Angle-adjustable narrow-band heat radiator based on corner hyperbolic phonon polaritons

Abstract

The invention discloses an angle-adjustable narrow-band heat radiator based on corner hyperbolic phonon polaritons. The heat radiator sequentially comprises a metal layer, a natural biaxial hyperbolic medium, a vacuum / air spacing layer and a one-dimensional medium grating. According to the angle-adjustable heat radiator, the biaxial hyperbolic medium and the gold layer are twisted as a whole, and the included angle between the radiating surface and the plane where the crystal axis of the natural biaxial hyperbolic medium is located is changed, so that the heat radiation direction is changed. The radiator can be produced on a large scale at low cost by utilizing processes such as nano photoetching and deposition. The narrow-band directional thermal radiation device obtained through the nano manufacturing technology is stable and reliable in performance, can generate thermal radiation with narrow bandwidth and small radiation angle, has the characteristics of adjustable direction, flexibility, convenience and the like, and is expected to be applied to the fields of directional heat dissipation, thermal camouflage and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to an angle-adjustable narrow-band thermal radiator based on cornered hyperbolic phonon polaritons. BACKGROUND

[0002] The thermal radiation of an object is usually broadband and non-directional. However, the practical application in the fields of infrared camouflage, infrared sensing, thermal imaging, etc. has certain requirements and limitations on the bandwidth and direction of thermal radiation; in addition, precise control of thermal radiation can significantly improve energy utilization efficiency and reduce energy waste. Therefore, effective regulation and control of thermal radiation is an important research direction at present and in the future. At present, in order to develop thermal management technology, researchers have carried out a large number of studies on the characteristics of thermal radiation. Existing structures can produce narrow-band directional thermal radiation, but the direction of the radiation is usually not easy to adjust. When the wavelength is fixed, the existing research mainly changes the direction by changing the period, thickness and other structural parameters, lacks the ability of rapid adjustment, and cannot adjust the direction of thermal radiation in real time according to environmental changes or actual needs. Individual research has realized rapid adjustment, but the manufacturing process is complex and the directionality is not strong. It is still a difficult problem to design a narrow-band, high-directional and convenient and flexible thermal radiator. SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the present application provides an angle-adjustable narrow-band thermal radiator based on cornered hyperbolic phonon polaritons, which aims to make the thermal radiator produce narrow-band directional radiation, and the direction can be adjusted in real time according to environmental changes or actual needs.

[0004] An angle-adjustable narrow-band thermal radiator based on cornered hyperbolic phonon polaritons, which comprises, in sequence, a metal layer, a natural biaxial hyperbolic medium, a vacuum or air spacing layer and a one-dimensional dielectric grating.

[0005] The material of the metal layer includes Au, Ag and Al; the natural biaxial hyperbolic medium supports phonon polaritons and has in-plane anisotropy.

[0006] The metal layer is a gold layer with a thickness of 0.1 microns, the natural biaxial hyperbolic medium is alpha-MoO3 with a thickness of 1 micron, the vacuum or air spacing layer has a thickness of 0.3 microns, and the one-dimensional dielectric grating is a one-dimensional silicon grating with a thickness of 1.2 microns and a width of 2.61 microns.

[0007] The one-dimensional dielectric grating is periodically distributed with a period of 4.35 microns and a filling ratio of 0.6.

[0008] The angle-adjustable thermal radiator changes the included angle between the radiation surface and the plane of the crystal axis of the natural biaxial hyperbolic medium by twisting the biaxial hyperbolic medium and the gold layer as a whole, thereby changing the direction of thermal radiation.

[0009] The angle-adjustable narrow-band heat radiator based on the corner hyperbolic phonon polariton is provided with a natural biaxial hyperbolic medium thickness, a vacuum or air spacing layer thickness, and a period is calculated according to ① a target wavelength / wave number and ② a radiation angle corresponding to a torsion angle of 0°; the thickness and filling ratio of the one-dimensional medium grating are determined through parameter scanning optimization; and the width of the one-dimensional medium grating is obtained according to the period and the filling ratio.

[0010] The angle-adjustable narrow-band heat radiator based on the corner hyperbolic phonon polariton, Directional heat dissipation: control the direction of heat radiation to avoid radiating heat to sensitive elements; angle-adjustable, that is, the heat dissipation direction is adjustable. Information encryption: information on the device can be observed only at a specific angle; real-time angle change.

[0011] The present application has the following advantages: (1) When the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium coincides with the radiation plane, the heat radiator of the present application produces narrow-band directional heat radiation at a wave number of 860 cm -1 -1, with a radiation angle of 0 degrees and a radiation peak value of 0.97.

[0012] (2) When the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium has an angle of 30 degrees, 40 degrees and 45 degrees with the radiation plane, respectively, the heat radiator of the present application produces narrow-band directional radiation at a wave number of 860 cm -1 -1, with a radiation angle of 19 degrees, 41 degrees and 63 degrees, respectively. When the grating height and filling ratio of the radiator change, the heat radiation direction remains stable and has robustness.

[0013] (3) When the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium continuously changes the angle with the radiation plane, the radiation angle of the heat radiator of the present application at a wave number of 860 cm -1 -1 continuously changes.

[0014] (4) The radiator can be mass-produced and low-cost produced by nano-lithography, deposition and other processes. The narrow-band directional heat radiator obtained by nano-manufacturing technology has stable and reliable performance, can produce heat radiation with narrow bandwidth and small radiation angle, has adjustable direction, is flexible and convenient, etc. The heat radiation direction can be adjusted according to the requirements, without the need to prepare a new structure, thereby reducing the cost; the device can be compatible with multiple working modes and can adapt to complex and multiple environments. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the angle-adjustable narrow-band heat radiator based on the corner hyperbolic phonon polariton.

[0016] Figure 2 is an embodiment of the present application, the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium coincides with the radiation plane, and the emissivity spectrum of TM polarized light with a radiation angle of 0 degrees; Figure 3 is Figure 2 is an embodiment, the natural biaxial hyperbolic medium 3 and the gold layer 4 are twisted, so that the angles between the planes formed by the

[100] and

[010] axes of the biaxial hyperbolic medium and the radiation plane are 30 degrees, 40 degrees, and 45 degrees, respectively, and the emissivity polar coordinate graph of TM polarized light is shown in the figure. Figure 4 is Figure 3 is an embodiment, the emissivity of the radiation changes with the radiation angle and the angle between the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium and the radiation plane.

[0017] In the figure, h1: one-dimensional dielectric grating thickness; h2: spacer layer thickness; h3: biaxial hyperbolic medium thickness; h4: gold layer thickness; L: one-dimensional dielectric grating period; d: one-dimensional dielectric grating width; α: the angle between the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium and the radiation plane; One-dimensional dielectric grating 1, spacer layer 2, natural biaxial hyperbolic medium 3, gold layer 4. DETAILED DESCRIPTION

[0018] In order to more clearly show the purpose, technical scheme and advantages of the present application, the present application will be further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0019] As Figure 1 shown, the present application relates to an adjustable narrow-band directional thermal radiator of hyperbolic phonon polaritons, which is composed of a gold layer 4, a natural biaxial hyperbolic medium 3, a spacer layer 2, and a one-dimensional dielectric grating 1 in sequence.

[0020] In order to excite hyperbolic phonon polaritons and produce narrow-band directional thermal radiation, the biaxial hyperbolic medium 3 is placed under the spacer layer 2 and the one-dimensional dielectric grating 1. In order to prevent energy from penetrating from the bottom to the outside, the gold layer 4 is placed under the biaxial hyperbolic medium 3.

[0021] Figure 1 In the embodiment, the radiation plane of the radiator is in the xoz plane, TM polarized light is radiated at an angle of θ in the radiation plane, and TM polarized light is linearly polarized light with the direction of magnetic field vibration perpendicular to the radiation plane. The

[010] axis of the biaxial hyperbolic medium is along the z axis, the plane formed by the

[100] and

[001] axes is parallel to the xoy plane, and the plane formed by the

[100] and

[010] axes has an angle with the xoz plane (the radiation plane). The natural biaxial hyperbolic medium 3 and the gold layer 4 are twisted, so that the angle can change from 0 degrees to 90 degrees. In the embodiment, the angle between the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium and the radiation plane is 45 degrees. Figure 1Under the shown geometry, the present application calculates the emissivity of the thermal emitter in the mid-infrared waveband range by using rigorous coupled-wave analysis method. The structure parameters of the adjustable narrow-band directional thermal emitter are obtained through optimization.

[0022] A specific embodiment of the present application is given below, when the bottom substrate material is a metal layer Au, the refractive index is referred to the literature

Liao Y L, Zhao Y., Scientific reports, 2020, 10(1): 1480.

[100] and

[010] axes and the radiation surface is 0 degrees, its dielectric constant tensor in the mid-infrared region can be expressed as: (1); Among them: (2); ε ∞ is the high-frequency dielectric constant, ω TO , ω LO are the transverse and longitudinal optical phonon frequencies, respectively, Θ is the damping constant.

[0023] ε ∞,x =4.0, ε ∞,y =5.2, ε ∞,z =2.4; ω TO,x =972; ω TO,y =851; ω TO,z =1004; ω LO,x =820; ω LO,y =545; ω LO,z =958; Θ x =4; Θ y =4; Θ z =2.

[0024] The one-dimensional dielectric grating has a thickness h1 of 1.2 μm, a spacer layer thickness h2 of 0.3 μm, a natural biaxial hyperbolic dielectric thickness h3 of 1 μm, a gold layer thickness h4 of 0.1 μm, a one-dimensional dielectric grating width d of 2.61 μm, a period L of 4.35 μm, and a fill ratio f. x =d / L=0.6. This set of structural parameters is based on preset ①target wavelength / wavenumber ②radiation angle corresponding to 0°, obtained through theoretical calculation and optimization. The key to achieving adjustability lies in the material composition; specific parameters can be adjusted according to the two requirements: ①target wavelength / wavenumber ②radiation angle corresponding to 0°.

[0025] Figure 2 This is an embodiment within the scope of the present invention. When the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium coincides with the radiating surface (i.e., α=0), the emissivity spectrum of TM polarized light with a radiation angle of 0 degrees is obtained. Figure 2 As can be seen, the thermal radiator of the present invention operates at a wavenumber of 860 cm⁻¹. -1 At a radiation angle of 0 degrees, narrow-band directional thermal radiation is generated, with a radiation peak of 0.97.

[0026] Figure 3 yes Figure 2 In the embodiment, the natural biaxial hyperbolic medium 3 and the gold layer 4 are twisted so that the angles between the plane formed by the

[100] and

[010] axes of the biaxial hyperbolic medium and the radiation plane are 30 degrees, 40 degrees, and 45 degrees, respectively. The emission polar coordinate diagram of TM polarized light is shown below. Figure 3 As can be seen from this, the thermal radiator of the present invention operates at a wavenumber of 860 cm⁻¹. -1 At these locations, narrowband directional radiation is generated, with radiation angles of 19 degrees, 41 degrees, and 63 degrees, respectively.

[0027] Figure 4 yes Figure 3 In the embodiment, a pseudo-color image showing the emissivity of a torsion natural biaxial hyperbolic medium 3 and a gold layer 4 as a function of the radiation angle and the angle between the plane formed by the biaxial hyperbolic medium

[100] and

[010] axes and the radiation surface.

[0028] When fabricating the tunable narrowband directional thermal radiator of hyperbolic phonon polaritons for the mid-infrared band of this invention, by appropriately selecting the thickness of the biaxial hyperbolic medium and the period of the one-dimensional grating, a narrowband directional thermal radiator with tunable thermal radiation direction can be obtained.

[0029] This radiator can be mass-produced at low cost using processes such as nanolithography and deposition. The narrow-band directional thermal radiation device obtained through nanofabrication technology has stable and reliable performance, can generate thermal radiation with narrow bandwidth and small radiation angle, and has the characteristics of adjustable direction and flexibility. It is an important thermal radiation device.

[0030] Those skilled in the art should understand that the above discussion of any embodiment is merely exemplary in nature and is not intended to imply that the disclosure, including the claims, be limited to these examples; under the idea of the present application, the above embodiments or technical features among different embodiments can also be combined, steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in details for the sake of brevity.

[0031] Embodiments of the application are intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any one of the above-described and other examples of the application can be combined with any other to create additional examples that fall within the scope of the present application. Various embodiments of the application can be implemented in hardware, software, or a combination thereof. The various embodiments of the application can be implemented in one or more computer programs or code that can be executable on a processor-based system affixed in a computer readable medium. As such, the elements of an embodiment of the application can be described in the general context of computer readable media storing computer code, program modules, or the like. Generally, programs include routines, program software, computer programs, or the like, that perform specified tasks when executed on a processor-based system or device. Computer readable media can be transitory or non-transitory. By way of example, and not limitation, computer readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of computer readable instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact discs and laser discs, Blu-ray discs, DVDs, and the like.

Claims

1. A narrowband thermal radiator with adjustable angle based on corner hyperbolic phonon polaritons, characterized in that: The thermal radiator comprises, in sequence, a metal layer, a natural biaxial hyperbolic medium, a vacuum or air spacer layer, and a one-dimensional dielectric grating.

2. The angle-adjustable narrowband thermal radiator based on corner hyperbolic phonon polaritons according to claim 1, characterized in that: The metal layer is made of Au, Ag, or Al; the natural biaxial hyperbolic medium supports phonon polaritons and has in-plane anisotropy.

3. The angle-tunable narrowband thermal radiator based on corner hyperbolic phonon polaritons according to claim 2, characterized in that: The metal layer is a gold layer with a thickness of 0.1 micrometers; the natural biaxial hyperbolic medium is α-MoO3 with a thickness of 1 micrometer; the vacuum or air spacer layer has a thickness of 0.3 micrometers; and the one-dimensional dielectric grating is a one-dimensional silicon grating with a thickness of 1.2 micrometers and a width of 2.61 micrometers.

4. The angle-adjustable narrowband thermal radiator based on corner hyperbolic phonon polaritons according to claim 3, characterized in that: The one-dimensional dielectric grating is periodically distributed with a period of 4.35 micrometers and a fill ratio of 0.

6.

5. The angle-tunable narrowband thermal radiator based on corner hyperbolic phonon polaritons according to claim 1, characterized in that: The angle-adjustable thermal radiator changes the direction of thermal radiation by twisting the biaxial hyperbolic medium and the gold layer as a whole, thereby altering the angle between the radiating surface and the plane containing the crystal axis of the natural biaxial hyperbolic medium.

6. The narrowband thermal radiator based on the angle-tunable hyperbolic phonon polariton according to claim 5, characterized in that: The thickness of the natural biaxial hyperbolic medium and the thickness of the vacuum or air spacer are given artificially. The period is calculated based on the radiation angle corresponding to ① target wavelength / wavenumber ② twist angle = 0°. The thickness and fill ratio of the one-dimensional dielectric grating are determined through parameter scanning optimization. The width of the one-dimensional dielectric grating is obtained based on the period and fill ratio.

7. The application of the angle-tunable narrowband thermal radiator based on the hyperbolic phonon polariton as described in claim 5, characterized in that: Directional heat dissipation: controls the direction of heat radiation to prevent heat from being radiated to sensitive components; the angle is adjustable, meaning the heat dissipation direction is adjustable.

8. The application of the angle-tunable narrowband thermal radiator based on the hyperbolic phonon polariton as described in claim 5, characterized in that: Information encryption: Information on the device can only be observed from a specific angle; the angle can be changed in real time.

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