124 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 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 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.

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.

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.

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 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 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.

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 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.

The application discloses a kind of high-power laser seed sources for multimodal medical imaging based on germanium saturable absorber, it is characterized in that, including first pump light source, second pump light source and laser resonator, the laser resonator is by first wave division multiplexer, second wave division multiplexer, erbium-doped optical fiber, polarization controller, polarization independent isolator, germanium saturable absorber, single-mode optical fiber, optical coupler sequentially connected, the first pump light source is connected with first wave division multiplexer, and second pump light source is connected with second wave division multiplexer.The germanium saturable absorber prepared in the application has good self-starting effect on pulse, the preparation method is simple, and the preparation cost is not high.And the stability of the obtained saturable absorber is good, and it can be used for passive mode locking for a long time.

The application provides a 2.8 mu m single-frequency fiber laser based on a pump-enhanced saturable absorber and belongs to the technical field of mid-infrared laser. The linear resonant cavity of the laser is composed of a low-refractivity fiber grating and a high-refractivity fiber grating, and a first pump coupler, an erbium-doped fluoride gain fiber, a pump light stripper and a pump-enhanced saturable absorber filter device are sequentially arranged in the cavity. The filter device contains enhanced pump light injected by a second pump source through a second pump coupler and used for exciting the absorption characteristics of the erbium-doped saturable absorption fiber; the laser of the first pump source is used for pumping the gain fiber to generate laser oscillation, and the enhanced pump light is used for forming a MHz-level ultra-narrow band dynamic grating in the saturable absorption fiber. The dynamic grating and the static filter of the fiber grating work cooperatively to realize stable single-longitudinal-mode selection, and finally the single-frequency laser is output from the first fiber end cap. The application realizes compact structure and high stability of 2.8 mu m single-frequency laser output.

The application belongs to the technical field of random number generation, and particularly relates to a random signal generation device based on a saturable absorber semiconductor laser. The device comprises a random self-pulsation entropy source, a photodetector and a pulse amplitude quantization module. The random self-pulsation entropy source adopts a saturable absorber semiconductor laser (preferably a DFB-SA structure), generates optical pulses with random amplitudes and stable repetition periods by injecting a driving current in a gain region and applying a reverse bias voltage in an absorption region; the photodetector adopts a PIN photodiode or an avalanche photodiode to convert the optical pulses into corresponding electrical pulses; and the pulse amplitude quantization module comprises a differential comparator and a peak detection circuit, which quantizes the peak value of the electrical pulses in each pulse period by using a fixed threshold or an adaptive threshold to generate a random bit sequence. The application realizes high-speed and high-stability random signal generation without an external electric clock, an ADC and digital post-processing, and has a simple device structure, low power consumption and high integration.

An optical device and a distance measuring device capable of appropriately detecting an emission timing of oscillation light are provided. An optical device according to the present disclosure includes: a light emitting element including a semiconductor section that is included in a first resonator causing light of a first wavelength to resonate and causes the light of the first wavelength to oscillate, a solid-state laser medium that is included in the first resonator and a second resonator causing light of a second wavelength to resonate and causes the light of the second wavelength to oscillate, and a saturable absorber included in the second resonator and emitting the light of the second wavelength; a detector detecting the light of the first wavelength or a drive current of the light emitting element; and an emission timing detecting unit detecting an emission timing of the light of the second wavelength on the basis of a detection result of the light of the first wavelength or the drive current of the light emitting element acquired using the detector.

The application provides a kind of laser radar exit laser frequency calibration device and method based on hollow cathode lamp, it is related to the technical field of laser radar, device includes: laser generation device, including first seed source and second seed source, the output frequency of one continuous light of first seed source is locked after frequency and the other continuous light is combined after frequency beating, compare output frequency with target frequency, generate the approximate value of lock frequency deviation;The continuous light output by second seed source is amplified after frequency calibration and output;Light source module is used to produce as incident light;Energy regulation module is used to adjust the light intensity of incident light;Absorption signal detection module includes hollow cathode lamp and reflector, for obtaining target saturated absorption spectrum, based on lamb dip method, the continuous light output by second seed source is calibrated according to target saturated absorption spectrum and the approximate value of lock frequency deviation.The frequency locking precision can be improved to 1MHz, which helps high-resolution detection of vertical velocity.

The application discloses a kind of dual-frequency modulation transfer spectroscopy laser frequency stabilization device and method, construct the dual-frequency modulation signal including first frequency component and second frequency component, according to dual-frequency modulation signal driving fiber electro-optic phase modulator to laser is carried out dual-frequency electro-optic phase modulation;Photoelectric detector carries out detection to the polarized beam splitter output light and obtains saturated absorption signal, to saturated absorption signal in turn carries out quadrature demodulation and low-pass filter processing and obtains first error signal and second error signal, first error signal and second error signal are superimposed to obtain dual-frequency error signal;Further, tunable laser is carried out closed-loop feedback control, realizes laser frequency stabilization.The application obtains two different frequency components error signal using dual-frequency modulation transfer spectroscopy detection technology, improves slope and intensity by adding operation, improves frequency discrimination sensitivity and anti-interference ability, is conducive to peak search determination and realizes the precision locking of laser frequency to rubidium absorption peak, with good practicability.

The invention provides a multilayer film saturable absorption mirror based on interference and an optimization method. The multilayer film saturable absorption mirror comprises a saturable absorption material film, a middle interference layer, a gold film and a silicon substrate, the thin film is a flat thin film with a saturable absorption characteristic; the middle interference layer is a ZnS thin film layer deposited on the gold reflector substrate; and the gold film and the silicon substrate jointly form a gold reflector substrate. The thin film interference cancellation condition is achieved by adjusting the thicknesses of the thin film and the middle interference layer, so that the linear reflectivity is extremely low when the light intensity is low; as the light intensity is enhanced, the refractive index of the material is changed and the absorption coefficient is reduced until the material is bleached by strong light, the optical lengths of the thin film and the middle interference layer do not meet destructive interference any more, so that the upper limit of the modulation depth cannot be greatly reduced due to the introduction of the middle interference layer. According to the invention, the linear reflectivity or transmittance of the thin film type saturable absorption mirror at low light intensity can be effectively reduced to enlarge the modulation range, the effect of improving the modulation depth is achieved, and the method is simple to operate, high in flexibility and universal.

The invention discloses a fusion-free femtosecond fiber laser only containing a gain fiber and a laser generation method. The laser is characterized in that an annular cavity comprises a polarization beam splitting crystal, a first fiber collimator, an erbium-doped fiber, a polarization controller and a second fiber collimator which are sequentially distributed in the annular direction; the two ends of the erbium-doped fiber are respectively connected with the first fiber collimator and the second fiber collimator in a screwed manner through two connection joints. The erbium-doped optical fiber is used for absorbing the pump light and generating emission laser; the input end of the third optical fiber collimator is connected with the output tail fiber of the pumping source through a connector, and the output direction of the third optical fiber collimator is aligned with the incident port of the polarization beam splitting crystal. The method comprises the following steps: exciting the erbium-doped fiber to radiate a long-wave-band gain pulse; under the combined action of the polarization controller and the polarization light splitting crystal, an equivalent saturated absorption effect is generated by utilizing nonlinear polarization rotation generated when the pulse is propagated in the gain optical fiber, so that the output of femtosecond pulse is realized. The femtosecond pulse generator can realize self-starting, long-term stable femtosecond pulse output with an extremely simple structure.

The application discloses a graphene-coated surface saturable absorber device of a multimode optical fiber with an internal microstructure, which adopts a mixed structure of graphene and a graded-index multimode optical fiber. The saturable absorber device comprises a first single-mode optical fiber, a mixed structure based on a multimode optical fiber, and a second single-mode optical fiber. The mixed structure based on the multimode optical fiber is composed of a tapered graded-index multimode optical fiber with an internal microstructure and a single-layer graphene film. The graded-index multimode optical fiber is first subjected to a micro-tapering treatment, then a microstructure is inscribed in the core inside the taper waist, then the graphene film is coated on the surface of the taper waist of the optical fiber, and finally the single-mode optical fibers are fused at both ends of the multimode optical fiber. The saturable absorber combines the nonlinear multimode interference effect in the multimode optical fiber and the saturable absorption characteristics of graphene, can perform secondary compression on the pulse width of a high-energy pulse, and thus obtains an ultrashort pulse. The application has the advantages of a solid structure, strong stability, a high damage threshold and the like, and provides an effective technical means for obtaining a stable ultrashort pulse mode locking.

The application discloses a kind of numerical simulation method and system of saturable absorber mode-locked fiber laser, method includes the following steps: setting simulation parameter;Input a noise pulse as the initial pulse of simulation system;The numerical solution of nonlinear Schrödinger equation is calculated by improved step-by-step Fourier method, and the evolution result that pulse is transmitted in optical fiber is obtained;The shaping effect of saturable absorber to pulse is simulated using the transmissivity function of saturable absorber;Coupler solver redistributes the energy of pulse;Post-processing module saves the data when pulse stops running, and it is drawn into the curve graph and three-dimensional graph of pulse shape and pulse spectrum.The simulation method and system disclosed in the application can solve the problem of low calculation precision of dispersion term in fiber laser simulation, greatly improve the simulation accuracy, and can more accurately predict the output characteristics of mode-locked fiber laser.

This invention discloses a method for preparing magnesium antimonide quantum dot optical limiting materials and their applications, belonging to the field of novel inorganic semiconductor quantum dot material preparation. The preparation method involves grinding magnesium antimonide powder in an agate mortar, then placing the ground magnesium antimonide powder in an appropriate amount of ionic liquid solvent. The solution is subjected to ice bath ultrasonic exfoliation, followed by a first centrifugation. The supernatant is then dialyzed, followed by a second centrifugation and freeze-drying to obtain magnesium antimonide quantum dot samples. The ionic liquid solvent used in this invention has advantages such as being green, environmentally friendly, having a high boiling point, and high conductivity. The obtained magnesium antimonide quantum dots have a size of 2 nm to 4 nm, exhibiting antisaturated absorption characteristics and high linear transmittance, balancing protective performance with normal optical functions, and showing good application prospects in fields such as nonlinear optics.

The application provides a 1.7-micron-band single-frequency fiber laser based on a composite glass optical fiber, which comprises a long linear cavity, and the long linear cavity comprises, in sequence, a high-reflection Bragg grating (3), a composite glass optical fiber (4), a saturable absorber (5) and a low-reflection Bragg grating (6). 3+ The composite glass optical fiber is a multimode optical fiber, has a double-clad structure, and the core is Tb 3+ The inner cladding is Tm 3+ The outer cladding is undoped rare earth composite glass. The 1.7-micron-band single-frequency fiber laser is compact in structure, high in efficiency and narrow in line width, and can be applied to the fields of gas sensing, precision measurement, laser radar and the like.