64 results about "Laser pulse width" patented technology

The invention discloses an area array Gm-APD detection laser radar distance drift error correction method and system, and belongs to the field of data processing. The method comprises the steps of building a single-photon laser ranging system, adjusting the width of a laser pulse, detecting a target distance by using an area array Gm-APD detection laser radar, carrying out repeated measurement on a certain plane for multiple times, obtaining arrival time distribution of a target single-photon event, carrying out weighted average after carrying out filtering and denoising on ranging signals, and obtaining a signal region ranging value. And estimating the average detection photon number of the received monopulse by using the statistical detection probability, and correcting the drift error. According to the method, the drift error caused by echo signal photon accumulation in the area array Gm-APD detection laser radar can be corrected, and the ranging error of the area array Gm-APD detection laser radar is reduced.

The invention provides a laser de-bonding method and device, electronic equipment and a storage medium. The method comprises the following steps: determining a de-bonding area on a semiconductor substrate to be de-bonded; wherein the de-bonding area is made of an inorganic material; selecting laser parameters of a pulse laser; wherein the pulse laser comprises any one of a nanosecond laser, a picosecond laser and a femtosecond laser, and the laser parameters comprise laser wavelength and laser pulse width and frequency; and controlling the pulse laser to irradiate the de-bonding area according to the laser parameters. According to the laser de-bonding method, a nanosecond laser, a picosecond laser or a femtosecond laser is adopted to irradiate a de-bonding area on a to-be-de-bonded device, so that de-bonding treatment is carried out on the de-bonding area, and the de-bonding efficiency of taking an inorganic material as a to-be-de-bonded material is improved.

The invention provides a laser removing method for a damaged coating on the surface of a metal base material and application of the laser removing method. The laser removing method comprises the following steps that the thickness and the shape of a damaged coating on the surface of a metal base material are obtained, working parameters of a laser device are determined, laser spots generated by the laser device are concentrated on the damaged coating area on the surface of the metal base material, and laser removing treatment is conducted; wherein the working parameters comprise laser power, laser pulse width, line spacing and laser frequency. According to the method, accurate control over the removing process can be achieved, the working parameters of the laser device are adjusted based on the parameters of the damaged coating, the cleaning depth and range can be accurately controlled, customized cleaning can be conducted according to different requirements when the damaged coating is removed, the damaged coating can be completely removed, and excessive cleaning or damage can be avoided. And for some thicker metal coatings or coatings which are difficult to remove at one time, the laser cleaning can be carried out repeatedly, and the damage to the base material is avoided.

The invention discloses an ultrafast laser partition impact strengthening method and device for a thin-wall covered edge of a composite blade. According to the method, the surface of the thin-wall covered edge is strengthened by utilizing the characteristics of instantaneous high pressure of shock waves induced by ultrafast laser and accurate and controllable propagation depth, and meanwhile, according to the thickness characteristics of different areas of the covered edge, laser with different pulse widths is selected to carry out partitioned strengthening treatment, so that accurate regulation and control of a surface residual stress field are realized on the premise of inhibiting deformation; the problem of cooperative control of surface strengthening deformation and a stress field of the thin-wall edge covering structure is solved. According to the thickness characteristics of different areas of the edge covering structure, based on the principle that the shorter the laser pulse width is, the shallower the shock wave propagation depth is, the shallow the depth of a residual stress field influence layer is and the edge covering structure is not prone to deformation, a femtosecond / picosecond pulse width laser combined shock peening method is provided, and femtosecond laser shock is adopted in a thin-wall area; femtosecond laser or picosecond laser with relatively long pulse width is adopted for impact in a wall thickness area, and precise regulation and control of a surface stress field are achieved on the premise of restraining thin-wall wrapping edge deformation.

The invention discloses a laser-induced sound cross-medium communication method based on passive relay PWM modulation, and relates to the technical field of cross-medium communication. The method comprises the following steps: adjusting the laser pulse width of to-be-sent information, and carrying out PWM modulation to obtain a PWM sequence; inputting the modulation sequence into a laser driving control module, and driving a laser to emit a laser pulse signal with specific pulse width change; laser energy is focused on the surface of a passive relay material, and when laser pulses with different pulse widths act on the material, different numbers of sound signals can be excited and generated; a receiving end captures sound signals propagating across media through a hydrophone, and demodulates the sound signals according to a mapping relation between pulse width and the number of the sound signals; and finally, original information is restored, so that cross-medium communication from air to water is completed. According to the invention, PWM modulation is combined with a passive relay material, and the system has the remarkable advantages of no need of underwater power supply, simple structure, high reliability and the like.

The invention discloses a laser medical equipment control method and device, equipment and a storage medium, and belongs to the field of laser medical equipment. Comprises: an information acquisition module for acquiring an image of a pigmented skin disease of a patient and a result of a skin pigment analyzer; the auxiliary diagnosis module is used for obtaining the type of the pigmented skin disease of the patient through image classification; the laser control module obtains a proper laser spot size, a proper laser energy density and a proper laser pulse width through a machine learning method; the laser positioning module is used for positioning the position of the pigmented skin disease of the patient through target detection; the skin feedback module is used for detecting the skin of the laser treatment part in real time through a camera; the laser treatment module positions the affected part according to the laser positioning module and treats the pigmented skin disease according to the parameters set by the laser control module. According to the invention, the accuracy and safety of laser treatment are improved by adopting a machine learning method, and the operation difficulty of laser treatment is reduced.

The invention belongs to the technical field of photoelectricity, and relates to a detector moving laser irradiation damage assessment method and system. The evaluation method comprises the following steps: determining mobile laser parameters and detector structure material attribute parameters; constructing a detector solid heat transfer transient model; setting physical field boundary conditions of the solid heat transfer transient model and performing grid division; setting solver parameters, specifically, inputting the moving laser pulse width and the moving laser frequency into a pre-trained linear neural network model, and calculating by applying an expression of the model to obtain the solver parameters; and based on the solver parameters, solving the solid heat transfer transient model in the solver, judging the thermal damage condition of the detector by calling domain ordinary differential and differential algebraic equation modules, and if it is determined that the detector is damaged, calculating the damage area and volume of the detector to obtain the spatial distribution condition of the damage area of the detector.

The invention provides a laser pulse width broadening device and a laser system. The laser pulse width broadening device comprises a first lens array, a plurality of optical fibers with different lengths, a second lens array and a focusing lens, the plurality of optical fibers with different lengths have the same incident plane and emergent plane; the first lens array divides the laser beam; the segmented laser beams are respectively transmitted in a plurality of optical fibers with different lengths, and the plurality of optical fibers with different lengths respectively emit a plurality of light beams with different delays based on the optical path difference of the plurality of optical fibers with different lengths; the second lens array collimates a plurality of light beams with different delays; and a plurality of light beams with different delays pass through the focusing lens and then are superposed to obtain uniformly distributed light beams with target sizes. The lens array can be used for segmenting light beams and coupling the light beams into optical fibers to improve the utilization rate of the light beams. The pulse width is broadened by using the optical path difference of the optical fibers with different lengths; the micro-lens array is used for collimating the light beams, the focusing lens is used for overlapping the light spots, small light spots are formed, and follow-up shaping and light beam coupling are facilitated.

A narrow-pulse-width multi-wavelength laser based on LED pumping comprises a reflecting mirror, a first LED pumping module, an optical rotation crystal, a second LED pumping module, an acousto-optic Q-switched crystal and an output mirror which are sequentially connected in series. The LED pumping module comprises a laser rod located in the center, a glass sleeve is arranged on the periphery of the laser rod in the length direction, a supporting frame is arranged on the periphery of the glass sleeve, a plurality of sets of water-cooling copper blocks are evenly arranged on the supporting frame, and an LED stacking array is arranged on the side, close to the glass sleeve, of each set of water-cooling copper blocks. Each LED stacking array comprises an LED light bar and a PCB (Printed Circuit Board) for fixing the LED light bar, and the PCB is connected with the water-cooling copper block; cooling water circulation modules are arranged at the two ends of the laser rod in the length direction respectively, and water through holes are formed in the cooling water circulation modules and the water cooling copper blocks respectively. A laser resonant cavity system of the laser takes an LED as a pumping source, combines an acousto-optic Q-switching technology, and simultaneously realizes compression of laser pulse width and multi-wavelength output.

The invention discloses an ultrafast laser welding method for a ceramic reinforced aluminum matrix composite, and aims to solve the problems that an existing ceramic reinforced aluminum matrix composite connecting method is low in strength, and high-precision welding and micro-area welding are difficult to realize. The ultrafast laser welding method comprises the steps that firstly, the to-be-connected surface of a to-be-welded part of the ceramic reinforced aluminum matrix composite is ground and polished; secondly, the composite materials to be welded are assembled in a butt joint mode; and thirdly, ultrafast laser is used for aligning a welding seam of the to-be-welded accessory, the laser pulse width is controlled to be 20 fs to 10 ps, the laser power is 1 W to 100 W, the welding speed is 0.01 mm / s to 3 mm / s, the defocusing amount is-150 microns to 0 microns, and ultrafast laser welding is conducted by controlling the path and the pass. According to the ultrafast laser welding method, the aluminum matrix and the reinforced phase can be well inhibited from reacting to generate a brittle compound, a welding seam with high density is obtained, the joint strength is remarkably improved, and therefore welding with the precision of micron order and below and micro-area welding are achieved.

The invention discloses a thermal lens self-adaptive double-resonant cavity pulse solid laser which comprises a total reflective mirror, an LD side pump gain module, a polaroid, a Q switch, a cube-corner prism, a first wedge lens group, a half-wave voltage switch, a first PBS prism, a first output mirror, a first reflecting prism, a second wedge lens group, a second output mirror, a second reflecting prism, a third wedge lens group and a second PBS prism. The Q switch comprises a lambda / 4 wave plate and a Q-switched crystal which are sequentially arranged on an output light path of the polaroid, the double resonant cavities comprise a short-cavity resonant cavity and a long-cavity resonant cavity, the short-cavity resonant cavity is composed of a first output mirror and a total reflective mirror, and the long-cavity resonant cavity is composed of a second output mirror and a total reflective mirror. According to the invention, through the self-adaptive thermal lens change design of the double resonant cavities, stable oscillation of the laser is ensured, so that the laser can keep highly consistent laser energy, pulse width and optical axis stability in a full pumping power range, and meanwhile, the laser pulse width is greater than 10ns when the single-oscillator-stage laser outputs large energy.

The invention belongs to the technical field of light beam synthesis, and particularly discloses a coherent synthesis light source regulation and control device and method for pulse output. Comprising a plurality of single-frequency lasers used for outputting single-frequency laser; the optical phase modulators are arranged in one-to-one correspondence with the single-frequency lasers and are used for performing phase adjustment on the single-frequency lasers; a plurality of polarizers which are arranged in one-to-one correspondence with the optical phase modulators and are used for carrying out polarization processing on the single-frequency laser after phase adjustment; the gathering device is used for carrying out focusing processing on the plurality of single-frequency lasers processed by the polaroid; the synthesis grating is used for coherently synthesizing the plurality of focused single-frequency lasers into a beam of pulse laser and outputting the pulse laser; the angles of the multiple single-frequency laser beams incident on the synthesis grating meet the grating diffraction synthesis relation. According to the invention, the diffractive optical element is adopted to coherently combine a plurality of continuously output single-frequency laser beams, so that high-average-power and high-peak pulse laser source output is realized, and the laser pulse width is adjustable.

The utility model discloses a femtosecond laser pulse width real -time monitoring device relates to optical instrument technical field, including main base plate, integral optical support module, integral optical support module is equipped with a plurality of, a plurality of integral optical support module is used for installing different optical elements, and optical elements include beam splitter, reflector, delay line and nonlinear crystal, and integral optical support module is vertically installed on main base plate through fixed peg, support stable clamping plate is formed with two clamping plates and is closed, and the round hole for clamping fixed peg is formed on support stable clamping plate, and both ends of support stable clamping plate are equipped with fixed hole, and the axial direction of fixed hole is perpendicular with the board face direction of support stable clamping plate, is used for further fixed integral optical support module group after clamping on main base plate. The utility model forms the door type frame structure through support stable clamping plate and makes a whole with a plurality of module, and the slight displacement and the shaking of each module top are restrained.

The invention discloses a low-repetition-frequency laser pointing stability improving device and method, and belongs to the field of lasers. According to the invention, the seed laser pulse of the MHz magnitude is used as the reference light to adjust the directivity of the light path, and compared with the main laser repetition frequency of the Hz magnitude, the sampling frequency of the subsequent directivity adjustment is greatly improved, so that the laser auto-collimation precision is improved. The use of the first shutter, the second shutter and the third shutter ensures the safety of the first detector and the second detector in the transmission process of the main laser when the energy difference between the main laser and the reference light is 9 orders of magnitude. The first detector images the first grating of the compressor to ensure that the positions of laser entering the compressor are the same, so that the consistency of laser pulse width and directivity can be ensured to a great extent, the second detector images the acting target to ensure that the acting positions are the same, and the stability of a subsequent radiation source is ensured. The laser directivity correction method is applied to laser directivity correction of hundred TW-level and PW-level lasers.

The invention relates to the technical field of glass laser processing, and discloses a laser processing method for making a black mark on a glass surface, which comprises the following steps: making a black mark line on the glass surface as visual positioning to carry out marking test and observe the marking effect; based on the marking test, obtaining laser data of the laser beam, obtaining a test mark line width and a preset black mark line width, obtaining a test expansion ratio, analyzing based on the test expansion ratio to obtain a test deviation value and a deviation ratio, and performing preliminary adjustment; based on the preliminary adjustment, obtaining the line width of the black mark on the glass, analyzing to obtain a processing expansion ratio, judging whether the marking effect of laser processing is qualified or not according to the obtained processing expansion ratio, generating different signals, and based on the unqualified signals, obtaining the laser power and the laser pulse width of the optical fiber laser; and an energy density value is obtained based on analysis of the obtained processing expansion ratio, and the laser power and the laser pulse width of the fiber laser are adjusted based on the obtained energy density value.

The application discloses a self-correlation instrument based on gallium oxide two-photon absorption ultraviolet femtosecond laser pulse width measurement, and belongs to the technical field of photoelectric regulation and control. The self-correlation instrument comprises a laser generating device, an optical delay system and a self-correlation signal acquisition device. The laser generating device is used for generating a first light beam and a second light beam. The optical delay system is connected with the laser generating device and is used for changing the time when the first light beam and the second light beam reach a sample to be measured. The self-correlation signal acquisition device is used for receiving two-photon photoelectric conversion signal change data caused by the sample to be measured being irradiated by the first light beam and the second light beam in sequence, and obtaining a self-correlation signal based on the two-photon photoelectric conversion signal change data. The application makes full use of the ultraviolet wave band absorption characteristics of gallium oxide to prepare an ultraviolet detector, and uses the self-correlation method to measure the photoelectric conversion signal generated by two-photon absorption of the gallium oxide ultraviolet detector to measure the pulse width of the 350-450 nm near-ultraviolet wave band femtosecond laser.

This invention relates to the field of laser ultrasonic nondestructive testing technology, specifically a method for optimizing laser source parameters during laser-induced ultrasound based on FEA (Feature-Enhanced Amplification). The invention obtains the geometric dimensions and material parameters of the insulator under test, constructs a geometric model, adds solid heat transfer and mechanical fields, and establishes a finite element model through thermal expansion coupling. Multiple laser pulse width and laser spot radius values ​​are determined and combined to obtain multiple parameter schemes. Each parameter scheme is applied to the finite element model as the time and spatial distribution parameters of the laser heat source, and transient calculations are performed. Displacement time-domain data of monitoring points are extracted and subjected to Fast Fourier Transform (FFT) to obtain frequency-domain data. The ultrasonic signal characteristics of each parameter scheme are compared and analyzed, and the parameter combination that meets the testing requirements is selected as the optimization result. This invention significantly reduces parameter optimization costs and improves testing efficiency through simulation-guided experiments.

The present invention belongs to the technical field of the interaction between laser and matter, and relates to a simulation method and system for the temperature field and stress field of a material irradiated by short-pulse laser. The simulation method includes: determining simulation parameters, including short-pulse laser irradiation parameters and material property parameters; constructing a thermo-mechanical coupling transient model of the material, and determining the boundary conditions of the heat transfer physical field and the solid mechanics physical field of the model; performing grid division on the thermo-mechanical coupling transient model, and configuring solver parameters; specifically: inputting the short-pulse laser pulse width and the short-pulse laser frequency into a pre-trained linear neural network model, and calculating to obtain the solver parameters; applying the solver to solve the thermo-mechanical coupling transient model to obtain the temperature field and stress field distribution of the material at different irradiation times. The simulation method of the present invention can comprehensively and accurately capture the complex transient physical process of the material under the action of short-pulse laser.

The invention relates to the technical field of material strengthening treatment, in particular to a gear surface laser strengthening method, a gear and a laser strengthening device. The method comprises the following steps that an obtained gear to be strengthened is divided into a plurality of areas to be strengthened, and the areas at least comprise a first area to be strengthened with the deformation smaller than a preset threshold value and a second area to be strengthened with the deformation larger than the preset threshold value during laser shock strengthening under the same condition; the divided first to-be-strengthened area and the divided second to-be-strengthened area are subjected to laser shock strengthening separately according to a preset first parameter set and a preset second parameter set; wherein the preset parameters of the first parameter group and the second parameter group comprise laser energy, laser pulse width and laser spot parameters, and each parameter value of the first parameter group is correspondingly greater than each parameter value of the second parameter group; the gear surface is subjected to laser strengthening through the gear surface laser strengthening method, and uniformity regulation and control of gear surface residual stress can be achieved to a certain extent.

The invention discloses a method for ultrafast laser welding of a ceramic reinforced aluminum-based composite material in a vacuum environment, and aims to solve the problems that high-precision welding and micro-area welding are difficult to realize by a traditional connection method of the existing ceramic reinforced aluminum-based composite material, the strength of a joint is limited by an ultrafast laser welding method, the thickness of a weldable workpiece is limited and the like. The ultrafast laser welding method in the vacuum environment comprises the steps that firstly, a to-be-connected face is ground and polished; secondly, the to-be-welded parts are assembled in a butt joint mode and placed in a vacuum cabin; 3, vacuumizing the vacuum chamber; and fourthly, ultrafast laser is aligned with the weld joint, the laser pulse width is controlled to be 200 fs to 10 ps, the laser power is 10 W to 120 W, the welding speed is 0.03 mm / s to 5 mm / s, and ultrafast laser welding is conducted. The obtained connector is almost free of welding deformation, the bending strength reaches 80% of that of base metal, high-precision welding and micro-area welding are achieved, meanwhile, the welding penetration depth can be effectively increased through the vacuum environment, and the thickness size range of weldable workpieces is enlarged.

The invention relates to a double-pulse modulation long-distance distributed optical fiber temperature sensing system which comprises a laser, laser output by the laser is transmitted to a grating and a first-stage laser modulator through a beam splitter, laser output by the first-stage laser modulator is transmitted to one port of a circulator through a first laser amplifier, and laser output by the second-stage laser modulator is transmitted to the other port of the circulator through a second laser amplifier. A lower port of the circulator is connected with the sensing optical fiber, a second lower port of the circulator is connected with the input end of the second laser amplifier, the grating and the output end of the second laser amplifier are connected with the signal processing module, and a second-level laser modulator is further arranged between the first-level laser modulator and the first laser amplifier. The laser pulse width output by the first-stage laser modulator is larger than that output by the second-stage laser modulator, and the first-stage laser modulator has laser intensity gain of at least one decibel. The dipulse modulation long-distance distributed optical fiber temperature sensing system provided by the invention has a relatively long detection distance under the condition that the resolution ratio is not reduced.

The present invention belongs to the field of optoelectronic technology and relates to a method and system for evaluating the damage of a detector caused by moving laser irradiation. The evaluation method includes: determining the parameters of the moving laser and the parameters of the detector's structural material properties; constructing a transient solid heat transfer model of the detector; setting the physical field boundary conditions of the transient solid heat transfer model and performing mesh division; setting the solver parameters, specifically: inputting the moving laser pulse width and the moving laser frequency into a pre-trained linear neural network model and using the expression of the model to calculate the solver parameters; based on the solver parameters, solving the transient solid heat transfer model in the solver, and determining the thermal damage condition of the detector by calling the domain ordinary differential and differential algebraic equation module. If it is determined that the detector has been damaged, calculate the damage area and volume of the detector to obtain the spatial distribution of the damaged area of the detector.

The invention provides a laser control system and a laser control method. The laser control system comprises a laser output device, a temperature sensor and a controller, and the output end of the laser output device is configured to be implanted into a target intervertebral disc; the temperature sensor is configured to be integrated at the output end of the laser output device and used for acquiring the real-time temperature in the target intervertebral disc; the controller is used for determining at least one of laser output parameters of the next laser pulse on the basis of the real-time temperature and / or the real-time temperature rise rate until it is determined that the actual total heat of the laser output device reaches the target total heat; the laser output parameters comprise laser pulse width, laser pulse frequency, peak power and average power. A closed-loop feedback system is established, and the difference between the actual total heat and the target total heat can be calculated according to the real-time temperature and the real-time heating rate, so that the parameters of the next laser pulse combination are dynamically adjusted, and the target repairing effect is accurately achieved.

The laser cleaning method for the oxide on the surface of the semiconductor comprises the steps that the semiconductor is placed in a negative-pressure vacuum chamber, and the surface of the semiconductor is located at the focal plane position of a laser pulser; the laser pulse frequency of the laser pulser is controlled to be 1 Hz to 200 Hz, and the laser pulse width of the laser pulser is controlled to be 0.1 ns to 100 ns; the average laser power of the laser pulser is controlled to be 100-1000W, and the laser energy density is controlled to be 0.1 J / cm < 2 >-2J / cm < 2 >. Compared with a traditional cleaning method, the method has the advantages that the treatment process is faster, higher surface cleaning quality is obtained, surface oxides of semiconductors are effectively removed, and secondary pollution to the environment is reduced.

The present application relates to a method, apparatus, device, and medium for measuring the performance parameters of a single-photon detector, which relates to the field of single-photon detection technology. The method includes: calculating and determining the total photon event count value within a first time domain range, calculating and determining the post-pulse event count value within a second time domain range, determining the post-pulse probability of each statistical sub-interval in a statistical histogram based on the post-pulse event count value and the total photon event count value, and determining the post-pulse probability of the single-photon detector to be measured based on the post-pulse probability of each statistical sub-interval; calculating and determining the first difference between the second peak time and the first peak time to determine the dead time of the single-photon detector to be measured; and calculating and determining the time jitter of the single-photon detector to be measured based on the laser pulse width, the time jitter of the synchronization pulse, and the time jitter of the multi-event statistical histogram time-to-digital converter. The present application greatly shortens the measurement time of the performance parameters of a single-photon detector.

The invention belongs to the field of laser ranging, and particularly relates to a semiconductor laser drive circuit, which is characterized in that in order to adapt to different power supply input characteristics, an input power supply is output to a filter circuit after passing through a voltage stabilizing circuit, and a secondary power supply is output to other unit circuits for use after noise and ripples are filtered by the filter circuit; the booster circuit provides driving voltage required for driving the laser; the numerical control circuit adjusts the amplitude of the driving circuit; the fixed width circuit is used for generating a laser driving signal with stable width; the trigger circuit is used for driving the semiconductor laser to output laser pulses. Compared with the prior art, low-cost, low-power-consumption and modular design is carried out on the semiconductor laser driving circuit in the semiconductor laser range finder, and the functions of obtaining a fixed-width laser driving signal through single-chip microcomputer driving, wide power input range, adjustable transmitting power and stable laser pulse width are achieved.

The invention provides a far-field laser measuring device, which relates to the technical field of laser parameter measurement and comprises a filter wheel rotating system, a laser power density detection module, a pulse width detection module and an upper computer. The filter wheel rotating system comprises a pulse width detection window and a plurality of laser wavelength detection windows; and the upper computer is used for controlling the filter wheel rotating system to rotate and receiving detection data acquired by the laser power density detection module and the pulse width detection module. The rotating filter wheel rotating system is matched with the laser power density detection module and the pulse width detection module, so that laser power density detection and laser pulse width detection processes are realized. When irradiated by laser, the laser power density detection module captures the laser at the first time, rotates based on the filter wheel rotating system, receives detection data acquired by the laser power density detection module and detection data acquired by the pulse width detection module, and realizes the rapid and accurate measurement process of laser with different wavelengths.

The manufacturing method of a laser pulse width shortening film according to the present invention includes: a filling step in which a graphene oxide colloid is filled into a container having an open upper surface; a covering step in which a guide film having a predetermined outer pattern perforated therein covers an opening of the container; a bonding step in which the graphene oxide colloid is filled into the inside of the outer pattern by the capillary principle; an agglomeration step in which a solvent of the graphene oxide colloid evaporates in the inside of the outer pattern to form a graphene film by agglomerating graphene oxide molecules; and a separation step in which at least the graphene film is separated from the guide film.

The invention discloses a terahertz fiber laser, which relates to the technical field of terahertz, and comprises a pumping source and an annular light path, and further comprises a doped fiber, a polarization control element and a saturable absorber which are arranged on the annular light path, pumping light emitted by the pumping source excites the doped optical fiber to radiate photons to form spontaneous radiation light, the saturable absorber has a polarization characteristic and is used for converting the received continuous laser into pulse laser, and the polarization control element is used for controlling the polarization state of light of the annular light path. And adjusting the state of the pulse laser output by the annular light path, according to the terahertz fiber laser, the width of the laser pulse emitted by the terahertz fiber laser is adjustable through the saturable absorber with the polarization characteristic, the polarization control element and the like which are arranged in the annular light path, and therefore the requirements for pulse lasers with different pulse widths in various fields such as biological medicine, communication, micromachining, remote sensing and military are met.

Systems and methods for optimizing laser damage threshold and induced phase change range in a method of writing phase change structures in a hydrogel material with a femtosecond laser writing system focusing a laser beam into the hydrogel material. A laser pulse width and a laser effective NA are selected for a given focused laser average power range to increase the laser damage threshold relative to use of laser pulse widths shorter than the selected laser pulse width and / or use of laser effective NAs greater than the selected laser effective NA. In a particular embodiment, the focused laser average power is from 1 to 5000 mW, the selected laser pulse width is greater than about 165 fs, and the selected laser effective NA is less than 0.50. Applications of the techniques described include laser induced refractive index change (LIRIC) customization of contact lenses, intra-ocular lenses, and other ophthalmic materials.