CN115483603A - Near-infrared laser based on silver selenide nanocrystalline and preparation method thereof - Google Patents
Near-infrared laser based on silver selenide nanocrystalline and preparation method thereof Download PDFInfo
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- CN115483603A CN115483603A CN202211287904.8A CN202211287904A CN115483603A CN 115483603 A CN115483603 A CN 115483603A CN 202211287904 A CN202211287904 A CN 202211287904A CN 115483603 A CN115483603 A CN 115483603A
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
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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
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
The laser technology has wide application in the fields of communication, medical treatment, scientific research and the like, and has great market demand. Laser threshold is one of the core problems in the research of the laser field, and how to reduce the laser threshold and search for new materials with low threshold is a subject of important attention in the laser technology.
In recent years, semiconductor nanocrystals have been the focus of research for optical gain materials due to their excellent luminescence properties such as continuously tunable wavelength, narrow-band emission, and high photoluminescence quantum yield. Thanks to the quantum confinement effect, the semiconductor nanocrystals exhibit a variety of superior properties as optical gain materials, such as tunable emission wavelength with the size of the semiconductor nanocrystal and temperature insensitive optical gain thresholds. However, due to the multiple degeneracy of the band edge states, in order to realize the optical gain of the band edge states, the semiconductor nanocrystals must contain more excitons than half the degeneracy of the band edge states, i.e., half the number of electrons that can be accommodated. For example, to achieve optical gain with an 8-fold degenerate PbSe nanocrystal with edge states, the exciton in the semiconductor nanocrystal must be greater than 4. This severely limits the optical gain threshold of semiconductor nanocrystals, making it difficult to achieve continuous optical or electrically pumped stimulated emission, but only pulsed laser pumping.
In view of the above, there is a need to provide a near-infrared laser based on silver selenide nanocrystals and a method for preparing the same, so as to obtain a laser with zero threshold, high stability, tunable emission wavelength in the near-infrared range, and environmental friendliness.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present invention provides a near-infrared laser based on silver selenide nanocrystals and a method for preparing the same, so as to obtain a laser with zero threshold, high stability, adjustable emission wavelength in the near-infrared range, and environmental friendliness.
In order to achieve the above and other related objects, the present invention provides a near-infrared laser based on silver selenide nanocrystals, which comprises in sequence:
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 tetragonal crystals with diameters ranging from 6nm to 10nm.
Optionally, the silver selenide nanocrystal layer consists of closely packed silver selenide nanocrystals.
Optionally, a product of a grating period and an effective refractive index of the dfg is equal to a band edge emission peak wavelength of the silver selenide nanocrystal.
Optionally, the near-infrared laser based on silver selenide nanocrystals further includes a packaging layer, and the packaging layer is located above the silver selenide nanocrystal layer.
Optionally, the substrate is made of one of silicon, mica, aluminum oxide and silicon dioxide; the distributed feedback grating layer is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride; the packaging layer is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride.
The invention also provides a preparation method of the near-infrared laser based on the silver selenide nanocrystal, which is used for preparing the near-infrared laser based on the silver selenide nanocrystal, and the preparation method comprises the following steps:
s1: providing a substrate, preparing a tetragonal silver selenide nanocrystal with the diameter range of 6-10 nm, and dispersing the silver selenide nanocrystal in a toluene solution to obtain a silver selenide nanocrystal toluene dispersion liquid;
s2: forming a distributed feedback grating layer on the substrate;
s3: and (2) spin-coating the silver selenide nanocrystalline toluene dispersion liquid obtained in the step (S1) on the distribution feedback grating layer to obtain a silver selenide nanocrystalline layer.
Optionally, in step S3, after the silver selenide nanocrystal toluene dispersion is spin-coated on the distribution feedback grating layer, the method further includes a step of annealing under the protection of an inert gas.
Optionally, in step S3, after the silver selenide nanocrystal layer is obtained, a step of forming an encapsulation layer on the silver selenide nanocrystal layer is further included.
As described above, the near-infrared laser based on silver selenide nanocrystals and the preparation method thereof of the present invention have the following beneficial effects:
the invention uses the tetragonal silver selenide nanocrystal with the diameter of 6 nm-10 nm as the optical gain medium, when the forbidden bandwidth of the tetragonal material silver selenide nanocrystal 11 is only 0.07eV, the environmental Fermi level 60 is higher than the conduction band bottom (as shown in figure 3 (a) and figure 3 (b)), and the conduction band bottom is occupied by electrons. Due to quantum confinement effects, silver selenide nanocrystals exhibit discrete energy levels similar to atoms, with forbidden bandwidths increasing as the size of the silver selenide nanocrystals decreases. When the diameter of the tetragonal silver selenide nanocrystal is reduced to 6nm (as shown in fig. 4 (a) and 4 (b)), the ambient fermi level 60 of the 6nm diameter silver selenide nanocrystal 12 is still above the band-edge electronic state 1S e Band edge electronic state 1S e Occupied by electrons in the unexcited state (as shown in FIG. 6 (a)), at which time band edge absorption is bleached, i.e., excitons are driven from 1S h State to 1S e The state transitions are forbidden and the band edge emission is forbidden, i.e., in the unexcited state, the silver selenide nanocrystal population is transparent to photons having the same energy as the forbidden bandwidth, and neither absorbs nor generates gain, as long as one silver selenide nanocrystal in the silver selenide nanocrystal layer 40 is excited by one energy greater than or equal to 1S h State and 1P e Photon excitation of energy gap between states (as shown in FIG. 6 (b)), band edge hole state 1S h The electrons on the surface are excited to 1P e States or excitations to higher energy levels and then relaxes to 1P e State at 1S h A cavity is left in the state, the silver selenide nanocrystal realizes the population inversion of the band edge state, and the whole silver selenide nanocrystal layer 40 forms optical gain at the band edge emission wavelength, so that the band edge state optical gain with zero threshold can be realized by using the tetragonal phase silver selenide nanocrystal with the diameter of more than 6 nm. When the diameter of the silver selenide nanocrystal is less than 6nm, for example, the ambient fermi level 60 of the silver selenide nanocrystal 13 with a diameter of 3nm is less than the band edge electronic state 1S e Band edge electronic state 1S e Not occupied by electrons (see fig. 5 (a))) And FIG. 5 (b), in which the band edge absorption is not bleached, i.e., the electron is from 1S h To 1S e That is, in the unexcited state, the silver selenide nanocrystal population exhibits absorption of photons having the same energy as the forbidden bandwidth. Because the silver selenide band edge state is 2-fold degeneracy, the population inversion can be obtained only if the number of excitons in each silver selenide nanocrystal, namely the number of absorbed photons, in the silver selenide nanocrystal population is larger than 1 on average. The diameter of the silver selenide nanocrystal is limited to be larger than 10nm, so that the quantum confinement effect is enhanced, and the general advantage of the nanocrystal as an optical gain material is obtained, namely the near-infrared emission wavelength and the temperature insensitive optical gain threshold which can be adjusted along with the size of the silver selenide nanocrystal.
The invention uses the tetragonal silver selenide nanocrystalline with the diameter of 6 nm-10 nm as the optical gain medium of the laser, thereby realizing the band-edge optical gain with zero threshold value; the invention utilizes quantum confinement effect to adjust the relative position of the tetragonal phase silver selenide nanocrystalline conduction band bottom and the environmental Fermi level by adjusting the size of the silver selenide nanocrystalline, thereby obtaining the band edge electronic state 1S e The silver selenide nanocrystal occupied by electrons has adjustable emission wavelength in a near infrared band, does not need to be added with a hole trapping agent which is easy to be oxidized, and has a band edge electron state 1S e The silver selenide nanocrystal occupied by electrons is stable in the atmospheric environment, and the crystal structure and the surface state cannot be damaged; the silver selenide material is a low-toxicity environment-friendly material and is environment-friendly.
Drawings
Fig. 1 shows a schematic structural diagram of a silver selenide nanocrystal of the invention.
Fig. 2 shows a schematic structural diagram of a near-infrared laser based on silver selenide nanocrystals of the invention.
Fig. 3 (a) shows a structural schematic diagram of a bulk material silver selenide nanocrystal of the invention, and fig. 3 (b) shows an energy level structural schematic diagram of the bulk material silver selenide nanocrystal of the invention.
Fig. 4 (a) is a schematic view showing the structure of a silver selenide nanocrystal with a diameter of 6nm of the present invention, and fig. 4 (b) is a schematic view showing the energy level structure of a silver selenide nanocrystal with a diameter of 6nm of the present invention.
Fig. 5 (a) is a schematic view showing the structure of silver selenide nanocrystals of the present invention having a diameter of 3nm, and fig. 5 (b) is a schematic view showing the structure of the energy level of the silver selenide nanocrystals of the present invention having a diameter of 3 nm.
Fig. 6 (a) shows a schematic diagram of an unexcited exciton state and energy level structure of the silver selenide nanocrystal with the diameter of 6nm, and fig. 6 (b) shows a schematic diagram of an excited exciton state and energy level structure of the silver selenide nanocrystal with the diameter of 6 nm.
Fig. 7 shows a schematic flow chart of the method for preparing a near-infrared laser based on silver selenide nanocrystals.
Fig. 8 to 11 are schematic structural diagrams showing steps of a method for preparing a near-infrared laser based on silver selenide nanocrystals according to the present invention.
Description of the element reference numerals
10, silver selenide nanocrystals; 11, bulk material silver selenide nanocrystals; 12, silver selenide nanocrystals with a diameter of 6 nm; 13, silver selenide nanocrystals with a diameter of 3 nm; 20, a substrate; 30, distributing a feedback grating; 40, silver selenide nanocrystalline layers; 50, an encapsulation layer; 60, ambient fermi level.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 11. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
Example one
As shown in fig. 1 to fig. 2, the present invention provides a near-infrared laser based on silver selenide nanocrystals, which sequentially includes:
the silver selenide nanocrystalline layer 40 is composed of silver selenide nanocrystals 10, wherein the silver selenide nanocrystals 10 are tetragonal crystals, and the diameter range of the silver selenide nanocrystals is 6 nm-10 nm (as shown in fig. 1).
The working principle of the embodiment is as follows: the energy of excited photons received by the near-infrared laser based on the silver selenide nanocrystal is greater than or equal to 1S of the silver selenide nanocrystal h State and 1P e Energy gap between states, band edge electronic state 1S of silver selenide nanocrystal 10 e The laser emission of the silver-selenide nanocrystal-based near-infrared laser may be output from the upper surface of the silver-selenide nanocrystal layer 40 or the lower surface of the substrate 20 while being occupied with electrons in an unexcited state.
In this embodiment, a tetragonal silver selenide nanocrystal with a diameter of 6nm to 10nm is used as an optical gain medium, and when the forbidden bandwidth of the tetragonal silver selenide nanocrystal 11 is only 0.07eV, the environmental fermi level 60 is higher than the conduction band bottom (as shown in fig. 3 (a) and 3 (b)), and the conduction band bottom is occupied by electrons. Due to quantum confinement effects, silver selenide nanocrystals exhibit discrete energy levels similar to atoms, with forbidden bandwidths increasing as the size of the silver selenide nanocrystals decreases. When the diameter of the tetragonal silver selenide nanocrystal is reduced to 6nm (as shown in fig. 4 (a) and 4 (b)), the ambient fermi level 60 of the 6nm diameter silver selenide nanocrystal 12 is still above the band-edge electronic state 1S e Band edge electronic state 1S e Occupied by electrons in the unexcited state (as shown in FIG. 6 (a)), and at this time, band edge absorption is bleached, i.e., excitons are driven from 1S h State to 1S e The transition of the states is forbidden and at the same time the band edge emission is also forbidden, i.e. in the unexcited state the silver selenide nanocrystal population is transparent to photons with energy equal to the forbidden bandwidth and neither absorbs nor generates gain as long as there is a silver selenide nanocrystal layer withA silver selenide nanocrystal with an energy greater than or equal to 1S h State and 1P e Photon excitation of energy gap between states (as shown in FIG. 6 (b)), band edge hole state 1S h The electrons on the surface are excited to 1P e States or excitations to higher energy levels and then relaxes to 1P e State at 1S h A cavity is reserved in the state, the silver selenide nanocrystal realizes the population inversion of the band edge state, and the whole silver selenide nanocrystal layer forms optical gain at the band edge emission wavelength, so that the band edge state optical gain with the zero threshold can be realized by using the tetragonal phase silver selenide nanocrystal with the diameter larger than 6 nm. When the diameter of the silver selenide nanocrystal is less than 6nm, for example, the ambient fermi level 60 of the silver selenide nanocrystal 13 with a diameter of 3nm is less than the band edge electronic state 1S e Band edge electronic state 1S e Unoccupied by electrons (as shown in FIGS. 5 (a) and 5 (b)), and the band edge absorption is not bleached, i.e., electrons are removed from 1S h To 1S e That is, in an unexcited state, the silver selenide nanocrystal population exhibits absorption of photons having the same energy as the forbidden bandwidth. Because the band edge state of the silver selenide is 2-fold degeneracy, the population inversion can be obtained only if the number of excitons in each silver selenide nanocrystal, namely the number of absorbed photons, in the silver selenide nanocrystal population is larger than 1 on average. The diameter of the silver selenide nanocrystal is limited to be larger than 10nm, so that the quantum confinement effect is enhanced, and the common advantages of the nanocrystal as an optical gain material, namely the adjustable near-infrared emission wavelength and the temperature insensitive optical gain threshold along with the size of the silver selenide nanocrystal, are obtained.
In the embodiment, the silver selenide nanocrystal with a tetragonal phase with the diameter of 6-10 nm is used as an optical gain medium of the laser, so that the band-edge optical gain with a zero threshold value is realized; in the embodiment, the relative positions of the conduction band bottom of the tetragonal phase silver selenide nanocrystal and the environmental Fermi level 60 are adjusted by adjusting the size of the silver selenide nanocrystal through the quantum confinement effect, so that the band-edge electronic state 1S is obtained e The silver selenide nanocrystal occupied by the electrons has adjustable emission wavelength in a near infrared band, does not need to add a hole trapping agent which is easy to oxidize, and has an edge electron state 1S e The silver selenide nanocrystals occupied by electrons are stable in atmospheric environment, and the crystals are in a crystal junctionThe structure and the surface state can not be damaged; the silver selenide material of the embodiment is a low-toxicity environment-friendly material and is environment-friendly.
As an example, the silver selenide nanocrystal layer 40 is composed of silver selenide nanocrystals 10 that are close-packed.
The silver selenide nanocrystals 10 are densely stacked, so that the net mode gain of the silver selenide nanocrystal layer 40 can be improved, and the laser emission intensity can be improved.
As an example, the product of the grating period and the effective refractive index of the dfg 30 is equal to the band edge emission peak wavelength of the silver selenide nanocrystal 10.
With this arrangement, optical feedback can be provided to the gain medium of the laser, i.e., the silver selenide nanocrystal layer 40, thereby obtaining laser emission.
As an example, the near-infrared laser based on silver selenide nanocrystals further includes an encapsulation layer 50, the encapsulation layer 50 being located over the silver selenide nanocrystal layer 40.
The encapsulation layer 50 is formed on the silver selenide nanocrystal layer 40, so that the stability of the near infrared laser based on the silver selenide nanocrystals can be further improved, and the service life of the near infrared laser is prolonged.
By way of example, the gratings of the distribution feedback grating 30 are arranged periodically, and the shape may be set according to practical situations, and is not limited herein, for example, the gratings are convex rectangular bodies, cylinders or polygonal cylinders with regular periods.
As an example, the material of the substrate 20 is one of silicon, mica, alumina and silicon dioxide; the distributed feedback grating layer 30 is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride; the material of the package layer 50 is one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride.
The materials used for the device structure of the near-infrared laser based on the silver selenide nanocrystal can be the same or different, and the device can be set according to actual needs without limitation as long as the device has good heat dissipation and stable performance.
In this embodiment, the substrate 20 is preferably made of aluminum oxide, the distributed feedback grating layer 30 is preferably made of aluminum oxide, and the encapsulation layer 50 is preferably made of aluminum oxide.
The alumina material is preferably used as a material for the device structure of the near-infrared laser based on the silver selenide nanocrystal because of low cost, good heat dissipation and good stability.
As an example, the silver selenide nanocrystal based near infrared laser further comprises a pump source for exciting the silver selenide nanocrystal layer 40.
The energy of the emitted photons of the pump source is more than or equal to the energy of the silver selenide nanocrystal 10 1S h State and 1P e And (3) energy gaps among states, wherein pump photons are injected from the upper surface of the packaging layer 50 or the lower surface of the substrate 20 to excite the near-infrared laser based on the silver selenide nanocrystal, so that laser emission of the laser is output from the upper surface of the packaging layer 50 or the lower surface of the substrate 20.
It should be noted here that, because 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 photon needs to be injected obliquely from the upper surface of the encapsulation layer 50 or the lower surface of the substrate 20 to avoid overlapping with the laser emission, and an inclination angle of the oblique injection of the pump photon can be set according to practical situations, which is not limited herein.
Example two
The embodiment provides a method for preparing a near-infrared laser based on silver selenide nanocrystals, which is used for preparing the near-infrared laser based on silver selenide nanocrystals in the first embodiment, and the preparation method includes:
s1: providing a substrate, preparing a tetragonal silver selenide nanocrystal 10 with the diameter range of 6-10 nm, and dispersing the silver selenide nanocrystal 10 in a toluene solution to obtain a silver selenide nanocrystal toluene dispersion liquid;
s2: forming a distributed feedback grating layer 30 on the substrate 20;
s3: and (2) spin-coating the silver selenide nanocrystalline toluene dispersion obtained in the step (S1) on the distribution feedback grating layer 30 to obtain a silver selenide nanocrystalline layer 40.
As shown in fig. 7 to 11, the present embodiment will be further described with reference to the accompanying drawings.
As shown in fig. 7 and 8, as an example, first, step S1 is performed to provide a substrate 20, prepare a silver selenide nanocrystal 10 having a diameter range of 6nm to 10nm and a tetragonal phase, and disperse the silver selenide nanocrystal 10 in a toluene solution to obtain a silver selenide nanocrystal toluene dispersion.
Preparing a tetragonal phase with the diameter of 6-10 nm by using a metal organic method and controlling the reaction time, and dispersing the silver selenide nanocrystal 10 in a toluene solution, wherein the concentration of the toluene solution needs to be adjusted to 20mg/ml. The material of the substrate 20 is one of silicon, mica, aluminum oxide and silicon dioxide, and in this embodiment, an aluminum oxide material is preferably used because of its low cost, good heat dissipation and good stability.
As shown in fig. 7 and 9, as an example, step S2 is performed to form a distributed feedback grating layer 30 on the substrate 20.
In this embodiment, the distributed feedback grating 30 is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride, and in this embodiment, an aluminum oxide material is preferably used because of its low cost, good heat dissipation and good stability. The distribution feedback grating 30 is periodically arranged, and the shape can be set according to the actual situation, which is not limited herein, for example, the distribution feedback grating is a regular periodic convex rectangular body, a cylinder or a polygonal cylinder, and the regular periodic convex rectangular body is preferably adopted due to the simplicity of the process. It should be noted here that the product of the grating period and the effective refractive index of the dfg 30 is equal to the band edge emission peak wavelength of the silver selenide nanocrystal 10, so as to provide optical feedback for the silver selenide nanocrystal layer 40, thereby obtaining laser emission. In this embodiment, a layer of aluminum oxide is formed on the substrate 20, and then a reactive ion etching method is used to etch an aluminum oxide distribution feedback grating on the surface of the aluminum oxide.
In another preferred embodiment, the substrate 20 and the distributed feedback grating layer 30 are both aluminum oxide materials, and can be integrated, a thick aluminum oxide substrate can be directly provided, and the aluminum oxide distributed feedback grating is etched on the surface of the aluminum oxide substrate by using a reactive ion etching method.
As shown in fig. 7 and 10, as an example, step S3 is performed next, and the silver selenide nanocrystal layer 40 is obtained by spin-coating the silver selenide nanocrystal toluene dispersion obtained in step S1 on the distribution feedback grating layer 30.
And (2) spin-coating the silver selenide nanocrystalline toluene dispersion liquid obtained in the step (S1) on the distribution feedback grating 30 at the rotating speed of 2500 rpm. In this example, the silver selenide nanocrystalline toluene dispersion was spin coated on the aluminum oxide distribution feedback grating at a rotation speed of 2500 rpm.
As a preferred example, in step S3, after the silver selenide nanocrystal toluene dispersion is spin-coated on the distribution feedback grating layer 40, a step of annealing under the protection of an inert gas is further included.
Annealing the distribution feedback grating layer 30 spin-coated with the silver selenide nanocrystal toluene dispersion liquid at 60 ℃ for half an hour under the protection of inert gas to increase the density of the stacked silver selenide nanocrystals, thereby obtaining the silver selenide nanocrystal layer 40. The annealed silver selenide nanocrystal 10 can improve the net mode gain of the silver selenide nanocrystal layer 40, and is beneficial to improving the laser emission intensity.
As shown in fig. 11, as a preferred example, after obtaining silver selenide nanocrystal layer 40 in step S3, a step of forming an encapsulation layer 50 on silver selenide nanocrystal layer 40 is further included.
The packaging layer 50 is deposited on the silver selenide nanocrystalline layer 40 by using an atomic layer deposition method, in this embodiment, the packaging layer 50 is made of aluminum oxide, that is, a layer of aluminum oxide is deposited on the silver selenide nanocrystalline layer 40 by using an atomic layer deposition method to form the packaging layer 50.
The encapsulation layer 50 is deposited on the silver selenide nanocrystal layer 40, so that the stability of a laser device can be further improved, and the service life of the laser device can be prolonged.
In summary, the present invention provides a near-infrared laser based on silver selenide nanocrystals and a preparation method thereof, wherein the near-infrared laser based on silver selenide nanocrystals sequentially includes: 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, the silver selenide nanocrystals are tetragonal, and the diameter range of the silver selenide nanocrystals is 6-10 nm. The invention uses the tetragonal silver selenide nanocrystalline with the diameter of 6 nm-10 nm as the optical gain medium of the laser, thereby realizing the band-edge optical gain with zero threshold value; the invention utilizes quantum confinement effect to adjust the relative position of the tetragonal phase silver selenide nanocrystal conduction band bottom and the environmental Fermi level by adjusting the size of the silver selenide nanocrystal, thereby obtaining the band edge electronic state 1S e The silver selenide nanocrystal occupied by the electrons has adjustable emission wavelength, does not need to add a hole trapping agent which is easy to oxidize, and has an edge electron state 1S e The silver selenide nanocrystal occupied by electrons is stable in the atmospheric environment, and the crystal structure and the surface state cannot be damaged; the silver selenide material is a low-toxicity environment-friendly material and is environment-friendly. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
Claims (9)
1. The near-infrared laser based on the silver selenide nanocrystal is characterized by sequentially comprising the following components in percentage by weight:
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, the silver selenide nanocrystals are tetragonal, and the diameter range of the silver selenide nanocrystals is 6-10 nm.
2. The near-infrared laser based on silver selenide nanocrystals, as recited in claim 1, wherein: the silver selenide nanocrystalline layer consists of the silver selenide nanocrystals which are closely stacked.
3. The silver selenide nanocrystal-based near-infrared laser of claim 1, wherein: the product of the grating period and the effective refractive index of the distributed feedback grating is equal to the band edge emission peak wavelength of the silver selenide nanocrystal.
4. The near-infrared laser based on silver selenide nanocrystals, as recited in claim 1, wherein: the near-infrared laser based on the silver selenide nanocrystal further comprises a packaging layer, and the packaging layer is located above the silver selenide nanocrystal layer.
5. The silver selenide nanocrystal-based near-infrared laser of claim 4, wherein: the substrate is made of one of silicon, mica, aluminum oxide and silicon dioxide; the distributed feedback grating layer is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride; the packaging layer is made of one of silicon dioxide, aluminum oxide, magnesium difluoride and lithium fluoride.
6. The silver selenide nanocrystal-based near-infrared laser of claim 1, wherein: the near-infrared laser based on the silver selenide nanocrystal further comprises a pumping source used for exciting the silver selenide nanocrystal layer.
7. A method for preparing a near-infrared laser based on silver selenide nanocrystals, which is used for preparing the near-infrared laser based on silver selenide nanocrystals as claimed in any one of claims 1 to 6, and which comprises the following steps:
s1: providing a substrate, preparing a tetragonal silver selenide nanocrystal with the diameter range of 6-10 nm, and dispersing the silver selenide nanocrystal in a toluene solution to obtain a silver selenide nanocrystal toluene dispersion liquid;
s2: forming a distributed feedback grating layer on the substrate;
s3: and (2) spin-coating the silver selenide nanocrystalline toluene dispersion liquid obtained in the step (S1) on the distribution feedback grating layer to obtain a silver selenide nanocrystalline layer.
8. The method for preparing a near-infrared laser based on silver selenide nanocrystals, as recited in claim 7, wherein: in step S3, after the silver selenide nanocrystal toluene dispersion is spin-coated on the distribution feedback grating layer, the method further includes a step of annealing under the protection of an inert gas.
9. The method for preparing a near-infrared laser based on silver selenide nanocrystals, as recited in claim 7, wherein: in step S3, after the silver selenide nanocrystal layer is obtained, a step of forming a package layer on the silver selenide nanocrystal layer is further included.
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