip in a hybrid manner. And a photon orbital angular momentum demodulator and a photoelectric detector array are packaged outside the thin film lithium niobate integrated optical chip. An annular cavity structure with a grating is integrated on the thin film lithium niobate integrated optical chip, so that a function of radiating a photon orbital angular momentum mode from an in-ring resonance echo wall mode from the grating is realized. Different from a traditional gyro chip which observes the change of the angular velocity based on the Sagnac phase change, the micro-ring integrated on the thin film lithium niobate chip can cause the change of a photon orbital angular momentum mode during rotation, and the corresponding angular velocity during rotation of the ring is measured by identifying the change of the photon orbital angular momentum. The scheme has the advantages of higher precision and integration level and no need of using an optical fiber ring.

The invention provides a sensitive ring structure applied to an interference type integrated optical gyroscope and a preparation method of the sensitive ring structure. A first waveguide layer, a coupling layer and a second waveguide layer are sequentially formed on a substrate, a plurality of oxide layers are formed, and the first waveguide layer, the coupling layer and the second waveguide layer are all wrapped in the oxide layers; a first interlayer is arranged between the first waveguide layer and the coupling layer, a second interlayer is arranged between the coupling layer and the second waveguide layer, and finally the sensitive ring structure applied to the interference type integrated optical gyroscope is formed. When coupling transmission is carried out between the first waveguide layer and the second waveguide layer, no cross phenomenon exists between the output waveguide and the waveguide coil, so that crosstalk between the waveguides can be reduced, transmission loss between the waveguides can be reduced, and the distance between the first waveguide ring and the second waveguide ring is not too close due to the existence of the coupling layer. And inter-layer coupling crosstalk can be further reduced.

The application belongs to the field of optical gyroscopes, and particularly relates to a high-sensitivity optical gyroscope based on a single-cavity PT symmetric structure and a design method thereof. The gyroscope is composed of a laser, a ring cavity, an S-shaped waveguide, a coupler and a photodetector. An active S-shaped waveguide and a passive S-shaped waveguide are coupled in the ring cavity. By adjusting the gain / loss value in the active / passive waveguide and the coupling coefficient of the coupler, the system can be adjusted to be near an exceptional point (EP). The gyroscope system at the EP can exhibit extremely high sensitivity to rotation speed. The ring cavity works below the laser threshold, and a power detection technology is used to measure the sensitivity of the gyroscope. Through the technology, the signal-to-noise ratio of the gyroscope can be accurately measured. In addition, by coupling two counter-propagating modes in the same optical resonator, instead of coupling two coupled modes in the double-resonator in the traditional scheme, the area can be reduced by 3 / 4, and the non-reciprocity error caused by the influence of different disturbance sources on the two resonant cavities in the general PT symmetric gyroscope can be suppressed.

The invention belongs to the technical field of optical gyroscopes, and particularly relates to a chip-level wide-spectrum resonant optical gyroscope based on differential detection and a working method thereof. The working light source ASE is connected with the coupler through the polarizer; the coupler is connected with a photoelectric detector PD I, a photoelectric detector PD II, a straight waveguide PM and an optical echo wall micro resonant cavity. The photoelectric detector PD I and the photoelectric detector PD II output detection signals to the signal processing circuit structure AMSP, the amplitude modulation signal circuit structure AMSP transmits alternating current signals with rotating speed information to the lock-in amplifier LIA, and after the alternating current signals pass through the low-pass filter LPF, high-frequency useless signals are filtered out, so that useful direct-current gyroscope rotating speed signals are output. The invention is used for solving the problems of high modulation frequency and obvious RIN noise when a resonant fiber-optic gyroscope driven by a wide-spectrum light source in the prior art inhibits relative intensity noise.

The invention discloses a random polymorphic wave modulation method of an interference type integrated optical gyroscope, which aims at a scene that the integration level of the integrated optical gyroscope is improved by compressing the length of an interference loop, the modulation frequency is obviously increased and crosstalk noise is introduced, and comprises the following steps of: firstly, according to a constraint condition and a preset modulation sequence library; generating a pseudo-random number sequence to construct a multi-state selector, and randomly selecting the sequence output at the current moment; generating another pseudo random number sequence at the same time; and a time-varying composite modulation generation matrix is constructed, and random multi-state wave modulation signals are uniformly represented and output. Then, collecting a digital quantity corresponding to the light intensity signal, and completing the angular velocity calculation of the integrated optical gyroscope through a demodulation sequence; according to the method, modulation voltage randomization is realized through a random polymorphic wave sequence state transition path, so that the crosstalk noise mean value is suppressed to be 0, the crosstalk noise introduced by high modulation frequency in the integrated optical gyroscope is effectively suppressed, and finally the dead zone of the gyroscope is reduced.

The invention provides a modular chip and an optical gyroscope chip. The modular chip comprises a plurality of branch optical paths; each branch optical path comprises a branch optical waveguide, a first evanescent wave coupler, a phase modulator, a second evanescent wave coupler and a first optical port coupler; the first end of the branch optical waveguide is divided into a plurality of waveguide branches, and each waveguide branch is connected with one branch optical path; the first end of the first evanescent wave coupler is connected with the first end of the waveguide branch, and the second end of the first evanescent wave coupler is connected with the first end of the phase modulator; the second end of the phase modulator is connected with the first end of the second evanescent wave coupler, and the second end of the second evanescent wave coupler is connected with the first end of the first optical port coupler; the second end of the branch optical waveguide is configured to be connected with an active or passive device, and the second end of the first optical port coupler is configured to be connected with an external element. According to the invention, a plurality of elements in the chip are integrated in the modular chip and are used for being connected with a plurality of elements, so that the universality of the chip is improved, and the cost is reduced.

A gyroscope comprises a source emitting a broadband beam, and a first waveguide arrangement that splits the beam into CCW and CW beams. First and second phase modulators are coupled to the waveguide arrangement and provide phase modulations or frequency shifts to the CCW and CW beams. An optical resonator is in communication with the phase modulators such that the CCW and CW beams are optically coupled into the resonator. A second waveguide arrangement receives the CCW and CW beams transmitted from the resonator. First and second RIN detectors are coupled to the second waveguide arrangement and respectively receive the CCW and CW beams. A rate detector receives the CCW and CW beams. A rate calculation unit receives intensity noise signals from the RIN detectors, and rate and intensity noise signals from the rate detector. The rate calculation unit performs a RIN subtraction technique to reduce intensity noise limited ARW.

The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

Aspects of the present disclosure are directed to the monolithic integration of an optical gyroscope fabricated on a planar silicon platform as a photonics integrated circuit with a MEMS accelerometer on the same die. The accelerometer can be controlled by the electronic circuitry that controls the optical gyroscope. Gaps may be introduced between adjacent waveguide turns to reduce crosstalk and improve the sensitivity and packing density of the optical gyroscope.

The present application relates to the technical field of optical gyroscopes, and specifically relates to a resonant fiber-optic gyroscope driven by a low-power broadband light source and a working method thereof. The fiber-optic gyroscope comprises an ASE light source, a circulator, a Y waveguide, a fiber resonant cavity, a first coupler, a second coupler, a photoelectric detector, and a signal processing unit. The ASE light source is connected to the circulator, and the circulator is connected to the input port of the Y waveguide and the photoelectric detector. The first coupler and the second coupler each have four ports. The Y waveguide is connected to port 1 of the first coupler and port 1 of the second coupler. The fiber resonant cavity is composed of the first coupler, the second coupler, and a section of fiber coil. Port 2 of the first coupler and port 2 of the second coupler are through-arm ports, and port 2 of the first coupler and port 2 of the second coupler are connected by means of 90° polarization axis rotation fusion splicing polarization maintaining optical fiber. The present application can significantly improve the utilization rate of the light source, effectively improve the stability and sensitivity of the system, and has significant engineering application potential.