Narrow spectrum narrow angle directional thermal radiator and method of making same
By using a stacked structure of distributed Bragg reflectors and resonant cavity components, and utilizing microcavity resonance theory and Brewster effect, an easy-to-fabricate narrow-spectrum, narrow-angle directional thermal radiator was fabricated, achieving independent control of angle and spectrum, thus improving the performance and processing efficiency of the thermal radiator.
Patent Information
- Application Number
- CN202411605858.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2044-11-11
AI Technical Summary
Existing thermal radiators are difficult to independently control in terms of angle and spectrum, and their complex structure makes them difficult to manufacture, which limits their efficient use in fields such as infrared detection and gas sensing.
A narrow-spectrum, narrow-angle directional thermal radiator is fabricated using a stacked structure of distributed Bragg reflectors and resonant cavity components, utilizing microcavity resonance theory and Brewster effect, and vacuum coating technology. The angle and spectrum can be independently controlled.
It achieves high emissivity with an angle broadening of less than 20° and a spectral broadening of less than 25nm, with a maximum emissivity of 0.97. The material is easy to obtain, the processing method is simple, the generation of impurities is reduced, and the film-forming properties and material stability are guaranteed.
Smart Images
Figure CN119414502B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of thermal radiation, in particular to a narrow-spectrum narrow-angle directional thermal radiator and a preparation method thereof. BACKGROUND
[0002] The thermal radiation of macroscopic objects has the characteristics of incoherence, wide spectrum, and emission rate not changing with angle, which limits the efficient use of thermal radiation in infrared detection, gas sensing, and other aspects. In recent years, various micro-nano structures such as gratings, photonic crystals, metamaterials, and super surfaces have been used to actively control the spectrum, direction, and polarization of thermal radiation using the interference effect of electromagnetic waves, which has practical applications in many fields such as infrared light sources, radiation detection, and thermal photovoltaic (TPV) waste heat utilization. For example, in a TPV cell, an effective spectral modulation method is crucial. On the one hand, the introduction of a narrow-spectrum narrow-angle directional radiator can enhance the matching between emitted photons and the photovoltaic band gap, significantly improving the hot spot conversion efficiency. Different photovoltaic devices have different viewing angle coefficients, so improving the ability of the radiator to independently control direction and spectrum can relax the requirements for device design. On the other hand, using a thermal radiator with directional characteristics can place the photovoltaic device outside the vacuum enclosure, thereby providing other effective cooling methods for the photovoltaic system. In addition, producing a coherent incandescent lamp requires limiting the wide spectrum and spatial diffusion characteristics of blackbody radiation to a narrow spectrum and angle range. A narrow-spectrum narrow-angle directional thermal emitter can be considered as a coherent thermal light source, which is of great significance in the field of lighting design such as coherent incandescent lamps.
[0003] However, although the current method designs a selective thermal emitter with good narrow-spectrum characteristics or directional characteristics, the emission angle range is either omnidirectional and cannot be adjusted, or cannot maintain the original emission angle when the wavelength is changed, showing significant angular dispersion. In addition, the emission angle and emission wavelength of these thermal emitters are strongly related to the refractive index of the material itself, making it difficult to achieve independent control of angle and spectrum. At the same time, there are few existing designs of thermal radiators with narrow-band and directional emission characteristics, which are complex in structure, difficult to process and produce, and lack of practical equipment. Therefore, considering the demand for narrow-spectrum narrow-angle directional thermal emitters with independent control ability in the fields of TPV systems, thermal radiation coherent light source design, infrared detection, etc., it is necessary to explore a simple and effective preparation method.
[0004] Therefore, the skilled person in the art is committed to providing a narrow-spectrum narrow-angle directional thermal radiator and a preparation method thereof, which is based on the theory of microcavity resonance and Brewster effect, and realizes independent control of angle and spectrum, and makes the thermal radiator easy to process. SUMMARY
[0005] In view of the defects in the prior art, the technical problem to be solved by the present application is how to provide a narrow-spectrum narrow-angle directional thermal radiator with independent regulation of angle and spectrum and a preparation method thereof.
[0006] To achieve the above-mentioned object, the present application provides a narrow-spectrum narrow-angle directional thermal radiator, comprising a distributed Bragg reflector component and a resonant cavity component, the distributed Bragg reflector component is arranged on the resonant cavity component, the distributed Bragg reflector component is a multilayer structure, the distributed Bragg reflector component can be directional transmission spectrum, the resonant cavity component is a multilayer structure, and the resonant cavity component can emit narrow-spectrum thermal radiation.
[0007] Further, the distributed Bragg reflector component is formed by alternately stacking a first medium and a second medium, the first medium and the second medium adopt dielectric materials, and the refractive index of the first medium is greater than the refractive index of the second medium.
[0008] Preferably, the first medium and the second medium are alternately stacked into four layers, and the first medium and the second medium are non-periodically stacked along the direction from the distributed Bragg reflector component to the resonant cavity component.
[0009] Further, the resonant cavity component is formed by stacking a metal and a third medium, and the third medium adopts a dielectric material.
[0010] Preferably, the resonant cavity component is a three-layer structure of metal-third medium-metal.
[0011] Further, the thickness of the metal layer close to the side of the distributed Bragg reflector component of the resonant cavity component is less than the skin depth of the metal, and the thickness of the metal layer away from the side of the distributed Bragg reflector component of the resonant cavity component is greater than the skin depth of the metal.
[0012] Preferably, the layers of the distributed Bragg reflector component, the layers of the resonant cavity component, and the connection between the distributed Bragg reflector component and the resonant cavity component are connected by a vacuum plating method.
[0013] The present application also provides a preparation method of the narrow-spectrum narrow-angle directional thermal radiator, comprising:
[0014] Using a silicon wafer as a substrate and using an electron beam evaporation device to process a metal layer;
[0015] Using a plasma-enhanced chemical vapor deposition process to process a third medium layer on the metal layer;
[0016] Using an electron beam evaporation device to process a metal layer on the third medium layer;
[0017] The first dielectric layer and the second dielectric layer are processed in an alternating manner using a plasma enhanced chemical vapor deposition process.
[0018] Preferably, it further comprises connecting the metal layer, the third dielectric layer in a discrete vacuum plating manner.
[0019] Preferably, it further comprises connecting the second dielectric layer and the metal layer, the first dielectric layer and the second dielectric layer in a one-time vacuum plating manner.
[0020] The present application has at least the following beneficial technical effects:
[0021] The narrow-spectrum narrow-angle directional thermal radiator based on the microcavity resonance theory and the Brewster effect has the advantages of excellent performance and easy implementation; the thermal radiator can realize narrow-spectrum narrow-angle directional heat emission, the angle spread is less than 20°, the spectral spread is less than 25nm, the maximum emissivity can reach 0.97, and has excellent selectivity; by adjusting the size parameters and materials of the structure, the corresponding wave spectrum and angle of the high-emission area can be independently regulated and freely designed, which has significant regulation advantages; the thermal radiator device is only composed of a film system structure, and the materials used are common metal and dielectric materials, which has less limitation on material selection.
[0022] The preparation method of the narrow-spectrum narrow-angle directional thermal radiator realizes the processing of multilayer films, can reduce the generation of impurities, and ensure good film forming property of the device and stable optical properties of the material; the processing method contains five vacuum operations, and the introduction of oxides in the metal layer and the dielectric layer can greatly increase the tight binding force between the layers.
[0023] The concept, specific structure and technical effects of the present application will be further described below with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 is a narrow-spectrum narrow-angle directional thermal radiator structure of an embodiment of the present application;
[0025] Figure 2 is a theoretically calculated polarized emission spectrum of the thermal radiator of an embodiment of the present application under environmental matching conditions;
[0026] Figure 3 is a preparation method flowchart of the thermal radiator of an embodiment of the present application;
[0027] Figure 4 is a measurement method schematic diagram of the thermal radiator of an embodiment of the present application;
[0028] Figure 5 is an experimentally measured polarized emission spectrum of the thermal radiator of an embodiment of the present application under environmental matching conditions;
[0029] Figure 6 This is a schematic diagram illustrating the decoupling and adjustable emission spectrum of the thermal radiator according to an embodiment of the present invention. Detailed Implementation
[0030] The preferred embodiments of the present invention are described below to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.
[0031] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.
[0032] This invention provides a narrow-spectrum, narrow-angle directional thermal radiator. By adjusting the structural dimensions and materials, the spectrum and angle corresponding to the high-emission region can be independently controlled, resulting in excellent narrow-spectrum, narrow-angle directional thermal radiation performance.
[0033] like Figure 1 The diagram shows the structure of the narrow-spectrum, narrow-angle directional thermal radiator of this embodiment. The radiator is composed of a distributed Bragg reflector component 1 and a resonant cavity component 2 stacked together. Typically, the distributed Bragg reflector component 1 is located above the resonant cavity component 2, and the signal enters the resonant cavity component 2 through the distributed Bragg reflector component 1. The distributed Bragg reflector component 1, based on the Brewster effect, exhibits spectral directional transmission characteristics, and its corresponding equivalent Brewster angle (i.e., selection angle) can be adjusted according to the medium material used. The resonant cavity component 2, based on the microcavity resonance effect, exhibits narrow-spectrum thermal emission characteristics, and its resonant wavelength can be adjusted according to the medium material and its thickness.
[0034] The distributed Bragg reflector component 1 is composed of alternating layers of a first dielectric and a second dielectric, forming a multi-layer structure. Along the direction from the distributed Bragg reflector component 1 to the resonant cavity component 2, the first dielectric layer and the second dielectric layer have an aperiodic structure, that is, the thicknesses of the first dielectric layer and the second dielectric layer are aperiodicly distributed.
[0035] Specifically, the distributed Bragg reflector component 1 in this embodiment has a four-layer structure, with two layers each of the first and second dielectric layers, namely, first dielectric layer 11, second dielectric layer 12, first dielectric layer 13, and second dielectric layer 14. The thicknesses of the first dielectric layer 11, second dielectric layer 12, first dielectric layer 13, and second dielectric layer 14 are non-periodic and can be selected according to actual needs.
[0036] The resonant cavity component 2 is formed by alternately stacking metal and the third medium, forming a multi-layer structure. Specifically, the resonant cavity component 2 of the embodiment is a three-layer structure, there are two metal layers and one third medium layer, and the metal layer 21, the third medium layer 22 and the metal layer 23 are sequentially arranged, forming a metal-third medium-metal structure.
[0037] In the embodiment, the first medium, the second medium and the third medium are all dielectric materials and are optically transparent materials, and can be semiconductor materials such as silicon and germanium, or oxide materials such as silicon dioxide and aluminum oxide; wherein the refractive index of the first medium is greater than the refractive index of the second medium. The metal can be a common material such as gold, chromium and tungsten, the thickness of the metal layer 21 needs to be less than the skin depth of the metal, and the thickness of the metal layer 23 needs to be greater than the skin depth of the metal.
[0038] The distributed Bragg reflector component 1 and the resonant cavity component 2 are decoupled from each other and jointly undertake the task of controlling the spectrum and angle. The layers of the distributed Bragg reflector component 1, the layers of the resonant cavity component 2 and the resonant cavity component 2 and the distributed Bragg reflector component 1 are connected by vacuum coating.
[0039] In a specific embodiment of the narrow-spectrum narrow-angle directional thermal radiator, the first medium layer is made of silicon, the second medium layer is made of silicon dioxide, the third medium layer is made of silicon, and the metal is gold. Under the condition of environmental matching, the p-polarized emission spectrum obtained by theoretical calculation is as shown in Figure 2 From the figure, it can be seen that there is a clear selective high emission region (emissivity E>0.5) in the p-polarized state, the angle spread of the high emission region is less than 20°, the spectrum spread is less than 0.025μm, and the maximum emissivity when the p-polarized light is incident can reach 0.97.
[0040] The application also provides a preparation method of the narrow-spectrum narrow-angle directional thermal radiator, as shown in Figure 3 The process of the preparation method is as follows.
[0041] A silicon wafer is used as a substrate, an electron beam evaporation device is used to process the film system of the metal layer 23, the thickness needs to be greater than the skin depth of the metal, and a 10nm chromium metal layer is needed as an adhesion layer; before processing the third medium layer 22, an oxide protective layer of 5nm is processed on the metal layer 23 by atomic layer deposition, and then the third medium layer 22 is processed by plasma enhanced chemical vapor deposition at a temperature of about 300℃, which will not damage the metal layer 23; finally, the metal layer 21 is processed by an electron beam evaporation device, and the thickness needs to be less than the skin depth of the metal. Electron beam evaporation, atomic layer deposition and plasma enhanced chemical vapor deposition are all carried out in a vacuum.
[0042] For the dielectric alternant distributed Bragg reflector component, the required second dielectric layer 14, first dielectric layer 13, second dielectric layer 12 and first dielectric layer 11 are processed in an alternant form by using a plasma enhanced chemical vapor deposition process under vacuum condition once, and the processing temperature is about 300℃.
[0043] The preparation method of the embodiment only needs 5 vacuum processes (indicated by the right arrow), which is beneficial to the close combination of each layer and ensures the good film forming property of the final film system structure. Figure 3
[0044] As shown in Figure 4 , the thermal radiator of the embodiment needs to use a prism with a certain refractive index for environment matching in the actual measurement process, the signal is emitted from one end, does not refract when passing through the semi-cylindrical prism, and enters the surface of the thermal radiator sample according to the original light path. Similarly, the reflected light leaves the prism without refraction, and the signal is absorbed by the receiving end. The background sample used in the measurement is an aluminum mirror.
[0045] According to the measurement scheme shown in Figure 4 , the angle-resolved spectrum measurement is performed on the thermal radiator sample, and the p-polarized emission spectrum of the thermal radiator under the environment matching condition is obtained as shown in Figure 5 . The experimental results are basically consistent with the theoretical calculation, which proves that the preparation method and the prepared thermal radiator are reasonable and feasible.
[0046] As shown in Figure 6 , the emission spectrum decoupling adjustable ability diagram of the structure with different materials and sizes and other parameters of the thermal radiator under the condition of p-polarized light incidence in the near-infrared region, in which n0 indicates the refractive index of the environment condition, n1 indicates the refractive index of the first dielectric material, n2 indicates the refractive index of the second dielectric material, d die indicates the thickness of the third dielectric; it can be seen from the figure that the narrow-spectrum narrow-angle directional spectrum has independent decoupling adjustable property. Further, by changing the material, thickness, layer number, environment matching condition, etc., the position of the high-emission region can be freely adjusted, and the narrow-spectrum narrow-angle directional selection region of the structure can be extended to the visible light region or the infrared region, and the method of regulation has universality.
[0047] The preferred embodiments of the present application are described in detail above. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the present application shall be within the protection scope determined by the claims.
Claims
1. A narrow spectrum, narrow angle directional thermal radiator characterized by, The distributed Bragg reflector component and the resonant cavity component are stacked, the distributed Bragg reflector component is a multilayer structure and can direct a transmission spectrum, and the resonant cavity component is a multilayer structure and can emit narrow-spectrum thermal radiation. The distributed Bragg reflector component is alternately stacked by a first medium and a second medium, the first medium and the second medium are dielectric materials, the refractive index of the first medium is greater than that of the second medium, the first medium and the second medium are alternately stacked into four layers, and the first medium and the second medium are non-periodically stacked along the direction from the distributed Bragg reflector component to the resonant cavity component. The resonant cavity component is a three-layer structure of metal-third medium-metal, and the third medium is a dielectric material.
2. The narrow-spectrum, narrow-angle directional thermal radiator of claim 1, wherein, The thickness of the metal layer close to the distributed Bragg reflector component is less than the skin depth of the metal, and the thickness of the metal layer away from the distributed Bragg reflector component is greater than the skin depth of the metal.
3. The narrow-spectrum, narrow-angle directional thermal radiator of claim 1, wherein, The layers of the distributed Bragg reflector component, the layers of the resonant cavity component, and the connection between the distributed Bragg reflector component and the resonant cavity component are connected by vacuum coating.
4. A method of producing a narrow spectrum, narrow angle directional thermal radiator as claimed in any one of claims 1 to 3, wherein, The method comprises the following steps: Using a silicon wafer as a substrate and using an electron beam evaporation device to process a metal layer; Using a plasma-enhanced chemical vapor deposition process to process a third medium layer on the metal layer; Using an electron beam evaporation device to process a metal layer on the third medium layer; Using a plasma-enhanced chemical vapor deposition process to process a first medium layer and a second medium layer in an alternating manner.
5. The method for preparing a narrow-spectrum, narrow-angle directional thermal radiator as described in claim 4, characterized in that, The method further comprises connecting the metal layer, the third medium layer in a discrete vacuum coating manner.
6. The method of producing a narrow-spectrum, narrow-angle directional thermal radiator according to claim 4, wherein The method further comprises connecting the second medium layer and the metal layer, and the first medium layer and the second medium layer in a one-time vacuum coating manner.