An ultra-bandwidth terahertz graphene absorber based on a gradient gear column array

Abstract

The present invention discloses an ultra-bandwidth terahertz graphene absorber based on a gradient gear column array. The absorber comprises a base layer, and a plurality of gear column array layers and a plurality of graphene planar layers disposed on the base layer. The gear column array layers and the graphene planar layers are alternately arranged to form a plurality of cascaded coupled resonant cavities of gear column arrays, graphene planar layers, and gear column arrays. Each gear column array layer also forms a plurality of gear column-gear column coupled resonant cavities. By disposing multiple layers of gear column arrays between multiple layers of graphene planar layers to form cascaded coupled resonant cavities, the present invention achieves a coupled resonant cavity effect that enhances coupling, thereby increasing absorption of incident electromagnetic waves and improving the absorption efficiency of the terahertz graphene absorber. The presence of a rich set of coupling modes in the cascaded coupled resonant cavities effectively increases the absorption bandwidth.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz absorbers, and in particular to an ultra-bandwidth terahertz graphene absorber based on a gradient gear column array. Background Art

[0002] With the rapid development of science and technology, electromagnetic wave absorption technology plays a vital role in energy conversion, photoelectric detection, and other fields. Research on terahertz absorption devices has attracted particular attention. Graphene, a novel semiconductor material, possesses metal-like conductivity and can generate surface plasmons in the terahertz band when stimulated. This can be flexibly controlled using an applied voltage, offering new application prospects for the development of tunable micro-terahertz absorption devices.

[0003] On the other hand, terahertz waves (0.1-10 THz) lie between the microwave and infrared bands, combining the advantages of both microwave and optical communications. They offer high signal-to-noise ratios and high resolution, making them suitable for communications. Furthermore, their longer wavelengths provide excellent penetration and minimize transmission attenuation. These characteristics give terahertz technology broad application prospects in fields such as communications, medicine, and astronomy.

[0004] However, due to the limitations of the characteristics of the graphene material itself, the terahertz absorption rate of the single-layer graphene in the actual terahertz absorber is very low, and the absorption bandwidth is limited, which brings certain limitations to practical applications.

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an ultra-bandwidth terahertz graphene absorber based on a gradient gear column array, aiming to solve the problems of low absorption rate and narrow absorption bandwidth of existing terahertz absorbers.

[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0008] An ultra-wideband terahertz graphene absorber based on a gradient gear column array comprises: a base layer and a plurality of gear column array layers and a plurality of graphene plane layers disposed on the base layer; wherein the gear column array layers and the graphene plane layers are alternately distributed, and the gear column array layers and the graphene plane layers form a plurality of gear column array-graphene plane layer-gear column array cascade coupled resonant cavities; and a plurality of gear column-gear column coupled resonant cavities are formed in each gear column array layer.

[0009] The ultra-wideband terahertz graphene absorber based on the gradient gear column array has the number of the gear column array layers being no less than 3, and the number of the graphene plane layers being no less than 2.

[0010] The ultra-wideband terahertz graphene absorber based on the gradient gear column array, wherein the gear columns in the gear column array layer are arranged in a square lattice or a triangular lattice; each of the gear columns includes 10 to 20 saw teeth and a central column arranged in the center of the gear column.

[0011] The ultra-wideband terahertz graphene absorber based on the gradient gear column array, wherein the cross-sectional shape of the central column is one of circular, elliptical, square, rectangular, triangular, and polygonal; the material of the gear column is a high-refractive-index medium, and the refractive index of the high-refractive-index medium is greater than 2.5; the material of the central column is a first low-refractive-index medium, and the refractive index of the first low-refractive-index medium is less than 2.0.

[0012] The ultra-wideband terahertz graphene absorber based on a gradient gear column array, wherein the gear columns are made of silicon and the central column is made of silicon dioxide.

[0013] The ultra-wideband terahertz graphene absorber based on a gradient gear column array, wherein the size of the gear columns gradually decreases in a direction away from the base layer.

[0014] The ultra-wideband terahertz graphene absorber based on a gradient gear column array, wherein the base layer includes a substrate plane layer and a reflection plane layer, the substrate plane layer is made of a second low-refractive-index medium, and the refractive index of the second low-refractive-index medium is less than 2.0.

[0015] In the ultra-wideband terahertz graphene absorber based on a gradient gear column array, the substrate plane layer is made of silicon dioxide, and the reflective plane layer is made of gold or silver.

[0016] The ultra-wideband terahertz graphene absorber based on the gradient gear column array is provided with an electrode on each of the graphene planar layers, and the electrode is one or both of a gold electrode and an alloy electrode.

[0017] The ultra-wideband terahertz graphene absorber based on the gradient gear column array is characterized in that a third low-refractive-index medium is filled between the gear column array layer and the graphene plane layer, and the refractive index of the third low-refractive-index medium is less than 2.0; the third low-refractive-index medium is a high molecular polymer.

[0018] Beneficial effects: The present invention discloses an ultra-bandwidth terahertz graphene absorber based on a gradient gear column array. A cascaded coupled resonant cavity is formed by arranging multiple layers of gradient gear column arrays between multiple layers of graphene planar layers. When an electromagnetic wave is incident on the graphene absorber, the graphene is stimulated to generate surface plasmons, and under the action of the photon localization effect, the energy of the electromagnetic wave is coupled to the surface plasmons. The resulting coupled resonant cavity effect can increase the coupling effect, thereby increasing the absorption of the incident electromagnetic wave and improving the absorption efficiency of the terahertz graphene absorber. In addition, the presence of rich coupling modes in the above-mentioned cascaded coupled resonant cavity effectively increases the absorption bandwidth, thereby improving the practical application range of the terahertz graphene absorber. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of the terahertz graphene absorber in the present invention.

[0020] Figure 2 This is a schematic diagram of the gear column structure in the terahertz graphene absorber of the present invention.

[0021] Figure 3 When the chemical potential of graphene is 0.8 eV, 1.0 eV, 1.2 eV, 1.4 eV, and 1.5 eV, the absorption curve of the terahertz graphene absorber of the present invention is obtained by calculation.

[0022] Figure 4 1 is an xy cross-sectional electric field amplitude distribution diagram of a single gear post in the topmost gear post array of the terahertz graphene absorber at a frequency of 6.0 THz in some embodiments.

[0023] Figure 5 1 is an xy cross-sectional electric field amplitude distribution diagram of a single gear post in the topmost gear post array of the terahertz graphene absorber at a frequency of 8.0 THz in some embodiments.

[0024] Figure 6 1 is an xy cross-sectional electric field amplitude distribution diagram of a single gear post in the topmost gear post array of the terahertz graphene absorber at a frequency of 11.0 THz in some embodiments. DETAILED DESCRIPTION

[0025] The present invention provides an ultra-wideband terahertz graphene absorber based on a gradient gear column array. To help those skilled in the art better understand the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, combined with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] Electromagnetic wave absorption technology holds significant application prospects in fields such as photoelectric detection and photovoltaics. With the rapid development of terahertz technology, significant research results have been achieved in terahertz absorption devices, particularly in the development of terahertz absorption devices using the emerging material graphene. Graphene, a novel material with a honeycomb-shaped, two-dimensional hexagonal carbon structure, can generate surface plasmons in the terahertz band when stimulated. It possesses excellent and unique optoelectronic properties and is considered an ideal successor to traditional semiconductor materials. However, single-layer graphene itself has a low absorption rate for electromagnetic waves. To overcome this technical problem, researchers have exploited the resonant cavity effect of multilayer film structures to enhance the absorption of single-layer graphene, or exploited noble metal surface plasmons to enhance the absorption of single-layer graphene. However, single-layer graphene absorbers have limitations in both absorption efficiency and absorption bandwidth. The present invention proposes combining multilayer graphene with a multilayer gear column array to form multiple cascaded coupled cavities. This resonance enhancement effect is used to achieve a terahertz graphene absorber with high absorption efficiency and a wide absorption bandwidth.

[0027] Based on this, the present invention provides an ultra-wideband terahertz graphene absorber based on a gradient gear column array, which includes: a base layer 10 and a plurality of gear column array layers 20 and a plurality of graphene plane layers 30 arranged on the base layer 10; wherein the gear column array layers 20 and the graphene plane layers 30 are alternately distributed, and the gear column array layers 20 and the graphene plane layers 30 form a plurality of gear column array-graphene plane-gear column array cascade coupled resonant cavities; and a plurality of gear column-gear column coupled resonant cavities are formed in each gear column array layer 20.

[0028] Specifically, the present invention is not limited to this embodiment. According to actual application requirements, the number of layers of the gear column array layer can be selected to be equal to or greater than 3 layers, and the number of layers of the graphene plane layer can be selected to be equal to or greater than 2 layers. Figure 1The terahertz graphene absorber includes a base layer 10, and a plurality of gear column array layers and a plurality of graphene plane layers are arranged in a vertical direction on the upper side of the base layer 10. In order to clearly illustrate the structural characteristics of the present invention, the plurality of gear column array layers described in this embodiment are described by taking a 7-layer gear column array as an example, namely, a first gear column array 21, a second gear column array 22, a third gear column array 23, a fourth gear column array 24, a fifth gear column array 25, a sixth gear column array 26, and a seventh gear column array 27; the plurality of graphene plane layers are described by taking a 6-layer graphene plane layer as an example, namely, a first graphene plane layer 31, a second graphene plane layer 32, a third graphene plane layer 33, a fourth graphene plane layer 34, a fifth graphene plane layer 35, and a sixth graphene plane layer 36. Each gear post in the multilayer gear post array 21-27 has a gear-shaped cross-section, and the center of each gear post includes a center post 41. The gear sizes of the multilayer gear post array 21-27 decrease gradually from bottom to top in the vertical direction. The base layer 10 includes a substrate plane layer 11 and a reflective plane layer 12. The substrate plane layer 11 is made of a second low-refractive-index medium having a refractive index less than 2.0, preferably silicon dioxide. The reflective plane layer is made of a precious metal, preferably gold or silver. The gap between the multilayer gear post array 21-27 and the multilayer graphene plane layer 31-36 can be filled with a third low-refractive-index medium 00, having a refractive index less than 2.0. In this embodiment, the third low-refractive-index medium 00 can be a polymer, preferably PMMA.

[0029] The multi-layer gear column arrays 21-27 and the multi-layer graphene plane layers 31-36 are arranged to be alternately distributed in the vertical direction on the upper side of the base layer 10, that is, the vertical direction on the upper side of the base layer 10 is distributed from bottom to top as the first gear column array 21, the first graphene plane layer 31, the second gear column array 22, the second graphene plane layer 32, the third gear column array 23, the third graphene plane layer 33, the fourth gear column array 24, the fourth graphene plane layer 34, the fifth gear column array 25, the fifth graphene plane layer 35, the sixth gear column array 26, the sixth graphene plane layer 36, and the seventh gear column array 27.

[0030] See Figure 1 In some embodiments, any layer of the gear column arrays 21-27 is provided with at least four gear columns. In general, each gear column array includes at least four gear columns, which can ensure that there is a coupled resonant cavity effect in at least four directions in each gear column array, and try to make the absorption efficiency of each location on the terahertz graphene absorber tend to be stable and uniform.

[0031] The gear sizes of the multi-layer gear column arrays 21-27 decrease gradually from bottom to top in the vertical direction, that is, the gear column size of the first gear column array 21 is larger than the gear column size of the second gear column array 22, the gear column size of the second gear column array 22 is larger than the gear column size of the third gear column array 23, the gear column size of the third gear column array 23 is larger than the gear column size of the fourth gear column array 24, the gear column size of the fourth gear column array 24 is larger than the gear column size of the fifth gear column array 25, the gear column size of the fifth gear column array 25 is larger than the gear column size of the sixth gear column array 26, and the gear column size of the sixth gear column array 26 is larger than the gear column size of the seventh gear column array 27; the gear sizes of the multi-layer gear column arrays 21-27 decrease gradually from bottom to top in the vertical direction. The purpose is that gear column arrays of different sizes correspond to different coupled resonant frequencies, which is conducive to the superposition of different resonant frequencies, thereby facilitating the increase of the absorption bandwidth of the graphene absorber.

[0032] See Figure 1 In some embodiments, any two adjacent gear column array layers among the plurality of gear column array layers at least partially overlap with the projection of the graphene plane layer sandwiched between the two gear column array layers. In this embodiment, any two adjacent gear column array layers among the plurality of gear column array layers completely overlap with the projection of the graphene plane layer sandwiched between the two gear column array layers. Specifically, the first gear column array 21 and the second gear column array 22 are symmetrical about the first graphene plane layer 31, the second gear column array 22 and the third gear column array 23 are symmetrical about the second graphene plane layer 32, and the third gear column array 23 and the fourth gear column array 24 are symmetrical about the second graphene plane layer 32. The third graphene planar layer 33 is symmetrical, the fourth gear column array 24 and the fifth gear column array 25 are symmetrical about the fourth graphene planar layer 34, the fifth gear column array 25 and the sixth gear column array 26 are symmetrical about the fifth graphene planar layer 35, and the sixth gear column array 26 and the seventh gear column array 27 are symmetrical about the sixth graphene planar layer 36. Thus, each group of gear columns corresponding to the upper and lower sides of any graphene planar layer will form a resonant cavity effect, which spreads across the entire surface of the graphene planar layer, resulting in a high absorptivity across the entire graphene planar layer. Regardless of the direction from which electromagnetic waves enter the graphene planar layer, they will be significantly absorbed. Furthermore, a gear column-gear column coupling resonant cavity is formed between two adjacent gear columns in any gear column array. All gear column-gear column resonant cavity effects further enhance the coupling effect on the surface of the graphene planar layer, improving the graphene planar layer's ability to absorb light beams, and increasing the absorption efficiency of the terahertz graphene absorber.

[0033] The multilayer gear column arrays 21-27 and the multilayer graphene plane layers 31-36 form a plurality of gear column array-graphene plane layer-gear column array cascade coupled resonant cavities, that is, the first gear column array 21, the first graphene plane layer 31, and the second gear column array 22 form a resonant cavity; the second gear column array 22, the second graphene plane layer 32, and the third gear column array 23 form a resonant cavity; the third gear column array 23, the third graphene plane layer 33, and the fourth gear column array 24 form a resonant cavity; the fourth gear column array 24, the fourth graphene plane layer 34, and the fifth gear column array 25 form a resonant cavity; the fifth gear column array 25, the fifth graphene plane layer 35, and the sixth gear column array 26 form a resonant cavity; the sixth gear column array 26, the sixth graphene plane layer 36, and the seventh gear column array 27 form a resonant cavity. When electromagnetic waves are incident, graphene is stimulated to generate surface plasmons, and under the action of the photon localization effect, the energy of the electromagnetic waves is coupled into the surface plasmons. The enhanced resonance effect generated by the above-mentioned cascaded multiple coupled resonant cavities can improve the electromagnetic wave coupling effect, thereby increasing the absorption of the incident electromagnetic waves and improving the absorption efficiency of the terahertz graphene absorber. In addition, the rich coupling modes in the cascaded coupled resonant cavities are used to effectively increase the absorption bandwidth, thereby obtaining a terahertz graphene absorber with high absorption and absorption energy bandwidth, which is suitable for detection and monitoring work in many fields such as chemistry, medicine, and environment.

[0034] See Figure 1 In some embodiments, an electrode is further provided on each graphene plane layer, and the electrode is one or both of a gold electrode and an alloy electrode; for example, a first gold electrode 51 is provided on the first graphene plane layer 31, a second gold electrode 52 is provided on the second graphene plane layer 32, a third gold electrode 53 is provided on the third graphene plane layer 33, a fourth gold electrode 54 is provided on the fourth graphene plane layer 34, a fifth gold electrode 55 is provided on the fifth graphene plane layer 35, and a sixth gold electrode 56 is provided on the sixth graphene plane layer 36. The chemical potentials of the corresponding six graphene plane layers 31-36 are controlled respectively by applying voltages to the six gold electrodes 51-56, thereby more flexibly controlling the absorption rate of the graphene plane layers.

[0035] In some embodiments, the material of the multi-layer gear column array is a high-refractive index medium, the refractive index of the high-refractive index medium is greater than 2.5, preferably silicon, and the gear columns in the gear column array layer are arranged in a square lattice arrangement or a triangular lattice arrangement or other regular lattice arrangement; each of the gear columns includes 10 to 20 saw teeth and a central column 41 arranged at the center of the gear column, and the cross-section of the central column 41 includes any one of a circle, an ellipse, a square, a rectangle, a triangle, and a polygon. Providing a central column in each gear column is equivalent to providing a resonant cavity in each gear column, which is beneficial to improving the absorption rate of the graphene planar layer. In addition, providing a central column in each gear column will enrich the electromagnetic field distribution pattern in the gear column, thereby increasing the absorption bandwidth of the terahertz graphene absorber.

[0036] See Figure 2 In some embodiments, each of the gear column arrays 21-27 is a 9*9 square lattice gear column array, and the interval period l0 of the gear column array is 23 μm. The height l1 of each gear column is set to 2.4 μm. Each gear column includes 12 symmetrically distributed saw teeth. The inner radius l2 of each gear is 2.4 μm. The center of each gear column includes a center column with a radius l3 of 1.6 μm that coincides with the center. The height of the center column is the same as the height of the gear column, which is 2.4 μm. The material of the center column is silicon dioxide. The gear post dimensions of the multi-layered gear post arrays 21-27 decrease gradually from bottom to top in the vertical direction. Specifically, the serration length l4 decreases gradually. For example, the serration length of each gear post in the first gear post array layer 21 is 7.4 μm, the serration length of each gear post in the second gear post array 22 is 7.25 μm, the serration length of each gear post in the third gear post array 23 is 7.1 μm, the serration length of each gear post in the fourth gear post array layer 24 is 6.95 μm, the serration length of each gear post in the fifth gear post array 25 is 6.8 μm, the serration length of each gear post in the sixth gear post array 26 is 6.65 μm, and the serration length of each gear post in the seventh gear post array 27 is 6.5 μm. It should be noted that these are merely illustrative examples, and the shapes and dimensions of the multi-layered gear post arrays 21-27 are not limited to the dimensions listed above. They can be determined based on specific applications and are not intended to be limiting.

[0037] In some embodiments, the material of the central column 41 is a first low-refractive-index medium having a refractive index less than 2.0, preferably silicon dioxide. The chemical and physical properties of silicon dioxide are very stable, which is conducive to long-term use and has a good effect on improving the absorption rate of the graphene planar layer.

[0038] See Figure 1In some embodiments, a first gold electrode 51 is further provided on the first graphene plane layer 31, a second gold electrode 52 is further provided on the second graphene plane layer 32, a third gold electrode 53 is further provided on the third graphene plane layer 33, a fourth gold electrode 54 is further provided on the fourth graphene plane layer 34, a fifth gold electrode 55 is further provided on the fifth graphene plane layer 35, and a sixth gold electrode 56 is further provided on the sixth graphene plane layer 36. Due to the particularity of graphene materials, under an applied voltage, the Fermi level of the graphene material itself will change, thereby changing the graphene's absorption rate of incident light. Therefore, in this embodiment, the conductivity of the first graphene plane layer 31 can be adjusted by controlling the first gold electrode 51, thereby changing the chemical potential parameters of the first graphene plane layer 51; the conductivity of the second graphene plane layer 32 can be adjusted by controlling the second gold electrode 52, thereby changing the chemical potential parameters of the second graphene plane layer 32; the conductivity of the third graphene plane layer 33 can be adjusted by controlling the third gold electrode 53, thereby changing the chemical potential parameters of the third graphene plane 33; the conductivity of the fourth graphene plane layer 34 can be adjusted by controlling the fourth gold electrode 54, thereby changing the chemical potential parameters of the fourth graphene plane layer 34; the conductivity of the fifth graphene plane layer 35 can be adjusted by controlling the fifth gold electrode 55, thereby changing the chemical potential parameters of the fifth graphene plane layer 35; the conductivity of the sixth graphene plane layer 36 can be adjusted by controlling the sixth gold electrode 56, thereby changing the chemical potential parameters of the sixth graphene plane layer 36. Gold and alloy electrodes are both good conductors of electricity and possess one or more properties, including oxidation resistance, corrosion resistance, low overvoltage, and resistance to passivation. These electrodes offer long-term stability and flexibility. This allows for flexible control of the absorption efficiency and range of terahertz graphene absorbers, avoiding the costly re-manufacturing required to adjust device parameters and enhancing their applications in chemistry, medicine, and the environment.

[0039] like Figure 3As shown, the chemical potential of the graphene material is adjusted from 0.8eV to 1.0eV, 1.2eV, 1.4eV, and finally to 1.5eV. The absorption frequency of the sensor increases with the increase in chemical potential, and the corresponding absorption rate is improved. At a chemical potential of 0.8eV, the absorption rate at a frequency of 6.0THz is 90.7%, and when the chemical potential increases to 1.5eV, the absorption rate at 6.0THz is 96.2%. At a chemical potential of 0.8eV, the absorption rate at a frequency of 8.0THz is 93.2%, and when the chemical potential increases to 1.5eV, the absorption rate at 8.0THz is 98.3%. At a chemical potential of 0.8eV, the absorption rate at a frequency of 10.0THz is 72.8%, and when the chemical potential increases to 1.5eV, the absorption rate at 10.0THz is 98.9%. Therefore, the present invention can adjust the chemical potential parameters of the graphene plane by controlling the applied voltage, thereby achieving the purpose of flexibly controlling the efficiency and range of the absorber. Figure 3 As shown in FIG. 1 , when the chemical potential is 1.5 eV, the absorption rate is maintained above 90% in the frequency range of 5.5 THz to 11.6 THz. Therefore, the present invention can achieve high-efficiency absorption in an ultra-wideband.

[0040] In some embodiments, the surface conductivity σ(ω, μ c , Γ, T) can be expressed by the Drude formula as:

[0041]

[0042] Where ω is the angular frequency, μ is c is the chemical potential, Γ=(2τ) -1 is the scattering rate, τ is the relaxation time, T is the temperature, ξ is the electron energy, is the reduced Planck constant, κ B is the Boltzmann constant, and e is the electron charge. One of the significant advantages of graphene is that its chemical potential μ c The DC bias voltage V can be adjusted over a wide frequency range. g This is because V g When it changes, its electric field E0 changes, causing the graphene carrier density n s Change, μ c There will also be corresponding changes.

[0043] Specifically, as one embodiment of the present invention, the thickness of the first graphene planar layer 31, the second graphene planar layer 32, the third graphene planar layer 33, the fourth graphene planar layer 34, the fifth graphene planar layer 35, and the sixth graphene planar layer 36 are all 0.35 nm. The first gold electrode 51, the second gold electrode 52, the third gold electrode 53, the fourth gold electrode 54, the fifth gold electrode 55, and the sixth gold electrode 56 are identical in shape, being rectangular parallelepiped electrodes with a length of 30 μm, a height of 1 μm, and a width of 1 μm. The thickness of the dielectric substrate planar layer in the base layer is 12 μm, and the thickness of the metal reflective layer is 2 μm. It should be noted that these are merely illustrative examples, and the dimensions of the multilayered gear column arrays 21-27, the multilayered graphene planar layers 31-36, the gold electrodes 51-55, the substrate planar layer 11 in the base layer, and the reflective planar layer 12 are not limited to the dimensions given above. These dimensions may be determined based on the specific application and are not intended to be limiting here.

[0044] Specifically, as an embodiment of the present invention, the direction of the long axis of the first gold electrode 51 is the y-axis, the direction perpendicular to the long axis of the first gold electrode 51 is the x-axis, and the direction perpendicular to the graphene plane layer 31 upward is the z-axis. Figure 1 As shown. The electromagnetic wave is incident vertically from above the seventh gear column array 27, and is coupled to the multi-layer gear column array and the multi-layer graphene planar layer through the multi-layer gear column array. Then, it is reflected back to the multi-layer gear column array and the multi-layer graphene planar layer through the metal reflective plane layer 12 of the base layer 10. Finally, the electromagnetic wave is reflected from above the seventh gear column array 27. Here, P is defined as 吸收 and P 反射 Represents the absorptivity and reflectivity, calculate the absorptivity P 吸收 =1-P 反射 The absorptivity of the terahertz graphene absorber is obtained.

[0045] like Figure 4 The figure shows the xy cross-sectional electric field amplitude distribution of the seventh gear column array 27, the topmost gear column array of the terahertz graphene absorber in this embodiment, at a frequency of 6.0 THz. As can be seen, strong electric fields exist in the central cavity and upper and lower teeth of the seventh gear column array 27, and strong absorption occurs at corresponding locations perpendicularly projected onto the sixth graphene planar layer 36.

[0046] like Figure 5 The figure shows the xy cross-sectional electric field amplitude distribution of the seventh gear column array 27, the topmost gear column array of the terahertz graphene absorber in this embodiment, at a frequency of 8.0 THz. As can be seen, strong electric fields exist in the central cavity and left and right teeth of the seventh gear column array 27, and strong absorption occurs at corresponding locations perpendicularly projected onto the sixth graphene planar layer 36.

[0047] like Figure 6 The figure shows the xy cross-sectional electric field amplitude distribution of the seventh gear column array 27, the topmost gear column array of the terahertz graphene absorber in this embodiment, at a frequency of 11.0 THz. As can be seen, strong electric fields exist in the central cavity of the seventh gear column array 27, along with all teeth near the central cavity and on the outer sides of the teeth on the left and right sides. These locations exhibit strong absorption at corresponding locations perpendicularly projected onto the sixth graphene planar layer 36.

[0048] In summary, the present invention discloses an ultra-wideband terahertz graphene absorber based on a multi-layer gradient gear column array, which includes: a base layer and a plurality of gear column array layers and a plurality of graphene plane layers arranged on the base layer; wherein the gear column array layers and the graphene plane layers are alternately distributed, and the gear column array layers and the graphene plane layers form a plurality of gear column array-graphene plane layer-gear column array cascade coupled resonant cavities; and a plurality of gear column-gear column coupled resonant cavities are formed in each gear column array layer. The present invention forms a cascaded coupled resonant cavity by arranging a multi-layer gradient gear column array between multiple layers of graphene planar layers. When an electromagnetic wave is incident on the graphene absorber, the graphene is stimulated to generate surface plasmons. Under the action of the photon localization effect, the energy of the electromagnetic wave is coupled to the surface plasmons. The resulting coupled resonant cavity effect can enhance the coupling effect, thereby increasing the absorption of the incident electromagnetic wave and improving the absorption efficiency of the terahertz graphene absorber. In addition, the presence of rich coupling modes in the above-mentioned cascaded coupled resonant cavity effectively increases the absorption bandwidth, thereby improving the practical application range of the terahertz graphene absorber.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An ultra-wideband terahertz graphene absorber based on a gradient gear column array, characterized in that: include: A base layer and a plurality of gear column array layers and a plurality of graphene plane layers disposed on the base layer; wherein the gear column array layers and the graphene plane layers are alternately distributed, and the gear column array layers and the graphene plane layers form a plurality of gear column array-graphene plane layer-gear column array cascade coupled resonant cavities; and a plurality of gear column-gear column coupled resonant cavities are formed in each gear column array layer; The number of layers of the gear column array layer is not less than 3, and the number of layers of the graphene plane layer is not less than 2; The gear posts in the gear post array layer are arranged in a square lattice or a triangular lattice; each of the gear posts includes 10 to 20 saw teeth and a central post arranged at the center of the gear post; The size of the gear column gradually decreases in a direction away from the base layer.

2. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 1, characterized in that: The cross-sectional shape of the central column is one of circular, elliptical, square, rectangular, triangular, and polygonal; the material of the gear column is a high-refractive-index medium, and the refractive index of the high-refractive-index medium is greater than 2.5; the material of the central column is a first low-refractive-index medium, and the refractive index of the first low-refractive-index medium is less than 2.

0.

3. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 1, characterized in that: The gear column is made of silicon, and the center column is made of silicon dioxide.

4. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 1, characterized in that: The base layer includes a substrate plane layer and a reflection plane layer. The substrate plane layer is made of a second low-refractive-index medium, and the refractive index of the second low-refractive-index medium is less than 2.

0.

5. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 4, characterized in that: The substrate plane layer is made of silicon dioxide, and the reflective plane layer is made of gold or silver.

6. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 1, characterized in that: An electrode is also provided on each of the graphene planar layers, and the electrode is one or both of a gold electrode and an alloy electrode.

7. The ultra-wideband terahertz graphene absorber based on a gradient gear column array according to claim 1, characterized in that: A third low-refractive-index medium is filled between the gear column array layer and the graphene plane layer. The refractive index of the third low-refractive-index medium is less than 2.

0. The third low-refractive-index medium is a high molecular polymer.

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