Tunable narrowband metamaterial absorber

Abstract

This invention relates to a tunable narrowband metamaterial absorber belonging to the fields of metamaterial absorbers and terahertz technology. The tunable narrowband metamaterial absorber is composed of an array of multiple identical absorber units. Each absorber unit is arranged from top to bottom with a strontium titanate layer (1), a dielectric layer (2), and a gold film (3). The length and width of the strontium titanate layer (1), the dielectric layer (2), and the gold film (3) are identical. A rectangular blind hole is etched on the absorber unit, penetrating the strontium titanate layer (1) to the upper surface of the dielectric layer (2). At the bottom of the rectangular blind hole, a graphene layer (4) is tightly attached to the upper surface of the dielectric layer (2). This tunable narrowband metamaterial absorber has dual-control functionality and is insensitive to polarization. By changing the Fermi level of the graphene layer, the absorption rate can be controlled; by changing the ambient temperature of the strontium titanate layer, the center frequency can be controlled.

Description

Technical Field

[0001] This invention, a tunable narrowband metamaterial absorber, belongs to the fields of metamaterial absorbers and terahertz technology. Background Technology

[0002] Terahertz technology has developed rapidly over the past few decades and is now widely used in wireless communication, sensors, and imaging. Along with the development of terahertz technology, various functional devices based on metamaterials have been proposed, such as fiber optic filters, absorbers, and polarization converters. Among them, metamaterial absorbers play an irreplaceable role in thermal emitters, photovoltaic cells, and stealth technology. Metamaterial absorbers can absorb incident electric and magnetic fields through metamaterial resonators. Traditional metamaterial absorbers are fixed-shape absorbers based on metallic structures. Under the condition of a determined structure, their electromagnetic response characteristics are also fixed and cannot be adjusted, which greatly limits their applications. If a metamaterial absorber with variable electromagnetic response could be designed, it would help expand the application range of absorbers and change the industrial landscape of absorbers. Summary of the Invention

[0003] To address the aforementioned technical requirements, this invention designs a tunable narrowband metamaterial absorber. This absorber has dual controllability and is insensitive to polarization. The absorption rate can be controlled by changing the Fermi level of the graphene layer, and the center frequency can be controlled by changing the ambient temperature of the strontium titanate layer.

[0004] The objective of this invention is achieved as follows:

[0005] A tunable narrowband metamaterial absorber consists of an array of multiple absorber units with identical structures. Each absorber unit is arranged from top to bottom with a strontium titanate layer, a dielectric layer, and a gold film. The length and width of the strontium titanate layer, dielectric layer, and gold film are all the same. A rectangular blind hole is etched in the center of each absorber unit, and the rectangular blind hole penetrates the strontium titanate layer to the upper surface of the dielectric layer. At the bottom of the rectangular blind hole, a graphene layer is attached to the upper surface of the dielectric layer.

[0006] The aforementioned tunable narrowband metamaterial absorber, wherein:

[0007] The structural parameters of the strontium titanate layer are 100 μm × 100 μm × 0.1 μm;

[0008] The cross-sectional dimensions of the rectangular blind hole are 13μm × 13μm;

[0009] The structural parameters of the dielectric layer are 100μm×100μm×14μm;

[0010] The structural parameters of the gold film are 100μm×100μm×1μm.

[0011] The above-mentioned tunable narrowband metamaterial absorber uses strontium titanate as the material for the strontium titanate layer, TOPAS as the material for the dielectric layer, gold as the material for the gold film, and graphene as the material for the graphene layer.

[0012] Beneficial effects:

[0013] The tunable narrowband metamaterial absorber of this invention is composed of an array of multiple absorber units with identical structures. Each absorber unit includes only a strontium titanate layer, a dielectric layer, a gold film, and a graphene layer. The structure is simple and easy to implement. This tunable narrowband metamaterial absorber has dual control functions and is insensitive to polarization. The absorption rate can be controlled by changing the Fermi level of the graphene layer, and the center frequency can be controlled by changing the ambient temperature of the strontium titanate layer. Attached Figure Description

[0014] Figure 1 This is a three-dimensional model structural diagram of the tunable narrowband metamaterial absorber of the present invention.

[0015] Figure 2 This is a three-dimensional model structural diagram of a single absorber unit in the tunable narrowband metamaterial absorber of the present invention.

[0016] Figure 3 The images show the absorption spectra of the present invention at different Fermi levels in graphene.

[0017] Figure 4 This is the absorption spectrum of the present invention under different temperature conditions.

[0018] Figure 5 This is the absorption spectrum of the present invention under different polarization angles.

[0019] In the figure: 1. Strontium titanate layer, 2. Dielectric layer, 3. Gold film, 4. Graphene layer. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0021] The tunable narrowband metamaterial absorber in this specific embodiment, such as Figure 1 As shown, the absorber unit is composed of an array of multiple identical absorber units. Each absorber unit has a strontium titanate layer 1, a dielectric layer 2, and a gold film 3 arranged sequentially from top to bottom. The length and width of the strontium titanate layer 1, the dielectric layer 2, and the gold film 3 are all the same. A rectangular blind hole is etched in the center of each absorber unit, penetrating the strontium titanate layer 1 to the upper surface of the dielectric layer 2. At the bottom of the rectangular blind hole, a graphene layer 4 is tightly attached to the upper surface of the dielectric layer 2. Figure 2 As shown;

[0022] In this specific embodiment, the strontium titanate layer 1 has structural parameters of 100 μm × 100 μm × 0.1 μm and is made of strontium titanate; the rectangular blind hole has a cross-sectional dimension of 13 μm × 13 μm; the dielectric layer 2 has structural parameters of 100 μm × 100 μm × 14 μm and is made of TOPAS with a relative permittivity of 3.8; the gold film 3 has structural parameters of 3100 μm × 100 μm × 1 μm and is made of gold with a conductivity of 4.56 × 10⁻⁶. 7 S / m; The structural parameters of graphene layer 4 are 13μm×13μm×0μm, and the material is graphene.

[0023] Under the above parameters, the normal incidence condition of terahertz waves was simulated, and the tuning performance of the tunable narrowband metamaterial absorber of the present invention was simulated and analyzed by FDTD software.

[0024] In the simulation experiment, the absorptivity A is defined as A = 1 - RT, where R is the reflectivity and T is the transmittance. Since the gold film 3 is set, the terahertz wave cannot be transmitted, that is, T = 0, so the absorptivity A is simplified to A = 1 - R.

[0025] Simulation Experiment 1

[0026] By applying an external voltage, the Fermi level of graphene layer 4 was adjusted to 0 EV, 0.2 eV, 0.4 eV, 0.6 eV, 0.8 eV, and 1.0 eV, respectively. Under these Fermi level conditions, the absorptivity curves are shown below. Figure 3 As shown, for a wave with a center frequency of 0.957 THz, the absorption rate can be dynamically adjusted from 30% to 100% by increasing the Fermi level of graphene layer 4. This indicates that the absorption rate can be controlled by adjusting the Fermi level of graphene layer 4 by controlling the applied voltage.

[0027] Simulation Experiment 2

[0028] Maintaining the Fermi level of graphene layer 4 at 1.0 eV, the ambient temperature of strontium titanate layer 1 was varied from 250 K to 400 K in 50 K increments. The resulting absorbance curves are shown below. Figure 4 As shown, when the temperature changes from 250K to 400K, the peak absorption rate remains above 99%, but the center frequency shifts from 0.957THz to 1.22THz. This indicates that the center frequency can be controlled by changing the temperature of the strontium titanate layer 1.

[0029] Simulation Experiment 3

[0030] While keeping the Fermi level of graphene layer 4 and the temperature of strontium titanate layer 1 constant, the polarization angle was varied from 0° to 90° in 10° steps. The resulting absorbance curve is shown below. Figure 5As shown, it can be seen that all the curves almost overlap, indicating that the tunable narrowband metamaterial absorber of the present invention is insensitive to polarization.

Claims

1. A tunable narrowband metamaterial absorber, comprising an array of multiple absorber units with identical structures, wherein each absorber unit is provided with a strontium titanate layer (1), a dielectric layer (2), and a gold film (3) from top to bottom; wherein the length and width of the strontium titanate layer (1), the dielectric layer (2), and the gold film (3) are all the same; characterized in that, A rectangular blind hole is etched in the center of the absorber unit, and the rectangular blind hole penetrates the strontium titanate layer (1) to the upper surface of the dielectric layer (2); at the bottom of the rectangular blind hole, the graphene layer (4) is attached to the upper surface of the dielectric layer (2); the material of the dielectric layer (2) is TOPAS.

2. The tunable narrowband metamaterial absorber according to claim 1, characterized in that, The following is stated: The structural parameters of the strontium titanate layer (1) are 100 μm × 100 μm × 0.1 μm; The cross-sectional dimensions of the rectangular blind hole are 13μm × 13μm; The structural parameters of the dielectric layer (2) are 100μm×100μm×14μm; The structural parameters of the gold film (3) are 100μm×100μm×1μm.

Images