62results about How to "High single pulse energy" patented technology

The invention relates to a high-energy low-repetition-frequency fiber laser, which comprises a pump light source used for providing energy for generating laser light, a gain fiber used for providing gains, a mode locking device used for modulating the laser light so as to generate ultrashort pulses, and a single-mode transmission fiber used for laser transmission, wherein the gain fiber, the single-mode transmission fiber and the mode locking device form a resonant cavity of the fiber laser; the generated laser light is oscillated in the resonant cavity; and under the condition that the lengths of the gain fiber and the mode locking device are not increased, the length of the single-mode transmission fiber is increased according to a relation that the length L of the resonant cavity is inversely proportional to the repetition frequency frep of the fiber laser and according to the reduction of the needed repetition frequency frep. By increasing the length of the resonant cavity, the high-energy low-repetition-frequency fiber laser reduces the repetition frequency of pulses in the resonant cavity, correspondingly improves the energy of a single pulse, further simplifies the structure of an amplification system, improves the efficiency of an amplifier and effectively reduces the cost.

The invention discloses a method and device for measuring the light frequency through a high-power optical fiber optics frequency comb. A mode locking pulse laser serves as an optics frequency comb seed resource to set up the high-power optical fiber optics frequency comb, and a carrier envelope phase signal of the optics frequency comb is locked at the zero frequency; the beat frequency is carried out on the output light of the optics frequency comb and continuous lasers to be tested, the repeated frequencies of the pulse of the optics frequency comb seed resource are finely adjusted through an externally loaded modulation signal, a plurality of sets of beat frequency signals corresponding to different repeated frequencies are obtained, and therefore the accurate measuring of the frequency of the continuous lasers to be tested can be achieved. The method and device have the advantages that the device is stable in structure, the measuring process is easy, and the application is flexible.

The invention discloses a MHz photonic crystal fiber ultra-short pulse laser based on a multichannel pulse compressor. The laser comprises a diode pumping source, a photonic crystal fiber, an intra-cavity pulse compressor, a semiconductor saturable absorber mirror and an extra-cavity pulse compressor, wherein the inter-cavity pulse compressor and the extra-cavity pulse compressor respectively are an intra-cavity multichannel pulse compressor and an extra-cavity multichannel pulse compressor. The main bodies of the multichannel pulse compressors are end mirrors in which two concave spherical surfaces are coaxially and oppositely arranged, each end mirror is provided with a rotating ring, and a concave spherical reflector is arranged in the rotating ring. The MHz photonic crystal fiber ultra-short pulse laser has the advantages that the low recurrence frequency of the pulse laser greatly reduces heat accumulation of pulse on components and prolongs the service life of the components, meanwhile, the intra-cavity multichannel compressor and the extra-cavity multichannel compressor with low loss and compact structure overcome the disadvantages of other chromatic dispersion compensation technologies, and the ultra-short pulse laser with low cost, high energy and high peak power output is realized.

The invention discloses a laser strobe active night vision method for remote night monitoring. In the method, a one-frame multi-pulse and multi-door working mode is adopted, in one frame time of exposure of an imaging device, a pulse laser emits a laser pulse sequence, a strobing gate works according to a preset strobing pulse sequence, and the imaging device receives a plurality of target echo signals from a target, therefore, the purpose of light accumulation and signal enhancement is achieved. The invention has good working environmental suitability, and can normally work under the condition of low visibility. Since a long-distance target can be observed at night by using the low-power pulse laser, the cost of the system is greatly reduced, the laser security of the system is improved, and especially the security of eyes is improved.

A conductively cooled high-repetition single frequency Nd: YAG Laser is disclosed. An improved resonance detection method is used to obtain an injection-seeded single frequency pulse laser. A laser resonator is a u-shaped cavity, which uses two high peak power LD to pump a laser crystal from ends. High-precision TEC is used to control the temperature of the laser crystal. With changes of applied voltage on piezoelectric ceramics, seed lights reflected twice from a Brewster angle polarizing sheet interfere with each other. Interference signals received by photodiodes are processed by a sequential control system and when there is a maximum value, Q-witch is opened by the sequential control system. And then a close-to-diffraction-limited single-rate pulse laser is output. According to changes of light extraction time, system can give a negative feedback so that a cavity length can be maintained stably. The invention possesses a high-repetition frequency, high energy, conduction cooling, narrow linewidth, high frequency stability, and a compact structure and can work stably.

The invention relates to an intracavity-frequency-doubling 532nm single-longitudinal-mode laser based on seed light injection. A resonance detection method is used for obtaining 1064nm single-frequency pulse laser for seed injection is obtained and 532nm single-longitudinal-mode pulse laser is obtained through intracavity frequency doubling. A laser resonant cavity is a U-shaped cavity. Two high-peak-power laser diodes (LD) are used for pumping laser crystals from an end surface, a high-precision thermoelectric cooler is used for controlling the temperature of the laser crystals and green light output is obtained through intracavity lithium triborate (LBO) frequency doubling. The intracavity-frequency-doubling 532nm single-longitudinal-mode laser based on seed light injection has the characteristics of high efficiency, high energy, conduction cooling, narrow line width, high frequency stability, compact structure and high working stability.

A narrow pulse fiber amplifier belongs to the laser technology field. The fiber amplifier contains the seed source laser, the seed optical coupling system, the gain fiber, the pumped source laser and the pumped coupling system, and the feature is that between the seed source laser and the gain fiber adding the pulse issued by the seed source laser to choose the pulse selector. The selected pulse sequence has the arbitrarily changing repetition frequency, and duration, through the high gain amplification of the fiber amplifier to obtain high-power, narrow pulse width laser pulse output. The invention has the advantages that it makes full use of the narrow pulse width of the seed source laser and the wide gain spectrum and high gain of the fiber amplifier, and adding the pulse selector to make the pulse repetition frequency and duration to be free to change. The invention can obtain narrow pulse width pulse sequence of low repetition frequency, whose single pulse energy and peak power can be significantly improved, but also avoiding the stimulated Brillouin scattering effect.

The invention relates to a near-infrared wavelength tunable totally-positive dispersion femtosecond optical fiber laser which comprises an optical fiber oscillator and a pulse width compression device. The optical fiber oscillator is connected with a band-pass filter through an LD pumping source, the band-pass filter is connected with a wavelength division multiplexer, the wavelength division multiplexer is connected with an ytterbium doped gain optical fiber, the ytterbium doped gain optical fiber is connected with a first single mode optical fiber, the first single mode optical fiber is connected with a discrete component, a collimating apparatus is connected with a second single mode optical fiber, and the second single mode optical fiber is welded with the wavelength division multiplexer. The pulse width compression device is connected with a high mirror through a second half wave plate, the high mirror is respectively connected with a second polarization splitting prism and two reflecting type optical gratings, the two reflecting type optical gratings are connected with a silver mirror, and the silver mirror is connected with a silver mirror bracket. The near-infrared wavelength tunable totally-positive dispersion femtosecond optical fiber laser is good in heat dissipation performance, high in light beam quality, compact in structure, small and exquisite in size, low in cost, high in light conversion efficiency and good in environmental stability.

Disclosed is a laser beam combination system. The laser beam combination system respectively performs total reflection processing on an S-polarization laser and a P-polarization laser through a first total reflection module and a second total reflection module so that incident S-polarization laser and the P-polarization laser can be adjusted to be horizontal and vertical. The S-polarization laser after the total reflection processing is reflected to the second polarization module via the first polarization module and then is reflected again by the second polarization module. The P-polarization laser after the total reflection processing is retracted by the second polarization module to the optical path of the S-polarization laser reflected by the second polarization module so as to finish beam combination of the S-polarization laser and the P-polarization laser. The mean power of a single frequency multiplication laser is reduced as a frequency increases. Therefore, after the S-polarization laser and the P-polarization laser are combined, the frequency is two times that of a single laser, yet the mean power is unchanged, i.e., the single pulse energy at a high frequency is improved, and accordingly, the laser processing speed can be enhanced.

The invention provides a system for realizing 3D printing of a high-molecular material by a picosecond laser. The system comprises a laser system, a control system, an infrared temperature measuring device and a feeding device. Temperature difference with the latest 3D printing job temperature is compensated through calibration, feedback and laser power control. The temperature difference can be accurately controlled within + / - 0.5 DEG C. The high-molecular material can be effectively prevented from warping and nonuniform processing phenomena during 3D printing process.

The invention discloses a high energy hybrid thulium-doped pulse laser single-frequency amplifier which comprises a seed resource, a wavelength division multiplexer, an optical fiber pumping source, a polarization-maintaining single-mode single-cladding thulium-doped optical fiber, an isolator, a beam splitter, an output end, a filter, an acoustic optical modulator, a semiconductor pumping source and a laser crystal. The high energy hybrid thulium-doped pulse laser single-frequency amplifier has the advantages of being simple in structure and stable in system, the optical fiber-solid combined method is used, optical fiber amplification is adopted for a prime stage, the capacity for amplifying small signals is effectively improved, crystal amplification is adopted for a post stage, the advantage that solid lasers are prone to generating low-multi-pulse pulsed light is developed, the nonlinear effect easily occurring in optical fiber amplifying under high power is effectively avoided, low-multi-pulse high-energy pulse output is accordingly achieved, and the good application aspect is achieved.

The invention discloses a double-resonant-cavity coupled all-fiber Q-switched mode-locked pulse laser. The double-resonant-cavity coupled all-fiber Q-switched mode-locked pulse laser comprises a pumping device, a laser resonant cavity, a gain optical fiber and a laser output device, wherein the laser is provided with a linear cavity or an annular cavity structure for outputting laser pump, whereinthe pumping device comprises a pumping source, an optical fiber beam combiner and a wavelength division multiplexer; the laser resonant cavity comprises a first reflection type fiber bragg grating, asecond reflection type fiber bragg grating, a semiconductor saturable absorption mirror, a third reflection type fiber bragg grating and a total reflection mirror; the gain optical fiber comprises afirst gain optical fiber and a second gain optical fiber; and the laser output device comprises an optical isolator, an annular device and an optical fiber beam splitter. The mode-locked pulse laser adopts the all-fiber structure, which is simple in design and compact in structure, and capable of effectively improving laser output efficiency and stability and outputting the Q-switched mode-lockingpulse with high single-pulse energy and narrow pulse width.

A white light generation based multi-color femtosecond laser generation device is characterized in that a splitting piece is arranged on a main light path to divide incident light into reflected light and transmission light; the reflected light is focused on a nonlinear crystal after sequentially passing a first attenuation piece, a first lens, a white gem piece, a first concave surface reflecting mirror, a small hole diaphragm, a chirp mirror and a second concave surface reflecting mirror; the transmission light is focused on the nonlinear crystal to be served as pump light after sequentially passing a second attenuation piece, a delay line which is formed by a first reflective mirror and the second reflective mirror, a third reflective mirror, a fourth reflective mirror, a fifth reflective mirror and a second lens. The white light generation based multi-color femtosecond laser generation device has the advantages of being simple in adjustment, compact in structure, stable in light of output signals and the like.

The invention relates to a femtosecond vortex pulse generator, which comprises a vortex beam generation system, a hollow-core fiber system and a pulse compression system, wherein the vortex beam generation system comprises a collimating lens group and a vortex beam generation unit used for transforming a gaussian beam into a vortex beam; the hollow-core fiber system comprises a coupling lens, a cylindrical vacuum chamber and a hollow-core fiber arranged in the vacuum chamber; and the pulse compression system comprises a concave reflector group for carrying out collimating and a pair of chirp mirrors. Only a relatively simple device is used, so that ultra-short and ultra-strong femtosecond vortex laser light can be generated and the femtosecond vortex pulse generator can be applied to the fields of attosecond optics, light filament research and micro-nano machining.

The invention relates to an optical fiber laser based on broad-band spectrum, which comprises a high-reflection coating plated reflection cavity mirror, a pumping source, an optical coupling device and a gain optical part reflection resonant device, wherein the optical fiber laser based on broad-band spectrum forms broadband laser to be output through a pair of broadband reflection resonant cavities, and the broadband laser is used as a seed laser for amplifying an optical fiber. The optical fiber laser based on broad-band spectrum disclosed by the invention has the characteristics of being low in threshold value and easy to pair, and efficiently inhibits nonlinear effect in the optical fiber, so that the single pulse energy and peak power of a pulse optical fiber laser are obviously promoted, and the stability of output power of the optical fiber laser is improved.

The invention discloses an ytterbium-doped multicore photonic crystal optical fiber mode-locked laser, which belongs to the technical field of laser. The laser has a sigma cavity structure, a main body of the laser is based on a ytterbium-doped multicore photonic crystal optical fiber, and a single-mode optical fiber is used as a mode selector for selecting modes; the laser works in a totally positive dispersion area, no chromatic dispersion compensating element is in a cavity, and a semiconductor saturable absorption mirror is used for starting mode locking. The invention has the advantages of stability and easy operation of mode selection and wide spectrum, narrow pulse width and high energy of output pulse; the mode field area of the used multicore photonic crystal optical fiber is two orders of magnitude larger than that of an ordinary optical fiber, the single pulse energy which can be supported by the multicore photonic crystal optical fiber is also more than 100 times than that of a traditional optical fiber laser, a used mode-selecting element is a single mode optical fiber, and the far-field distribution of an output mode field is gauss distribution.

The invention discloses a high-energy hundreds of picoseconds laser device based on stimulated Brillouin scattering pulse compression, and belongs to the field of optical instruments, so as to solve the problem that the prior laser can not realize narrow pulse high energy single longitudinal mode output. According to the scheme of the invention, after p polarized light generated by an oscillator passes through a beam expanding telescope, the light transmits a light isolation system, the transmitted p polarized light is amplified and changes into s polarized light via a 90-DEG rotor, the s polarized light is further amplified and then converted into circular polarized light via a 1 / 4 wave plate, continuous reflection via two plane mirrors is sequentially carried out, a direction is changed, the light then enters a stimulated Brillouin scattering generation unit, and stimulated Brillouin scattering is generated. Generated back Stokes light is returned along the original path, continuous reflection via two plane mirrors is sequentially carried out, a direction is changed, the light is converted into p polarized light via a 1 / 4 wave plate, the p polarized light is amplified and then converted into s polarized light via a 90-DEG rotor, and the s polarized light is further amplified and separated by a second polarized film and reflected out of the light path.

The invention discloses a double-coating large-mode-area photon crystal flysecond laser directly obtaining micro joule-level single pulse energy, belonging to the field of laser technique and nonlinear optics, where the laser main body is based on double-coating large-mode-area photon crystal optical fiber of polarization-protection structure and adopts high-power LD laser to directly pump; the laser uses grating pair to compensate dispersion, starts mode locking with the help of semiconductor saturable absorber mirror (SESAM), and controls polarization by wave plate and polarization beam splitter and implements tunable output; laser resonant cavity keeps net positive dispersion inside and runs in self-similar mode locking mode and outside-cavity dispersion compensation is made on the output pulse and the pulse is 100-200fs wide. And the advantages: the laser has good stability, and the output pulse has high energy and high repeating frequency. And the invention can effectively avoid split of pulse running at high energy.

The invention relates to the technical field of optical fiber laser transmission, and in particular relates to a laser amplification optical fiber for preventing self-convergence damage, which comprises a hollow optical fiber and a gain optical fiber, wherein the rear end of the gain optical fiber is connected with the hollow optical fiber along the laser transmission direction. The gain optical fiber is connected with the hollow optical fiber so as to prevent optical fiber damage caused by optical field convergence due to a self-convergence effect generated during the process of transmitting, amplifying and oscillating the gain optical fiber, so that single fiber power amplification limit performance of the gain optical fiber is improved, and the obtained pulse energy is greatly improved.

The invention relates to a laser treating equipment whose emission wavelength is 593nm, 594nm, or 589nm which is near to ideal the absorption peak 577nm of oxidized hemoglobin, and since it is the full-solid laser treating equipment, compared to dyestuff laser, said treating equipment can significantly reduce the cost. The pulse length of output laser is 3-100ms which is continuously adjustable and each pulse can be divided into two or more 0.2-3ms long-pulse laser. Said long pulse laser treating equipment can replace present dyestuff laser treating equipment to treat the erythema lesion.

The invention relates to an ultra-high-power laser space beam combination system, an ultra-high-power space beam combination laser system, and a group central computer control system. According to theultra-high-power laser space beam combination system, an optical path adjusting module comprises a beam expander, a collimating mirror and a reflector, a plurality of the optical path adjusting modules form an optical path area array, the optical path area array is installed on an angle swinging head, and the angle swinging head is installed on a rotary platform; and a numerical control system controls the rotary platform and the angle swinging head to form linkage with the optical path adjusting modules on the optical path area array, so that laser beams emitted by a plurality of laser devices converge at one point in a space beam combination manner. By integrating the plurality of optical path adjusting modules, and controlling the rotary platform and the angle swinging head to form linkage with the optical path adjusting modules by means of the numerical control system, the technical problem of how to gather energy of all the laser devices to implement intelligent tracking and irradiation on an arbitrary target and enable long-distance output of the laser beams under the command of a computer is solved.

The invention discloses a high-repetition-frequency high-energy nanosecond pulse laser and a using method thereof. The high-repetition-frequency high-energy nanosecond pulse laser comprises a pump laser, a laser gain pool, an unstable resonant cavity and an electro-optical Q-switching device. A pump laser beam outputted by the pump laser is pumped from the end face of a gain medium of the laser gain pool, is transmitted into the laser gain medium and provides energy for the resonant cavity; laser oscillates in an unstable resonant cavity composed of a concave reflector, a convex reflector anda scraper mirror, pulse modulation is conducted through the electro-optic Q-switching device, and finally pulse laser is outputted from the scraper mirror. The invention provides the laser for realizing high repetition frequency (greater than or equal to 200Hz), large energy (greater than or equal to 20J) and narrow pulse width by single-cavity oscillation. The laser has the advantages of being high in efficiency, simple in structure, good in magnification, reliable in use, high in environment adaptability and the like, and can be widely applied to industrial processing, especially to the field of cladding impact strengthening.

The invention belongs to the technical field of fiber laser, and discloses a saturable absorber with saturable absorption and anti-saturable absorption characteristics, application thereof and a passive Q-switched fiber laser device, and the saturable absorber comprises a 980nm LD pumping source, a 980nm / 1550nm wavelength division multiplexer, a 10% output coupler, an erbium-doped gain fiber, a polarization independent isolator, a single-mode fiber, a polarization controller and a Fe3O4-PI composite film, wherein the Fe3O4-PI composite film is cut into a square with the side length of 0.5 mm and then placed on the optical fiber jumper head. According to the passive Q-switched fiber laser, the output characteristics of the passive Q-switched fiber laser are adjusted and optimized through the saturable absorber with saturable absorption and anti-saturable absorption characteristics, the output characteristics of the passive Q-switched fiber laser are greatly optimized, the pulse width and the repetition frequency are compressed, meanwhile, the monopulse energy and the peak power are improved, the output performance of the passive Q-switched fiber laser is improved, and the Q-switched pulse is high in stability.

The invention provides a chirped pulse compression device and a laser. The chirped pulse compression device comprises the following components: a translation roof prism and a grating which are spaced oppositely, wherein all angles are arranged in a total reflection manner; and a reflector assembly which comprises a plurality of reflectors which are all located between the grating and the translation roof prism; wherein after incident light is emitted to the grating, the incident light is diffracted by the grating to form first light which is emitted to the reflector assembly along a first direction, and the first light is reflected back to the reflector assembly after being reflected by the reflector assembly for multiple times and translated by the reference surface position of the translational roof prism, and then is reflected for many times; and the light returns and enters the grating along the direction symmetrical with the first direction relative to the normal direction, and then is subjected to secondary diffraction by the grating to form a second light meeting the grating diffraction condition. The chirped pulse compression device provided by the invention can improve the utilization rate of the grating region and increase the compressible pulse width so as to improve the pulse output single pulse energy and reduce the cost.

The invention provides a subnanosecond green laser. The subnanosecond green laser comprises a subnanosecond seed source for emitting seed light, a multi-stage amplification structure for performing multi-stage amplification on the seed light, and a frequency doubling conversion structure for performing frequency doubling conversion on the amplified seed light, the multi-stage amplification structure comprises a first-stage amplification light path, a second-stage amplification light path and a third-stage amplification light path; the first-stage amplification light path comprises a first seed light path, a first laser crystal, a 0-degree reflecting mirror and a first pumping module which are arranged in sequence; the second-stage amplification light path comprises a second seed light path, a second laser crystal, a 0-degree reflecting mirror and a second pumping module which are arranged in sequence; and the third-stage amplification light path comprises a third seed light path, a third laser crystal, a pumping spectroscope and a third pumping module which are arranged in sequence. According to the subnanosecond green laser provided by the invention, the output green laser has the characteristics of high repetition frequency, high average power and high monopulse energy, and can meet market application requirements.

The invention discloses a laser strobe active night vision method for remote night monitoring. In the method, a one-frame multi-pulse and multi-door working mode is adopted, in one frame time of exposure of an imaging device, a pulse laser emits a laser pulse sequence, a strobing gate works according to a preset strobing pulse sequence, and the imaging device receives a plurality of target echo signals from a target, therefore, the purpose of light accumulation and signal enhancement is achieved. The invention has good working environmental suitability, and can normally work under the condition of low visibility. Since a long-distance target can be observed at night by using the low-power pulse laser, the cost of the system is greatly reduced, the laser security of the system is improved,and especially the security of eyes is improved.

The invention relates to the technical field of lasers, and provides a non-resonant subnanosecond pulse laser. The laser comprises a voltage-decreased Q modulating module, a pumping source as well asa pumping coupling unit, a dichroic mirror, a laser gain medium, a Q switch and a reflecting mirror which are arranged along the direction of a transmitting light path of the pumping source in sequence; the pumping coupling unit is used for focusing pumping light transmitted by the pumping source onto the laser gain medium through the dichroic mirror, the dichroic mirror is arranged slantly, and ahigh transparency film is coated at the end, facing the dichroic mirror, of the laser gain medium; and the voltage-decreased Q modulating module is electrically connected with the Q switch. The hightransparency film is coated at the end, facing the dichroic mirror, of the laser gain medium, the pumping coupling unit is used for being focused onto the high transparency film completely after passing through the dichroic mirror, laser light can be output inside the cavity through once transition, the pulse width is effectively controlled, and the single pulse energy is further improved. Moreover, due to the fact that the voltage-decreased Q modulating module is adopted in the laser, a 1 / 4 wave plate does not need to be arranged.

The invention discloses a high-repetition-frequency high-energy nanosecond-level pulse laser and a method for using the same, comprising: a pump laser, a laser gain pool, an unstable resonant cavity, and an electro-optic Q-switching device. The pump laser beam output by the pump laser is pumped from the end face of the gain medium of the laser gain cell, transmitted into the laser gain medium, and provides energy to the resonant cavity; It oscillates in the unstable resonant cavity and performs pulse modulation through the electro-optic Q-switching device, and finally the pulsed laser is output from the scraper mirror. The invention provides a laser with single-cavity oscillation realizing high repetition frequency (≥200Hz), high energy (≥20J) and narrow pulse width. The laser will have the characteristics of high efficiency, simple structure, good scalability, reliable use, and strong environmental adaptability. It can be widely used in industrial processing, especially in the field of cladding impact strengthening.

The invention discloses a handheld laser cleaning device. According to the handheld laser cleaning device of the invention, a main control board, a laser, a laser power source, a galvanometer drivingboard and an acousto-optic modulator driver are arranged in a shell; a zero-degree total reflection mirror, a pumping source, an acoustic-optical modulator, an output mirror and a first 45-degree total reflection mirror are arranged on the bottom plate of the laser; the pumping source is connected with a cooling-water machine through a water pipe; the laser power source, the galvanometer driving board and the acoustic-optical modulator driver are all in signal connection with the output end of the main control board; the second 45-degree total reflection mirror is arranged behind the first 45-degree total reflection mirror; a coupling head is arranged on the left side of the second 45-degree total reflection mirror; a laser cleaning head is connected with the coupling head through an optical fiber and located outside the shell; a galvanometer is arranged in the laser cleaning head; the galvanometer is in signal connection with the output end of the galvanometer driving board; and the galvanometer driving board is in signal connection with the output end of the main control board. The peak power of the laser emitted by the laser is high.

A 473nm electro-optic q-switch laser comprises a local oscillator stage, an amplifier stage and an extracavity frequency doubling stage. A convex-concave cavity suitable for high-power laser output is adopted for a resonant cavity of the local oscillator stage, a double-end pulse pump is in bonding with a neodymium-doped yttrium aluminium garnet (Nd:YAG) crystal, an electro-optic q-switch generates 946nm fundamental frequency light, high-power 946nm laser is obtained through the amplifier stage, and 473nm blue light laser is generated by two lithium triborate (LBO) crystals placed in a cascade mode finally. The 473nm electro-optic q-switch laser has the advantages of being high in repetition frequency, narrow in pulse width, high in single pulse energy and good in light beam quality, and is suitable for underwater measurement of a high-precision laser radar.