42 results about "Laser threshold" patented technology

The invention provides a low-cost ytterbium-doped Yb calcium silicate niobium aluminum gallium laser crystal and a preparation method and application thereof. According to the invention, Al < 3 + > is introduced to replace 50% Ga < 3 + >, Yb < 3 + > ions are doped, and the Yb: Ca3NbAl < x > Ga < 3-x > Si2O14 laser crystal (0lt; xlt; and 3) the raw material cost is greatly reduced, the growth period is shortened, the laser performance of the crystal is improved, the absorption cross section and the emission cross section of the crystal are increased, the half-peak width of absorption and emission peaks is broadened, the oblique efficiency and the light conversion efficiency of continuous laser output are further improved, the laser threshold value is reduced, and watt-level continuous laser output is obtained.

This invention discloses a YAG-based composite laser ceramic and its preparation method. The composite laser ceramic has a five-layer structure from top to bottom: a microstructured concave YAG transparent ceramic, an Nd:YAG transparent ceramic, a YAG transparent ceramic I, a Ce,Nd:YAG transparent ceramic, and a YAG transparent ceramic II. The microstructured concave YAG transparent ceramic is used to reduce the temperature gradient and compensate for the thermal lensing effect; the Nd:YAG transparent ceramic is used to collect the energy emitted by the microstructured concave YAG transparent ceramic and to transfer the energy; the Ce,Nd:YAG transparent ceramic is used for laser energy transfer; and the YAG transparent ceramic I and YAG transparent ceramic II are used to reduce the ceramic thermal lensing effect. It is prepared using thermal bonding technology. The composite laser ceramic of this invention emits bright yellow light near 1064 nm when excited by a laser with a pump source of 808 nm. Furthermore, the composite laser ceramic has a light-to-light conversion efficiency of 19.85% and a laser threshold of 410 mW.

The utility model relates to the technical field of laser equipment, in particular to a laser assembly, a solid-state laser and laser processing equipment, and the laser assembly comprises a birefringent crystal which is used for emitting solid-state laser under the pumping effect, and the solid-state laser comprises two pieces of orthogonal polarized light with different wavelengths; the Q switch is arranged at one end of the birefringent crystal and is used for controlling the output of the solid-state laser; and the dual-wavelength output coupler is arranged at one end, deviating from the birefringent crystal, of the Q switch and is used for coupling and outputting two orthogonal polarized lights in the solid-state laser. Through the mode, the energy loss in the laser pumping cavity can be reduced, so that the laser threshold value is reduced, and the laser output power is improved.

The present invention discloses a quantum dot laser with a low threshold and a preparation method thereof, which includes a quartz substrate, a silica periodic grating, a quantum dot layer, and a silica protective layer stacked in sequence. The quantum dot layer is composed of closely packed mercury selenide quantum dots with a diameter of 4.8 nm to 6.6 nm, mercury sulfide quantum dots with a diameter of 4 nm to 5.2 nm, quantum dots with a core / alloy / shell structure of mercury selenide / mercury cadmium selenide / cadmium selenide with an effective exciton diameter of 4.8 nm to 6.4 nm, or quantum dots with a core / alloy / shell structure of mercury sulfide / mercury cadmium sulfide / cadmium sulfide with an effective exciton diameter of 4 nm to 5 nm. The present invention realizes environmentally stable electron doping in quantum dots by controlling the size of the quantum dots, uses the doped quantum dots as the gain medium of the laser, and further realizes a low gain threshold, a low laser threshold, sustainable continuous laser output, and a designable output wavelength.

In an embodiment a laser circuit includes a video digital-to-analog converter configured to provide a video signal current having a pulse form, a bias digital-to-analog converter configured to provide a bias current and a laser with a first and a second terminal, wherein the first terminal of the laser is coupled to the video digital-to-analog converter and to the bias digital-to-analog converter, wherein a value of the bias current is smaller than a laser threshold value of the laser, wherein a laser current includes the video signal current and the bias current, wherein, in case of a pulse of the video signal current, the laser current is higher than the laser threshold value, and wherein steps between consecutive setable current values of the laser current are smaller in the video digital-to-analog converter than in the bias digital-to-analog converter.

A method of accounting for signal noise in a hybrid laser system is described. The hybrid laser system includes a high reflectivity mirror, a nitrogen-vacancy center diamond, a microwave antenna, a dichroic mirror, a half-vertical cavity surface emitting laser (VCSEL), a birefringent filter, an etalon, an output coupler, and a photodiode. The method includes: measuring a shift in a left-hand side frequency as related to an optically detected magnetic resonance (ODMR) frequency peak of an ODMR signal; measuring a shift in a right-hand side frequency as related to the ODMR frequency peak; normalizing the shift in the left-hand side frequency; normalizing the shift in the right-hand side frequency; and comparing the shift in the left-hand side frequency to the shift in the right-hand side frequency to determine a technical noise associated with the ODMR signal.

An optical fiber sensor capable of simultaneously measuring temperature and strain belongs to the field of optical fiber sensing technology and is composed of a pump source, a wavelength division multiplexer, a 3-dB coupler, a polarization-maintaining optical fiber, an optical fiber grating, a fixed base, a translation stage, an erbium-doped optical fiber wound between the fixed base and the translation stage, a 10:90 optical coupler, and a random grating. The present invention utilizes erbium-doped optical fiber to provide optical gain, and through laser pumping by a pump source, Er 3+ It absorbs pump light and generates stimulated radiation. After reaching the output laser threshold, it generates random laser output. The Sagnac loop structure and fiber Bragg grating are used as temperature sensors, and the erbium-doped fiber winding device is used as a strain sensor. By detecting the wavelength and intensity changes of the output light, the temperature and strain can be measured simultaneously. It has the characteristics of simple manufacturing process, low cost, high sensitivity, etc., and can perform sensing measurements on different ring mirrors.

Light-emitting device configured to emit radiation, comprising: a substrate (50); an epitaxic structure (20) comprising in succession a first DBR stack (21), a light-emitting stack (22), a second DBR stack (23) and several discrete first and second contact regions (241), wherein the light-emitting device emits coherent light having a far-field angle of less than 15 degrees, at a forward current between a laser threshold current and a saturation current therein, and incoherent light at a forward current less than the laser threshold current, wherein the epitaxial structure (20) is arranged on the substrate (50) and further comprises: several first radiation-emitting areas in a first column; and several second radiation-emitting areas in a second column; a conductive layer (60) on the epitaxial structure (20); wherein the contact areas (241) are arranged in a two-dimensional field and are configured to direct a spatially limited current in the light-emitting device to the several first radiation-emitting areas and the several second radiation-emitting areas; and wherein one of the several first contact areas includes a first latitude (w3') and one of the several second contact areas includes a second latitude (w3) that differs from the first latitude (w3').

The invention relates to a low-threshold laser and a preparation method thereof, and belongs to the technical field of lasers. The low-threshold laser of the present invention comprises: a silicon dioxide substrate; the first hexagonal boron nitride layer is arranged on the surface of the silicon dioxide substrate; the monomolecular layer crystal is arranged on the surface of the first hexagonal boron nitride layer; the monomolecular layer crystal is composed of 3, 4, 9, 10-perylenetetracarboxylic dianhydride and a derivative thereof, and the 3, 4, 9, 10-perylenetetracarboxylic dianhydride and the derivative thereof are in long-range ordered arrangement according to a J aggregation mode; the second hexagonal boron nitride layer is arranged on the surface of the monomolecular layer crystal; a sandwich structure formed by the first hexagonal boron nitride layer, the monomolecular layer crystal and the second hexagonal boron nitride layer is an optical resonator. The low-threshold laser realizes continuous laser excitation and output, the wavelength range coverage is wide, the laser threshold is as low as 1.6 nW, and the laser emission stability is high.

The application discloses a preparation method of full-color laser carbon dots based on rhodamine B derivation, which comprises the following steps: ultrasonic dispersion of rhodamine B in a liquid solvent, continuous heating in an autoclave, and preparation of green, yellow, red and near-infrared light carbon dots after filtration, elution, purification and freeze-drying; when rhodamine B is mixed with NaOH or KOH solid, heating is carried out in a beaker to prepare blue light carbon dots; in the application, rhodamine B is used as a precursor, and the carbon dots are synthesized by a solvothermal method; the excellent gain performance of rhodamine B is expanded from orange and red to the whole visible light and near-infrared light region; even the emission effect can be enhanced through cross-linking; the gain performance of the carbon dots is higher than that of rhodamine B, and the carbon dots have higher fluorescence quantum yield, higher radiation transition rate, lower laser threshold and more excellent laser stability.

The invention discloses an anti-oxidation preparation method of two-dimensional tin-based perovskite and application of the two-dimensional tin-based perovskite in a low-threshold long-life laser. According to the method, a double-oxidation inhibition strategy is introduced, the large-size single crystal is synthesized by adopting a two-step growth method in an oxygen-free environment, and Sn < 2 + > oxidation is inhibited by adding electron donating molecules to interact with Sn < 2 + >. The method comprises the following specific steps: dissolving an organic ammonium salt, tin iodide and electron donating molecules in a mixed solvent of hydriodic acid and hypophosphorous acid, and crystallizing through an in-situ two-step supersaturated solution cooling method to obtain the high-purity two-dimensional tin-based perovskite single crystal. The nanosheet obtained through mechanical stripping is used as a gain medium and a resonant cavity, the laser threshold value as low as 0.88 mu J / cm < 2 > is achieved under femtosecond laser excitation, and excellent photoluminescence stability and laser stability are shown. According to the invention, the problems that tin-based perovskite is easy to oxidize and has many defects are solved, and a new idea is provided for the design of the lead-free perovskite nano laser.

The present application relates to a kind of based on optical wavefront shaping and acoustic focusing to realize multimodal photoacoustic angiography method, comprising the following steps: carrying out regional positioning output optimal matching region coordinate, excitation optimal matching region coordinate photoacoustic effect;Focus on laser by wavefront shaping module;Through pulse generator excitation ultrasonic transducer generates ultrasonic pulse;Photoacoustic pressure wave signal and ultrasonic signal are in turn through amplification filter and analog-digital converter;The excited photoacoustic pressure wave and ultrasonic signal are in turn through acoustic focusing adjustment module enhancement;Digital enhancement photoacoustic signal and enhanced ultrasonic signal are carried out image reconstruction.The present application is based on optical wavefront shaping and acoustic focusing to realize multimodal photoacoustic angiography method, system, device, processor and its computer readable storage medium, improve laser energy utilization efficiency, reduce laser threshold, reduce equipment cost, improve deep tissue photoacoustic signal intensity and distribution uniformity.

The application discloses a multi-pass uniform pumping laser device based on blackbody absorption, which comprises a pumping light source, a waveguide and a solid laser medium arranged along an optical path, and a curved surface reflecting device which is arranged on the same side of the pumping light source relative to the solid laser medium and forms a blackbody structure with the solid laser medium, and is used for reflecting the pumping light emitted after being absorbed by the solid laser medium back to the solid laser medium, so that the solid laser medium absorbs the pumping light for multiple passes, and generates and laterally outputs a laser beam. The application utilizes the curved surface reflecting device and the solid laser medium to form a blackbody structure to absorb the pumping light for multiple passes, increases the absorption length of the solid laser medium, can realize uniform pumping, reduces the thermal gradient, reduces the laser threshold, and improves the laser efficiency.

The invention relates to a method for realizing multi-mode photoacoustic angiography based on optical wavefront shaping and acoustic focusing, which comprises the following steps of: carrying out region positioning to output an optimal matching region coordinate, and exciting a photoacoustic effect of the optimal matching region coordinate; the laser is focused through the wavefront shaping module; an ultrasonic transducer is excited by a pulse generator to generate ultrasonic pulses; enabling the photoacoustic pressure wave signal and the ultrasonic signal to pass through an amplification filter and an analog-to-digital converter in sequence; the excited opto-acoustic pressure waves and ultrasonic signals are sequentially enhanced through an acoustic focusing adjustment module; and performing image reconstruction on the digitalized enhanced photoacoustic signal and the enhanced ultrasonic signal. By adopting the method, system and device for realizing multi-mode photoacoustic angiography based on optical wavefront shaping and acoustic focusing, the processor and the computer readable storage medium thereof, the energy utilization efficiency of the laser is improved, the threshold of the laser is reduced, the equipment cost is reduced, and the photoacoustic signal intensity and distribution uniformity of deep tissues are improved.

The application belongs to the field of optical gyroscopes, and particularly relates to a high-sensitivity optical gyroscope based on a single-cavity PT symmetric structure and a design method thereof. The gyroscope is composed of a laser, a ring cavity, an S-shaped waveguide, a coupler and a photodetector. An active S-shaped waveguide and a passive S-shaped waveguide are coupled in the ring cavity. By adjusting the gain / loss value in the active / passive waveguide and the coupling coefficient of the coupler, the system can be adjusted to be near an exceptional point (EP). The gyroscope system at the EP can exhibit extremely high sensitivity to rotation speed. The ring cavity works below the laser threshold, and a power detection technology is used to measure the sensitivity of the gyroscope. Through the technology, the signal-to-noise ratio of the gyroscope can be accurately measured. In addition, by coupling two counter-propagating modes in the same optical resonator, instead of coupling two coupled modes in the double-resonator in the traditional scheme, the area can be reduced by 3 / 4, and the non-reciprocity error caused by the influence of different disturbance sources on the two resonant cavities in the general PT symmetric gyroscope can be suppressed.

The present invention discloses a temperature-tuned RGB cholesteric liquid crystal laser and a preparation method thereof. The structure of the temperature-tuned RGB cholesteric liquid crystal laser includes an optical resonant cavity, and the optical resonant cavity sequentially includes a first reflective layer, a perovskite quantum dot layer, and a second reflective layer from bottom to top; wherein, the first reflective layer includes a cholesteric liquid crystal layer and a polymer protective layer disposed on the cholesteric liquid crystal layer; the cholesteric liquid crystal layer has fluidity; the polymer protective layer does not have fluidity. The present invention has excellent properties such as low laser threshold, high radiation intensity, and good repeatability, and can emit red, green, and blue lasers with specific reflection center wavelengths of the liquid crystal reflective layer at different temperatures, having good application prospects.

The invention discloses a repetition frequency pulse cluster holmium laser and holmium laser equipment. The holmium laser generates laser output of a repetition frequency pulse cluster by adopting pumping of the repetition frequency pulse cluster. The laser pulse cluster comprises at least two sub-pulses, aiming at the quasi 3-energy-level characteristic of holmium laser, when the emission starting moment of the next sub-pulse is located at the long trailing of the previous sub-pulse, the energy of the upper energy level of the laser ion at the tail of the previous laser sub-pulse is turned from waste to treasure, and the energy of the lower energy level of the laser ion at the tail of the previous laser sub-pulse is converted from waste to treasure. The laser threshold value of the next laser sub-pulse is remarkably reduced, the laser working efficiency is improved, high laser sub-pulse energy output under higher PPS is achieved, and the heat effect in a laser working medium is effectively reduced. And the laser energy at the tail of the previous laser sub-pulse generates an injection locking effect on the starting of the next laser sub-pulse, so that the laser beam quality is remarkably improved. The period of the sub-pulse is smaller than the upper energy level service life of the holmium laser and is equivalent to the thermal relaxation time of the stone of the laser lithotripsy target object. When the equipment is used for crushing stones in body fluid, the stone crushing efficiency is high. And bubbles or hollow channels generated by the front laser sub-pulses in water or body fluid are clamped by laser energy at the long tail parts of the front laser sub-pulses and are kept stable until the subsequent sub-pulses appear, so that the characteristics of small stone movement in an operation, convenience in operation, safety and the like are realized.

The invention discloses an ultraviolet emission organic semiconductor and a synthesis method thereof, an ultraviolet emission organic semiconductor single crystal and an organic electroluminescent device based on the ultraviolet emission organic semiconductor single crystal. A stilbene derivative molecule 5F-BBPS is designed and synthesized, a thin single crystal with uniform thickness and the size of more than 25 microns can be prepared by using a macro sublimation method, the crystal can realize laser emission under 360nm femtosecond laser pumping at a lower threshold (less than 4 mu J / cm < 2 >), the measured electron mobility of a field effect transistor made of the single crystal material is 1.03 E-4 cm < 2 > V <-1 > s <-1 >, and the electron mobility of the field effect transistor is 1.03 E-4 cm < 2 > V <-1 > s <-1 >. The organic light emitting diode made of the single crystal material can be lightened. The 5F-BBPS single crystal has a low laser threshold value, and can become a very competitive material in optional materials for realizing the continuous optical pumping organic laser.

The application discloses a kind of for single-color multimode laser output spherical host-guest type micro-nano laser and its preparation method, the micro-nano laser is by the spherical metal organic hybrid material host with distortion topological network structure and laser dye guest composition.Wherein the composition of spherical metal organic hybrid material host is:Zn, organic ligand 2,4,6-tri (3,5-dicarboxyphenyl amino) -1,3,5-triazine, N,N-dimethylformamide.Guest is laser dye.The application is based on spherical metal organic hybrid material as the resonant cavity of micro-nano laser, utilizes its super-smooth surface and excellent circular boundary, avoids boundary scattering loss, effectively provides sufficient feedback for laser oscillation, realizes single-color multimode laser output with high quality factor, narrow half-width, wide mode interval and low laser threshold.Effectively solve the problem that existing micro-nano laser is mostly crystal material, and there is a lot of boundary scattering loss.

The invention discloses a wavelength-adjustable hybrid plasmon micro-nano laser based on TPP and SPP, and belongs to the technical field of lasers, and the wavelength-adjustable hybrid plasmon micro-nano laser comprises a one-dimensional photonic crystal heterostructure based on surface plasmon and Tamm plasmon polariton mode coupling; the one-dimensional photonic crystal heterostructure is formed by stacking a plurality of layers of thin films and sequentially comprises a metal layer, a dielectric spacer layer, a distributed Bragg reflector (DBR) and a substrate from top to bottom. According to the invention, hybridization of two different optical modes is adopted, so that the interaction between surface light and substances is enhanced. Compared with a TPP mode and an SPP mode, the hybrid mode solves the problem of large metal loss and improves the Q value. In the application of the laser, the high Q value characteristic and the Purcell effect of a hybrid mode are utilized, and a four-level gain system is introduced to effectively compensate the loss, so that the laser threshold is remarkably reduced, and the problem that the plasmon laser threshold is too high is solved.

The application provides a 3*3 coupler optimized self-starting O-band eight-character cavity mode-locked laser, relates to the technical field of fiber communication and nonlinear optics, and comprises a pump light source, a wavelength division multiplexer, a bismuth-doped optical fiber, a 1*2 coupler, a 3*3 coupler, an isolator and a polarization controller; the wavelength division multiplexer, the bismuth-doped optical fiber, the 1*2 coupler and the polarization controller form a main ring, the isolator forms a mirror ring, and the main ring and the mirror ring are connected through the 3*3 coupler. The laser constructed by the application utilizes the 120-degree or 2pi / 3 phase shift provided by the 3*3 coupler, significantly reduces the self-starting laser threshold and improves the output power, has a higher power damage threshold compared with a conventional saturable absorbing material, and is a high-efficiency and stable solution provided for the technical field of optical communication and laser.

A very strong selection mechanism is provided in a tunable vertical cavity surface emitting laser (VCSEL) by manipulating the laser threshold to be different for TE and TM polarization by a employing a subwavelength grating in the laser cavity. The laser selects the polarization with the lowest threshold. The grating does not diffract and does not add loss to the cavity. It works by creating a large birefringence layer between the semiconductor and air sub-cavities of the full VCSEL. Multilayer stack calculations show that this results in a lower threshold for the TM polarization over the TE. This subwavelength grating layer, in one embodiment, replaces the AR coating on the semiconductor surface.

This invention discloses a functional polymer / liquid crystal composite semiconductor micro / nano laser and its fabrication method. This laser utilizes the Rayleigh instability of the cylindrical liquid interface to form a functional polymer / liquid crystal spindle structure with a specific morphology on the surface of semiconductor micro / nanowires. This constructs a composite optical microcavity that enhances optical field confinement and suppresses radiation loss, thereby improving the quality factor of the resonant cavity, compressing the resonant linewidth, and lowering the laser threshold. Furthermore, by controlling the size parameters of the functional polymer / liquid crystal spindle and its coverage position on the semiconductor micro / nanowire surface, effective control of the resonant mode is achieved. Based on the relevant properties of the semiconductor material and the polymer / liquid crystal cladding material, this invention exhibits excellent photostability under pulsed light pumping and long-term detection conditions, significantly enhancing the device's specific recognition capability of analyte molecules and its high-sensitivity sensing performance.

The application discloses a Q-switched laser resonator single-pass loss simulation inversion calculation method and system, and belongs to the technical field of laser simulation. The method comprises the following steps: initializing basic parameters related to a resonator and a laser medium; calculating a laser threshold energy storage according to the basic parameters; calculating the energy storage of a laser crystal under different pump currents according to the laser threshold energy storage; calculating the output energy simulation value under each pump current according to the energy storage of the laser crystal; comparing the output energy simulation value with the actual measured value, and obtaining the final simulation result of the resonator single-pass loss according to the comparison result. The application does not need a large number of experimental tests, has low simulation error, is suitable for multiple pump working conditions, is applicable to the loss solving and performance optimization of various Q-switched solid-state lasers, and can significantly improve the laser design efficiency and simulation precision.

The application discloses a wavelength-controllable hybrid plasmonic micro-nano laser based on TPP and SPP, and belongs to the technical field of lasers, comprising a one-dimensional photonic crystal heterostructure based on coupling of a surface plasmon and a Tamm plasmon mode; the one-dimensional photonic crystal heterostructure is stacked by multiple thin films, and from top to bottom, the one-dimensional photonic crystal heterostructure comprises a metal layer, a dielectric spacer layer, a distributed Bragg reflector (DBR) and a substrate. The application adopts hybridization of two different optical modes, and enhances the interaction between surface light and matter. Compared with the TPP mode and the SPP mode, the hybrid mode solves the problem of large metal loss, and improves the Q value. In the application of the laser, the high Q value characteristic and the Purcell effect of the hybrid mode are utilized, and a four-level gain system is introduced to effectively compensate for the loss, so that the laser threshold is significantly reduced, and the problem of high threshold of the plasmonic laser is solved.

The application belongs to the technical field of laser, and discloses a steady-state simulation method, equipment and storage medium of a solid laser. A pump source model is constructed to calculate pump light intensity and photon flux; a crystal heat source distribution is solved based on the pump light intensity, a three-dimensional temperature field and a thermal lens focal length are obtained by using a step-by-step Fourier solving method; the stability is analyzed by dynamically updating the equivalent g parameter and the curvature radius of the resonant cavity by using the thermal lens focal length; the pump absorption and gain distribution are calculated in combination with the pump light intensity, the photon flux and the crystal boundary reflection characteristics; the pump-laser mode overlap factor is calculated based on the beam parameter calculated according to the equivalent g parameter, the pump light intensity and the laser light intensity; the laser threshold power is calculated, and the output power is calculated in combination with the threshold power and the input pump power; the steady-state laser field is iteratively solved based on the equivalent g parameter, the thermal lens focal length and the gain distribution, and finally the simulation result is output, the dynamic coupling feedback of the thermal lens focal length and the resonant cavity parameter is realized, and the simulation precision is significantly improved.

A threshold magnetometer includes a vertical cavity surface-emitting laser with a first material that is disposed in one of the layers. The first material is configured as an absorbent material or emission material to light propagating in the optical resonator. As an absorbent material, the first material absorbs light when exposed to radio frequency (RF) radiation at one or more resonant frequencies. As an emission material, the first material intensifies light when exposed to RF radiation at one or more resonant frequencies. The resultant intensity change can be detected and used to determine characteristics of an external magnetic field.

The invention provides a red light perovskite laser, and relates to the technical field of semiconductor lasers. The red light perovskite laser comprises a perovskite active layer, and two sides of the perovskite active layer are respectively provided with a buffer layer and a reflector from inside to outside in sequence. And the perovskite active layer is a Cs (Pb, Mn) I3 thin film. And the buffer layer is a CsPbBr3 thin film. The reflector comprises a GaN substrate, a reflecting film is epitaxially grown on one side, facing the buffer layer, of the GaN substrate, and the reflecting film is formed by overlapping a GaN film and an n +-GaN film. According to the red light perovskite laser and the preparation method provided by the invention, the red light perovskite laser not only has good stability, but also can reduce non-radiative recombination and reduce the internal loss of an active region, thereby reducing the laser threshold and improving the output efficiency.

The invention discloses a low-threshold quantum dot laser and a preparation method thereof. The low-threshold quantum dot laser comprises a quartz substrate, a silicon dioxide periodic grating, a quantum dot layer and a silicon dioxide protective layer which are sequentially stacked. The quantum dot layer is composed of densely stacked mercury selenide quantum dots with the diameter of 4.8 nm to 6.6 nm, mercury sulfide quantum dots with the diameter of 4 nm to 5.2 nm, and mercury selenide / mercury cadmium selenide / cadmium selenide core / alloy / shell structure quantum dots with the effective exciton diameter of 4.8 nm to 6.4 nm or mercury sulfide / mercury cadmium sulfide / cadmium sulfide core / alloy / shell structure quantum dots with the effective exciton diameter of 4 nm to 5 nm. According to the invention, environment-stable electron doping in the quantum dots is realized by controlling the size of the quantum dots, and the doped quantum dots are used as a gain medium of the laser, so that low gain threshold, low laser threshold, sustainable continuous laser output and designable output wavelength are realized.

The application discloses a preparation method of a near-infrared vertical cavity surface laser with low threshold and high gain based on weakly confined quantum dots, and belongs to the technical field of quantum dot lasers. A CdS shell layer is grown on the weakly confined double-tapered CdSe quantum dots, and the thickness of the CdS shell layer is controlled to be 2 layers by controlling the injection amount of dodecanethiol; the CdSe / CdS quantum dots are spin-coated on the high-reflection surface of two Bragg reflectors (DBRs); and the surfaces coated with the quantum dots are close to each other and are spliced to form a vertical cavity surface laser. The vertical cavity surface laser constructed by taking the weakly confined double-tapered hexahedral CdSe / CdS quantum dots as deep red gain material has deep red / near-infrared laser emission of 720 nm, an extremely low laser threshold of 11.23 µJ / cm 2 and an extremely wide gain bandwidth of 670-730 nm.