328 results about "Tunable laser" patented technology

The invention provides an OFDR sensing system and method for rapidly positioning strain based on a time domain difference algorithm, and relates to the technical field of optical fiber sensing. The OFDR sensing system comprises a narrow linewidth tunable laser light source, a first optical fiber coupler, a main interferometer, an auxiliary interferometer and a data acquisition and signal processing module; laser emitted by the narrow linewidth tunable laser light source is divided into two paths through the first optical fiber coupler, one path of light enters the main interferometer, and the other path of light enters the auxiliary interferometer; the main interferometer and the auxiliary interferometer respectively output a main interferometer optical signal and an auxiliary interferometer optical signal to the data acquisition and signal processing module; the data acquisition and signal processing module is used for performing nonlinear compensation on the optical signal of the main interferometer by using the optical signal of the auxiliary interferometer, and performing cross-correlation operation on a reference optical signal of the main interferometer and a measurement optical signal of the main interferometer which are based on the strain-free state and the strain state of the sensing optical fiber and are subjected to nonlinear compensation; and obtaining the strain position and the strain value of the sensing optical fiber.

The invention relates to the technical field of gas detection, in particular to a dual-wavelength-based adaptive methane detection method and system, and the method comprises the following steps: collecting environmental interference characteristics of a to-be-detected gas environment in real time; synchronously emitting a first laser beam and a second laser beam to a to-be-detected gas environment according to the tunable laser source; receiving optical signals of the first laser beam and the second laser beam and converting the optical signals into electric signals; calculating a light intensity difference value of the first laser beam and the second laser beam based on the electric signal to generate a differential absorption signal; performing optical differential compensation on the differential absorption signal, outputting a methane concentration value, and performing environmental drift compensation on the methane concentration value based on environmental interference characteristics; and performing real-time threshold value judgment on the methane concentration value, and if the methane concentration value exceeds a preset threshold value, triggering a local early warning signal. According to the invention, the problem that the detection precision is reduced due to the fact that methane absorption signal common-mode noise and absorption coefficient drift cannot be synchronously inhibited due to dust concentration and temperature and humidity interference in a dynamic complex environment under a mine is effectively solved.

The invention discloses an external cavity tunable laser linewidth compression system for realizing wavelength phase locking based on mutual injection of gain chips. The external cavity tunable laser linewidth compression system comprises a red light semiconductor laser main gain chip, a first collimation optical system, a blazed grating, a tuning rotating mirror, a reflector, a power supply driving system and a double-path feedback amplification system, the double-path feedback amplification system comprises a first secondary gain chip, a second secondary gain chip, a second collimation optical system, a third collimation optical system and a polarization-free beam splitter prism; and the red light semiconductor laser main gain chip, the first secondary gain chip and the second secondary gain chip are all connected with the power supply driving system. Therefore, the technical problems of low output infrared light power, poor stability and narrow mode-hopping-free tuning range in the prior art are solved, and high-power, narrow-linewidth, high-stability and large-range mode-hopping-free continuous tuning red light output can be realized.

The invention provides a tunable laser source output wavelength adjusting device and method, and the method comprises the steps: starting a tunable laser source, carrying out the preheating, and resetting a motor motion unit; acquiring an initial light-emitting wavelength based on a pre-stored relation curve between the light-emitting wavelength of the laser source and the position of the motor; controlling the output wavelength of the laser source through the coarse tuning parameter of the motor motion unit, traversing the tunable output range of the tunable laser source, and collecting the wavelength position of the reflection peak value of the fiber bragg grating and the corresponding optical power value; according to the reflection peak wavelength position, through voltage regulation and control of stacked piezoelectric ceramics, step scanning is carried out according to a target wavelength, and a laser source output wavelength is dynamically adjusted to obtain a fine scanning wavelength; and judging whether the deviation between the fine scanning wavelength and the target wavelength meets the preset precision or not, if so, locking the output wavelength, otherwise, repeatedly regulating and controlling until the conditions are met. According to the invention, traditional current-wavelength dependence is broken through, and wavelength demodulation is realized through electromechanical collaborative calibration and two-stage scanning.

The invention discloses an acousto-optic combined detection and fusion positioning method and device for underground gas leakage, and belongs to the technical field of industrial safety monitoring. In order to solve the problems of high false alarm rate, insufficient positioning precision, poor dynamic environment adaptability and the like of a single sensor in the prior art, the invention provides a multi-modal signal space-time collaborative fusion technical scheme which specifically comprises an acousto-optic heterogeneous sensor, an integrated MEMS ultrasonic array and a tunable laser spectrum module. Microsecond-level synchronous acquisition of acousto-optic signals is realized through a GPS taming clock, and a cross-correlation time delay compensation model is designed to eliminate space-time mismatch errors. And designing a three-stage dynamic fusion framework: improving LMS adaptive filtering to suppress industrial noise, establishing a light intensity attenuation model in combination with dust environment concentration, carrying out multi-modal feature extraction of acousto-optic signals, carrying out signal preliminary fusion, and judging a gas leakage condition. And constructing an acousto-optic Bayesian joint probability model, and calculating the leakage posterior probability. And optimizing positioning parameters based on a double-Kalman filter group, predicting sound wave time delay by forward filtering, and correcting a light diffusion coefficient by backward filtering to realize three-dimensional coordinate solution. Temperature, humidity and dust concentration parameters are fused in real time, a sound velocity calculation model and a light intensity attenuation factor are corrected, and the robustness of complex working conditions is improved. According to the invention, the advantages of acousto-optic signals are combined, errors of various complex environmental factors are further fused and compensated, the overall error is greatly reduced, and the method has the characteristic of dynamic adaptation, and is very suitable for gas leakage detection and positioning in complex environments such as underground environments and the like.

The present invention relates in one aspect to an absorption spectroscopy apparatus for measuring one or more gases in an atmosphere, wherein the apparatus comprises a wavelength-tunable laser source, a control circuit configured to provide an electrical drive current to the wavelength-tunable laser source; wherein the control circuit is configured to create the electrical drive current as a modulated drive current, wherein the modulated drive current alternates between at least a first and a second drive current, the first drive current configured to cause the wavelength-tunable laser source to emit laser radiation at a first wavelength and the second drive current configured to cause the wavelength-tunable laser source to emit laser radiation at a second wavelength, different from the first wavelength, and wherein the modulated drive current defines a sequence of pulses, each pulse having a non-rectangular pulse shape.

The invention discloses a method and device for measuring a crystal electro-optical coefficient at low voltage, and relates to the technical field of photoelectric coefficient measurement, and the method comprises the steps: employing a wavelength tunable laser as an incident light source of a crystal electro-optical coefficient detection system; before an incident light source is input into a to-be-measured laser crystal, a wave plate is added to serve as a phase compensator to generate phase delay phi 1, and meanwhile the to-be-measured laser crystal generates phase delay phi 2 under the action of direct-current voltage; when the crystal electro-optical coefficient detection system is a half-wave voltage detection system; adjusting the wavelength of the tunable laser so that 3pi / 4 is less than or equal to phi1lt; pi; when the crystal electro-optical coefficient detection system is a full-wave voltage detection system, the wavelength of the tunable laser is adjusted to enable 7pi / 4 to be smaller than or equal to phi1lt; 2pi. As the used light source is the wavelength tunable laser, phi 1 can be adjusted in a large range by changing the wavelength, so that phi 2 and the test voltage are changed, the purpose of measuring the electro-optical coefficient of the crystal at low voltage is achieved, and the test safety is improved.

The invention relates to the technical field of optical fiber sensing, in particular to a tunable laser parameter optimization method for fiber bragg grating demodulation, which comprises the following steps of: setting scanning ranges of currents of a left Bragg reflector and a right Bragg reflector, generating a current combination sequence according to arc radius parameters, inputting the current combination into a tunable laser, collecting an output wavelength, and identifying a wavelength tuning channel and a central point thereof; and arranging the center points of the channels in sequence, and generating smooth and continuous channel center lines on the left current dimension and the right current dimension by adopting cubic spline interpolation so as to obtain a continuous and executable tuning path. According to the method, a smooth and continuous channel center line is constructed through a segmented arc scanning path and cubic spline interpolation, and an initial lookup table is formed by combining phase current fine scanning and ordered splicing, so that high-quality wavelength coverage under low sampling amount is realized, and the problems of data redundancy and channel boundary mode hopping in a traditional method are solved.

The invention relates to the technical field of laser light source measurement, and discloses a wide-range narrow-linewidth laser wavelength and linewidth measurement system, which can be flexibly matched with the center frequency of laser to be measured through the arrangement of a tunable laser, breaks through the strict limitation of the existing beat frequency method on the center frequency, effectively expands the measurement range, and improves the measurement accuracy. By combining the synergistic effect of the absorption cell and the locking loop, the system stability is improved, the measurement precision of narrow linewidth laser is guaranteed, the integration time can be flexibly adapted without tedious adjustment of a delay optical path or change of parameters of acquisition equipment through the cooperation of the optical modulator and the delay optical fiber, the problem of inconsistent measurement resolution under different integration time is avoided, and the measurement accuracy is improved. And the accuracy of short-time measurement is obviously improved. The system integrates wavelength and line width measurement functions, can measure line width, center wavelength and long-time frequency stability of to-be-measured laser, is reasonable in structural design, retains the advantage of high precision of a beat frequency method, overcomes the defects that an existing method is narrow in measurement range and inconvenient to adjust integral time, and improves the measurement accuracy of the to-be-measured laser. And the measurement requirements of wide-range and narrow-linewidth laser are met.

The invention relates to the technical field of gas monitoring, and provides a spectrum analysis-based gas leakage monitoring system, which comprises a tunable laser source, an optical curtain forming device, a scanning optical sensor, a spectrum analysis module, a three-dimensional spectrum model construction module, a leakage traceability and diffusion prediction module, an intelligent early warning module and a snapshot type multispectral imaging unit, and an open optical path and a distributed multi-node layout are adopted. According to the invention, through the steps of optical screen scanning, spectral data acquisition and processing, three-dimensional dynamic model construction, intelligent analysis leakage determination, leakage traceability visualization and adaptive learning, precise monitoring, identification, traceability and early warning of gas leakage are realized; gas identification, leakage traceability and diffusion prediction are realized based on a three-dimensional dynamic model, deep learning and fluid mechanics, the monitoring effect is optimized by adopting distributed layout and self-adaptive learning, rapid disposal is assisted by graded early warning, and the accuracy, real-time performance and safety of gas leakage monitoring are greatly improved.

According to an aspect of the present inventive concept there is provided a laser system for generating a frequency modulated continuous wave, FMCW, light signal, the system comprising: a tunable laser for generating the FMCW light signal; an optical measurement unit configured to receive a portion of the FMCW light signal, and to output, via an optical hybrid coupler, at least two angle diversity signals based on a difference between a first and second signal formed by splitting the portion of the FMCW light signal wherein the second signal is delayed relative to the first signal, wherein a pair of signals of the at least two angle diversity signals have a fixed phase shift relative to each other; and a control unit configured to: receive the at least two angle diversity signals, estimate, based on the at least two angle diversity signals, a compensation needed for adjusting a non-linearity of a frequency chirp of the tunable laser, and output a corresponding control signal to the tunable laser, wherein the control signal is configured to improve a linearity of the frequency chirp.

Provided are a silicon-based tunable filter, laser and an optical module. The tunable laser comprises a semiconductor optical amplifier and a silicon photonic integrated chip, wherein a first coupler, a phase regulator and a tunable filter are provided on the silicon photonic integrated chip; the tunable filter comprises a flat-top band-pass filter structure, a Mach-Zehnder interferometry (MZI) structure and a micro ring resonation (MRR) structure, which are cascaded; gain light emitted by the semiconductor optical amplifier is coupled to the silicon photonic integrated chip by means of the first coupler, and a narrowband filtered optical signal is output by means of the tunable filter; and the phase of the gain light is regulated by means of the phase regulator so as to output single-peak narrowband laser light with a tunable target wavelength.

The utility model discloses a tunable laser light source for spectrum sensing, which comprises a tunable DFB laser array chip, a star coupler chip, an SOA array chip and an optical fiber array which are connected through waveguides, tunable lasers in each row are connected through waveguides, the lasers with adjacent wavelengths are distributed on different waveguides, and the optical fiber array is connected with the star coupler chip. The light output end of each waveguide is provided with an SOA. According to the utility model, the star-shaped coupler is adopted to uniformly distribute energy of light with different wavelengths of the tunable laser array to each light output waveguide, and the energy respectively enters different fiber grating sensors or fiber MEMS sensors and the like to realize temperature or strain sensing at the same time and realize multiplexing tree-shaped sensing and demodulation at the same time; the energy loss in the transmission process is reduced; the chips of different material systems are coupled by adopting a photon lead bonding or butt joint growth technology, the photon lead bonding technology does not need high-precision alignment, the processing efficiency is high, low-cost hybrid integration among the chips is realized, and the device is integrally compact.

The invention relates to the field of microcavity photonics and the technical field of control, and provides a temperature locking method and device based on an optical microcavity absorption peak position, and the method comprises the steps: employing a tunable laser to output continuous light, and obtaining a transmission spectrum power curve; manually adjusting the output wavelength of the tunable laser, and recording the wavelength interval as a rough absorption peak position when a wave band with significantly reduced transmission spectrum power is detected; automatically adjusting the output wavelength of the tunable laser, and continuously scanning in the rough wavelength interval of the absorption peak position to obtain the absorption peak position; the offset between the position of the absorption peak and the position of a target absorption peak of the optical microcavity in a natural room temperature state is calculated, and the detected position of the absorption peak is stably maintained at the position of the target absorption peak by automatically heating or refrigerating the optical microcavity. Through the method, the problems of heat conduction path delay and thermal field gradient between the microcavity and the sensor are avoided, and the response speed and precision of wavelength drift compensation are improved.

The application belongs to the technical field of chemical detection, and particularly relates to a Raman-LIBS-mass spectrometry combined analysis device and analysis method. The Raman-LIBS-mass spectrometry combined analysis device comprises a multiple-reflection time-of-flight mass spectrometer, a LIBS spectrometer, a Raman spectrometer and a shared module. The shared module comprises a first incident light path system, a second incident light path system, a high-definition observation system, a vacuum sample bin, a vacuum system and a control system. The first incident light path system is used for generating a femtosecond laser beam and performing three-dimensional ablation on a sample. The second incident light path system is used for combining tunable lasers into a resonance ionization light path. Compared with the prior art, the application can realize in-situ micro-area ultra-high resolution element and isotope analysis and imaging, realize ultra-trace element, isotope analysis and isotope ratio analysis under strong matrix interference, and can also perform high-resolution molecular structure and composition analysis and Raman scattering imaging.

The invention provides an optical feedback resonance enhanced forward Brillouin demodulation structure, which comprises a tunable laser, a first polarization controller, an erbium-doped optical fiber amplifier, an optical coupler, an optical isolator, a forward Brillouin gain optical fiber, a band-pass filter and a photoelectric detector, a second polarization controller; and a spectrum analyzer. The first polarization controller is connected with a port a of the optical coupler, a port b of the optical coupler is connected with an input end of the erbium-doped optical fiber amplifier, an output end of the erbium-doped optical fiber amplifier is connected with the optical isolator, the optical isolator is connected with the band-pass filter, the band-pass filter is connected with the forward Brillouin gain optical fiber, and the optical fiber is fed back to a port c of the coupler through the second polarization controller. The output power of the erbium-doped optical fiber amplifier is controlled, and the polarization states of the pump light and the feedback laser are controlled by the first polarization controller and the second polarization controller, so that the forward Brillouin effect is amplified.

The present invention concerns a tunable Dense Wavelength Division Multiplex (DWDM) intra cavity laser device having a first optical wave guide having a first optical grating section, a second optical wave guide having a second optical grating section, an active gain section spatially separated from the second optical grating section and a phase section, and a DWDM-filter having an intra-cavity ring resonator located between the first optical wave guide and the second optical wave guide for coupling optical waves between the first and second optical wave guides. The tunable laser device is tunable in a discrete manner depending on a length of the ring resonator that is selected such that the free spectral range of the ring resonator matches a predetermined fixed wavelength spacing grid.

The embodiment of the invention provides a laser module, an optical module and communication equipment, and relates to the technical field of optical communication, the laser module is specifically a tunable laser, the wavelength tuning range of the laser module is large, and the manufacturing process is simple. The laser module comprises a laser and an optical filtering assembly which are sequentially arranged in the first direction. The laser is used for outputting the optical signal of the first wave band. The optical filtering assembly is used for receiving the optical signals of the first wave band and the first electric signal, the optical signals of the target wavelength in the optical signals of the first wave band are selected to be output according to the first electric signal, and the target wavelength is related to the first electric signal.

The invention discloses an FBG (Fiber Bragg Grating) and F-P (Fabry-Perot) cavity multiplexing air pressure sensing system, which comprises a linear tunable laser 1, a Mach-Zehnder interference device 2, a sensing array 3 and a processing unit 4, and is characterized in that an output optical coupler of the linear tunable laser 1 is connected with the Mach-Zehnder interference device 2; the linear tunable laser 1 and the Mach-Zehnder interference device 2 are directly connected with the processing unit 4, and the sensing array 3 is an FBG and F-P cavity sensor multiplexing array and is connected with the Mach-Zehnder interference device 2; according to the invention, multiplexing and distance positioning of the FBG and the F-P cavity sensor are realized, temperature compensation is carried out on pressure measurement while the spatial resolution can reach 20 [mu] m for temperature measurement, and the FBG-F-P cavity sensor can be widely applied to the fields of aviation, precision manufacturing and the like.

The application discloses a method for stably preparing a nonlinear frequency conversion device and a corresponding wideband tunable laser, wherein duty cycle modulation is realized by deleting a specific position electrode distribution instead of precisely operating electrode width, so that the stability of the preparation process is greatly improved. In addition, by selecting, for example, magnesium-doped lithium niobate material to prepare the nonlinear frequency conversion device, a wideband optical window is ensured, by chirping the polarization lithium niobate along the light propagation direction, the frequency conversion spectrum is expanded, and by modulating the polarization duty cycle, the tuning curve is optimized, and the output power fluctuation is reduced.

This invention discloses a method and structure for fabricating a photonic integrated device. The method includes: dividing a substrate sequentially into a pre-modulator region, a post-modulator region, a pre-grating region, a gain region, and a post-grating region; growing a first active layer after fabricating a selected-area epitaxial mask pattern in the gain region; growing a second active layer in the pre-modulator region after mask etching; growing a third active layer in the grating region after mask etching; finally, fabricating the grating; and completing the fabrication of the cladding, electrical contact layer, inverted shallow ridge waveguide structure, electrical isolation trench, and electrodes. This method achieves the integration of multiple materials through a single selected-area epitaxial growth and a single docking growth, saving material growth steps and reducing manufacturing costs. The gain region and post-modulator region achieve bandgap shift through selected-area epitaxial material growth, and the design of photofluorescence wavelength differences in each region enables multi-wavelength tuning and efficient modulation, providing a solution for the integration of wide-wavelength tunable lasers and dual-electric absorption modulators.

This invention provides a wind erosion monitoring system and method based on distributed optical fiber, belonging to the field of optical-based wind and sand monitoring technology. It includes: constructing a wind erosion monitoring system comprising a linearly tunable laser, an optical isolator, a first coupler, an upper branch, a lower branch, a sand particle capture sensor, a photoelectric detection and acquisition module, and a host computer; utilizing the Rayleigh scattering signal of the linearly swept laser in the sensing optical fiber and the interference with a reference light, the vibration information distributed along the optical fiber is obtained by demodulating the beat frequency signal; combining the constructed sand particle impact and optical fiber coupling model, the dynamic strain generated by sand particle impact is converted into phase changes, realizing the acquisition of sand particle impact location, sand particle size, and sand particle quantity. This invention enables continuous distributed monitoring of wind and sand flows with high spatial resolution, and has advantages such as resistance to electromagnetic interference, strong environmental adaptability, and multi-parameter sensing, and can operate stably for a long time in harsh desert environments.

This invention discloses a laser cleaning device and method for surfaces made of multiple materials, belonging to the field of industrial manufacturing technology. Addressing the problems of poor adaptability, imprecise endpoint determination, narrow material compatibility, and high process development costs in existing laser cleaning methods, the device comprises a central control module, a multi-wavelength tunable laser, a laser-induced breakdown spectroscopy device, an AI spectral model, a process digital twin system, and a multi-physics field coupling simulation module, forming a closed-loop control system. The cleaning method achieves cleaning by constructing a digital twin model, using LIBS-AI coupling to identify material states, simulating and optimizing parameters, monitoring cleaning across multiple modes, intelligently determining the endpoint, and iteratively optimizing the process. In this invention, the device effectively improves adaptability and cleaning accuracy through real-time component identification, dynamic wavelength adjustment, multi-source signal fusion criteria, and simulation prediction. It can adapt to a wide range of spectral materials, shorten the process cycle, and is suitable for high-precision laser cleaning of multiple materials and complex surfaces.

This improves the degradation of the cross-correlation coefficient caused by the error between the set frequency and the actual frequency of the light source, and makes it possible to improve the degradation of the measurement accuracy of strain and temperature. [Solution] The light source unit has a frequency-stabilized wavelength-tunable laser that generates continuous light, and a first optical coupler splits the continuous light generated by the light source unit into two, sending one to a second optical coupler and the other to an optical frequency measurement unit. The optical frequency measurement unit measures the frequency of the continuous light generated by the light source unit, and the second optical coupler further splits the continuous light split by the first optical coupler into two, sending one as probe light to the optical pulse generation unit and the other as local light to a detection unit. The detection unit measures the frequency change Δf by means of coherent time domain reflectometry and a means for heterodyne detection of the Rayleigh scattered light and the local light resulting from Rayleigh scattering of pulsed light in the fiber under test. max and means for acquiring the

The application provides a resonator system, comprising N-stage cascaded resonators, N being an integer greater than 1, each resonator comprising a resonant cavity and a thermal phase shifter, in each resonator, the thermal phase shifter is integrated on the resonant cavity, the thermal phase shifters in the N-stage cascaded resonators are connected in series, a first end of the thermal phase shifter in the first-stage resonator is connected to a preset voltage, a second end of the thermal phase shifter in the N-stage resonator is grounded, a connecting node between the thermal phase shifters in two adjacent resonators is connected to an adjustable voltage, and the resistances of the thermal phase shifters in the N-stage resonators are equal. The resonator system can make the phase difference change of two adjacent resonant cavities linearly related to the control voltage connected to the connecting node between the thermal phase shifters in two adjacent resonators, simplifies the control method of the vernier micro-ring resonator, and reduces the number of required control voltages. The application also provides an adjustable laser and a control method of the resonator system.

An optical device includes: a multi-mode interference waveguide that includes a first end portion in a first direction and a second end portion in opposite direction to the first direction; a first port that is arranged in the first end portion; a second port that is arranged in the first end portion; a third port that is arranged in the second end portion and that is positioned at a center of the second end portion in the second direction; and two fourth ports that are arranged in the second end portion and that are positioned on both sides of the third port in the second direction.

The invention belongs to the technical field of tunable lasers, and particularly relates to a grating scribed line density testing method and system based on a tunable laser, and the system comprises the tunable laser, a mechanical arm, a testing module and a control module. The characteristic that the tunable output range of a tunable laser (carrier) is sensitive to the grating scribed line density is fully utilized, and the mapping relation between waveguide coupling output multi-wavelength and the grating diffraction angle (or the displacement stride of an actuator) is deeply analyzed; according to the method, automatic analysis of the to-be-measured grating scribed line density under different batches, different substrate materials and different manufacturing process conditions is realized, and on the basis, accurate and rapid screening of qualified gratings suitable for tunable laser assembly is realized.

The application discloses a frequency modulation rate variable laser linear frequency modulation device and a frequency modulation method thereof. The device comprises a wideband tunable laser, a micro-optical lens, a beam splitter, an adjustable optical delay unbalanced MZ interferometer, a balanced photodetector, a phase discriminator, a loop filter, an up / down switch control circuit and an integrator. The adjustable optical delay unbalanced MZ interferometer comprises two couplers and an adjustable optical fiber delay line unit. According to the relationship between the linear frequency modulation light frequency and time of the upper and lower arms of the interferometer, when the delay amount of the adjustable optical fiber delay line unit changes, the frequency modulation rate of the output laser can be changed. The application changes the time delay of the light by using the adjustable optical fiber delay line, so that the frequency modulation rate can be changed.

A wavelength-tunable laser includes a substrate, a waveguide layer over the substrate, and a cladding over the waveguide layer. The wavelength-tunable laser further includes an active layer in a part of the waveguide layer, and a tunable wavelength filter in at least one end region of the waveguide layer in a direction along which light is to be guided.

The utility model provides a kind of multi-wavelength output tunable laser, including pump source, reflection unit, optical path unit: reflection unit includes first reflector, second reflector and third reflector, wherein, first reflector is arranged in the propagation direction of pump source optical path, and it is located in the rear end of pump source;Second reflector is located in the reflected light path of the first reflector, and third reflector is located in the transmission light path of the second reflector;First reflector, second reflector and third reflector have different reflectivity;Optical path unit includes first optical path unit, second optical path unit and third optical path unit, wherein, first optical path unit is arranged on the transmission light path of the first reflector, second optical path unit is arranged on the single optical path of the second reflector, and the third optical path unit is arranged on the reflected light path of the third reflector.