A laser based on aluminum nitride nanowires

Abstract

The present invention discloses a laser based on aluminum nitride nanowires, comprising a substrate and a single aluminum nitride nanowire disposed on the substrate; the aluminum nitride nanowire is parallel to the substrate, and a Fabry-Perot resonator is formed between two end faces of the aluminum nitride nanowire. The laser based on aluminum nitride nanowires in this application uses a single aluminum nitride nanowire as the gain medium, which is conducive to realizing laser output with a wavelength below 280 nm.

Description

Technical Field

[0001] The present invention relates to the technical field of lasers, and particularly to a laser based on aluminum nitride nanowires. Background Art

[0002] Nanowire lasers are very popular in application fields such as data storage, medical treatment, biology, and chemical fluorescence sensing. In existing nanowire lasers, the nanowires are CdS (cadmium sulfide), ZnO (zinc oxide), and GaN (gallium nitride), and the radiation wavelengths of the nanowire lasers have covered the range from near ultraviolet to visible light. Due to the advantages of these wide-bandgap semiconductor materials such as high breakdown electric field, thermal conductivity, and electron mobility, they have great development potential in the fields of high temperature, high frequency, radiation resistance, and short-wavelength light emission.

[0003] However, due to the bandgap width of CdS being 2.45 eV, the corresponding emission wavelength is 507 nm; the bandgap width of ZnO is 3.2 eV, and the corresponding emission wavelength is 390 nm; the bandgap width of GaN is 3.4 eV, and the corresponding emission wavelength is 364 nm. For the stimulated emission of semiconductor nanowires under optical pumping, linear optical pumping is usually achieved by using pump light with a shorter wavelength, which greatly limits the output wavelength range and application of nanowire lasers. The existing technology can only achieve laser output in the UV-A (output wavelength 315 - 400 nm) and UV-B (280 - 315 nm) ranges, and it is difficult to achieve laser output below 280 nm. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a laser based on aluminum nitride nanowires, including a substrate and a single aluminum nitride nanowire disposed on the substrate; the aluminum nitride nanowire is parallel to the substrate, and a Fabry - Perot resonator is formed between the two end faces of the aluminum nitride nanowire.

[0005] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the laser further includes a femtosecond laser excitation source.

[0006] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the end faces of the aluminum nitride nanowires have a grating structure.

[0007] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the end faces of the aluminum nitride nanowires have a coating layer.

[0008] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the femtosecond laser is an ultraviolet femtosecond laser, and the laser is a solar-blind ultraviolet laser.

[0009] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the wavelength of the ultraviolet femtosecond laser is greater than 200 nm and less than 400 nm.

[0010] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the repetition frequency of the femtosecond laser is adjustable from 1 kHz to 200 kHz.

[0011] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the substrate is a MgF2 substrate.

[0012] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the diameter of the aluminum nitride nanowires is 0.05 - 1000 μm.

[0013] As an improvement of the laser based on aluminum nitride nanowires provided by the present invention, the length of the aluminum nitride nanowires is 10 - 5000 μm.

[0014] This application has the following beneficial effects:

[0015] A laser based on aluminum nitride nanowires proposed by the present invention uses a single aluminum nitride nanowire as the gain medium, and forms a Fabry - Perot resonator between the two end faces of the aluminum nitride nanowire, so that the aluminum nitride nanowire serves as both the gain medium and the resonator of the laser; the nanowires in this application are aluminum nitride nanowires, and aluminum nitride has an ultra - wide bandgap of 6.2 eV, which is beneficial to realizing laser output below 280 nm. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a laser based on aluminum nitride nanowires according to an embodiment of the present invention;

[0017] Figure 2 It is a schematic diagram of the Fabry - Perot resonator of a laser based on aluminum nitride nanowires according to an embodiment of the present invention.

[0018] Reference Signs:

[0019] Substrate (1), Aluminum Nitride Nanowire (2), Femtosecond Laser (3), Left End Face (5), Right End Face (4). Detailed Embodiments

[0020] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solution in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0022] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The following will further describe the technical solution of the present invention in detail through the drawings and embodiments.

[0025] Figure 1 It is a schematic structural diagram of a laser based on aluminum nitride nanowires according to an embodiment of the present invention.

[0026] As Figure 1As shown in the figure, a laser based on aluminum nitride nanowires proposed by the present invention includes a substrate (1) and semiconductor nanowires disposed on the substrate (1). The semiconductor nanowires in this application are single aluminum nitride nanowires (2). Among them, the aluminum nitride nanowires (2) are arranged parallel to the substrate (1).

[0027] The aluminum nitride nanowires (2) have good single crystal quality, atomically smooth surfaces, and relatively high refractive indices, and can effectively confine light within sub-wavelength dimensions. The end faces of the aluminum nitride nanowires (2) have a certain reflectivity, such that the left end face (5) and the right end face (4) of the aluminum nitride nanowires (2) form two mirrors, as Figure 2 shown, a Fabry–Pérot (F-P) resonator is formed between these two end faces.

[0028] The single aluminum nitride nanowire (2) serves as the gain medium. Aluminum nitride has an ultra-wide bandgap of 6.2 eV, and the corresponding emission wavelength is 200 nm - 210 nm, which is conducive to realizing laser output below 280 nm. The stimulated emission of a laser with this structure has good optical mode characteristics, can generate high-brightness laser light, and the generated laser light is output from the end faces of the aluminum nitride nanowires (2).

[0029] The laser also includes an excitation source, and the excitation source can adopt an electrical pumping or optical pumping method. Preferably, the excitation source in this application is a femtosecond laser (3). The repetition frequency of the femtosecond laser (3) is adjustable from 1 kHz to 200 kHz and has a very high peak power density.

[0030] As a more preferred solution, the excitation source is an ultraviolet femtosecond laser (3), and the laser is a solar-blind ultraviolet laser. The wavelength of the ultraviolet femtosecond laser is greater than 200 nm and less than 400 nm. When using an ultraviolet femtosecond laser, the excitation source is a two-photon absorption pump, and the aluminum nitride nanowires (2) achieve population inversion and laser output through two-photon absorption. Two-photon excitation using an ultraviolet femtosecond laser with a high peak power density can effectively achieve solar-blind ultraviolet laser output of the aluminum nitride nanowires (2). In a specific embodiment, the wavelength range of the ultraviolet femtosecond laser is 210 - 390 nm.

[0031] If the ultraviolet femtosecond laser is replaced with femtosecond lasers of other wavelengths, if the wavelength of the pumped femtosecond laser is less than 200 nm, the excitation source is a single-photon absorption linear pump. If the wavelength of the pumped femtosecond laser is greater than 400 nm, the excitation source is a multi-photon absorption non-linear pump, and the efficiency is relatively low.

[0032] The embodiments of the present application preferably adopt ultraviolet femtosecond laser two-photon excitation with a high peak power density. Compared with single-photon excitation, ultraviolet femtosecond laser two-photon excitation has a greater penetration depth, can achieve more efficient optical coupling, and at the same time reduce non-radiative recombination caused by surface defects of nanowires, improving the laser output performance of the laser.

[0033] Aluminum nitride (AlN) has an ultra-wide bandgap of 6.2 eV. According to the known optical quantum energy formula E = (hc / λ), the photon energy of ultraviolet femtosecond laser is 3.1 eV - 4.8 eV. Therefore, when the femtosecond laser is used as the excitation source, aluminum nitride nanowires (2) can simultaneously absorb two femtosecond laser photons. Under the action of the externally applied excitation source, ultraviolet femtosecond laser, the electrons of aluminum nitride nanowires (2) transition to the high-energy state and achieve population inversion, thereby generating stimulated radiation, and emitting laser with a wavelength in the solar-blind ultraviolet band from the end face, capable of achieving solar-blind ultraviolet laser output of about 200 nm. For example, solar-blind ultraviolet band laser with a reference wavelength range of 200 - 210 nm can be output. Thus, deeper ultraviolet laser output of the nanowire ultraviolet laser is achieved, and the ultraviolet laser in this band can be applied in optical imaging, positioning and identification, medical detection, etc.

[0034] Aluminum nitride nanowires (2) themselves serve as a Fabry–Pérot (F-P) resonator. Under ultraviolet femtosecond laser two-photon excitation, the stimulated radiation of this structure has good optical mode characteristics, capable of generating high-brightness solar-blind ultraviolet monochromatic light. The generated laser is output from the end face of the aluminum nitride nanowires, which is very suitable for coupling to nanophotonic components, such as quantum dots, metal nanoparticles, plasmonic waveguides, and biological specimens.

[0035] As a gain medium, aluminum nitride nanowires (2) have good surface crystallization and flat end faces. The diameter of aluminum nitride nanowires (2) is 0.05 - 1000 μm. The length of aluminum nitride nanowires (2) is 10 - 5000 μm.

[0036] As a preferred solution, a grating structure is provided on the end face of the aluminum nitride nanowires (2). The grating structure is, for example, an FBG grating structure inscribed on the end face, and its purpose is to enhance end face reflection and reduce the mirror loss of the aluminum nitride nanowires. When light waves propagate in the nanowires and interact with the metal grating, they are reflected by the end face, thus forming gain feedback. In order to improve the end face reflectivity, reduce the lasing threshold, and enhance the laser output efficiency, in addition to providing a grating structure on the end face of the aluminum nitride nanowires (2), a coating layer can also be provided on the end face of the aluminum nitride nanowires (2). The coating is, for example, a gold film. However, it can be understood that the grating structure and the coating are not limited thereto. As a more preferred solution, both coating and grating can be provided on the end face. The grating can be inscribed on the end face first, and then the coating can be formed.

[0037] The substrate (1) of the specific embodiment of the present application is preferably a MgF2 substrate (1). MgF2 is a low refractive index crystal, which can effectively prevent the leakage of optical signals.

[0038] The laser of the present application has a wide range of applications in the fields of quantum computing, display, lighting, biology, gas sensing, medical diagnosis, high-density storage, and materials science.

[0039] The present application has the following beneficial effects:

[0040] A laser based on aluminum nitride nanowires proposed by the present invention uses a single aluminum nitride nanowire as the gain medium, and forms a Fabry-Perot resonator between the two end faces of the aluminum nitride nanowire, so that the aluminum nitride nanowire serves as both the gain medium and the resonator of the laser; the nanowire of the present application is an aluminum nitride nanowire, and aluminum nitride has an ultra-wide bandgap of 6.2 eV, which is beneficial to realizing laser output below 280 nm.

[0041] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The accompanying drawings show the preferred embodiments of the present application, but do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements on some of the technical features. Any equivalent structure directly or indirectly using the content of the specification and drawings of the present application in other related technical fields is equally within the scope of the patent protection of the present application.

Claims

1. A laser based on aluminum nitride nanowires, characterized in that, It includes a substrate and a single aluminum nitride nanowire disposed on the substrate; the aluminum nitride nanowire is parallel to the substrate, and a Fabry-Perot resonator is formed between the two end faces of the aluminum nitride nanowire; The laser further includes a femtosecond laser excitation source. The femtosecond laser is an ultraviolet femtosecond laser, and the wavelength range of the ultraviolet femtosecond laser is 210 - 390 nm. The excitation source is a two-photon absorption pump, so that the aluminum nitride nanowire absorbs two femtosecond laser photons simultaneously. Under the action of the externally applied ultraviolet femtosecond laser excitation source, the electrons of the aluminum nitride nanowire transition to a high energy level state and achieve population inversion to generate stimulated emission; the laser is a solar-blind ultraviolet laser, and the emission wavelength of the aluminum nitride nanowire is 200 - 210 nm.

2. The laser according to claim 1, characterized in that, The end face of the aluminum nitride nanowire has a grating structure.

3. The laser according to claim 1, wherein The end face of the aluminum nitride nanowire has a coating layer.

4. The laser according to claim 1, characterized in that, The repetition frequency of the femtosecond laser is adjustable from 1 kHz to 200 kHz.

5. The laser according to claim 1, characterized in that, The substrate is a MgF2 substrate.

6. The laser according to claim 1, characterized in that, The diameter of the aluminum nitride nanowire is 0.05 - 1000 μm.

7. The laser according to claim 5, characterized in that, The length of the aluminum nitride nanowire is 10 - 5000 μm.

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