CN115483603A - Near-infrared laser based on silver selenide nanocrystals and its preparation method - Google Patents

Abstract

The invention provides a near-infrared laser based on silver selenide nanocrystalline and a preparation method thereof, wherein the near-infrared laser based on the silver selenide nanocrystalline sequentially comprises the following components: the device comprises a substrate, a distributed feedback grating layer and a silver selenide nanocrystalline layer; the silver selenide nanocrystalline layer is composed of silver selenide nanocrystals, and the silver selenide nanocrystals are in a tetragonal phase with the diameter range of 6-10 nm. The silver selenide nanocrystal is used as an optical gain medium of the laser, so that the band-edge state optical gain with zero threshold is realized; the relative position of the conduction band bottom of the silver selenide nanocrystal and the Fermi level of the environment is adjusted by adjusting the size of the silver selenide nanocrystal by utilizing the quantum confinement effect, so that the band edge electronic state 1S is obtained _e The silver selenide nanocrystalline occupied by electrons has adjustable near-infrared emission wavelength, does not need to be added with a hole trapping agent which is easy to oxidize, is stable in atmospheric environment, and has a crystal structure and a surface state which cannot be damaged; the silver selenide material of the inventionThe material is a low-toxicity environment-friendly material and is environment-friendly.

Description

Near-infrared laser based on silver selenide nanocrystals and its preparation method

technical field

The invention relates to the technical field of semiconductor optoelectronic devices, in particular to a near-infrared laser based on silver selenide nanocrystals and a preparation method thereof.

Background technique

Laser technology has a wide range of applications in communication, medical treatment, scientific research and other fields, and has great market demand. Laser threshold is one of the core issues in the field of laser research. How to reduce the laser threshold and find new materials with low threshold is the focus of laser technology.

In recent years, semiconductor nanocrystals have become a research hotspot of optical gain materials due to their excellent luminescent properties such as continuously tunable wavelength, narrow-band emission, and high photoluminescence quantum yield. Thanks to the quantum confinement effect, semiconductor nanocrystals exhibit a variety of superior properties as optical gain materials, such as tunable emission wavelength and temperature-insensitive optical gain threshold with the size of semiconductor nanocrystals. However, due to the multiple degeneracy of the band-edge states, to achieve the optical gain of the band-edge states, the number of excitons contained in the semiconductor nanocrystal must be greater than half of the degeneracy of the band-edge states, that is, half of the number of electrons that can be accommodated. For example, to achieve optical gain in PbSe nanocrystals with 8-fold degenerate band-edge states, the number of excitons in semiconductor nanocrystals must be greater than 4. This severely limits the optical gain threshold of semiconductor nanocrystals, making it difficult to achieve excitation and emission of continuous optical pumping or electrical pumping, and can only be pumped with pulsed lasers.

In view of the above, it is necessary to provide a near-infrared laser based on silver selenide nanocrystals and its preparation method to obtain a laser with zero threshold, high stability, adjustable emission wavelength in the near-infrared range and environmental protection.

Contents of the invention

In view of the shortcomings of the prior art described above, the object of the present invention is to provide a near-infrared laser based on silver selenide nanocrystals and a preparation method thereof, so as to obtain zero threshold, high stability, and emission wavelengths that can be used in the near-infrared range. Tuning and environmentally friendly lasers.

In order to achieve the above purpose and other related purposes, the invention provides a near-infrared laser based on silver selenide nanocrystals, said near-infrared laser based on silver selenide nanocrystals comprises in turn:

Substrate, distributed feedback grating layer and silver selenide nanocrystalline layer;

The silver selenide nanocrystal layer is composed of silver selenide nanocrystals, the silver selenide nanocrystals are in a tetragonal crystal phase, and the diameter ranges from 6nm to 10nm.

Optionally, the silver selenide nanocrystal layer is composed of closely packed silver selenide nanocrystals.

Optionally, the product of the grating period of the distributed feedback grating and the effective refractive index is equal to the band-edge emission peak wavelength of the silver selenide nanocrystal.

Optionally, the silver selenide nanocrystal-based near-infrared laser further includes an encapsulation layer, and the encapsulation layer is located above the silver selenide nanocrystal layer.

Optionally, the material of the substrate is one of silicon, mica, aluminum oxide and silicon dioxide; the material of the distributed feedback grating layer is silicon dioxide, aluminum oxide, magnesium difluoride and One of lithium fluoride; the material of the encapsulation layer is one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride.

The present invention also provides a method for preparing a near-infrared laser based on silver selenide nanocrystals, which is used to prepare the above-mentioned near-infrared laser based on silver selenide nanocrystals. The preparation method includes:

S1: Provide a substrate, and prepare silver selenide nanocrystals with a diameter ranging from 6nm to 10nm and a tetragonal crystal phase, and then disperse the silver selenide nanocrystals in a toluene solution to obtain a toluene dispersion of silver selenide nanocrystals ;

S2: forming a distributed feedback grating layer on the substrate;

S3: Spin-coat the toluene dispersion of silver selenide nanocrystals obtained in step S1 on the distribution feedback grating layer to obtain a silver selenide nanocrystal layer.

Optionally, in step S3, after the toluene dispersion of silver selenide nanocrystals is spin-coated on the distributed feedback grating layer, the step of annealing under the protection of an inert gas is also included.

Optionally, in step S3, after obtaining the silver selenide nanocrystal layer, a step of forming an encapsulation layer on the silver selenide nanocrystal layer is also included.

As mentioned above, the silver selenide nanocrystal-based near-infrared laser and its preparation method of the present invention have the following beneficial effects:

The present invention utilizes silver selenide nanocrystals with a diameter of 6nm to 10nm in a square crystal phase as an optical gain medium, and when the band gap width of the bulk material silver selenide nanocrystals 11 in a tetragonal crystal phase is only 0.07eV, the environmental Fermi level is 60 Above the bottom of the conduction band (as shown in Figure 3(a) and Figure 3(b)), the bottom of the conduction band is occupied by electrons. Due to the quantum confinement effect, silver selenide nanocrystals exhibit discrete energy levels similar to atoms, and the forbidden band width increases with the decrease of the size of silver selenide nanocrystals. When the diameter of the silver selenide nanocrystal of the tetragonal crystal phase is reduced to 6nm (as shown in Figure 4 (a) and Figure 4 (b)), the environmental Fermi level of the silver selenide nanocrystal 12 with a diameter of 6nm is 60 is still higher than the band-edge electronic state 1S _e , which is occupied by electrons in the unexcited state ₍ as shown in Figure 6(a)), at this time, the band-edge absorption is bleached, that is, the excitons from The transition from the _h state to the 1S _e state is forbidden, and at the same time, the band-edge emission is also forbidden, that is to say, in the unexcited state, the silver selenide nanocrystal population is transparent to photons with the same energy as the forbidden band width, both Neither absorption nor gain can be produced, as long as there is a silver selenide nanocrystal in the silver selenide nanocrystal layer 40 excited by a photon with an energy greater than or equal to the energy gap between the 1S _h state and the 1P _e state (as shown in Figure 6(b) shown), the electrons on the band-edge hole state 1S _h are excited to the 1P _e state or to a higher energy level and then relax to the 1P _e state, leaving a hole in the 1S _h state. This silver selenide nanocrystal Then the inversion of the number of particles in the band-edge state is realized, and the entire silver selenide nanocrystal layer 40 forms an optical gain at the band-edge emission wavelength. Edge state light gain. When the diameter of silver selenide nanocrystals is less than 6 nm, for example, the ambient Fermi level 60 of silver selenide nanocrystals 13 with a diameter of 3 nm is lower than the band-edge electronic state 1S _{e ,} which is not occupied by electrons (As shown in Figure 5(a) and Figure 5(b)), at this time, the band edge absorption is not bleached, that is, the transition of electrons from 1S _h to 1S _e is not prohibited, that is, in the unexcited state In this case, the silver selenide nanocrystal population exhibits absorption for photons with the same energy as the forbidden band width. Because the silver selenide band edge state is double-degenerate, only when the average number of excitons in each silver selenide nanocrystal in the silver selenide nanocrystal population, that is, the number of absorbed photons, is greater than 1, the population inversion can be obtained. Restricting the diameter of silver selenide nanocrystals to be greater than 10nm is to enhance the quantum confinement effect and obtain the general advantages of nanocrystals as optical gain materials, that is, the near-infrared emission wavelength and temperature insensitivity that can be adjusted with the size of silver selenide nanocrystals Optical gain threshold.

The present invention uses silver selenide nanocrystals with a diameter of 6nm to 10nm in a square crystal phase as the optical gain medium of the laser, and realizes a zero-threshold band edge state optical gain; the present invention uses the quantum confinement effect to adjust the silver selenide nanocrystal The size of the crystal can be used to adjust the relative position of the conduction band bottom of the tetragonal silver selenide nanocrystal and the environmental Fermi level, so as to obtain the silver selenide nanocrystal whose band-edge electronic state 1S _e is occupied by electrons, and the emission wavelength is in the near-infrared band Internally adjustable, no need to add easily oxidized hole scavengers, and the silver selenide nanocrystals whose band-edge electronic state 1S _e is occupied by electrons are stable in the atmospheric environment, and the crystal structure and surface state will not be destroyed; The silver selenide material of the invention is a low-toxic, environment-friendly material and is environmentally friendly.

Description of drawings

Fig. 1 is a schematic diagram showing the structure of silver selenide nanocrystals of the present invention.

Fig. 2 is a schematic diagram showing the structure of a near-infrared laser based on silver selenide nanocrystals of the present invention.

Fig. 3(a) is a schematic diagram showing the structure of the bulk material silver selenide nanocrystal of the present invention, and Fig. 3(b) is a schematic diagram showing the energy level structure of the bulk material silver selenide nanocrystal of the present invention.

Figure 4(a) shows a schematic diagram of the structure of silver selenide nanocrystals with a diameter of 6nm in the present invention, and Figure 4(b) shows a schematic diagram of the energy level structure of silver selenide nanocrystals with a diameter of 6nm in the present invention.

Figure 5(a) shows a schematic diagram of the structure of the silver selenide nanocrystal with a diameter of 3nm in the present invention, and Figure 5(b) shows a schematic diagram of the energy level structure of the silver selenide nanocrystal with a diameter of 3nm in the present invention.

Fig. 6 (a) shows that the silver selenide nanocrystal with a diameter of 6nm of the present invention is in the unexcited excitonic state and the energy level structure schematic diagram, and Fig. 6 (b) shows that the silver selenide nanocrystal with a diameter of 6nm of the present invention is in Schematic diagram of the excitonic state and energy level structure after excitation.

FIG. 7 is a schematic flow chart of the method for preparing a near-infrared laser based on silver selenide nanocrystals of the present invention.

FIG. 8 to FIG. 11 show the structural schematic diagrams presented in each step of the preparation method of the silver selenide nanocrystal-based near-infrared laser according to the present invention.

Component designation description

10, silver selenide nanocrystals; 11, bulk material silver selenide nanocrystals; 12, silver selenide nanocrystals with a diameter of 6nm; 13, silver selenide nanocrystals with a diameter of 3nm; 20, substrate; 30, distributed feedback Grating; 40, silver selenide nanocrystalline layer; 50, encapsulation layer; 60, ambient Fermi level.

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

See Figures 1 through 11. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, so that only the components related to the present invention are shown in the diagrams rather than the number, shape and Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

Embodiment one

As shown in Figures 1 to 2, the present invention provides a near-infrared laser based on silver selenide nanocrystals, the near-infrared laser based on silver selenide nanocrystals includes in turn:

Substrate 20, distributed feedback grating layer 30 and silver selenide nanocrystalline layer 40 (as shown in Figure 2);

The silver selenide nanocrystal layer 40 is composed of silver selenide nanocrystals 10, and the silver selenide nanocrystals 10 are in a tetragonal crystal phase with a diameter ranging from 6 nm to 10 nm (as shown in FIG. 1 ).

The working principle of this embodiment is: the excited photon energy received by the near-infrared laser based on silver selenide nanocrystals is greater than or equal to the energy gap between the 1S _h state and the 1P _e state of the silver selenide nanocrystals, and the silver selenide When the band-edge electronic state 1S _e of the nanocrystal 10 is occupied by electrons in an unexcited state, the laser emission of the near-infrared laser based on the silver selenide nanocrystal can be emitted from the upper surface of the silver selenide nanocrystal layer 40 or The lower surface of the substrate 20 is output.

This embodiment utilizes silver selenide nanocrystals with a diameter of 6nm to 10nm in the tetragonal crystal phase as the optical gain medium. When the band gap of the bulk material silver selenide nanocrystals 11 in the tetragonal crystal phase is only 0.07eV, the environmental Fermi level 60 is higher than the bottom of the conduction band (as shown in Figure 3(a) and Figure 3(b)), and the bottom of the conduction band is occupied by electrons. Due to the quantum confinement effect, silver selenide nanocrystals exhibit discrete energy levels similar to atoms, and the forbidden band width increases with the decrease of the size of silver selenide nanocrystals. When the diameter of the silver selenide nanocrystal of the tetragonal crystal phase is reduced to 6nm (as shown in Figure 4 (a) and Figure 4 (b)), the environmental Fermi level of the silver selenide nanocrystal 12 with a diameter of 6nm is 60 is still higher than the band-edge electronic state 1S _e , which is occupied by electrons in the unexcited state ₍ as shown in Figure 6(a)), at this time, the band-edge absorption is bleached, that is, the excitons from The transition from the _h state to the 1S _e state is forbidden, and at the same time, the band-edge emission is also forbidden, that is to say, in the unexcited state, the silver selenide nanocrystal population is transparent to photons with the same energy as the forbidden band width, both No absorption and no gain, as long as one silver selenide nanocrystal in the silver selenide nanocrystal layer is excited by a photon whose energy is greater than or equal to the energy gap between the 1S _h state and the 1P _e state (as shown in Figure 6(b) shown), the electrons on the band-edge hole state 1S _h are excited to the 1P _e state or to a higher energy level and then relax to the 1P _e state, leaving a hole in the 1S _h state, and the silver selenide nanocrystal The particle number inversion of the band-edge state is realized, and the entire silver selenide nanocrystal layer forms an optical gain at the band-edge emission wavelength, so the use of a tetragonal silver selenide nanocrystal with a diameter greater than 6nm can achieve a zero-threshold band-edge state light gain. When the diameter of silver selenide nanocrystals is less than 6 nm, for example, the ambient Fermi level 60 of silver selenide nanocrystals 13 with a diameter of 3 nm is lower than the band-edge electronic state 1S _{e ,} which is not occupied by electrons (As shown in Figure 5(a) and Figure 5(b)), at this time, the band edge absorption is not bleached, that is, the transition of electrons from 1S _h to 1S _e is not prohibited, that is, in the unexcited state In this case, the silver selenide nanocrystal population exhibits absorption for photons with the same energy as the forbidden band width. Because the silver selenide band edge state is double-degenerate, only when the average number of excitons in each silver selenide nanocrystal in the silver selenide nanocrystal population, that is, the number of absorbed photons, is greater than 1, the population inversion can be obtained. Restricting the diameter of silver selenide nanocrystals to be greater than 10nm is to enhance the quantum confinement effect and obtain the general advantages of nanocrystals as optical gain materials, that is, the near-infrared emission wavelength and temperature insensitivity that can be adjusted with the size of silver selenide nanocrystals Optical gain threshold.

This embodiment uses silver selenide nanocrystals with a diameter of 6nm to 10nm in a square crystal phase as the optical gain medium of the laser, and realizes a zero-threshold band edge state optical gain; this embodiment utilizes the quantum confinement effect to adjust the selenide The size of the silver nanocrystals is used to adjust the relative position of the conduction band bottom of the tetragonal silver selenide nanocrystals and the environmental Fermi level 60, so as to obtain the silver selenide nanocrystals whose band-edge electronic state 1S _e is occupied by electrons, and the emission wavelength is at It is adjustable in the near-infrared band, without adding easily oxidized hole trapping agents, and the silver selenide nanocrystals whose band-edge electronic state 1S _e is occupied by electrons are stable in the atmospheric environment, and the crystal structure and surface state will not change. Destroyed; the silver selenide material of this embodiment is a low-toxic, environmentally friendly material that is environmentally friendly.

As an example, the silver selenide nanocrystal layer 40 is composed of the silver selenide nanocrystals 10 closely packed.

Packing the silver selenide nanocrystals 10 closely can increase the net mode gain of the silver selenide nanocrystal layer 40, which is beneficial to increase the laser emission intensity.

As an example, the product of the grating period of the distributed feedback grating 30 and the effective refractive index is equal to the band-edge emission peak wavelength of the silver selenide nanocrystal 10 .

Such an arrangement can provide optical feedback for the gain medium of the laser, that is, the silver selenide nanocrystal layer 40 , so as to obtain laser emission.

As an example, the near-infrared laser based on silver selenide nanocrystals further includes an encapsulation layer 50 , and the encapsulation layer 50 is located above the silver selenide nanocrystal layer 40 .

Forming the encapsulation layer 50 on the silver selenide nanocrystal layer 40 can further improve the stability of the silver selenide nanocrystal-based near-infrared laser and prolong its service life.

As an example, the gratings of the distributed feedback grating 30 are arranged periodically, and the shape can be set according to the actual situation, and there is no limitation here, such as regular periodic raised rectangles, cylinders or polygonal cylinders.

As an example, the material of the substrate 20 is one of silicon, mica, aluminum oxide and silicon dioxide; the material of the distributed feedback grating layer 30 is silicon dioxide, aluminum oxide, magnesium difluoride and one of lithium fluoride; the material of the encapsulation layer 50 is one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride.

The materials used in the device structure of the silver selenide nanocrystal-based near-infrared laser can be the same or different, as long as the device has good heat dissipation and stable performance. There is no limit here, and it can be set according to actual needs.

In this embodiment, the material of the substrate 20 is preferably aluminum oxide, the material of the distributed feedback grating layer 30 is preferably aluminum oxide, and the material of the packaging layer 50 is preferably aluminum oxide.

The aluminum oxide material is preferred as the material for the device structure of the near-infrared laser based on silver selenide nanocrystals because of its low cost, good heat dissipation and good stability.

As an example, the near-infrared laser based on silver selenide nanocrystals further includes a pump source for exciting the silver selenide nanocrystal layer 40 .

The emission photon energy of the pump source is greater than or equal to the energy gap between the silver selenide nanocrystal 10 1S _h state and the 1P _e state, and the pump photons are emitted from the upper surface of the packaging layer 50 or the lower surface of the substrate 20 The injection is to excite the near-infrared laser based on silver selenide nanocrystals, so that the laser emission of the laser is output from the upper surface of the encapsulation layer 50 or the lower surface of the substrate 20 .

It should be noted here that since the laser emission is output from the upper surface of the encapsulation layer 50 or the lower surface of the substrate 20 along the vertical direction of the device, the pump photons need to be emitted from the upper surface of the encapsulation layer 50 or the lower surface of the substrate 20 The oblique implantation on the surface avoids coincidence with the laser emission, and the inclination angle of the oblique injection of pump photons can be set according to the actual situation, which is not limited here.

Embodiment two

This embodiment provides a method for preparing a near-infrared laser based on silver selenide nanocrystals, which is used to prepare the near-infrared laser based on silver selenide nanocrystals in the first embodiment. The preparation method includes:

S1: Provide a substrate, prepare silver selenide nanocrystals 10 with a diameter ranging from 6nm to 10nm and a tetragonal crystal phase, and then disperse the silver selenide nanocrystals 10 in a toluene solution to obtain silver selenide nanocrystals in toluene Dispersions;

S2: forming a distributed feedback grating layer 30 on the substrate 20;

S3: Spin-coat the toluene dispersion of silver selenide nanocrystals obtained in step S1 on the distributed feedback grating layer 30 to obtain a silver selenide nanocrystal layer 40 .

As shown in FIG. 7 to FIG. 11 , this embodiment will be further described below in conjunction with the accompanying drawings.

As shown in Figures 7 and 8, as an example, step S1 is first performed to provide a substrate 20, and to prepare a silver selenide nanocrystal 10 with a diameter ranging from 6nm to 10nm and a tetragonal crystal phase, and then the silver selenide The nanocrystal 10 is dispersed in the toluene solution to obtain the silver selenide nanocrystal toluene dispersion.

The silver selenide nanocrystal 10 in the tetragonal crystal phase with a diameter of 6nm to 10nm is prepared by using a metal-organic method and controlling the reaction time, and the silver selenide nanocrystal 10 is dispersed in a toluene solution, wherein the toluene solution The concentration needs to be adjusted to 20mg/ml. The material of the substrate 20 is one of silicon, mica, aluminum oxide and silicon dioxide. In this embodiment, the aluminum oxide material is preferably used because of its low cost, good heat dissipation, and good stability. .

As shown in FIG. 7 and FIG. 9 , as an example, step S2 is followed to form a distributed feedback grating layer 30 on the substrate 20 .

The material of the distributed feedback grating 30 in this embodiment is one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride. In this embodiment, the material of aluminum oxide is low in cost. Good heat dissipation and good stability are preferred. The distributed feedback grating 30 is periodically arranged, and the shape can be set according to the actual situation, and there is no limitation here. For example, it is a regular periodic raised rectangle, cylinder or polygon cylinder. A raised rectangular body with regular periodicity. It should be noted here that the product of the grating period of the distributed feedback grating 30 and the effective refractive index is equal to the band-edge emission peak wavelength of the silver selenide nanocrystal 10, providing optical feedback for the silver selenide nanocrystal layer 40 , so as to obtain laser emission. In this embodiment, a layer of Al2O3 is formed on the substrate 20 first, and then a reactive ion etching method is used to etch the Al2O3 distributed feedback grating on the surface of the Al2O3.

In another preferred embodiment, the substrate 20 and the distributed feedback grating layer 30 are made of Al2O3 material, which can be set as one body, and a thick Al2O3 substrate can be directly provided, and the reactive ion etching method can be used in the The aluminum oxide distributed feedback grating is etched on the surface of the aluminum oxide substrate.

As shown in Figure 7 and Figure 10, as an example, then proceed to step S3, spin-coat the silver selenide nanocrystalline toluene dispersion liquid obtained in step S1 on the distribution feedback grating layer 30 to obtain silver selenide nanocrystals crystal layer 40.

Spin-coat the toluene dispersion of silver selenide nanocrystals obtained in step S1 on the distribution feedback grating 30 at a speed of 2500 rpm. In this embodiment, the toluene dispersion of silver selenide nanocrystals is spin-coated on the aluminum oxide distribution feedback grating at a speed of 2500 rpm.

As a preferred example, in step S3, after the toluene dispersion of silver selenide nanocrystals is spin-coated on the distributed feedback grating layer 40, annealing under the protection of an inert gas is also included.

Annealing the distributed feedback grating layer 30 spin-coated with the toluene dispersion of silver selenide nanocrystals under the protection of an inert gas at 60° C. for half an hour to increase the density of the stacked silver selenide nanocrystals to obtain the silver selenide nanocrystalline layer 40 . The annealed silver selenide nanocrystal 10 can increase the net mode gain of the silver selenide nanocrystal layer 40 , which is beneficial to increase the laser emission intensity.

As shown in FIG. 11 , as a preferred example, in step S3 , after obtaining the silver selenide nanocrystal layer 40 , a step of forming an encapsulation layer 50 on the silver selenide nanocrystal layer 40 is also included.

The encapsulation layer 50 is deposited on the silver selenide nanocrystalline layer 40 by atomic layer deposition. A layer of aluminum oxide is deposited on the silver selenide nanocrystalline layer 40 to form the encapsulation layer 50 .

Depositing the encapsulation layer 50 on the silver selenide nanocrystalline layer 40 can further improve the stability of the laser device and prolong the service life of the laser.

In summary, the present invention provides a near-infrared laser based on silver selenide nanocrystals and a preparation method thereof. The near-infrared laser based on silver selenide nanocrystals comprises in turn: a substrate, a distributed feedback grating layer, and a silver selenide Nanocrystalline layer: the silver selenide nanocrystalline layer is composed of silver selenide nanocrystals, the silver selenide nanocrystals are in a tetragonal crystal phase, and the diameter ranges from 6nm to 10nm. The present invention uses silver selenide nanocrystals with a diameter of 6nm to 10nm in a square crystal phase as the optical gain medium of the laser, and realizes a zero-threshold band edge state optical gain; the present invention utilizes the quantum confinement effect to adjust the crystallite size to adjust the relative position of the conduction band bottom of the tetragonal silver selenide nanocrystals and the ambient Fermi level, so as to obtain the silver selenide nanocrystals whose band-edge electronic state 1S _e is occupied by electrons, the emission wavelength is adjustable, and no need Add the hole trapping agent that is easily oxidized, and the silver selenide nanocrystal that band edge electronic state 1S _e is occupied by electron is stable under atmospheric environment, and crystal structure and surface state also can not be destroyed; Selenization of the present invention The silver material is an environmentally friendly material with low toxicity and is friendly to the environment. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention shall still be covered by the claims of the present invention.

Claims (9)

1. a near-infrared laser based on silver selenide nanocrystals, characterized in that, said near-infrared laser based on silver selenide nanocrystals comprises successively: Substrate, distributed feedback grating layer and silver selenide nanocrystalline layer; The silver selenide nanocrystal layer is composed of silver selenide nanocrystals, the silver selenide nanocrystals are in a tetragonal crystal phase, and the diameter ranges from 6nm to 10nm. 2. The near-infrared laser based on silver selenide nanocrystals according to claim 1, characterized in that: the silver selenide nanocrystal layer is composed of closely packed silver selenide nanocrystals. 3. the near-infrared laser based on silver selenide nanocrystals according to claim 1, is characterized in that: the grating period of described distributed feedback grating and the product of effective refractive index are equal to the band edge emission of described silver selenide nanocrystals peak wavelength. 4. The near-infrared laser based on silver selenide nanocrystals according to claim 1, characterized in that: the near-infrared laser based on silver selenide nanocrystals also includes an encapsulation layer, and the encapsulation layer is located on the selenide above the silver nanocrystal layer. 5. the near-infrared laser based on silver selenide nanocrystal according to claim 4, is characterized in that: the material of described substrate is the one in silicon, mica, aluminum oxide and silicon dioxide; The material of the feedback grating layer is one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride; the material of the packaging layer is silicon dioxide, aluminum oxide, magnesium difluoride and fluorine One of the lithium oxides. 6. the near-infrared laser based on silver selenide nanocrystals according to claim 1, is characterized in that: the near-infrared laser based on silver selenide nanocrystals also includes a pumping source, for the silver selenide The nanocrystalline layer is excited. 7. A method for preparing a near-infrared laser based on silver selenide nanocrystals, used to prepare the near-infrared laser based on silver selenide nanocrystals as described in any one of claims 1 to 6, wherein the Said preparation method comprises: S1: Provide a substrate, and prepare silver selenide nanocrystals with a diameter ranging from 6nm to 10nm and a tetragonal crystal phase, and then disperse the silver selenide nanocrystals in a toluene solution to obtain a toluene dispersion of silver selenide nanocrystals ; S2: forming a distributed feedback grating layer on the substrate; S3: Spin-coat the toluene dispersion of silver selenide nanocrystals obtained in step S1 on the distribution feedback grating layer to obtain a silver selenide nanocrystal layer. 8. the preparation method based on the near-infrared laser of silver selenide nanocrystal according to claim 7 is characterized in that: in step S3, described silver selenide nanocrystal toluene dispersion liquid is spin-coated on described distribution feedback After the grating layer, an annealing step under the protection of inert gas is also included. 9. the preparation method of the near-infrared laser based on silver selenide nanocrystal according to claim 7, it is characterized in that: in step S3, after obtaining described silver selenide nanocrystal layer, also include in described selenide A step of forming an encapsulation layer on the silver nanocrystal layer.

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