Ultra-wideband high-efficiency absorber

Abstract

The invention discloses an ultra-wideband high-efficiency absorber in the technical fields of optics, material science and energy, which takes silicon dioxide (SiO2) as a substrate, and a titanium (Ti) nano rectangular body array is arranged above the substrate; a silicon nitride (Si3N4) regular hexagonal prism array is constructed on the top of the titanium layer, six cylindrical holes are etched in the midpoint of each vertex of a regular hexagon on the bottom surface of the titanium layer, and magnesium fluoride (MgF2) is filled in the cylindrical holes to form magnesium fluoride nano cylinders; a chromium (Cr) ring and a silicon nitride ring are sequentially superposed at the top end of the hexagonal prism and are tangentially matched with the hexagon on the top surface of the hexagonal prism. According to the UWB-HEA, the incident wavelength ranges from 400 nm to 4000 nm, the designed efficient absorption range (namely absorption band) of the UWB-HEA covers from near-infrared 855 nm to mid-infrared 3540 nm, about 2685 nm, the average absorption rate of 96.67% is achieved under TM waves, and the highest absorption rate is 99.66%; the average absorption rate of 96.44% is achieved under TE waves, the highest absorption rate is 99.72%, and the absorption rate is almost unrelated to polarization. In order to reduce radiation energy loss of an object, an ideal solar heat absorber needs to realize efficient light absorption in a wide wave band range.

Description

Technical Field

[0001] The invention relates to an ultra-wideband high-efficiency absorber in the fields of optics, materials science and energy technology. Background Art

[0002] Metamaterials are a type of artificial composite material with a subwavelength unit structure. Their dielectric constant and magnetic permeability can break through the physical limitations of natural materials, thus giving light, sound and electromagnetic waves great freedom in control. [1-3] . Although absorption loss is generally considered a disadvantage in metamaterials, it can be transformed into an effective mechanism when designing artificial light absorbers. An optical perfect absorber is an optical device that can achieve close to 100% light absorption in a specific band. Its core principle is to convert incident light energy into heat energy or other forms of energy by suppressing reflection and transmission. In recent years, this technology has shown great and extensive application prospects in the fields of optical communications, broadband thin-film thermal emitters, photothermal cells and photovoltaic cells. Qian et al. reported an ultra-broadband metasurface perfect absorber based on TiN nanostructures. [4] Its absorption band covers the ultraviolet to near-infrared region and is insensitive to the polarization state, with an average absorption rate of 90.0%; Liu et al. proposed a metasurface cutoff perfect absorber for solar wavelengths based on a dual-resonance Si and GaAs nanoring array. [5] , with an average absorption of up to 91.0% in the absorption band. Researchers are currently trying to develop high-efficiency absorbers with higher absorption rates and wider bandwidths.

[0003] [1] Pendry, JB, Holden, AJ, Robbins, DJ and Stewart, WJ, Magnetism from conductors and enhanced nonlinear phenomena, IEEE Transactionson Microwave Theory and Techniques 1999, 47, 2075-2084. [2] Pendry, JB, Holden, AJ, Stewart, WJ and Youngs, I., Extremely Low Frequency Plasmons in Metallic Mesostructures, Physical Review Letters 1996, 76, 4773-4776. [3] Veselago, VG, The electrodynamics of substances withsimultaneously negative values of ε and μ, Soviet Physics Uspekhi 1968, 10,509-514. [4] Qian, Q., Sun, P., Zhang, C., Liu, T., Chen, H., Li, F., Cheng, L., Zhao, L., Li, X. and Wang, C., A broadband and polarization-independent metasurface perfect absorber for hot-electron photoconversion, Nanoscale 2022,14, 14801-14806. [5] Liu, X., Qian, Q., Chen, H., Fan, L., Cheng, L., Zhao, L. andWang, C., Metasurface cutoff perfect absorber in a solar energy wavelengthband, Applied Optics 2023, 62, 7766-7772. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultra-wideband high-efficiency absorber that achieves high-efficiency absorption in the near-infrared to mid-wave infrared range and is almost independent of polarization.

[0005] To achieve the above objectives, the present invention provides an ultra-wideband high-efficiency absorber, comprising a SiO2 substrate, on which is a titanium nanomatrix array, whose diameter is consistent with the array period P and whose height is h1; and on the titanium nanomatrix array is a silicon nitride regular hexagonal prism array, whose distance from the center of the regular hexagon on the bottom surface to the vertex of the regular hexagon on the bottom surface is half of the array period P and whose height is h2.

[0006] As a further improvement of the present invention, one nanocylinder is etched at the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, resulting in a total of six nanocylinder etchings. Magnesium fluoride material is filled inside the six nanocylinder etchings to form six magnesium fluoride nanocylinders. The radius of each magnesium fluoride nanocylinder is r1, and the height is the same as that of the silicon nitride regular hexagonal prism array, which is h2.

[0007] As a further improvement of the present invention, above the silicon nitride regular hexagonal prism array, there are a chromium ring and a silicon nitride ring from bottom to top, the outer ring radius of the two rings is √3P / 4, the ring structure is tangent to each side of the regular hexagon on the top surface of the regular hexagonal prism array structure, the inner ring radius of the two rings is r2, the height of the chromium ring is h3, and the height of the silicon nitride ring is h4.

[0008] As a further improvement of the present invention, it is set that P=400nm, h1=300nm, h2=170nm, h3=15nm, h4=200nm, r1=35nm, r2=60nm, and the overall height of the absorber is less than 3 times the array period P.

[0009] Compared to existing technologies, the proposed absorber achieves highly efficient absorption across the 855-3540 nm wavelength range, virtually independent of polarization. This provides an innovative solution for developing ideal solar thermal absorbers, with crucial applications in renewable energy fields such as solar thermal photovoltaics and solar thermal energy utilization. Specifically, the proposed ultra-wideband, high-efficiency absorber exhibits slightly different cross-sectional views in the X and Y directions, primarily due to the silicon nitride hexagonal prism array and six magnesium fluoride nanocylinder layers. This makes the ultra-wideband, high-efficiency absorber polarization-dependent. When the incident light field is a TM (transverse magnetic) wave, the average absorption rate is 91.55% within the 400-4000nm band, and the average absorption rate in the absorption band (855-3540nm) reaches 96.67%, with a maximum absorption rate of 99.66%. When the incident light field is a TE (transverse electric) wave, the average absorption rate is 91.28% within the 400-4000nm band. The absorption band remains from 855 to 3540nm, and the average absorption rate within this range reaches 96.44%, with a maximum absorption rate of 99.72%. A comprehensive analysis and comparison of the absorption rates of TM and TE waves shows that the ultra-wideband high-efficiency absorber has better overall absorption performance when TM waves are incident, and the absorption effect is almost independent of polarization. The reason is that this ultra-wideband high-efficiency absorber is essentially a polarization-dependent device due to the slight asymmetry between the regular hexagonal prism array and the six-cylinder etching in the X and Y directions. However, its six-fold rotationally symmetric topological structure in the top-down view makes it insensitive to the polarization direction at vertical incidence. Therefore, the difference in the wide-spectrum average absorption rate between TM and TE waves is less than 0.3%, showing an effect that is almost independent of polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1(a) Schematic diagram of the ultra-wideband high-efficiency absorber structure proposed in this patent (5×5 period); (b) A top view of the ultra-wideband high-efficiency absorber with the top two ring layers removed; (c) A split-and-recombined diagram of the UWB-HEA unit structure along the X-axis. The optimized structural parameters are P = 400nm, h1 = 300nm, h2 = 170nm, h3 = 15nm, h4 = 200nm, r1 = 35nm, and r2 = 60nm; (d) The theoretical absorption spectrum of the UWB-HEA in the 400nm to 4000nm band for TM and TE waves, respectively. Light is incident along the -Z direction, as indicated by the arrow in (a).

[0011] Figure 2 is the effect of parameter P on the absorption performance of the absorber.

[0012] Figure 3 is the influence of parameter h1 on the absorption performance of the absorber.

[0013] Figure 4 is the influence of parameter h2 on the absorption performance of the absorber.

[0014] Figure 5 is the influence of parameter h3 on the absorption performance of the absorber.

[0015] Figure 6 is the influence of parameter h4 on the absorption performance of the absorber.

[0016] Figure 7 (a) The effect of parameter r1 on the absorption performance of the absorber when no material is filled in the etched hole; (b) The effect of parameter r1 on the absorption performance of the absorber when MgF2 is filled in the etched hole.

[0017] Figure 8 is the influence of parameter r2 on the absorption performance of the absorber. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to the accompanying drawings: An ultra-wideband high-efficiency absorber includes a SiO2 substrate, a titanium nanomatrix array on the SiO2 substrate, whose diameter is consistent with the array period P and whose height is h1, and a silicon nitride regular hexagonal prism array on the titanium nanomatrix array, whose distance from the center of the regular hexagon on the bottom surface to the vertex of the regular hexagon on the bottom surface is half of the array period P and whose height is h2.

[0019] One nanocylinder is etched at the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, resulting in a total of 6 nanocylinder etchings. Magnesium fluoride material is filled inside the 6 nanocylinder etchings to form 6 magnesium fluoride nanocylinders. The radius of each magnesium fluoride nanocylinder is r1, and the height is the same as that of the silicon nitride regular hexagonal prism array, which is h2.

[0020] Above the silicon nitride regular hexagonal prism array, from bottom to top are a chromium ring and a silicon nitride ring. The outer ring radius of the two rings is √3P / 4. The ring structure is tangent to each side of the regular hexagon on the top surface of the regular hexagonal prism array structure. The inner ring radius of the two rings is r2. The height of the chromium ring is h3, and the height of the silicon nitride ring is h4.

[0021] Set P=400nm, h1=300nm, h2=170nm, h3=15nm, h4=200nm, r1=35nm, r2=60nm, and the overall height of the absorber is less than 3 times the array period P.

[0022] In the present invention, SiO2 is used as a substrate for compatibility with semiconductor processes. A titanium (Ti) nanomatrix array is formed on the SiO2 substrate, with a diameter consistent with the array period P and a height of h1. A silicon nitride (Si3N4) regular hexagonal prism array is formed on the titanium nanomatrix. The distance between the center of the regular hexagon on the bottom surface and the vertex of the regular hexagon on the bottom surface is half of the period P, which allows for close alignment of the sides of the silicon nitride regular hexagonal prism array structure with the titanium nanomatrix array, reducing manufacturing errors. A nanocylinder is etched at the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, resulting in a total of six nanocylinder etchings. Magnesium fluoride (MgF2) material is then filled within the six nanocylinder etchings to form six magnesium fluoride nanocylinders. Each magnesium fluoride nanocylinder has a radius of r1 and a height of h2, the same as that of the silicon nitride regular hexagonal prism array. Above the silicon nitride hexagonal prism array, from bottom to top, are a chromium (Cr) ring and a silicon nitride (Si3N4) ring. The outer radius of each ring is √3P / 4, ensuring that the ring structure is tangent to each side of the regular hexagon on the top of the hexagonal prism array. The inner radius of each ring is r2. The height of the chromium ring is h3, and the height of the silicon nitride ring is h4. After optimizing various parameters, P = 400nm, h1 = 300nm, h2 = 170nm, h3 = 15nm, h4 = 200nm, r1 = 35nm, and r2 = 60nm were obtained. During the optimization process, the overall height of the absorber was strictly controlled to be less than 3 times the period to minimize high-order diffraction.

[0023] The present invention will be further explained below with reference to the accompanying drawings. Figure 1(a) Schematic diagram of our proposed ultra-wideband high-efficiency absorber (UWB-HEA). A SiO2 substrate is used for compatibility with semiconductor processes. A titanium (Ti) nanomatrix array is formed on the SiO2 substrate. Its diameter matches the array period, P, and its height is h1. On the titanium nanomatrix is a silicon nitride (Si3N4) regular hexagonal prism array. The distance between the center of the regular hexagon on the bottom surface and the vertex of the regular hexagon on the bottom surface is half of the period P, which facilitates the close fit of the side of the silicon nitride regular hexagonal prism array structure with the titanium nanomatrix array to reduce manufacturing errors. The height is h2. Among them, one nanocylinder is etched at the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, resulting in a total of 6 nanocylinder etchings. Magnesium fluoride (MgF2) material is filled inside the 6 nanocylinder etchings to form 6 magnesium fluoride nanocylinders. The radius of each magnesium fluoride nanocylinder is r1, and the height is the same as that of the silicon nitride regular hexagonal prism array, which is h2. Figure 1 (b) shows a top view of the ultra-wideband, high-efficiency absorber without the top two rings. Above the silicon nitride hexagonal prism array, from bottom to top, are a chromium (Cr) ring and a silicon nitride (Si3N4) ring. The outer radius of both rings is √3P / 4, ensuring that the ring structures are tangent to each side of the regular hexagon on the top of the hexagonal prism array. The inner radius of both rings is r2. The height of the chromium ring is h3, and the height of the silicon nitride ring is h4.

[0024] After optimizing various parameters, we obtained P = 400nm, h1 = 300nm, h2 = 170nm, h3 = 15nm, h4 = 200nm, r1 = 35nm, and r2 = 60nm. During the optimization process, the overall height of the absorber was strictly controlled to be less than three times the period to minimize high-order diffraction. We define the region with an absorptivity greater than 90% as the high-efficiency absorption zone. The proposed UWB-HEA covers a high-efficiency absorption range from 855nm to 3540nm, approximately 2685nm.

[0025] The proposed ultra-wideband high-efficiency absorber has slightly different cross-sectional views in the X and Y directions, mainly reflected in the silicon nitride regular hexagonal prism array and the six magnesium fluoride nanocylinder layers. Therefore, the ultra-wideband high-efficiency absorber is polarization-dependent. The influence of different incident light fields on the absorber absorption spectrum curve is shown in the figure. Figure 1As shown in (d), when the incident light field is a TM (transverse magnetic) wave, the average absorption rate in the 400-4000nm band is 91.55%, and the average absorption rate in the absorption band (855-3540nm) is as high as 96.67%, with a maximum absorption rate of 99.66%. When the incident light field is a TE (transverse electric) wave, the average absorption rate in the 400-4000nm band is 91.28%, and the absorption band remains from 855 to 3540nm. Within this range, the average absorption rate is as high as 96.44%, with a maximum absorption rate of 99.72%. A comprehensive analysis and comparison of the absorption rates of TM and TE waves shows that the ultra-wideband high-efficiency absorber has better overall absorption performance when TM waves are incident, and the absorption performance is almost independent of polarization. The reason for this is that the ultra-wideband, high-efficiency absorber exhibits subtle asymmetry in the X and Y cross-sections of the regular hexagonal prism array and the hexagonal etch, making it inherently polarization-dependent. However, its six-fold rotationally symmetric topological structure, when viewed from above, makes it polarization-insensitive at normal incidence. Consequently, the difference in the broadband average absorptivity between TM and TE waves is less than 0.3%, making it virtually polarization-independent. Therefore, to simplify the design, the following optimizations are performed assuming the incident light field is a TM wave.

[0026] Notably, the absorption spectrum also exhibits efficient absorption characteristics in the 466-495nm band, with an absorption peak in this band exhibiting an absorptivity of 92.47%. This phenomenon is primarily due to the incident light exciting the generation of electron-hole pairs in the ultraviolet region, which in turn triggers a strong resonance effect. This resonance effect significantly enhances the material's ability to absorb light in this band, leading to a significant increase in absorptivity and the formation of a distinct absorption peak. This phenomenon can be explained by quantum mechanics' transition theory and the physical mechanism of light-matter interaction, indicating that the material has high light absorption efficiency in this band, which has important guiding significance for the design and application of light-absorbing materials.

[0027] When other simulation parameters remain unchanged, as the array period P changes, the absorptivity of the structure to the incident light changes as shown in the following figure: Figure 2 As shown in Figure 2. We set the simulation range from 390nm to 430nm and the simulation step size to 10nm. Figure 2 As can be seen, when P is small, the absorption in the absorption band is low (the lowest average absorption is 96.35%). When the period P = 400nm, the absorption in the absorption band reaches its highest point, with an average absorption of 96.67%. As the P value increases further, although the absorption band expands from 855-3540nm to 874-3720nm, the absorptivity of the absorption band decreases to varying degrees. In other words, while the absorption band expands, some absorptivity is sacrificed. To maintain both high absorption and a wide bandwidth in the absorption band, we set P = 400nm in our ultra-wideband high-efficiency absorber.

[0028] When other simulation parameters remain unchanged, as the height h1 of the titanium nanomatrix changes, the absorptivity of the structure to the incident light changes as shown in the following figure: Figure 3 As shown in Figure 2. We set the simulation range from 280nm to 320nm and the simulation step size to 10nm. Figure 3 As can be seen, h1 has little to do with the absorptivity. When h1 is small, the minimum absorptivity at 3150nm is 98.47%, slightly lower than the 98.63% at h1 of 300nm. When h1 exceeds 300nm, there is little impact on device performance. We set h1 to 300nm to reduce the size of the structure, which is an advantage in manufacturing.

[0029] When other simulation parameters remain unchanged, as the height of the silicon nitride hexagonal prism and the etching height h2 of the six nano-cylinders change, the absorption rate of the structure to the incident light changes as shown in the following figure: Figure 4 As shown in Figure 2. We set the simulation range from 160nm to 180nm and the simulation step size to 5nm. Figure 4 As can be seen, as the h2 value shifts by 170nm, the absorption of the absorption band decreases to varying degrees. Within the absorption band (855-3540nm) at h2 of 170nm, the average absorptivity decreases from 96.67% to 85.27% at h2 of 165nm. This indicates that changes in h2 have a significant impact on the absorptivity of the absorption band. When h2 is small, the absorptivity in the absorption band is generally low and the absorption bandwidth is narrow. When h2 increases, the absorption bandwidth gradually deviates from the visible light region, and the absorptivity in the absorption band close to the visible light region decreases, resulting in a decrease in absorption performance. To keep the absorber's absorption bandwidth as close to the visible light region as possible and maintain a high absorptivity, we set h2 to 170nm in our ultra-wideband high-efficiency absorber.

[0030] When other simulation parameters remain unchanged, as the height h3 of the chrome ring changes, the absorptivity of the structure to the incident light changes as shown in the following figure: Figure 5 As shown in Figure 2. We set the simulation range to be from 5nm to 25nm, and the simulation step size to be 5nm. Figure 5As can be seen, when the h3 value is low, the absorptivity of the absorption band is also low. For example, when h3 is 5nm, ignoring the ultraviolet region, the absorption band only extends from 807 to 1100nm, and the absorption bandwidth is far inferior to the 855 to 3540nm when h3 is 15nm. As the height of h3 gradually increases, the absorptivity increases. However, when h3 exceeds 15nm and reaches 20nm, although the absorption band range expands, the absorptivity is poor. When h3 is further increased to 25nm, the increase in absorptivity comes at the expense of the length of the absorption bandwidth. Specifically, the absorption bandwidth decreases from 855 to 3540nm when h3 = 15nm to 855 to 3540nm when h3 = 15nm. This shows that changes in h3 have a significant impact on the absorptivity of the absorption band. To maximize the absorption bandwidth of the absorber and maintain high absorptivity, we set h3 to 15nm in our ultra-wideband high-efficiency absorber.

[0031] When other simulation parameters remain unchanged, as the height h4 of the silicon nitride ring changes, the absorptivity of the structure to the incident light changes as shown in the following figure: Figure 6 As shown in Figure 2. We set the simulation range from 180nm to 220nm and the simulation step size to 10nm. Figure 6 As can be seen, when the h4 value is low, the overall absorptivity of the absorption band is also low. For example, when h4 is 180nm, the average absorption within the absorption band (826-3550nm) is approximately 96.40%, which is lower than the 96.67% average absorptivity within the absorption band (855-3540nm) when h4 is 200nm. As the height of h4 increases, the absorption bandwidth slightly widens, but the absorptivity is slightly lower than the average absorption when h4 is 200nm. Overall, h4 does not significantly affect absorptivity. However, to maximize the absorber's absorption bandwidth and maintain high absorptivity, we set h4 to 200nm in our ultra-wideband, high-efficiency absorber.

[0032] Etch the silicon nitride regular hexagonal prism array. At the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, etch one nanocylinder each, and obtain a total of 6 nanocylinder etchings. The radius of each nanocylinder etching is r1 and the height is h2. We set the simulation range of the radius r1 of the nanocylinder etching to be from 25nm to 45nm, and the simulation step size is 5nm. When no material is filled inside the etching, the change process of the structure's absorption rate of the incident light is as follows Figure 7 (a) When the magnesium fluoride material is filled inside the etching, the absorption rate of the structure to the incident light changes as shown in Figure 7(b) shows that the overall absorptivity of the structure without a filler material is lower than that of the structure with a magnesium fluoride filler material. Furthermore, the change in the radius of the six nanocylinders in the unfilled state significantly affects the absorptivity, resulting in a better overall absorption effect when filled with magnesium fluoride. The fundamental reason for the significant improvement in absorptivity achieved by filling the etched interior with magnesium fluoride is that its dielectric properties optimize the impedance matching and electromagnetic field localization of the metasurface. When the etched cavity is hollow, the sudden change in the dielectric constant between silicon nitride and air leads to strong interfacial reflection, limiting light energy coupling. The addition of magnesium fluoride acts as an impedance gradient layer, effectively reducing the impedance mismatch between silicon nitride and free space, significantly suppressing reflection losses and allowing more incident light to enter the structure. Furthermore, the magnesium fluoride filler enhances the electric field localization in the etched cylindrical region: its moderate dielectric constant more densely confines the resonant electric field to the etched boundary and the silicon nitride material, significantly enhancing the interaction strength between light and the silicon nitride lossy medium, and efficiently converting light energy into heat through the material's intrinsic dissipation. Furthermore, magnesium fluoride optimizes the resonant mode coupling between etched units by smoothing the electromagnetic field distribution, achieving a critical coupling state at r1 = 35nm—a synergistic effect of minimizing reflection and suppressing transmission, resulting in strong broadband absorption. Its dielectric buffering effect also reduces the structure's sensitivity to dimensional variations, giving the design a higher manufacturing tolerance. Therefore, when magnesium fluoride is filled inside the etched unit, when r1 is 35nm, the ultra-wideband, high-efficiency absorber not only has a high absorptivity but also a long absorption bandwidth, providing a high tolerance for manufacturing errors in actual production.

[0033] When other simulation parameters remain unchanged, as the inner radius r2 of the chromium ring and the silicon nitride ring changes, the absorptivity of the structure to the incident light changes as shown in the following figure: Figure 8 As shown in Figure 2. We set the simulation range to be from 40nm to 80nm, and the simulation step size to be 10nm. Figure 8 As can be seen, when r2 is small, while absorption in the absorption band is high, the absorption bandwidth is sacrificed. For example, when r2 is 40 nm, the absorption bandwidth is 893–3500 nm, significantly smaller than the 855–3540 nm absorption bandwidth when r2 is 40 nm. Absorption in the absorption band reaches its maximum when the period P is 400 nm, with an average absorption of 96.67%. As the radius r2 increases, the absorptivity of the absorption band decreases to varying degrees, reaching an inflection point at r2 of 60 nm. To maintain both high absorption and a wide bandwidth in the absorption band, we set r2 to 60 nm in our ultra-wideband, high-efficiency absorber.

[0034] This patent invents an ultra-wideband, high-efficiency absorber. It uses a silicon dioxide substrate topped with a titanium nanomatrix array. A silicon nitride hexagonal prism array is constructed atop the titanium layer. Six cylindrical holes are etched at the midpoints of each hexagonal vertex on the bottom surface and filled with magnesium fluoride to form magnesium fluoride nanocylinders. A chromium ring and a silicon nitride ring are stacked on top of the hexagonal prisms, tangentially matching the hexagonal top surface of the hexagonal prisms. The proposed UWB-HEA has a high-efficiency absorption range (i.e., absorption band) from 855nm in the near-infrared to 3540nm in the mid-wave infrared, approximately 2685nm, for incident wavelengths ranging from 400nm to 4000nm. It achieves an average absorption rate of 96.67% for TM waves and a maximum absorption rate of 99.66%; it achieves an average absorption rate of 96.44% for TE waves and a maximum absorption rate of 99.72%, which is almost independent of polarization. In order to suppress the radiation energy loss of an object, an ideal solar thermal absorber needs to achieve efficient absorption in the widest possible bandwidth. The high-efficiency absorber proposed in this patent has this spectral selectivity feature, providing an innovative solution for the development of an ideal solar thermal absorber. It has vital applications in the field of renewable energy, such as solar thermal photovoltaics and solar thermal energy utilization.

[0035] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features therein according to the disclosed technical content without creative labor, and these substitutions and modifications are all within the protection scope of the present invention.

Claims

1. An ultra-wideband high-efficiency absorber, characterized by: It includes a SiO2 substrate, on which is a titanium nanomatrix array, whose diameter is consistent with the array period P and the height is h1; on the titanium nanomatrix array is a silicon nitride regular hexagonal prism array, whose distance between the center of the regular hexagon on the bottom surface and the vertex of the regular hexagon on the bottom surface is half of the array period P and the height is h2.

2. The ultra-wideband high-efficiency absorber according to claim 1, characterized in that: One nanocylinder is etched at the center of the regular hexagon on the bottom surface of the silicon nitride regular hexagonal prism array and the midpoint of each vertex of the regular hexagon on the bottom surface, resulting in a total of 6 nanocylinder etchings. Magnesium fluoride material is filled inside the 6 nanocylinder etchings to form 6 magnesium fluoride nanocylinders. The radius of each magnesium fluoride nanocylinder is r1, and the height is the same as that of the silicon nitride regular hexagonal prism array, which is h2.

3. The ultra-wideband high-efficiency absorber according to claim 2, characterized in that: Above the silicon nitride regular hexagonal prism array, from bottom to top are a chromium ring and a silicon nitride ring. The outer ring radius of the two rings is √3P / 4. The ring structure is tangent to each side of the regular hexagon on the top surface of the regular hexagonal prism array structure. The inner ring radius of the two rings is r2. The height of the chromium ring is h3, and the height of the silicon nitride ring is h4.

4. The ultra-wideband high-efficiency absorber according to claim 3, characterized in that: Set P=400nm, h1=300nm, h2=170nm, h3=15nm, h4=200nm, r1=35nm, r2=60nm, and the overall height of the absorber is less than 3 times the array period P.

Images