Wide-spectrum, small-angle and asymmetric heat emitter of atmospheric window

Abstract

The invention relates to a wide-spectrum, small-angle and asymmetric heat emitter of an atmospheric window, and belongs to the technical field of heat managers. The invention aims to solve the technical problem that an existing heat emitter is limited by a main factor that heat radiation coherence is poor, and broadband concentrated emission of heat radiation in a specific direction cannot be achieved. Comprising a grating structure, a resonant cavity structure, a metal reflection structure and a substrate which are arranged in sequence. According to the invention, a super-directional radiation emission technology based on non-reciprocal waveguide is utilized, and through combination of the non-reciprocal waveguide and the Bruunnst effect, heat radiation energy is intensively distributed at an emission angle of + 30-+ 70 degrees in a wave band range of 10-14 [mu] m; the possibility that emission energy is highly focused in a designated area in a wide wave band range of thermal radiation is achieved.

Description

Technical Field

[0001] The invention relates to a heat emitter and belongs to the technical field of heat managers. Background Art

[0002] Thermal radiation, as a ubiquitous physical phenomenon, plays an important role in many engineering and technical fields such as energy, power, optoelectronics, military technology, and optomechanical systems. For a long time, the basic theory and application research of thermal radiation has been continuously enriched and deepened, and it has become an extremely active branch in the field of thermal science and is constantly integrated with other disciplines. The exploration of its mechanism has also shown far-reaching significance in different scientific fields. However, with the rapid development of modern science and technology and the continuous evolution of thermal radiation application scenarios, thermal radiation research is ushering in new opportunities and challenges, and people are in urgent need of constantly updating and improving relevant theoretical systems to adapt to the development of the times. In particular, with the development of micro / nanotechnology, it has had a profound impact in many fields such as energy conversion and storage devices, electronic components, electromechanical systems, and medical devices, and has promoted the efficient miniaturization of these devices. The rapid development of these technologies has also aroused people's attention to micro / nanoscale heat transfer issues. Thermal science issues have also become an indispensable part of these micro / nanotechnology applications, and may even become a bottleneck hindering the further development of these technologies. Therefore, in order to keep up with the continuous progress of micro / nanotechnology and explore new areas of science, it is necessary to deeply understand and explore the physical mechanisms of heat transfer at the micro / nanoscale. From a microscopic perspective, thermal radiation originates from the fluctuating electromagnetic field inside the material at non-zero temperature and has the characteristics of incoherence and omnidirectionality. Compared with highly directional light sources such as lasers, these characteristics hinder its precise operation and widespread application. Using large spectral bandwidth to design the angular characteristics of thermal emission and absorption can effectively suppress the directional noise and parasitic heat load of thermal devices such as thermal imaging and camouflage. More importantly, achieving unidirectional radiative heat transfer is indispensable for thermal energy harvesting devices such as thermal circulators and time-symmetric photovoltaic devices that reach the Landsberg efficiency limit. Controlling the directionality of the emitted far-field thermal radiation is a fundamental challenge. Traditional strategies refer to achieving concentrated emission of thermal radiation in a specific direction through specific designs and materials, thereby controlling the directionality and angular distribution of thermal radiation, but it can only limit the angular selectivity of thermal emission to a relatively narrow bandwidth, while thermal radiation is a broadband phenomenon. The ability to confine the emitted thermal radiation to a fixed narrow angular range over a wide bandwidth is an important but lacking capability. In the prior art, the publication number is CN111338011A, and the name of the invention is a method for realizing ultra-wideband light absorption enhancement using a composite microstructure. Its technical solution includes a full-angle high absorption solution to achieve large-scale, dispersed radiation, which cannot be concentrated, resulting in high energy consumption.

[0003] Therefore, it is urgent to propose a wide-spectrum, small-angle, asymmetric thermal emitter for the atmospheric window to solve the above-mentioned technical problems. Summary of the invention

[0004] In order to solve the technical problem that the existing thermal emitters are limited by the main factor of poor thermal radiation coherence and cannot achieve broadband concentrated emission of thermal radiation in a specific direction, a wide-spectrum, small-angle, asymmetric thermal emitter for an atmospheric window is provided. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive overview of the invention. It is not intended to identify the key or important parts of the invention, nor is it intended to limit the scope of the invention.

[0005] The technical solution of the present invention:

[0006] A wide-spectrum, small-angle, asymmetric heat emitter for an atmospheric window comprises a grating structure, a resonant cavity structure, a metal reflective structure and a substrate, wherein the grating structure, the resonant cavity structure, the metal reflective structure and the substrate are arranged in sequence.

[0007] Preferably, the grating structure comprises a plurality of cells, the cells are arranged in a linear array, and each cell contains a plurality of gratings.

[0008] Preferably, the cell size of the grating structure is 10-20 μm, the cell contains eight gratings, the size difference between two adjacent gratings is 100-200 nm, the eight gratings are arranged in sequence, the spacing between the gratings is 500-900 nm, and the thickness of the grating structure is 100-200 nm.

[0009] Preferably, the material of the periodic gradient grating structure is aluminum or ITO, and the thickness is 100-200 nm.

[0010] Preferably: the resonant cavity structure is made of intrinsic silicon, and its doping concentration shall not be higher than 10 17 cm -3 The thickness of the high dielectric material resonant cavity film is 100 to 300 nm.

[0011] Preferably, the metal reflective structure is composed of a reflective coating film, the material of the reflective coating film is aluminum, and the thickness of the reflective coating film is 10 μm.

[0012] Preferably: the metal material is deposited on the stage surface of the substrate by magnetron sputtering to form a metal reflective structure, and the high dielectric material is deposited on the upper surface of the metal reflective structure by magnetron sputtering to form a resonant cavity structure.

[0013] Preferably, the substrate is made of a silicon carbide wafer, the substrate resistance is 1 kiloohm to 1 megohm, the substrate surface roughness is less than 10 nm, the stage is formed by etching on the substrate using photolithography technology, and the stage thickness is 1 μm.

[0014] The present invention has the following beneficial effects:

[0015] The present invention solves the problem that traditional broadband thermal radiation strategies can only realize narrow-angle thermal radiation technology or asymmetric thermal radiation technology in a single manner and cannot organically unify the two. The present invention utilizes super-directional radiation emission technology based on non-reciprocal waveguides. By combining non-reciprocal waveguides with the Brunost effect, the thermal radiation energy is concentrated at an emission angle of +30 to +70 degrees within the 10 to 14 μm band, thereby realizing the possibility of highly focusing the emitted energy of thermal radiation within a wider band within a specified area.

[0016] The heat radiation of the present invention has a high degree of focusing, and can illuminate (heat) a specific area as required, thereby reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural diagram of a wide-spectrum, small-angle, asymmetric thermal emitter for an atmospheric window of the present invention;

[0018] Figure 2 is a graph showing changes in emissivity with wavelength and emission angle in a TM polarization mode provided by an embodiment of the present invention;

[0019] Figure 3 3 is a graph showing the variation of average emissivity with emission angle at different frequencies in the TM polarization mode provided according to an embodiment of the present invention.

[0020] In the figure: 1-grating structure, 2-resonance cavity structure, 3-metal reflection structure, 4-substrate. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0022] Specific implementation method 1: Combination Figure 1-3 The present embodiment is described. The present embodiment is a wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window, comprising a grating structure 1, a resonant cavity structure 2, a metal reflective structure 3 and a substrate 4. The grating structure 1, the resonant cavity structure 2, the metal reflective structure 3 and the substrate 4 are arranged in sequence from top to bottom.

[0023] The grating structure 1 is a periodic gradient grating structure, which includes a number of uniformly arranged cells, each of which includes a number of gratings; the periodic gradient grating structure of the thermal emitter is prepared by etching using a photolithography preparation technology;

[0024] The cell size of the grating structure 1 is 10-20 μm, each cell contains eight gratings of different sizes, the size difference between two adjacent gratings is 100-200 nm, the eight gratings are linearly arranged in order from small to large, the spacing between adjacent gratings is 500-900 nm, and the thickness of the grating structure 1 is 100-200 nm;

[0025] The matrix material of the periodic gradient grating structure is composed of strong plasma polaritons such as aluminum or ITO, and is prepared on a high dielectric material resonant cavity film by magnetron sputtering method, with a thickness of 100-200nm, and the matrix material thickness is 100nm;

[0026] The resonant cavity structure 2 is a high dielectric material resonant cavity composed of intrinsic silicon, and its doping concentration shall not be higher than 10 17 cm -3 , the thickness of the high dielectric material resonant cavity film is 100 to 300 nm;

[0027] The metal reflective structure 3 is a metal reflective surface, which is composed of a reflective coating film. The material of the reflective coating film is aluminum, and the thickness of the reflective coating film is 10 μm.

[0028] The metal material is deposited on the stage surface of the substrate 4 by magnetron sputtering to form a metal reflective structure 3, and the high dielectric material is deposited on the upper surface of the metal reflective structure 3 by magnetron sputtering to form a resonant cavity structure 2;

[0029] The substrate 4 is made of a silicon carbide wafer, the resistance of the substrate 4 is 1 kilo-ohm to 1 megohm, the surface roughness of the substrate 4 is less than 10 nm, the receiving end stage is formed by etching on the receiving end substrate 4 using photolithography technology, the stage thickness is 1 μm, and the thickness of the substrate is greater than or equal to 100 μm;

[0030] The thermal emitter can concentrate the thermal radiation energy at an emission angle of +30 to +70 degrees within the 10 to 14 μm band, that is, the emissivity is greater than or equal to 0.7 and is concentrated at an emission angle of +30 to +70 degrees, thereby realizing the possibility of highly focusing the thermal radiation energy within a specified area within a wider band. The thermal emitter has broad application prospects and important commercial value in fields that require efficient energy utilization, precise directional thermal radiation, and have special requirements for asymmetric working conditions, such as aerospace, precision manufacturing, medical instruments, optoelectronic detection, environmental monitoring, and new energy development.

[0031] The core of the present invention is to enable incoherent physical behaviors such as thermal radiation to be similar to lasers, with high coherence and focusing, so as to illuminate (heat) specific areas as needed and reduce energy consumption.

[0032] Embodiment 1:

[0033] like Figure 1 As shown, a wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window is composed of a grating structure 1, a resonant cavity structure 2, a metal reflection structure 3 and a substrate 4, wherein the grating structure 1, the resonant cavity structure 2, the metal reflection structure 3 and the substrate 4 are arranged in sequence from top to bottom; the periodic gradient grating structure adopts an aluminum strip grating with increasing or decreasing changes, the minimum grating width is 900nm, the maximum grating width is 2500nm, and 8 gratings constitute one period; the width difference between adjacent gratings is 300nm, the spacing between adjacent gratings is 900nm, and the grating thickness is 100nm; the resonant cavity structure 2 is made of an intrinsic silicon thin film with a thickness of 400nm;

[0034] like Figure 2 As shown, when the radiation wavelength of the wide-band, small-angle, asymmetric thermal emitter not provided by Example 1 of the present invention changes, the emissivity changes with the emission angle. It can be seen that when the radiation wavelength is 10 μm, the emissivity of the device in the forward emission and the reverse emission is basically the same; when the wavelength is 11 μm, the device begins to show a significant increase in emissivity from an angle of 24°, and when the angle is 70°, the emissivity is close to 1, and then it shows high emissivity;

[0035] like Figure 3 As shown, the wide-spectrum, small-angle, asymmetric thermal emitter provided in Example 1 of the present invention has an emissivity greater than or equal to 0.7 in the infrared emission band of 10-14 microns and is concentrated at an emission angle of +30 to +70 degrees; this further proves that the device provided by the present invention realizes the possibility of highly focusing the emitted energy of thermal radiation in a wider band within a specified area, breaking through the single functional limitation of traditional narrow-angle thermal radiation technology or asymmetric thermal radiation technology.

[0036] Embodiment 2:

[0037] The difference between this embodiment 2 and embodiment 1 is that the thickness of the grating structure 1 is 50 nm, the other steps and parameters are the same as those of embodiment 1, and the average emissivity at different frequencies can still maintain good asymmetric and narrow-angle characteristics;

[0038] In summary, the wide-band, small-angle, asymmetric thermal emitter provided by the present invention exhibits many advantages over traditional designs; its wide-band characteristics enable the emitter to cover a wider wavelength range, thereby more effectively utilizing thermal radiation energy from different bands, improving energy utilization efficiency, and exhibiting comprehensive performance in multiple fields such as thermal imaging and sensing; at the same time, the small-angle design enhances the directionality of thermal radiation and reduces energy loss in unnecessary directions, which is crucial for improving energy transfer efficiency and accurately controlling the direction of thermal radiation; in addition, the asymmetric structure enables the thermal emitter to be customized and optimized according to actual working conditions, thereby improving its flexibility and adaptability in different application scenarios, especially in the fields of urban centralized heating, building energy conservation, etc., which can significantly improve energy utilization efficiency and reduce costs; in summary, the wide-band, small-angle, asymmetric thermal emitter is simple and ingenious in design, easy to control costs, and has broad application prospects and important commercial value in multiple fields by virtue of its unique advantages.

[0039] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wide-spectrum, small-angle, asymmetric thermal emitter for an atmospheric window, characterized in that: It comprises a grating structure (1), a resonant cavity structure (2), a metal reflection structure (3) and a substrate (4), wherein the grating structure (1), the resonant cavity structure (2), the metal reflection structure (3) and the substrate (4) are arranged in sequence.

2. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 1, characterized in that: The grating structure (1) comprises a plurality of cells, each of which contains a plurality of gratings.

3. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 2, characterized in that: The cell size of the grating structure (1) is 10-20 μm, and the cell contains eight gratings. The size difference between two adjacent gratings is 100-200 nm. The eight gratings are arranged in order of size, and the spacing between the gratings is 500-900 nm. The thickness of the grating structure (1) is 100-200 nm.

4. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 3, characterized in that: The material of the periodic gradient grating structure is aluminum and ITO, and the thickness is 100-200nm.

5. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 1, characterized in that: The resonant cavity structure (2) is made of intrinsic silicon, and its doping concentration shall not be higher than 10 17 cm -3 The thickness of the high dielectric material resonant cavity film is 100 to 300 nm.

6. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 5, characterized in that: The metal reflective structure (3) is formed by a reflective coating film, the material of the reflective coating film is aluminum, and the thickness of the reflective coating film is 10 μm.

7. The wide-spectrum, small-angle, asymmetric heat emitter of an atmospheric window according to claim 6, characterized in that: The metal material is deposited on the surface of a substrate (4) by magnetron sputtering to form a metal reflective structure (3), and the high dielectric material is deposited on the surface of the metal reflective structure (3) by magnetron sputtering to form a resonant cavity structure (2).

8. A wide-spectrum, small-angle, asymmetric heat emitter for an atmospheric window according to claim 1 or 7, characterized in that: The substrate (4) is formed by a silicon carbide wafer, the resistance of the substrate (4) is 1 kiloohm to 1 megohm, the surface roughness of the substrate (4) is less than 10 nm, and the stage is formed by etching on the substrate (4) using photolithography technology, and its thickness is 1 μm.

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