199 results about "Longitudinal mode" patented technology

The invention discloses a spot-size converter (SSC) and a high-power external cavity laser chip, the external cavity laser chip comprises a wide-ridge gain chip and a passive external cavity chip, one end of the wide-ridge gain chip is plated with a high-reflection film as a reflection end, and the other end of the wide-ridge gain chip is plated with an antireflection film to realize low reflection; and efficient coupling of the fundamental mode of the wide-ridge gain chip with the size far larger than that of the single-transverse-mode waveguide and the small-size single-mode waveguide is realized by integrating the SSC. The SSC converts a large-size mode field and a small-size mode field mutually and effectively reduces optical coupling loss, mode selection and output wavelength adjustability are achieved by adjusting the longitudinal mode phase shifter and the micro-ring filter, part of power is fed back to the wide-ridge gain chip to construct external cavity resonance, and high-power output is achieved. According to the SSC, the device size can be remarkably reduced, a wide-ridge gain chip and an inter-chip hybrid integration process are compatible, and the tuning flexibility, the integration level and the overall stability of the laser are further improved while high-power output is kept.

The invention provides a quasi-continuous thulium-doped fiber laser capable of synchronously suppressing relaxation oscillation and self-pulse, relates to the technical field of fiber laser, and is used for simultaneously realizing suppression of a self-pulse effect and a relaxation oscillation peak. Comprising a continuous driving module, a pulse driving module, a semiconductor laser pumping source, a high-reflectivity fiber bragg grating, a low-reflectivity fiber bragg grating, a beam combiner, a thulium-doped gain fiber, a passive fiber, a cladding pumping stripper and a laser output port, the continuous pump light and the pulse pump light are respectively driven by the continuous driving module and the pulse driving module to output continuous pump light and pulse pump light; the high-reflectivity fiber bragg grating and the low-reflectivity fiber bragg grating form a resonant cavity structure, the thulium-doped gain fiber serves as a gain medium of the thulium-doped fiber laser and absorbs pump light to generate population inversion, laser oscillation is formed by combining the resonant cavity of the laser, relaxation oscillation suppression is achieved, and meanwhile longitudinal mode distribution of the laser is effectively disrupted.

The invention provides a patterned photonic crystal laser and a preparation method thereof, the laser comprises a substrate, and a first mask layer, a photonic crystal layer and a second mask layer which are sequentially deposited on the substrate, a light emitting area is etched in the central area of the second mask layer, and transparent conductive layers are deposited on the surface of the second mask layer and the light emitting area; a p-annular electrode is arranged on the surface of the transparent conductive layer on the second mask layer, and an n-annular electrode is arranged below the substrate; the photonic crystal layer is composed of a nanorod array and a polymer filled in gaps of nanorods; holes distributed in a patterned array are etched in the surface of the first mask layer, and nanorods are epitaxially grown in hole areas; the nanorod is formed by sequentially depositing a substrate contact layer, a first waveguide layer, a multi-quantum well layer, a second waveguide layer, a coating layer and a component gradient layer. According to the invention, through collaborative design optimization of all the layers, emission of laser with specific wavelength and preparation of a laser emitting laser with single longitudinal mode, narrow linewidth and stable wavelength are realized.

The invention provides a two-dimensional measurement method for the temperature of a combustion field, which comprises the following steps: tuning laser frequency to be stabilized in the center of an iodine molecule absorption line, outputting a narrow-linewidth single-longitudinal-mode continuous light beam by a laser, dividing the light beam into two light beams by a spectroscope, enabling one light beam to pass through a reference light path and be used for acquiring an instrument function of a VIPA-based spectrograph, and enabling the other light beam to pass through a reference light path; the other beam of light is incident into a combustion field as exciting light and interacts with gas in the combustion field to generate a scattering signal, the light receiving system collects and filters the scattering signal to obtain filtered Rayleigh-Brillouin scattering (FRBS), and the filtered Rayleigh-Brillouin scattering (FRBS) is transmitted to the spectrograph and the CCD through the optical fiber for spectral resolution and signal acquisition. The scanning system completes two-dimensional profile scanning of a combustion field, retrieves the temperature of an acquired FRBS spectral line through an FRBS theoretical model, and achieves two-position measurement of the temperature of the combustion field. The method can be provided for retrieving the gas temperature based on FRBS in a high-temperature environment containing strong mie scattering or strong background light, can adapt to different environments and requirements, and provides higher flexibility.

The invention provides a frequency stabilization device and method for any detuning frequency of a laser. The frequency stabilization device comprises a pumping laser atomic resonance point frequency stabilization structure, a cavity length locking structure of an optical resonant cavity and a frequency stabilization structure for detecting any detuning frequency of the laser. The frequency of the pumping laser is stabilized at an atomic resonance point through a saturated absorption frequency stabilization method, and then the cavity length of an optical resonant cavity is locked by taking the frequency-stabilized pumping light as a reference. Two modulation signals with different frequencies are superposed by adopting Bias Tee, biphase modulation is applied to detection laser through an electro-optic phase modulator, a stable error signal is demodulated while a modulation sideband is generated, then a first-order sideband is locked on a longitudinal mode, close to an optimal detuning point, of an optical resonant cavity, and a second-order sideband is locked on a longitudinal mode, close to the optimal detuning point, of the optical resonant cavity. Continuous frequency tuning in the laser frequency stabilization process is detected by adjusting the first-order sideband frequency. According to the invention, the size and the cost are reduced.

The invention provides a double-FP waveguide type laser integrated with a surface grating. The double-FP waveguide type laser comprises an N-face metal electrode layer; an N-type substrate, a lower separation limiting layer, an active layer, an upper separation limiting layer and a double-FP-type ridge waveguide layer are sequentially stacked on the N-face metal electrode layer, and the double-FP-type ridge waveguide layer comprises two FP-type ridge waveguides which are arranged in parallel in the first direction; the ohmic contact layer is arranged on each FP type ridge waveguide; and the P-surface metal electrode layer is arranged on the ohmic contact layer. The laser is high in integration, external light feedback and external light injection are not needed, weak periodicity caused by light feedback is avoided, intra-cavity mode distribution is regulated and controlled by changing waveguide distribution and current injection conditions, multiple nonlinear states such as single-period, multi-period and four-wave mixing are achieved, and on-chip chaotic light signal output of a single longitudinal mode is generated.

The invention relates to the technical field of semiconductor lasers, in particular to a multi-wavelength semiconductor laser. Comprising a semiconductor PN junction, and an inclined array waveguide region, a beam splitting MMI structure, a gain array waveguide, a beam combining MMI structure and a super-symmetric waveguide array which are sequentially arranged on the surface of the semiconductor PN junction in the longitudinal mode light beam transmission direction; the inclined array waveguide region comprises Bragg reflection gratings and inclined array waveguides, the Bragg reflection gratings are arranged on ridge surfaces of inlet ends of the inclined array waveguides, cavity lengths of waveguides in the inclined array waveguides are different, and the Bragg reflection gratings are parallel; seed sources output by the inclined array waveguide region are injected into the beam splitting MMI structure, and the seed sources are uniformly distributed and coupled into each waveguide of the gain array waveguide; the gain array waveguide is a parallel waveguide; the super-symmetric waveguide array is used for providing further gain to a fundamental mode and loss to a high-order mode. The antenna has the advantages of simple preparation, high gain, high single-mode performance, small size and high integration.

The utility model discloses an optical feedback type formaldehyde detection device which comprises a semiconductor laser, an absorption cell is mounted at the output end of the semiconductor laser, and a piezoelectric ceramic crystal is mounted on one side of the absorption cell; a photodiode and a laser diode are arranged in the semiconductor laser, and the output end of the laser diode is connected to the input end of the photodiode through an optical signal; the output end of the photodiode is provided with a Fourier transform module; the input end of the laser diode is provided with a driving module; a formaldehyde sampling pump is arranged at the input end of the absorption tank; the input end of the piezoelectric ceramic crystal is provided with a control module. The device adopts the length change of piezoelectric ceramics to modulate the light wave phase, forms carrier waves absorbed by formaldehyde gas, and has the advantage of reducing the detection difficulty; the laser device adopted by the device is a single longitudinal mode semiconductor laser device, laser wavelength can be finely adjusted according to a formaldehyde gas absorption wave band, and the device has the advantage of high sensitivity.

The invention relates to a sensor (1) for determining the concentration of a gas in a gas mixture, comprising a multireflexion cell (2) and at least one acoustic resonator (3), wherein: the multireflexion cell (2) has a light emitter (2.3) so that the light generated by the light emitter (2.3) can be emitted into a chamber (2.1) of the multireflexion cell (2); the light emitter (2.3) is designed to emit light with an intensity according to a first modulation frequency and to emit the light with the intensity according to a second modulation frequency; a part of the acoustic resonator (3) is connected to the chamber (2.1) in such a way that acoustic signals can be coupled in by means of the multireflexion cell (2); the multireflexion cell (2) is designed to couple the acoustic signal of the gas which has been excited by the light emitted according to the first modulation frequency as an acoustic longitudinal mode into the acoustic resonator (3) and to couple the acoustic signal of the gas which has been excited with the light emitted according to the second modulation frequency as an acoustic radial mode into the acoustic resonator (3); the sensor (1) comprises detectors (4) arranged in the acoustic resonator (3) for detecting the acoustic signals and an analyzer (5) connected to the detectors (4) for signal transmission. In this way, a sensor (1) having long-time stability is provided.

The invention discloses a frequency stabilization and line width narrowing method for a semiconductor laser, and relates to the application of the semiconductor laser in a PDH frequency locking technology, and the method comprises the steps: S1, carrying out the first beam splitting of transmission and reflection of a light beam of a DFB laser, reflecting the reflected light beam back into the laser, and suppressing random phase noise generated by spontaneous radiation; s2, the transmission beam subjected to phase noise suppression is subjected to second-time beam splitting of transmission and reflection, the transmission beam subjected to second-time beam splitting is isolated and then passes through an electro-optic phase modulator, a carrier generated by the electro-optic phase modulator is coupled to an ultra-stable cavity, an interference signal generated by the carrier and a sideband reflection signal serves as a frequency discrimination signal, and the frequency discrimination signal is transmitted to the ultra-stable cavity; locking the carrier frequency to the longitudinal mode frequency of the ultra-stable cavity; and S3, the reflected light beam in the second beam splitting is coupled to an IQ modulator, carrier suppression single-side-band laser is generated, and the frequency-tunable narrow-linewidth frequency ultra-stable light source is obtained by changing the frequency of the radio frequency signal.

The invention relates to the technical field of lasers, and discloses an edge-emitting laser with a longitudinal mode and transverse mode selection function and a preparation method of the edge-emitting laser. The edge-emitting laser comprises a chip element, a mode modulation structure and an insulating layer, a ridge waveguide structure is arranged at the top of the chip element, and the mode modulation structure is located on one side of the ridge waveguide structure at the top of the chip element; the mode modulation structure comprises an annular cavity and an annular cavity electrode layer, and the annular cavity and the annular cavity electrode layer are spaced by an insulating layer; a P-type contact metal layer is arranged on the top of the chip element and located on the outer side of the ridge waveguide structure. According to the edge-emitting laser capable of selecting the longitudinal mode and the transverse mode at the same time, the mode modulation structure is arranged on the main ridge-shaped edge of laser feedback in the edge-emitting laser, flexible regulation and control of output of the longitudinal mode and the transverse mode in the ridge-shaped edge-emitting laser are achieved through the mode coupling principle, and external optical assemblies do not need to be added; the integration level and the compactness are good, and the technology is compatible with an existing laser.

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.

The invention discloses a laser device mode hopping detection method, and relates to the technical field of laser detection. Comprising the following steps: a to-be-tested laser emits an optical signal, and the optical signal of the laser is converted into an electric signal; and analyzing the frequency spectrum of the electric signal, and determining whether the laser generates mode hopping or not by judging whether a cross relaxation signal caused by double longitudinal modes exists in the frequency spectrum or not. The laser mode hopping detection method provided by the invention is simple in structure, can realize mode hopping real-time monitoring only through the photoelectric detector and the spectrum analyzer, and is low in cost and convenient to deploy; an interferometer or a delay fiber is not needed in the detection process, the anti-interference capability is high, and mode hopping is visually judged through frequency spectrum changes.

The invention relates to a green semiconductor laser based on hybrid integration, and belongs to the technical field of optoelectronic integration. The laser comprises a silicon nitride chip and a gallium nitride chip which are bonded through a BCB bonding layer, wherein the gallium nitride chip is used for generating laser and coupling the laser into the silicon nitride chip. A receiving unit, a mode selection unit and a reflection output unit are arranged in the silicon nitride chip. The receiving unit is used for receiving the laser coupled by the gallium nitride chip; the mode selection unit is used for realizing longitudinal mode selection and narrowing of laser; and the reflection output unit is used for realizing reflection enhancement of the laser and outputting the laser subjected to mode selection and line width narrowing. According to the invention, the high-quality green light semiconductor laser based on hybrid integration can be realized, the difficult problems of high gallium nitride waveguide preparation difficulty, narrow laser line width, difficulty in integration with a silicon-based photon chip and the like can be avoided, and a green light semiconductor laser realization scheme is provided for application of biological monitoring, visible light communication and the like.

The invention provides a high-power ultra-narrow linewidth optical fiber laser source module. The laser source module comprises a multi-longitudinal-mode optical fiber laser, an optical fiber circulator, an optical fiber beam splitter and a high-quality-factor optical fiber annular cavity. Laser output by the multi-longitudinal-mode fiber laser sequentially passes through a second port and a third port of the fiber circulator to reach an input port of the fiber beam splitter; the laser output from the first output port of the optical fiber beam splitter is used as the output of the whole laser source module; and the laser output from the second output port of the optical fiber beam splitter sequentially passes through the first port and the fourth port of the high-quality factor optical fiber annular cavity and returns to the resonant cavity of the multi-longitudinal mode optical fiber laser from the first port of the optical fiber circulator to form an optical feedback loop. Compared with a traditional ultra-narrow linewidth fiber laser source, the ultra-narrow linewidth fiber laser source can break through dependence of the traditional ultra-narrow linewidth fiber laser source on a single-frequency fiber laser, and further has the advantages of being high in output power, narrow in spectral linewidth and good in all-fiber system integration.

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 modulation system and method for outputting high-power continuous single longitudinal mode laser. The modulation system comprises an LD pumping source, a coupling lens and an NPRO crystal. Pumping laser emitted by the LD pumping source passes through the coupling lens, then is incident at an angle of 45 degrees with the normal of the incident plane of the NPRO crystal, is reflected by the total emission plane, and then is emergent at an angle of 45 degrees with the normal of the incident plane of the NPRO crystal, so that a non-planar annular cavity structure is formed; and carrying out coating design on the incident plane of the NPRO crystal. The whole structure is simple and easy to adjust, no extra insertion loss exists, the light path adjusting difficulty is reduced, the NPRO crystal is accurately coated, the loss can be further reduced, and the output power is improved compared with other methods.

The invention provides a multi-longitudinal-mode fiber laser weak current detection method based on a magnetic rotation sensitive material, and the method comprises the following steps: building a multi-longitudinal-mode fiber laser weak current detection system; a relationship between the magnetic field intensity and the current in the DC coil; determining the relationship between the intra-cavity loss and the Faraday rotation angle of the multi-longitudinal-mode fiber laser resonant cavity within the magnetic field range which does not reach the magnetic saturation intensity of the magneto-optical material; calculating a current value when the magnetic field reaches the magnetic saturation intensity value of the magneto-optical material; when the to-be-measured current value on the coil is between 0 and the critical current, calculating the to-be-measured current value; the magneto-optical sensor is arranged in the multi-longitudinal-mode fiber laser resonant cavity, and the corresponding relation between light intensity change and weak current is constructed through the matching relation between the magneto-optical sensor and the multi-longitudinal-mode fiber laser resonant cavity, so that small current change which is difficult to measure by a traditional sensor can be detected, and high-sensitivity measurement is realized.

To provide a semiconductor laser element that can make a longitudinal mode of an oscillation wavelength a single mode or close to the single mode.SOLUTION: A semiconductor laser element includes a nitride semiconductor multilayer body including a first end surface, a second end surface, and an optical waveguide. The nitride semiconductor multilayer body includes a first n-side nitride semiconductor layer, a second n-side nitride semiconductor layer, an active layer, and a p-side nitride semiconductor layer. The first n-side nitride semiconductor layer includes a diffraction grating part including a periodic structure in which the refractive index periodically changes along a resonance direction of the optical waveguide, and a non-diffraction grating part existing between the diffraction grating part and the first end surface and not including the periodic structure. The active layer includes an n-side well layer and an n-side barrier layer. The second n-side nitride semiconductor layer is a nitride semiconductor layer containing In and Ga. The thickness of the second n-side nitride semiconductor layer is larger than that of the n-side barrier layer.SELECTED DRAWING: Figure 2

A semiconductor laser element capable of achieving a single or nearly single longitudinal mode of an oscillation wavelength is provided. A semiconductor laser element includes a nitride semiconductor laminate including a first end surface, a second end surface, and an optical waveguide. The nitride semiconductor laminate includes a first n-side nitride semiconductor layer, a second n-side nitride semiconductor layer, an active layer, and a p-side nitride semiconductor layer. The first n-side nitride semiconductor layer includes a diffraction grating region provided with a periodic structure in which a refractive index changes periodically along a resonance direction of the optical waveguide, and a non-diffraction grating region located between the diffraction grating region and the first end surface and not provided with the periodic structure.wherein the active layer includes an n-side well layer and an n-side barrier layer, wherein the second n-side nitride semiconductor layer is a nitride semiconductor layer containing In and Ga, and wherein a thickness of the second n-side nitride semiconductor layer is greater than a thickness of the n-side barrier layer.,

According to the external cavity laser tuning device and method, the gain chip, the collimating lens, the wedge-shaped lens and the diffraction grating are sequentially installed along the optical axis, the rotating pivot point of the diffraction grating is arranged at the intersection point of the optical axis and the diffraction surface of the diffraction grating, and the device is simple in structure and low in cost. The cavity length is tuned by longitudinally translating a wedge-shaped lens mounted between a collimating lens and a diffraction grating, meanwhile, a rotating pivot point is arranged at the central position of the diffraction grating, and the rotation of the diffraction grating only affects frequency selection and does not affect a longitudinal mode, so that the influence of unstable mechanical structure and heat sensitivity on the cavity length in the rotation process is reduced to a great extent, and the cavity length is tuned. Therefore, the stability of wavelength tuning is improved, and wide-range mode-hopping-free wavelength tuning is optimized.

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 lasers, and discloses a narrow-linewidth subnanosecond laser. The narrow-linewidth subnanosecond laser comprises a pumping source, a resonant cavity and a coupling system, the pumping source, the resonant cavity and the coupling system are arranged along the same optical axis, and the pumping source serves as gain laser. A laser crystal, a polaroid, a quarter-wave plate, an electro-optical modulator and a Bragg grating are sequentially arranged in the resonant cavity along an optical axis. The end face of the Bragg grating away from the coupling system is plated with a beam-splitting film. Laser forms oscillation in the resonant cavity, and the Bragg grating plays a role in screening longitudinal modes, so that narrow linewidth output is realized. The polaroid and the quarter-wave plate are matched to play roles of polarization analysis and light splitting. The voltage on the electro-optical modulator is periodically adjusted to periodically adjust the loss in the resonant cavity so as to output the subnanosecond pulse laser.

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 pipeline long-distance guided wave detection system and a detection method thereof, and relates to the technical field of guided wave detection. Torsional mode signals and longitudinal mode signals reflected by guided waves in a target pipeline are collected; the frequency dispersion characteristic of the torsional mode signal is corrected, and the echo characteristic of the torsional mode is determined through the amplitude difference and the phase offset of the corrected torsional mode signal in the circumferential sensor array; compensating the axial symmetry vibration amplitude in the longitudinal modal signal through the attenuation coefficient of the axial propagation of the guided wave in the pipeline structure body and the correlation constraint of the intensity of the guided wave between the axially adjacent sensors, and extracting the echo characteristics of the longitudinal modal; multi-mode guided wave cooperative detection is conducted on the target pipeline according to the echo features of the torsional mode and the longitudinal mode, the defect echo features of the target pipeline are obtained, the defect position of the inner wall of the target pipeline is positioned based on the defect echo features, multi-mode guided wave cooperative detection can be achieved, and therefore the pipeline defect detection precision is improved.

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 embodiment of the invention provides a complex special-shaped structure three-dimensional stress inversion method based on ultrasonic characteristic guided waves, and the method comprises the steps: obtaining first ultrasonic characteristic guided waves corresponding to a plurality of characteristic guided wave modes of a detected special-shaped structure in a detection process, the multiple characteristic guided wave modes comprise at least two of a longitudinal mode, a torsional mode and a bending mode; according to the first ultrasonic characteristic guided waves corresponding to the multiple characteristic guided wave modes, first group velocities corresponding to the multiple characteristic guided wave modes of the detected special-shaped structure are calculated, and a first group velocity matrix is obtained; and inputting the first group velocity matrix into a pre-trained physical information neural network model to obtain the current stress information of the detected special-shaped structure, through the scheme of the embodiment of the invention, the stress information of the special-shaped structure can be calculated through the pre-trained physical information neural network model, and the accuracy of the stress information of the detected special-shaped structure is improved. And high-efficiency and high-precision nondestructive stress measurement is achieved.

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.