Ultra-broadband polarization-insensitive metamaterial solar absorber

Abstract

The present invention discloses an ultra-wideband polarization-insensitive metamaterial solar absorber belonging to the field of micro-nano optoelectronic technology. The absorber is an array structure composed of multiple identical units in the XOY plane, each of which includes, from bottom to top, a substrate layer, a dielectric layer, and a metamaterial layer. The metamaterial layer includes, from the inside to the outside, a quadrangular pyramid structure, a cylindrical structure, and four cylindrical structures. The quadrangular pyramid structure is concentrically arranged with the cylindrical structure and embedded in the cylindrical structure, and the four cylindrical structures are evenly distributed outside the cylindrical structure. The present invention has only three physical structures, the substrate layer, and the dielectric layer, which is easy to process and manufacture, reducing costs. Within the 300nm-4000nm band, the average absorption rate can reach above 96.5%, achieving ultra-wideband high absorption rate. Within the 0-70° incident angle range, the average absorption rate can reach above 92%, achieving polarization insensitivity.

Description

Technical Field

[0001] The invention discloses an ultra-wideband polarization-insensitive metamaterial solar absorber belonging to the technical field of micro-nano optoelectronics. Background Art

[0002] Energy is the backbone of human economic and social development. However, the production and utilization of traditional fossil energy sources often leads to environmental pollution, and as energy demand grows, reserves are rapidly declining. Therefore, developing clean energy to reduce fossil energy consumption has become a pressing need for current socioeconomic development. As the most widely used, most abundant, and most easily converted clean energy source, solar energy has always garnered the most attention, and its utilization remains a hot topic in scientific research.

[0003] Solar absorbers are key components in solar thermal conversion, directly impacting the efficiency of both solar thermal conversion and thermophotovoltaic systems. The solar energy spectrum includes ultraviolet, visible, and infrared light, which account for approximately 9%, 46%, and 45% of the energy reaching Earth, respectively. Research on solar absorbers that can cover these wavelengths is crucial for the development and utilization of solar energy.

[0004] Since its introduction, solar absorbers have shown great application prospects in seawater desalination, sewage treatment, and solar thermal conversion. Currently, solar absorbers are developing towards ultra-high absorption effects under wide-band and wide-angle incident light.

[0005] Metamaterials are artificially designed composite materials that can exhibit electromagnetic properties that natural materials do not possess. The specific properties mainly depend on the artificially designed unit structure. Applying metamaterials to solar absorbers and through the selection of materials and design of structures can help achieve ultra-high absorption effects under wide-band and large-angle incident light. Summary of the Invention

[0006] To achieve the above objectives, the present invention designs an ultra-wideband polarization-insensitive metamaterial solar absorber with excellent absorption effect within the solar spectrum range. It has only three physical structures: a substrate layer, a dielectric layer, and a metamaterial layer, which is easy to process and manufacture, reducing costs. In the 300nm-4000nm band, the average absorption rate can reach above 96.5%, achieving ultra-wideband high absorption rate; in the 0-70° incident angle range, the average absorption rate can reach above 92%, achieving polarization insensitivity.

[0007] The object of the present invention is achieved like this:

[0008] An ultra-wideband polarization-insensitive metamaterial solar absorber comprises an array structure composed of multiple identical units in the XOY plane. Each unit comprises, from bottom to top, a base layer, a dielectric layer, and a metamaterial layer. The dielectric layer is closely attached to the base layer, and the metamaterial layer is disposed above the dielectric layer. The metamaterial layer comprises, from the inside to the outside, a quadrangular pyramid structure, a cylindrical structure, and four cylindrical structures. The quadrangular pyramid structure is concentrically arranged with the cylindrical structure and embedded in the cylindrical structure. The four cylindrical structures are evenly distributed outside the cylindrical structure.

[0009] The projections of the base layer and the dielectric layer onto the XOY plane are squares, with boundaries parallel to the X and Y directions; the cross-section of the quadrangular pyramid structure projected onto the XOY plane is a square, with boundaries parallel to the X and Y directions; the cross-sections of the four cylindrical structures are four circles, with the centers of the four circles forming a square, with boundaries parallel to the X and Y directions;

[0010] The base layer is made of gold, the dielectric layer is made of gallium arsenide, and the metamaterial layer is made of titanium.

[0011] The ultra-broadband polarization-insensitive metamaterial solar absorber mentioned above,

[0012] The structural parameters of the base layer are: 800nm×800nm×300nm;

[0013] The structural parameters of the dielectric layer are: 800nm×800nm×100nm;

[0014] The structural parameters of the tetrahedral structure are: upper side length 70nm, lower side length 350nm, height 190nm;

[0015] The structural parameters of the cylindrical structure are: inner radius 280nm, outer radius 320nm, height 190nm;

[0016] The structural parameters of the cylindrical structure are: radius 50 nm, height 190 nm, and a distance from the center of the cylinder structure of 352.55 nm.

[0017] Beneficial effects:

[0018] First, the ultra-wideband polarization-insensitive metamaterial solar absorber of the present invention consists of only three physical structures: a substrate layer, a dielectric layer, and a metamaterial layer. The substrate layer is made of gold, the dielectric layer is made of gallium arsenide, and the metamaterial layer is made of titanium. The structure is simple, the materials are common, and the process is easy, thereby reducing costs.

[0019] Second, the ultra-wideband polarization-insensitive metamaterial solar absorber of the present invention can achieve an average absorption rate of more than 96.5% in the 300nm-4000nm band, achieving ultra-wideband high absorption rate.

[0020] Third, the ultra-wideband polarization-insensitive metamaterial solar absorber of the present invention can achieve an average absorption rate of more than 92% within the incident angle range of 0-70°, achieving polarization insensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the three-dimensional structure of the ultra-wideband polarization-insensitive metamaterial solar absorber of the present invention.

[0022] Figure 2 Schematic diagram of the three-dimensional structure of each unit.

[0023] Figure 3 Schematic diagram for defining the dimensional parameters of the substrate layer, dielectric layer, and metamaterial layer.

[0024] Figure 4 This is a screenshot of the simulation software interface of the ultra-wideband polarization-insensitive metamaterial solar absorber of the present invention.

[0025] Figure 5 for Figure 4 Graphs of absorption, transmission, and reflection effects in .

[0026] Figure 6 is the absorption rate curve under the change of metamaterial layer height.

[0027] Figure 7 is the absorption rate curve under the change of sunlight polarization angle.

[0028] Figure 8 is the absorptivity curve under the change of sunlight incident angle.

[0029] In the figure: 1 base layer, 2 dielectric layer, 3 metamaterial layer, 3-1 quadrangular pyramid structure, 3-2 cylindrical structure, 3-3 cylindrical structure. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Specific implementation method 1

[0032] The ultra-wideband polarization-insensitive metamaterial solar absorber in this embodiment is an array structure composed of multiple identical units in the XOY plane, such as Figure 1As shown, each of the units includes, from bottom to top, a base layer 1, a dielectric layer 2, and a metamaterial layer 3. The base layer 1 is closely attached to the dielectric layer 2, and the dielectric layer 2 is provided with a metamaterial layer 3. The metamaterial layer 3 includes, from inside to outside, a quadrangular pyramid structure 3-1, a cylindrical structure 3-2, and four cylindrical structures 3-3. The quadrangular pyramid structure 3-1 is concentrically arranged with the cylindrical structure 3-2 and embedded in the cylindrical structure 3-2. The four cylindrical structures 3-3 are evenly distributed outside the cylindrical structure 3-2. Figure 2 As shown;

[0033] The projections of the base layer 1 and the dielectric layer 2 onto the XOY plane are squares, with boundaries parallel to the X and Y directions. The cross-section of the quadrangular pyramid structure 3-1 projected onto the XOY plane is a square, with boundaries parallel to the X and Y directions. The cross-sections of the four cylindrical structures 3-3 are four circles, with the centers of the four circles forming a square, with boundaries parallel to the X and Y directions.

[0034] The base layer 1 is made of gold, the dielectric layer 2 is made of gallium arsenide, and the metamaterial layer 3 is made of titanium.

[0035] The structural parameters of the base layer 1 are: 800nm×800nm×300nm;

[0036] The structural parameters of the dielectric layer 2 are: 800nm×800nm×100nm;

[0037] The structural parameters of the quadrangular pyramid structure 3-1 are: upper side length 70nm, lower side length 350nm, and height 190nm;

[0038] The structural parameters of the cylindrical structure 3-2 are: inner radius 280nm, outer radius 320nm, height 190nm;

[0039] The structural parameters of the cylindrical structure 3-3 are: radius 50nm, height 190nm, and the distance between the center of the cylindrical structure 3-2 and the cylindrical structure 3-2 is 352.55nm.

[0040] The schematic diagram of the size parameter definition of the substrate layer, dielectric layer and metamaterial layer is as follows Figure 3 shown. Specific implementation method 2

[0042] The ultra-wideband polarization-insensitive metamaterial solar absorber in this specific embodiment is simulated and tested using FDTD-Solutions software on the basis of the specific embodiment 1. The simulation interface is as follows: Figure 4 As shown, Figure 4 The absorption, transmission and reflection effect curves in Figure 5The absorptivity of the absorber is determined by the reflectivity and transmittance. The absorptivity of the ultra-wideband polarization-insensitive metamaterial solar absorber is calculated using A(λ) = 1-T(λ)-R(λ); where A(λ), T(λ), and R(λ) represent the absorptivity, transmittance, and reflectivity of the absorber, respectively, and λ represents the wavelength of the incident light.

[0043] According to Kirchhoff's law, using:

[0044]

[0045] in, represents the average absorption rate of the absorber, λ max is the maximum value within the wavelength range of the incident light, λ min It is the minimum value within the wavelength range of the incident light.

[0046] Calculation of the average absorptivity of an ultra-broadband polarization-insensitive metamaterial solar absorber.

[0047] It can be calculated from the above two formulas that in the 300nm-4000nm band, the absorptivity of the ultra-wideband polarization-insensitive metamaterial solar absorber is higher than 0.9, and the average absorptivity of the ultra-wideband polarization-insensitive metamaterial solar absorber is higher than 96.5%. Specific implementation method three

[0049] In the ultra-wideband polarization-insensitive metamaterial solar absorber according to this specific embodiment, the performance of the metamaterial layer 3 under different parameters is simulated.

[0050] The light source is incident from the metamaterial layer 3, the dielectric layer 2, and the substrate layer 1, and the simulation is performed using FDTD-Solutions. The simulation results are as follows:

[0051] In simulation experiment 1, the height of the base layer 1 is kept at 300nm, the height of the dielectric layer 2 is kept at 100nm, the side length of the square projected by the base layer 1 and the dielectric layer 2 on the XOY plane is 800nm, the inner radius of the cylindrical structure 3-2 is 280nm, the outer diameter is 320nm, the upper side length of the quadrangular pyramid structure 3-1 is 70nm, and the lower side length is 350nm. The height of the metamaterial layer 3 is increased from 1700nm to 2100nm in steps of 100nm, and the absorptivity curve of the ultra-wideband polarization-insensitive metamaterial solar absorber is obtained, as shown in FIG. Figure 6 As shown, it can be seen that as the height of the metamaterial layer 3 increases, the broadband absorption phenomenon is always maintained, and a good absorption effect is achieved.

[0052] In simulation experiment 2, the height of the base layer 1 is kept at 300nm, the height of the dielectric layer 2 is kept at 100nm, the side length of the square projected by the base layer 1 and the dielectric layer 2 in the XOY plane is 800nm, the inner radius of the cylindrical structure 3-2 is 280nm, the outer diameter is 320nm, the height of the metamaterial layer 3 is 1900nm, the upper side length of the quadrangular pyramid structure 3-1 is 70nm, and the lower side length is 350nm. The polarization angle of the sunlight is increased from 0° to 90° in steps of 10°, and the absorptivity curve of the ultra-wideband polarization-insensitive metamaterial solar absorber is obtained, as shown in FIG. Figure 7 As shown, it can be seen that with the increase of the polarization angle of sunlight, the absorption curve does not change at all, showing polarization insensitivity.

[0053] In simulation experiment 3, the height of the base layer 1 is kept at 300nm, the height of the dielectric layer 2 is kept at 100nm, the side length of the square projected by the base layer 1 and the dielectric layer 2 in the XOY plane is 800nm, the inner radius of the cylindrical structure 3-2 is 280nm, the outer diameter is 320nm, the height of the metamaterial layer 3 is 1900nm, the upper side length of the quadrangular pyramid structure 3-1 is 70nm, and the lower side length is 350nm. The incident angle of sunlight is increased from 0° to 60° in steps of 10°, and the absorption rate curve of the ultra-wideband polarization-insensitive metamaterial solar absorber is obtained, as shown in FIG. Figure 8 As shown, it can be seen that with the continuous increase of the incident angle of sunlight, the absorption rate is maintained above 90% in the spectral range of 300nm-4000nm, and the average absorption rate is always above 95%, achieving good absorption effect in a wider range of incident angles.

Claims

1. An ultra-wideband polarization-insensitive metamaterial solar absorber, comprising an array structure composed of a plurality of identical units in an XOY plane, wherein each unit comprises, from bottom to top, a base layer (1), a dielectric layer (2), and a metamaterial layer (3), wherein the dielectric layer (2) is closely attached to the base layer (1), and the metamaterial layer (3) is arranged above the dielectric layer (2); the projections of the base layer (1) and the dielectric layer (2) onto the XOY plane are square, and the boundaries are parallel to the X direction and the Y direction; It is characterized in that The metamaterial layer (3) comprises, from the inside to the outside, a quadrangular pyramid structure (3-1), a cylindrical structure (3-2), and four cylindrical structures (3-3); the quadrangular pyramid structure (3-1) is concentrically arranged with the cylindrical structure (3-2) and embedded in the cylindrical structure (3-2); and the four cylindrical structures (3-3) are evenly distributed outside the cylindrical structure (3-2); The cross section of the quadrangular pyramid structure (3-1) is projected onto the XOY plane to form a square, with its boundaries parallel to the X and Y directions; the cross sections of the four cylindrical structures (3-3) are four circles, with the centers of the four circles forming a square, with their boundaries parallel to the X and Y directions; The base layer (1) is made of gold material, the dielectric layer (2) is made of gallium arsenide material, and the metamaterial layer (3) is made of titanium material.

2. The ultra-wideband polarization-insensitive metamaterial solar absorber according to claim 1, characterized in that: The structural parameters of the base layer (1) are: 800nm×800nm×300nm; The structural parameters of the dielectric layer (2) are: 800nm×800nm×100nm; The structural parameters of the tetrahedral structure (3-1) are: upper side length 70nm, lower side length 350nm, height 190nm; The structural parameters of the cylindrical structure (3-2) are: inner radius 280nm, outer radius 320nm, height 190nm; The structural parameters of the cylindrical structure (3-3) are: radius 50nm, height 190nm, and the distance from the center of the cylindrical structure (3-2) is 352.55nm.

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