55 results about "Longitudinal mode" patented technology

The invention discloses a device for generating Mach-Zehnder interference, a photo-thermal spectrum gas sensing device based on the device and a detection method, and belongs to the technical field of laser spectrum gas sensing. The interference device sequentially comprises an optical frequency comb and a first light beam splitter on a light transmission path; a movable arm reflector group is arranged on the light path of one light beam B in the two light beams split by the first light beam splitter, the path of the light beam B is changed through the movable arm reflector group, the light beam B intersects with the light path of the other light beam C, and a beam combiner is arranged at the intersection; the movable arm reflector group is connected with a driving mechanism, the driving mechanism is used for driving the movable arm reflector group to do linear motion, and the track of the linear motion is parallel to the straight line where the light beam B is located. The interference device does not need to use a local oscillator optical comb and a signal optical comb to carry out multi-heterodyne interference, can directly use the moving speed of a movable arm reflector group in a Mach-Zehnder interference structure to calculate a down-conversion factor, and maps each longitudinal mode of the signal optical comb in an optical frequency to a radio frequency component one by one.

Provided in the present application is a laser longitudinal mode measurement device, comprising a filtering module (20) for filtering laser, a tuning module (30) for at least adjusting the bandpass position of the filtering module, and a detection module (40) for detecting laser. Laser from a laser device (10) is filtered by the filtering module and then output, and is transmitted to the detection module for measurement. A filtering module is provided, such that single-longitudinal-mode laser can be obtained after laser is filtered by the filtering module; a tuning module adjusts the bandpass position of the filtering module, such that the frequency range of the laser can be sequentially scanned; and by means of a detection module, the number of longitudinal modes can be obtained, thereby filling the gap where the number of longitudinal modes of laser cannot be measured, and thus making accurate measurement of the number of longitudinal modes of the laser possible.

The invention discloses a laser acceleration tabulation method, which belongs to the technical field of optical fiber sensing and signal processing, is used for constructing a laser wavelength current lookup table, and comprises the following steps of: initializing a laser, configuring five paths of current to carry out two-dimensional nested cyclic scanning, and measuring the central wavelength and side mode rejection ratio of an optical signal. Constructing a central wavelength sequence and dividing a continuous longitudinal mode region; constructing a theoretical sampling grid and a theoretical sampling point set, calculating the number of actual sampling points by using a Gaussian distribution rule, and constructing a sparse measurement training data set; and constructing and training a K singular value decomposition model, and inputting the to-be-detected target wavelength list into the trained K singular value decomposition model to obtain a wavelength current lookup table. According to the method, the K singular value decomposition algorithm is fused into the laser wavelength current lookup table construction process, so that the time cost is reduced, the measurement load is reduced, the deployment flexibility is enhanced, and the construction efficiency of the laser wavelength current lookup table is greatly improved.

The invention relates to the technical field of solid lasers, and particularly provides a narrow-linewidth tunable dual-wavelength laser output system based on data driving, which comprises a pumping source, a resonant cavity, a data acquisition unit and a data receiving and driving device, a single gain medium, two F-P etalon and an F-P angle regulator are arranged in the resonant cavity, the inclination angles of the two F-P etalon are adjusted through an F-P angle adjuster so as to perform longitudinal mode selection and wavelength tuning on the output laser of the resonant cavity; a neural network screening model is arranged in the data receiving and driving device, the neural network screening model is used for learning the mapping relation between intracavity parameters and output laser optical parameters, and dual-wavelength simultaneous locking and line width prediction are achieved through dual-etalon collaborative mode selection and data driving of the neural network screening model. According to the invention, the complexity of the system is greatly simplified, and dual-wavelength, narrow-linewidth, high-stability, repeatable and automatic laser output regulation and control which cannot be achieved by a traditional architecture are realized functionally.

The invention provides a control method and system of a reconfigurable optical phased array device. The control system comprises an MEMS micromirror array, a silicon-based waveguide array, a mode switching device and a controller, and the controller is configured to configure laser output parameters including a central wavelength, a tuning range and single longitudinal mode output control information, initialize the phase shifter position of each array element of the optical phased array, and control the phase shifter position of each array element of the optical phased array. Setting an initial deflection angle of the MEMS micromirror array and initializing a working state of the mode switching device; and receiving target scene information and judging whether the target scene information is changed or not, if so, generating a control instruction according to the target scene information, and controlling the optical phased array device according to the control instruction. The high integration of the optical system is realized by utilizing the high integration characteristic of the silicon-based optical chip and combining the design of the MEMS micromirror array and the mode switching device, and the overall performance and efficiency of the system are improved.

The invention provides a tunable external cavity laser chip and a preparation method thereof, and relates to the technical field of lasers, the chip comprises a planar optical waveguide loop and a gain chip; a narrow-band transmission peak of a micro-ring resonator and an interference passband of a multi-channel interference module are preliminarily aligned through a phase shifter array and a first micro-ring phase shifter in a planar optical waveguide loop, and selection of a lasing working point is completed; and the common phase shifter and the second micro-ring phase shifter are used for cooperative driving, laser frequency sweeping is carried out on the basis of preliminary alignment, and accurate alignment of a narrow-band transmission peak and an external cavity longitudinal mode is maintained in the whole frequency sweeping process. Through cooperative driving of the common phase shifter and the micro-ring phase shifter, the sweep frequency bandwidth of the laser is increased, and frequent mode hopping of output laser in the tuning process is avoided; meanwhile, the periodic alignment reflection phenomenon in a reflection spectrum is avoided, the utilization rate of the gain interval of the semiconductor gain chip is greatly improved, and a larger tuning range is obtained under the condition that the quality of light beams is kept unchanged.

The invention discloses a wavelength tunable laser. The wavelength tunable laser comprises a base station; the resonant cavity is arranged on the base station; the gain medium is arranged on the base station and is positioned in the resonant cavity, so that the pump light forms oscillation light propagating in the resonant cavity when entering the gain medium, and the oscillation light forms output light of the tunable laser; the mode selecting part is arranged on the base station, is positioned on a propagation path of the oscillating light and is used for selecting light with corresponding wavelength from the oscillating light to form single longitudinal mode output light; and the first temperature control device is connected with the base station and is used for controlling the temperature of the base station to change the length of the resonant cavity so as to adjust the wavelength of the single longitudinal mode output light. The resonant cavity, the gain medium and the mode selection part are all arranged on the base station, the temperature of the base station is adjusted, the base station deforms due to the thermal expansion and cold contraction property, the length of the resonant cavity is changed, the oscillation light propagation optical path in the resonant cavity is changed, single longitudinal mode wavelength tuning of the wavelength tunable laser can be achieved, the structure is simple, and cost is low. And the tuning operation is relatively simple.

The utility model discloses a wavelength tunable 2 [mu] m single longitudinal mode all-solid-state pulse laser, which belongs to the technical field of lasers, and comprises a pumping source, the output end of the pumping source is provided with a 1: 2 optical coupling system, the output end of the 1: 2 optical coupling system is provided with an input mirror, the output end of the input mirror is provided with a Tm: YAP crystal, and the Tm: YAP crystal is used for generating 2 [mu] m laser; the output end of the Tm: YAP crystal is provided with an acousto-optic modulator, the output end of the acousto-optic modulator is provided with an etalon, the output end of the etalon is provided with a birefringence filter, and the output end of the birefringence filter is provided with an output mirror. The wavelength tunable 2 [mu] m single longitudinal mode all-solid-state pulse laser is simple in structure, can stably generate 2 [mu] m laser, provides a wider wavelength tuning range and more direct tuning, and realizes narrower spectral width at the same time.

The application provides a semiconductor structure and a preparation method thereof and a semiconductor laser, and relates to the field of lasers. The semiconductor structure comprises a substrate, a first waveguide layer, a resonant structure and a second waveguide layer; the first waveguide layer is arranged on the surface of the substrate along the thickness direction; the resonant structure comprises an active region, an input layer and an output layer; the active region, the input layer and the output layer are arranged on the side of the first waveguide layer away from the substrate; in a plane parallel to the plane in which the substrate is located, the input layer and the output layer are located on the two sides of the active region, and the output layer is arranged obliquely; in the direction away from the substrate, the output layer is away from the input layer; the second waveguide layer is arranged on the side of the resonant structure away from the surface of the first waveguide layer, and the second waveguide layer is connected with the resonant structure. The application can reduce the possibility of interference effect between reflected light and the light field in the FP cavity, make the longitudinal mode output of the semiconductor structure more stable, and improve the spectral purity of the semiconductor structure.

The utility model discloses a multi-channel multi-wavelength semiconductor laser light source device for optical I / O. A parallel multi-wavelength semiconductor DFB laser array prepared based on REC technology, a beam splitting / routing device under different material systems and an optical fiber array FA are connected through optical coupling components, and a large number of laser channels are integrated. The parallel multi-wavelength semiconductor DFB laser array prepared on the basis of the REC technology is good in single longitudinal mode stability and accurate in wavelength control, the stability and improvement of the performance of a data transmission system are facilitated, the PWB waveguide coupling mode can be adopted, integration of a large number of laser channels can be achieved more easily, and the integration efficiency is improved. The size of the device is further reduced, and the device has better mechanical reliability.

The invention discloses a metasurface grating waveguide based on a silicon carbide substrate and an enhanced display system, and belongs to the technical field of optoelectronic device manufacturing, and the key points of the technical scheme are that the metasurface grating waveguide comprises a tunable light source, a spatial light modulator, a metasurface grating waveguide, an imaging device and a processing device, modulating the phase distribution of the light to obtain a light beam carrying image information; the processing device is used for adjusting the wavelength of light emitted by the tunable light source and the length of an optical resonant cavity according to the current temperature, and the optical resonant cavity is located in the tunable light source; the metasurface grating waveguide comprises a silicon carbide substrate and is used for conducting a light beam emitted by the focusing lens to the pupil expander so that the pupil expander can output image information to human eyes, the length of the outer cavity is adjusted firstly so that the longitudinal mode frequency can be aligned with the gain peak corresponding to the target wavelength, then the current is adjusted so that the wavelength can reach the target wavelength, and therefore image information can be obtained. The problem of uneven final imaging brightness can be solved while mode hopping is avoided.

The invention discloses a miniaturized adjustment-free ultra-narrow linewidth composite filtering external cavity semiconductor laser, which belongs to the field of semiconductor lasers and is sequentially provided with a gain chip, an aspherical lens, a first FP etalon, a second FP etalon, an interference filter, a partial reflector, an optical isolator and a polarization maintaining optical fiber collimator. Wherein the first FP etalon and the second FP etalon are superposed in a non-coaxial mode to form a free spectral range difference, a longitudinal mode interval difference is generated through a Vernier effect, and a longitudinal mode interval generated by the Vernier effect is controlled by adjusting a dip angle difference between the first FP etalon and the second FP etalon. Through machining precision, optical coupling optimization and an automatic assembly technology, the problems of wide tuning bandwidth, ultra-narrow linewidth, multi-dimensional performance collaboration and environmental adaptability are synchronously solved.

The invention provides a control method and device of a pulse laser and the pulse laser, and belongs to the technical field of lasers, and the method comprises the steps: controlling the linear loss in a resonant cavity to be at a first loss level through a linear loss modulator before a pulse is established, maintaining the first loss level for a preset time, and enabling the interior of the resonant cavity to establish preliminary oscillation light; the longitudinal mode selector is used for screening out a target longitudinal mode from the preliminary oscillation light; and utilizing the linear loss modulator to control the linear loss in the resonant cavity to be at a second loss level so as to drive the target longitudinal mode to be quickly amplified in the resonant cavity, thereby forming and outputting pulse laser. According to the invention, the first loss level is forcibly maintained for a period of time before the pulse is generated, and the precise screening of the target longitudinal mode is completed in the initial oscillation light circulation of the long period of time by using the longitudinal mode selector, so that the problem of frequency drift between pulses in the pulse laser is effectively solved.

The application discloses a super surface grating waveguide based on a silicon carbide substrate and an enhanced display system, and belongs to the technical field of optoelectronic device manufacturing, and the technical scheme is characterized by comprising a tunable light source, a spatial light modulator, a super surface grating waveguide, an imaging device and a processing device, the spatial light modulator is used for receiving light emitted by the tunable light source, modulating the phase distribution of the light, and obtaining a light beam carrying image information; the processing device is used for adjusting the wavelength of the light emitted by the tunable light source and the length of an optical resonant cavity according to the current temperature, the optical resonant cavity is located in the tunable light source; the super surface grating waveguide comprises a silicon carbide substrate and is used for conducting the light beam emitted by a focusing lens to a pupil expander, so that the pupil expander outputs image information to a human eye, and the application can avoid mode jumping and solve the problem of uneven final imaging brightness by adjusting the length of an external cavity first, aligning the gain peak corresponding to the target wavelength of the longitudinal mode frequency, and then adjusting the current to make the wavelength reach the target wavelength.

This invention relates to the field of solid-state laser technology, specifically providing a data-driven narrow-linewidth tunable dual-wavelength laser output system. The system includes a pump source, a resonant cavity, a data acquisition unit, and a data receiver and driver. The resonant cavity contains a single gain medium, two F-P etalons, and an F-P angle adjuster. The tilt angle of the two F-P etalons is adjusted by the F-P angle adjuster to perform longitudinal mode selection and wavelength tuning of the output laser. The data receiver and driver incorporate a neural network screening model. This model learns the mapping relationship between intracavity parameters and output laser optical parameters, utilizing the dual etalons for collaborative mode selection. The data-driven approach of the neural network screening model achieves simultaneous dual-wavelength locking and linewidth prediction. This invention significantly simplifies system complexity and functionally achieves dual-wavelength, narrow-linewidth, high-stability, repeatable, and automated laser output control, which is impossible with traditional architectures.

This invention provides a single longitudinal mode fiber laser based on a linear main cavity combined with a traveling wave auxiliary cavity, relating to the technical field of laser equipment. The laser includes: a first reflecting device, a gain medium, a composite sub-cavity, a second reflecting device, and a pump source. The composite sub-cavity includes a first circulator, a second circulator, a first beam splitter, and a second beam splitter. The first circulator and the second circulator are connected to the resonant cavity. The first circulator is connected to both the first beam splitter and the second beam splitter, and the transmission direction of the optical paths connecting the first circulator to both the first and second beam splitters is unidirectional. The second circulator is connected to both the first and second beam splitters, and the transmission direction of the optical paths connecting the second circulator to both the first and second beam splitters is unidirectional. A unidirectional circulating optical path is formed between the first and second beam splitters.

The invention discloses a three-parameter automatic relocking frequency stabilization single longitudinal mode laser system, and relates to the technical field of laser frequency locking, optical precision measurement and artificial intelligence. The technical key points of the invention are as follows: a three-parameter servo controller is added in a traditional PDH frequency locking system, and in order to solve the problem of frequency stabilization, two collected error signals are input to the three-parameter servo controller for analysis and calculation; the intelligent control module performs automatic relocking processing or double-parameter control signal output according to the state of the system so as to realize double-parameter control of the laser and the piezoelectric ceramic; in order to solve the problem of single longitudinal mode laser output, another collected error signal is input into the three-parameter servo controller, and feedback control is performed through an internal proportional-integral-differentiating circuit, so that the insertion angle of the etalon is adjusted, and then single longitudinal mode laser output is realized. According to the invention, the problems of poor frequency stabilization performance and single longitudinal mode laser output in a complex environment are solved.

The invention relates to the technical field of semiconductor laser devices, in particular to a high-power-density distributed feedback type laser chip and a preparation process thereof. According to the technical scheme, the chip comprises a chip body, the chip body comprises a back electrode, a substrate, a lower waveguide layer, a lower limiting layer, an active layer, an upper limiting layer, an upper waveguide layer, a highly-doped layer and a front electrode which are sequentially stacked from bottom to top, and graphene layers are arranged on the sides, close to the active layer, of the lower limiting layer and the upper limiting layer. According to the invention, the graphene heat conduction layer and the conical bulge and micropore array are introduced between the active layer and the limiting layer, so that heat is directly and quickly dredged, thermal resistance and interface strain are reduced, heat accumulation is relieved from the source, and the reliability of the chip is improved; the artificial micro-nano grating formed by the conical structure and the DFB built-in grating cooperatively enhance longitudinal mode feedback, and improve the side mode rejection ratio and the light field limiting factor. Meanwhile, mode locking and 1 microsecond-level wavelength tuning are achieved through array type current injection, and the light spot and coupling efficiency is improved in cooperation with a unit-level micro lens.

The application discloses a kind of based on valley power lockout semi-out cavity linear polarization interference light source and its design method.The device includes laser power supply, laser, heating wire, heat preservation glue, beam splitter BS, PD photocell and laser frequency stabilization system;Design method is crucial in that: the laser is three longitudinal mode semi-out cavity linear polarization helium-neon laser, laser built-in Brewster window, and the key parameters of the laser are calculated by longitudinal mode light intensity coupling model, two side modes can be completely suppressed, form the high proportion valley bottom in light intensity harmonic curve, to facilitate frequency stabilization algorithm identification to realize central longitudinal mode frequency locking.The method of the application can make the output power of the laser reach 2.4mW or more, overcome the shortcomings of traditional double longitudinal mode frequency stabilization interference light source power limitation, improve single mode power conversion efficiency, provide a new type of frequency stabilization technology and new type of interference light source for the rapid development of ultra-precision machining and measurement technology and various fields such as single mode conversion complete, high output power, good wavelength stability.

The invention provides a distributed feedback laser and a performance verification method thereof, and a grating structure, the grating structure of the distributed feedback laser comprises a first grating section and a second grating section, a phase shift grating is arranged between the first grating section and the second grating section, and the grating transverse width of the first grating section is smaller than the grating transverse width of the second grating section. The coupling coefficient of the first grating section is smaller than that of the second grating section. The distributed feedback laser comprises a high-reflection film coating end and an anti-reflection film coating end, the first grating section is close to the high-reflection film coating end, and the second grating section is close to the anti-reflection film coating end. The grating sections with different coupling coefficients are designed in a segmented manner, and the phase shift grating is introduced between the grating sections, so that the photon distribution can be homogenized, the longitudinal space hole burning effect is effectively inhibited, the line width is narrowed, and the single longitudinal mode stability is enhanced.

The invention relates to an injection laser automatic frequency stabilization device and method based on cold atom imaging feedback. The device comprises a primary cooling light path, a secondary cooling light path, a charge-coupled device and a control module. The first-stage cooling light path and the second-stage cooling light path are used for outputting single longitudinal mode laser by using the seed laser, injecting the single longitudinal mode laser into the plurality of injection lasers and then outputting cooling laser into the vacuum system; the charge-coupled device is used for acquiring a cold atom cloud image in the magneto-optical trap of the vacuum system in real time; the control module is used for automatically locking the plurality of injection lasers to a single longitudinal mode state according to the brightness of the cold atom cloud image and a preset sequence; and according to the brightness change of the cold atom cloud image, judging the injection laser which is unlocked and re-locking the injection laser. The problems that a traditional injection locking system is large in size, insufficient in automation, dependent on manpower, poor in environmental adaptability and the like are solved.

The invention provides a device and a method for simultaneously measuring a magnetic field and a temperature, and belongs to the technical field of optical fiber magnetic field sensing. Comprising a pumping source, a wavelength division multiplexer, an erbium-doped optical fiber, a circulator, an optical fiber grating magnetic field sensing unit, a temperature sensing optical fiber, a first optical fiber coupler, a polarization controller, a second optical fiber coupler, a photoelectric detector, a frequency spectrograph and a micro spectrograph. Monitoring the variable quantity of the laser output wavelength through the micro spectrometer, and monitoring the variable quantity of the laser longitudinal mode beat frequency signal frequency through the frequency spectrograph; based on a pre-calibrated double-parameter sensing matrix, the temperature and the magnetic field can be measured at the same time by constructing the double-parameter sensing matrix by utilizing the measured and calculated magnetic field variation and temperature variation to be measured.

The application provides a single-longitudinal-mode fiber laser which comprises a main cavity and a passive eye-shaped composite ring cavity filter module. The passive eye-shaped composite ring cavity filter module is required to select a single longitudinal mode from dense longitudinal modes of the main cavity, and the effective passband 3dB bandwidth of the eye-shaped composite ring cavity filter module must be 1-1.5 times of the longitudinal mode interval of the main cavity, and the effective free spectral range must be 0.5-1 times of the wavelength selection channel bandwidth, so that the single longitudinal mode laser output can be realized under the wavelength switching of the laser.

The invention relates to the technical field of photoelectrons, and discloses a distributed feedback laser and a preparation method thereof, and the distributed feedback laser comprises a substrate layer, a separation limiting heterostructure, a coupling grating layer, a dielectric layer, an anode and a cathode. Bragg gratings are sectionally arranged on the side wall of the ridge waveguide of the coupling grating layer along the cavity length, each grating at least comprises two grating sections with different coupling coefficients, and a quarter-wavelength phase shift region is arranged at the center of the cavity; the end face of the cavity can adopt an anti-reflection or high-reflection coating film combination. The coupling coefficient and length ratio of each section is determined according to the end face reflectivity, target coupling coefficient distribution is achieved by changing parameters such as the side wall etching depth, the uniformity of photon density distributed along the cavity length is improved, the longitudinal space hole burning effect is restrained, and narrower line width is achieved while single longitudinal mode output is kept; the distributed feedback laser is simple in structural technological process, low in requirement for mask and etching precision and suitable for narrow-linewidth light sources with different cavity lengths and end face reflection conditions.

The invention discloses an electric power iron tower buried anchor rod corrosion guided wave monitoring method and device and a medium, and belongs to the technical field of electric power facility state monitoring and nondestructive testing. According to the method, ultrasonic guided waves in a longitudinal mode and a torsional mode are excited and received at the exposed end of an anchor rod, and the propagation time of echoes reflected from the buried end of the anchor rod is accurately extracted; calculating wave velocities V1 and V2 and a wave velocity ratio R of the two modes; the influence of soil environment change on V1 and V2 is consistent, so that the wave velocity ratio R is kept stable; the rigidity and mass distribution of the anchor rod can be differentially changed by the corrosion defect, so that the R value is specifically changed; according to the method, accurate and quantitative diagnosis and early warning of the corrosion state of the anchor rod can be achieved by establishing the healthy reference wave velocity ratio Ri and the diagnosis threshold value delta based on the statistical confidence interval and monitoring whether the subsequent wave velocity ratio Rnew value exceeds the threshold value or not, and the technical bottleneck that a traditional single-mode monitoring method is greatly interfered by the environment is effectively overcome.

A method and device for generating 260 nm wavelength low-noise all-solid-state ultraviolet laser, 808 nm laser pumps Nd:YVO4 crystal to generate 914 nm wavelength linearly polarized stimulated radiation fluorescence, the fluorescence is amplified and oscillated in the first laser oscillation cavity and realizes longitudinal mode compression by combining phase modulation longitudinal mode filter, generates 914 nm wavelength low-noise linearly polarized near-infrared laser, and is converted into 457 nm wavelength low-noise linearly polarized blue laser by intracavity frequency doubling; the 457 nm low-noise linearly polarized blue laser pumps Sm:YLF crystal in two directions to generate 605 nm wavelength linearly polarized orange-red stimulated radiation fluorescence, the fluorescence is amplified and oscillated in the second laser oscillation cavity and forms 605 nm wavelength low-noise linearly polarized orange-red laser after phase modulation filtering; the remaining 457 nm wavelength low-noise linearly polarized blue laser and the 605 nm wavelength low-noise linearly polarized orange-red laser of the pumped Sm:YLF crystal are nonlinearly frequency-converted by intracavity sum frequency, the polarization controller is used to optimize the polarization matching degree of the two lasers to improve the sum frequency efficiency, and 260 nm wavelength low-noise all-solid-state ultraviolet laser output is obtained.

The application provides a semiconductor laser, which comprises, from bottom to top, a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer and an upper limiting layer; the active layer is a periodic structure composed of a well layer and a barrier layer; the refractive index coefficient of the well layer is greater than that of the barrier layer; the dielectric constant of the well layer is greater than that of the barrier layer; and the piezoelectric polarization coefficient of the well layer is greater than that of the barrier layer. The application differentiates the refractive index coefficient, the dielectric constant and the piezoelectric polarization coefficient of the well layer and the barrier layer in the active layer, thereby improving the photon degeneracy, making the stimulated radiation of the laser greater than the spontaneous radiation, improving the coherence, the limiting factor and the slope efficiency of the transverse mode, reducing the number of longitudinal modes and the mode variation, improving the time coherence of the longitudinal mode and the far field FFP image quality, the beam quality factor and the focusing spot resolution.

The invention provides a single-longitudinal-mode hollow-core optical fiber gas laser and an operation method. The single-longitudinal-mode hollow-core optical fiber gas laser comprises a tunable pumping source, a first annular resonant cavity structure arranged on the outer side of the tunable pumping source and a gas filling and vacuumizing system connected with the inner side of the first annular resonant cavity structure. The tunable pumping source controls the output wavelength of the pumping seed source through the direct-current power supply so as to be matched with the absorption wavelength of the gain gas and output pumping light; a first air chamber and a second air chamber in the first annular resonant cavity structure are arranged on the five-dimensional adjusting frame, and the first annular resonant cavity structure is used for generating single longitudinal mode laser; and the gas filling and vacuumizing system is used for performing vacuumizing and gain gas filling on the hollow-core optical fiber in the first annular resonant cavity structure. Through the annular resonant cavity structure and the cavity length design, intermediate infrared single longitudinal mode laser can be effectively generated.

Methods, apparatuses, and other aspects for microacoustic resonators are disclosed. In one aspect, an apparatus includes: a temperature compensation layer (712) comprising a first surface and a second surface opposite to the first surface; and a piezoelectric layer (704) having a first surface and a second surface opposite to the first surface, wherein the piezoelectric layer is disposed on the first surface of the temperature compensation layer, wherein the second surface of the piezoelectric layer faces the first surface of the temperature compensation layer, and wherein the piezoelectric layer has an orientation configured to excite longitudinal modes. The apparatus also includes an electrode structure comprising an interdigital transducer (702) disposed on the first surface of the piezoelectric layer, wherein the second surface of the temperature compensation layer faces the air gap (714).

The invention relates to a single-frequency narrow-linewidth external cavity fiber laser which comprises an inner cavity, an outer cavity and three FBGs, two FBGs are basic reflectors and are located at the two ends of the inner cavity and the two ends of the outer cavity respectively, the third FBG is located between the inner cavity and the outer cavity and serves as a common reflector of the two cavities, and the inner cavity and the outer cavity are welded to the two ends of an erbium-doped fiber respectively. The FBG Fabry-Perot cavity is used as the outer cavity structure of the laser, the narrow-band reflection loss spectrum of the outer cavity is utilized, the single longitudinal mode selection condition is ensured, the harsh requirements for the cavity length and high doping concentration of the gain fiber section are relieved, the interference of the pumping heat effect on the work of the laser is further relieved, the manufacturing cost and difficulty are reduced, and the laser has good application prospects. And the length of the conventional cavity can be expanded from 0.02 m to 0.10 m.