213 results about "Saturable absorption" patented technology

The invention discloses a high-tolerance synchronous dual-band pulse laser, and relates to the field of lasers, and the laser comprises a first resonant cavity and a second resonant cavity; the first resonant cavity comprises a first pumping source and an optical annular cavity formed by sequentially connecting a first wavelength division multiplexer, a first thulium-doped optical fiber, a first optical coupler, a first isolator, a second wavelength division multiplexer, a high-nonlinearity saturable absorber, a third wavelength division multiplexer and a first polarization controller; the second resonant cavity comprises a second pumping source and an optical annular cavity which is formed by sequentially connecting a fifth wavelength division multiplexer, a second erbium-doped fiber, a second optical coupler, a second wavelength division multiplexer, a high-nonlinearity saturable absorber, a third wavelength division multiplexer, an electric control adjustable delay line, a fourth wavelength division multiplexer, a second polarization controller and a second isolator, and the fifth wavelength division multiplexer, the second erbium-doped fiber, the second optical coupler, the high-nonlinearity saturable absorber, the third wavelength division multiplexer, the electric control adjustable delay line, the fourth wavelength division multiplexer, the second polarization controller and the second isolator; and the first optical coupler and the second optical coupler respectively output synchronization pulses in the wave bands of 2 microns and 1.5 microns. The device is compact in structure, low in manufacturing cost, convenient to operate and capable of covering the mid-infrared band of 2 microns.

The invention relates to a self-calibration atomic wavelength meter. The self-calibration atomic wavelength meter comprises a saturated absorption spectrum light path for locking a detection laser frequency on a cesium atom energy level transition line based on a saturated absorption spectrum; the double-peak spectrum light path scans the frequency of a coupled laser after the frequency of the detection laser is locked by a saturated absorption spectrum, and when the detection laser and the coupled laser jointly act on alkali metal atoms and are subjected to resonance excitation, an electromagnetic induced transparency effect is generated; when the detection laser is detuned, the detection laser and the combined laser jointly act on the alkali metal atoms to generate non-resonance excitation, a double-peak EIT spectrum with Doppler frequency shift is generated, and the wavelength measurement of the current detection laser can be completed based on the linear relation between the double-peak spectrum interval and the detuning amount of the detection laser. In addition, the double-peak spectrum interval is compared with the atomic energy level transition frequency, the difference between the double-peak spectrum interval and the atomic energy level transition frequency serves as an error signal to be fed back to the control end of the detection laser, the frequency of the detection laser is tuned to the reference frequency standard, and calibration of the wavemeter can be achieved.

The invention discloses an all-fiber structure pulse laser based on a superfine single-crystal fiber and a preparation method thereof. The all-fiber structure pulse laser comprises a gain single-crystal fiber and a pulse modulation single-crystal fiber, and the gain single-crystal fiber and the pulse modulation single-crystal fiber form a superfine single-crystal fiber heterogeneous bonding structure through thermocompression bonding; the gain single-crystal optical fiber serves as a laser gain medium, the pulse modulation single-crystal optical fiber serves as a saturable absorber, the gain single-crystal optical fiber is provided with a high-reflection grating, the high-reflection grating and an oblique-angle low-reflection end arranged at the tail end of the pulse modulation single-crystal optical fiber form a resonant cavity, and pump light is input into the gain single-crystal optical fiber and enters the resonant cavity through the high-reflection grating. And the oblique-angle low-reflection end outputs pulse laser. The gain section and the modulation section are fused into an integrated structure through the superfine single crystal optical fiber bonding technology, the high-reflection grating is inscribed through the femtosecond laser direct writing technology, low-reflection-mirror oblique angle processing is carried out at the output end, space coupling loss is eliminated, and all-optical-fiber monolithic integration is achieved.

The invention discloses a dual-wavelength mode-locked laser generating device and a dual-wavelength mode-locked laser generating method, and belongs to the technical field of optical communication, and the dual-wavelength mode-locked laser generating device comprises a pumping source, an optical integration module, a gain optical fiber, a saturable absorber and a dual-wavelength pulse independent polarization mode linear coupling regulation and control structure, linear coupling strength of cross-polarization components in two wavelength pulses is independently regulated and controlled by using a structure of a polarization controller and a polarization maintaining optical fiber, and dual-wavelength mode-locked pulse laser of different types of pulse combinations can be obtained. The coherent pulse light source with unique spectral characteristics can provide a low-cost light source for the fields of high repetition frequency optical combs, all-fiber architecture high repetition frequency soliton sequences and microwave photonics.

The invention provides a gas saturation absorption optical path structure based on dual optical path enhancement, which belongs to the field of laser optical path design and comprises an optical fiber circulator, a gas absorption chamber and an optical fiber reflector. A first port of the optical fiber circulator is connected with a laser output optical fiber, a second port of the optical fiber circulator is connected with an input collimator of the gas absorption chamber, and a third port of the optical fiber circulator is connected with a detector and is used for providing frequency reference for gas absorption; and the optical fiber reflector is connected with the output end of the gas absorption chamber. According to the invention, the physical contradiction between the air chamber size and the optical path gain is broken through, and a compact frequency stabilization system with miniaturization and high stability is realized.

The invention relates to a nanosecond fiber laser and method for high-order chaotic pulses. A fiber ring cavity of the laser comprises a wavelength division multiplexer, an erbium-doped fiber, a first polarization controller, an analyzer, a second polarization controller, an output coupler, a dispersion control unit, a fiber isolator and a band-pass filter which are connected in sequence. The method comprises the steps that pumping continuous light is coupled into the laser through the wavelength division multiplexer; pumping continuous light is absorbed by using an erbium-doped optical fiber and is stimulated to radiate a long-wave-band gain pulse; under the combined action of the first polarization controller, the polarization analyzer and the second polarization controller, an equivalent saturable absorption effect is generated by utilizing nonlinear polarization rotation generated when gain pulses are propagated in an optical fiber, and large anomalous dispersion is introduced to realize generation of nanosecond pulses; through the band-pass filter, nanosecond pulses are allowed to be generated, and meanwhile, the nonlinear increasing speed of propagation and accumulation of the nanosecond pulses in the cavity is controlled, so that order-by-order generation of high-order chaotic pulses is realized. According to the invention, reliable output of high-order chaotic pulses can be realized.

The invention discloses a reflective pumping detection nondestructive testing device and method capable of saturatively absorbing uniformity in a mirror surface. The device is based on a wavelength degeneracy pumping-detection principle, and comprises a femtosecond laser source, a beam splitter, an optical delay line, a double-frequency optical chopper, a two-dimensional precision translation stage, a coaxial focusing system, a spatial filtering diaphragm arranged in a reflection light path, a photoelectric detector, a lock-in amplifier and a signal processing unit. According to the method, different point positions of a sample are accurately positioned through a two-dimensional translation stage, a nonlinear differential reflectance dynamic curve of each point is measured under low power, the maximum differential reflectance and the carrier lifetime are extracted as characteristic parameters, the spatial relative standard deviation of the characteristic parameters is calculated, and lossless and quantitative in-plane uniformity evaluation is realized. According to the method, the interference of the pump light is effectively filtered through the space filtering diaphragm, the signal-to-noise ratio is remarkably improved in combination with the phase-locked amplification technology, and the problem that the nonlinear optical performance uniformity of the saturable absorber mirror cannot be quantitatively evaluated through a traditional method is solved.

A passively, Q-switched laser is described. The laser may operate at an eye-safe lasing wavelength of 1.34 microns and use a gain element of Nd:YVO4 and a saturable absorber element of V:YAG with a space separating the gain element and saturable absorber element. The Q-switched laser is pumped by a grating stabilized laser diode. The laser may be used in laser ranging applications.

Apparatus, systems, and methods for a bidirectional mode-locked all-polarization maintaining fiber laser with two counter-propagating, orthogonally polarized pulses are applicable in a variety of applications. A mode-locked fiber laser can be realized with a laser cavity including a first polarization maintaining gain fiber, a second polarization maintaining gain fiber, and a saturable absorber. The saturable absorber can be arranged with the first polarization maintaining gain fiber and the second polarization maintaining gain fiber to generate two counter-propagating pulses, being orthogonally polarized with respect to each other. The laser cavity can include a circulator arranged to provide separate paths for the two counter-propagating pulses in a portion of the fiber laser cavity.

A ring resonator (10) and a NALM (20) configured as a saturable absorption mechanism constitute a laser oscillator. A multiport BPF (12) is provided to a path through which light propagates in the laser oscillator, the multiport BPF (12) passing light in a prescribed band of the propagating light, and branching light outside of the prescribed band as monitoring light (L). A photodetector (1) detects the monitoring light (L). A control unit (2) controls the oscillation state of the light propagating through the laser oscillator on the basis of the intensity of the monitoring light (L), thereby controlling the mode synchronization of the light propagating through the laser oscillator.

The invention discloses a mode-locked laser based on cross-polarization feedback injection and a control method thereof, and belongs to the technical field of lasers, a light beam emitted by a VCSEL laser is divided into two beams through an optical splitter, the first beam is divided into a first TM mode light beam and a first TE mode light beam through a first polarization-maintaining beam splitter, the two beams form an annular loop on a light path, and the first TM mode light beam and the first TE mode light beam form an annular loop on the light path; and a half-wave plate is arranged on the loop. And the two beams of light are respectively and oppositely propagated along the annular loop, return to the VCSEL laser after being subjected to polarization state conversion by the half-wave plate, are reflected by a resonant cavity of the VCSEL laser again, are coupled into the resonant cavity after being subjected to secondary polarization state conversion by the half-wave plate, and finally finish the output of the mode-locked laser. The laser reaches a mode-locked state by adjusting the angle of the half-wave plate. The laser uses an orthogonal polarization feedback injection mechanism, does not need to use a saturable absorber and a polarization inverter, is simple in structure and easy to implement, greatly reduces the cost and complexity of a system, and meets the requirements of different application scenes.

A self-calibration atomic wavemeter, including a saturated absorption spectrum optical path based on saturated absorption spectrum to lock the probe laser frequency on cesium atomic energy level transition line; a double-peak spectrum optical path scans the coupling laser frequency after the probe laser frequency is locked by the saturated absorption spectrum, when the probe laser and the coupling laser jointly act on the alkali metal atom and resonantly excite, the electromagnetic induced transparency effect is generated; and when the probe laser is detuned, the probe laser and the coupling laser jointly act on the alkali metal atom to produce non-resonant excitation, and the double-peak EIT spectrum with Doppler frequency shift is generated, based on the linear relationship between the double-peak spectrum interval and the probe laser detuning amount, the wavelength measurement of the current probe laser can be completed, in addition, the double-peak spectrum interval and the atomic energy level transition frequency are compared, and the difference between the two is taken as an error signal feedback to the control end of the probe laser, and the frequency of the probe laser is tuned to the reference frequency benchmark, so that the calibration of the wavemeter can be realized.

This invention discloses a passively mode-locked fiber laser with switchable transverse modes and an optical communication system, relating to the field of ultrafast optical technology. The passively mode-locked fiber laser comprises a pump source and a laser resonator. The laser resonator comprises a wavelength division multiplexer, a gain fiber, a few-mode isolator, a first polarization controller, a saturable absorber, a second polarization controller, a mode-selective photon lantern, and a few-mode coupler, all connected in sequence along the direction of light propagation. Compared to existing technologies, the present invention offers low insertion loss and high spatial mode selection flexibility, making it widely applicable in communications, industrial processing, detection, and other fields.

The present invention provides a light-emitting device that improves the peak value of the light pulses used for irradiation. [Solution] The light-emitting device has a spacer portion that includes a saturable absorption layer provided between a first electrode, which is a back electrode, and a resonator portion. The spacer portion has a first spacer layer provided on the first side with respect to the saturable absorption layer, and a second spacer layer provided on the second side with respect to the saturable absorption layer. The first spacer layer and the second spacer layer are of a first conductivity type.

The invention provides a continuous variable quantum key modulation system and an optical waveguide unit preparation method, and belongs to the field of quantum communication, the continuous variable quantum key modulation system comprises an integrated amplitude modulation module and a modulation control module, the integrated amplitude modulation module comprises an optical waveguide unit of an integrated Mxene film layer, a modulation light input unit and a signal light coupling unit; the modulation control module receives the modulation instruction and transmits a modulation parameter corresponding to the modulation instruction to the integrated amplitude modulation module; the modulated light input unit receives modulated light, and excites the saturation absorptivity of the Mxene film layer according to the input light power; the signal light coupling unit receives the signal light and couples the signal light and the modulated light to the optical waveguide unit; and the optical waveguide unit is used for performing all-optical amplitude modulation on the modulated light and the signal light based on the modulation frequency to obtain a modulated optical signal after the saturated absorptivity of the Mxene film layer is excited. As the system can stably output ideal pulse light, the problem of information leakage caused by imperfect light pulse is avoided.

This invention discloses a wavelength-tunable dual-cavity ultrafast fiber laser based on rotating optical fibers and its control method, relating to the field of laser technology. The dual-cavity ultrafast fiber laser of this invention integrates a wavelength division multiplexer within a dual-ring resonant cavity, structurally integrating two wavelength channels, each containing an independent gain fiber, to achieve dual-color soliton output and reduce gain competition. By setting an adjustable rotating fiber filter, consisting of a polarization controller, rotating optical fibers, and a polarization-dependent isolator, in the multiplexing section, the center wavelength of both wavelengths is tunable. Simultaneously, the two sub-cavities share the same saturable absorber to achieve passive synchronous mode-locking, and a delay line is introduced into one of the channels to adjust the equivalent cavity length, achieving repetition frequency matching and timing alignment between the two sub-cavities, thereby obtaining stable, tunable, and synchronous dual-wavelength ultrashort pulse output.

The invention provides a portable mid-infrared pulse fiber laser, a working method and a laser system thereof. The portable mid-infrared pulse fiber laser comprises a pumping source, a first convex lens, a dichroic mirror, a second convex lens, a rare earth ion doped fiber, a third convex lens, a fourth convex lens, a vanadium dioxide saturable absorber, a semiconductor heating sheet, a direct current power supply and a wire which are sequentially arranged along an optical axis. According to the working method, the temperature of the vanadium dioxide saturable absorber is controlled by starting electric control of the semiconductor heating sheet and adjusting the control voltage of the direct-current power supply; when the temperature reaches heat balance, a pumping source is started; the power of the pumping source is increased until the power threshold of the passive Q-switched pumping light is reached, and the dichroscope outputs mid-infrared passive Q-switched pulse laser. The laser system comprises the laser and a control circuit. Under the condition of low pumping power, high-peak-power, high-pulse-energy and nanosecond-level narrow-pulse-width mid-infrared passive Q-switched pulse fiber laser output is achieved; and the portability and the practicability of the laser are improved due to the portability and long-endurance design.

A pulsed laser device including: a III-V-on-silicon type hybrid pulsed laser source, including a gain section and a saturable absorber section which rest on a photonic substrate, and a longitudinal waveguide located in the photonic substrate; a control optical device including an optical pulse emitter source and a lateral waveguide located in the photonic substrate; the waveguides being sized so that the confinement factor Γlae / SA, Γlai / G in the quantum wells of the corresponding section of the optical mode of the lateral waveguide is higher than the confinement factor IL / ms, in the quantum wells of the semiconductor medium, of the optical mode of the longitudinal waveguide.

The present invention discloses a watt-class linear cavity single-frequency fiber oscillator based on dynamic refractive index grating regulation. The oscillator comprises two sections of active optical fiber, which are pumped by two pump sources respectively. The two sections of active optical fiber fully absorb the pump power while still retaining unpumped portions. The standing wave effect in the linear cavity laser generates narrowband refractive index modulation gratings in the unpumped portions of the two sections of active optical fiber. Therefore, the two sections of active optical fiber serve as gain media to provide laser gain and as saturable absorbers to produce a frequency selection effect. The narrowband refractive index modulation gratings in the two sections of active optical fiber form a vernier effect, which enhances frequency selection and ensures that the power output level of the single-frequency fiber oscillator reaches the watt level.

The application provides a saturable absorption device, a preparation method and a low-threshold starting pulse mode-locked laser, and relates to the technical field of lasers. The application discloses a method for preparing a high-quality bismuth copper selenium oxide single crystal by a chemical vapor transport method, and a saturable absorption device prepared by simply using the high-quality bismuth copper selenium oxide single crystal can be applied to a pulse mode-locked laser, and can generate super-short pulse laser output, has high stability and a high signal-to-noise ratio, and has a low starting threshold.

This invention provides a semiconductor mode-locked laser and its fabrication method, relating to the field of optoelectronics. It addresses the problem in existing technologies where femtosecond pulses are difficult to output due to self-phase modulation and dispersion effects, thereby avoiding the use of external pulse compression technology and reducing production costs. The semiconductor mode-locked laser includes a mirror region, a gain region, and a saturable absorption region. The gain region is located between the mirror region and the saturable absorption region and is connected to both regions. The semiconductor mode-locked laser also includes a substrate, and a chirped grating layer and an active layer disposed on the same side of the substrate. The chirped grating layer is located in the mirror region and includes multiple gratings with a grating period linearly decreasing along the emission direction of the semiconductor mode-locked laser. The active layer is located in the gain region and the saturable absorption region, and the distance between the chirped grating layer and the substrate is greater than the distance between the active layer and the substrate.

The application discloses an interference filter type multi-wavelength erbium-doped fiber laser based on optical path difference regulation, relates to the technical field of a ring-shaped tunable multi-wavelength erbium-doped fiber laser, and comprises a pump source, a wavelength division multiplexer, an erbium-doped fiber, an isolator, a first optical fiber coupler, a three-paddle polarization controller, a polarizer, a Mach-Zehnder interferometer filter containing an adjustable delay line, a black phosphorus saturable absorber and an extrusion type polarization controller which constitute a ring cavity. By connecting a 0-6.6 cm continuous adjustable delay line to one arm, the optical path difference of the filter two arms is accurately regulated, and continuous precise tuning of wavelength spacing of 0.3 nm to 1.54 nm is realized; meanwhile, by combining the nonlinear polarization rotation effect and the hybrid mode-locking mechanism of the few-layer black phosphorus, the mode-locking threshold is significantly reduced, and the long-term stability of the pulse is improved. The laser can realize stable emission of up to six wavelengths at the same time, the wavelength drift is less than 0.75 nm, and the power fluctuation is less than 7.0 dB.

The invention relates to an optical fiber-based optical calculation nonlinear activation device, which comprises a micro-nano optical fiber, the micro-nano optical fiber comprises a conical region and standard single-mode optical fibers positioned at two ends of the conical region, a two-dimensional material is deposited on the surface of the conical region, and the two-dimensional material has two absorption mechanisms of saturated absorption and anti-saturated absorption. Different light transmission curves can be obtained on the basis, nonlinear processing of input light signals is achieved, nonlinear operation of input and output is completed, the relaxation time of the two-dimensional material is in the picosecond magnitude, after one-time light calculation is completed, rapid resetting can be achieved within extremely short time, energy does not need to be additionally applied to change the state, the response speed is extremely high, and the method is suitable for large-scale popularization and application. The optical computing nonlinear activation device can meet the requirement for high-speed optical computing, the computing speed of an optical computing system is remarkably increased, and the invention further provides a manufacturing method and system of the optical computing nonlinear activation device.

The invention belongs to the technical field of optical fiber lasers, and discloses a multi-soliton-state adjustable optical fiber laser based on a time delay polarization multiplexing structure. The fiber laser comprises a laser pumping source, a wavelength division multiplexer, an erbium-doped gain fiber, a polarization independent isolator, a mode locking device based on a carbon nanotube saturable absorber, a polarization beam splitter, a polarization beam combiner and an output coupler which are sequentially connected through a single-mode fiber. A time delay polarization multiplexing structure of the optical fiber laser adopts a combination of a polarization beam splitter, a single-mode optical fiber and a polarization beam combiner, and the lengths of the single-mode optical fibers on two branches are obviously different. Therefore, traditional solitons conforming to independent mode locking of the long and short cavities can be output, and long-cavity or short-cavity-dominated master-slave soliton equally-spaced soliton beams and long-cavity and short-cavity periodic alternately-spaced pulse output can be generated. According to the invention, by introducing a time delay polarization multiplexing structure, the limitation of a traditional annular cavity is broken through, and a new solution is provided for the generation and dynamic regulation of multiple soliton states.

The low-noise atom modulation spectrum detection system comprises a signal generator, sine wave signals generated by the signal generator are divided into two paths, one path is output to a laser device, and laser with modulation information is modulated in a current control mode; and the other path provides a reference signal for demodulation of the lock-in amplifier, the output laser is divided into pump light and probe light to ensure generation of saturated fluorescence in the rubidium atom steam chamber, then a low-noise silicon photoelectric detector is used for detecting a saturated fluorescence signal, and the lock-in amplifier demodulates and outputs the modulated saturated fluorescence signal. And meanwhile, a detection path of the saturated absorption spectrum is reserved, so that comparison with a modulated saturated fluorescence spectrum signal is facilitated. According to the invention, the requirement on the size of the atom steam chamber is obviously reduced, and the method is suitable for the application scenes of the Suppler spectrum, such as high-sensitivity, low-noise, anti-interference and miniaturized laser frequency stabilization and atom hyperfine structure detection.

The invention belongs to the technical field of lasers, and particularly relates to a saturable absorber based on liquid metal and a regulation and control method thereof.The saturable absorber comprises an optical fiber, a first two-dimensional material layer and a liquid metal layer; the first two-dimensional material layer is arranged on the end face of the optical fiber, and the liquid metal layer is arranged on the first two-dimensional material layer. By introducing the combination of the liquid metal and the first two-dimensional material layer, the comprehensive advantages of high dynamic adjustability, nonlinear absorption enhancement, efficient fiber integration, intelligent electromagnetic regulation and control and interface stability improvement are realized, and a new technical scheme is provided for a high-performance ultrafast laser and a tunable photonic device.

There is included a spacer portion including a saturable absorption layer provided between a first electrode, which is a back electrode, and a resonator portion. The spacer portion has a first spacer layer provided on the first side with respect to the saturable absorption layer and a second spacer layer provided on the second side with respect to the saturable absorption layer. Each of the first spacer layer and the second spacer layer is of a first conductivity type.

The invention discloses a single-mode fiber laser and method capable of generating multiple dark soliton outputs, and the laser is characterized in that a fiber ring cavity comprises a wavelength division multiplexer, an erbium-doped fiber, a first polarization controller, an analyzer, a second polarization controller, a first output coupler, a fiber isolator, a band-pass filter and an input coupler which are connected in sequence; the input end of the extra-cavity pulse replication unit is connected with the first output coupler through the second output coupler, and the output end of the extra-cavity pulse replication unit is connected with the input coupler. The method comprises the steps that pumping continuous light is coupled into the laser through the wavelength division multiplexer; the erbium-doped fiber is stimulated to radiate a long-wave-band gain pulse; a first polarization controller, an analyzer and a second polarization controller act together to serve as a mode locking starting device, an equivalent saturable absorption effect is generated by nonlinear polarization rotation generated when gain pulses are propagated in an optical fiber, and meanwhile output of a plurality of dark solitons is achieved through the frequency multiplication capacity of an extra-cavity pulse replication unit. The dark soliton generator can output a plurality of dark solitons.

The invention relates to the technical field of optical fiber lasers, in particular to a polarization maintaining optical fiber laser capable of switching pulses and a modulation method of the polarization maintaining optical fiber laser. The polarization-maintaining fiber laser capable of switching the pulses comprises a pumping source used for outputting pumping light; a polarization-maintaining wavelength division multiplexer, a polarization-maintaining optical fiber, a polarization-maintaining optical fiber isolator, a directional carbon tube saturable absorber and a polarization-maintaining coupler are sequentially connected in the light emitting direction of the pumping source; the directional carbon tube saturable absorber is coupled to the end face of the polarization-maintaining jumper, an included angle is formed between the directional carbon tube saturable absorber and the laser polarization direction in the polarization-maintaining jumper, and mode-locked pulses in various states are generated by adjusting the included angle. By directionally adjusting the included angle between the laser polarization direction and the directional carbon tube saturable absorber, more convenient, faster and more stable pulse switching is realized. According to the invention, an optical path structure or an optical element does not need to be frequently adjusted, and accurate pulse state switching can be realized only by adjusting the included angle between the polarization maintaining optical fiber and the directional carbon tube saturable absorber.

The invention provides Nd-doped molybdenum disulfide with adjustable near-infrared nonlinear absorption and a preparation method of the Nd-doped molybdenum disulfide, belongs to the technical field of nano materials, and aims to solve the technical problem of poor near-infrared photoelectric property of MoS2. The preparation method of the Nd-doped molybdenum disulfide comprises the following steps: dissolving a molybdenum source, a sulfur source, a neodymium source and a reducing agent into a solvent to prepare a reaction solution, and performing solvothermal reaction to prepare the Nd-doped molybdenum disulfide nano material. The prepared MoS2 nanosheet is rich in VS, and the band gap of the MoS2 nanosheet is reduced to 0.75 eV and is obviously lower than the standard band gap (1.28-1.98 eV) of intrinsic MoS2, so that the nonlinear optical response at the wavelength of 1064 nm is successfully realized, the SA effect is shown, and the MoS2 nanosheet can be applied to devices such as a saturable absorber, an optical switch and a laser mode locker. Furthermore, by introducing Nd < 3 + > for doping, controllable conversion of nonlinear absorption behavior from SA to RSA along with light intensity change is realized.