CN211402799U

CN211402799U - Dual-band terahertz wave absorber with graphene super-surface

Info

Publication number: CN211402799U
Application number: CN201922216171.9U
Authority: CN
Inventors: 胡丹; 王红燕; 朱巧芬
Original assignee: Anyang Normal University
Current assignee: Anyang Normal University
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2020-09-01
Anticipated expiration: 2029-11-29

Abstract

The utility model provides a graphite alkene surpasses surperficial dual-band terahertz wave absorber now. The super-surface wave absorber is composed of a plurality of wave absorber units, each wave absorber unit is composed of a bottom metal film (1), a middle medium layer (2) and a top graphene film (3), which are sequentially arranged from bottom to top, and the bottom metal film (1), the middle medium layer (2) and the top graphene film (3) are mutually attached. The bottom metal film (1) is an all-metal film, the top graphene film (3) is patterned single-layer graphene, and the geometric center of the patterned single-layer graphene, the geometric center of the middle dielectric layer (2) and the geometric center of the bottom metal film (1) are on the same straight line. The utility model has the advantages of high absorption rate, wide incident angle, insensitive polarization and the like.

Description

Dual-band terahertz wave absorber with graphene super-surface

Technical Field

The invention relates to the technical field of terahertz, in particular to a dual-band terahertz wave absorber with a graphene super-surface.

Background

Terahertz waves are electromagnetic spectra in the spectral range between the microwave and infrared bands. Terahertz waves have several unique properties: the terahertz waves have strong penetrating power to a plurality of nonpolar substances such as cartons, plastics, cloth and the like microwaves, so that the terahertz waves can detect hidden substances; the wavelength of the terahertz wave is shorter than that of the microwave, so that the terahertz wave has higher spatial resolution in the aspect of imaging; and thirdly, the photon energy of the terahertz wave is lower (1 THz-4 meV) and the biological tissue cannot be damaged. Compared with terahertz waves, the photon energy of X-rays is in the keV range, which may cause genetic damage to biological tissues and skin cancer. And fourthly, because the vibration and rotation energy levels of macromolecules are mostly in the terahertz wave band, the spectral information of the macromolecules can be obtained through the terahertz time-domain spectroscopy technology, and the material structures and physical properties of the macromolecules are analyzed and identified through the characteristic frequency.

It is due to these properties that terahertz waves have important applications in the fields of communications (broadband communications), radar, electronic countermeasure, electromagnetic weapons, astronomy, medical imaging (unmarked genetic testing, imaging at the cellular level), nondestructive testing, security inspection (biochemical inspection), and the like. Terahertz imaging technology and terahertz spectroscopy technology thus constitute two major key technologies for terahertz applications. In recent years, terahertz wave generation source and terahertz wave detection are recognized as two key problems restricting the development of terahertz technology. The absorption and energy capture of the terahertz wave are the basis for realizing terahertz detection and are the core problems of terahertz wave calibration, regulation, conversion and application. Therefore, the development of the terahertz technology is facilitated. The existing method generally has the defects of complex structure, low absorptivity, large structure size, difficult integration and the like. Aiming at the defects, the dual-frequency terahertz wave has the advantages of dual-frequency absorption, high absorption rate, wide incident angle, simple structure, easiness in integration and the like.

Disclosure of Invention

The invention provides a dual-band terahertz wave absorber with a graphene super-surface.

The purpose of the invention is realized as follows: the super-surface wave absorber is composed of a plurality of wave absorber units, each wave absorber unit is composed of a bottom metal film (1), a middle medium layer (2) and a top graphene film (3), which are sequentially arranged from bottom to top, and the bottom metal film (1), the middle medium layer (2) and the top graphene film (3) are mutually attached. The bottom metal film (1) is an all-metal film, the top graphene film (3) is patterned single-layer graphene, and the geometric center of the patterned single-layer graphene, the geometric center of the middle dielectric layer (2) and the geometric center of the bottom metal film (1) are on the same straight line.

The cross section of each unit is square, and the side length P of each unit is 2.1 microns.

The thickness d of the bottom layer metal film (1) is 0.5 micrometer and is made of one of gold, silver, copper or aluminum.

The intermediate dielectric layer (2) is silicon dioxide, the thickness t of the intermediate dielectric layer is 3.6 microns, and the relative dielectric constant is 3.9.

Patterning the single-layer graphene structure; the pattern consists of four rhombuses with completely identical geometric shapes and a disc; the four rhombuses are arranged in a vertical mirror symmetry mode and a left mirror symmetry mode and a right mirror symmetry mode; one vertex angle of two vertex angles corresponding to the four rhombus long diagonal lines is right opposite to the middle points of four edges of the middle medium layer, and the vertex angle of the other vertex angle, the geometric center of the disc, the geometric center of the middle medium layer (2) and the geometric center of the bottom metal film (1) are on the same straight line.

The two diagonal lengths L1 and L2 of the rhombus are respectively 1.0 micron and 0.7 micron, and the radius r of the disc is 0.2 micron.

Compared with the prior art, the invention has the following remarkable advantages:

1. the top layer of the super-surface wave absorber adopts a patterned single-layer graphene, so that the super-surface wave absorber is simple and compact in structure, perfectly symmetrical and easy to realize, and has the polarization insensitivity;

2. the super-surface wave absorber provided by the invention can realize two absorption peaks in the frequency range of 6-16 THz, and both have nearly perfect absorption rate;

3. the incident angle is in the range of 0-50 degrees, and the invention can still keep good absorption effect.

Drawings

FIG. 1: a schematic diagram of a three-dimensional structure of a dual-band terahertz wave absorber based on a graphene super surface is provided.

FIG. 2: a graphene super-surface-based dual-band terahertz wave absorber main schematic diagram is provided.

FIG. 3: double-frequency-band terahertz wave absorber upward-looking schematic diagram based on graphene super-surface.

FIG. 4: a performance curve diagram of a dual-band terahertz wave absorber based on a graphene super surface is provided.

FIG. 5: and under the TM mode, a performance diagram of the dual-band terahertz wave absorber based on the graphene super surface is obtained when the wave is incident at 0-70 degrees.

FIG. 6: and under the TE mode, a performance diagram of the dual-band terahertz wave absorber based on the graphene super surface is obtained when the wave is incident at 0-70 degrees.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1 to 3, a dual-band terahertz wave absorber with a graphene super-surface comprises a plurality of wave absorbing units continuously arranged along a plane. The wave absorber unit consists of a bottom metal film (1), a middle medium layer (2) and a top graphene film (3) which are sequentially arranged from bottom to top, wherein the bottom metal film (1), the middle medium layer (2) and the top graphene film (3) are mutually attached. The bottom metal film (1) is an all-metal film, the top graphene film (3) is patterned single-layer graphene, and the geometric center of the patterned single-layer graphene, the geometric center of the middle dielectric layer (2) and the geometric center of the bottom metal film (1) are on the same straight line.

When a plurality of wave absorbing units are continuously arranged along a plane, the bottom metal film 1 and the middle loss medium 2 are connected into a whole, and the top graphene films (3) are mutually isolated, so that each wave absorbing unit works independently.

As an embodiment, the three-layer structure of each wave-absorbing unit has the following dimensional parameters: the lattice period P is 2.1 microns, the top graphene film (3) is patterned single-layer graphene, and the patterned single-layer graphene consists of four rhombuses with identical geometric shapes and a disc; the two diagonal line lengths L1 and L2 of the rhombus are respectively 1.0 micron and 0.7 micron, and the radius r of the disc is 0.2 micron; the thickness of the top graphene film (3) is 1 nanometer; the bottom layer metal film (1) is made of gold, and the thickness d of the bottom layer metal film is 0.5 micrometer; the intermediate dielectric layer (2) is shown to be silicon dioxide with a thickness t of 3.6 microns and a relative dielectric constant of 3.9.

The absorption rate of the graphene super-surface dual-band terahertz wave absorber is defined as a ═ 1-R-T, where R is a reflectance and T is a transmittance. In order to maximize the absorption, it is desirable that the reflectance and transmittance be as small as possible over the entire frequency range. The bottom layer of the wave absorbing unit designed by the invention is an all-metal film (1), electromagnetic waves cannot be transmitted, and the transmissivity approaches to zero, so that the absorption rate calculation formula can be simplified to be A-1-R.

The simulation result of this embodiment under normal incidence of electromagnetic waves is shown in fig. 4, and is calculated by the CST MicrowaveStudio software. As can be seen from the graph, when a voltage is supplied between the graphene layer and the base metal layer, the absorption rate for terahertz is 99.45% or more at both 10.39THz and 12.40, and a dual-band high absorption rate is achieved.

In the embodiment, the performance of the dual-band terahertz wave absorber based on the graphene super-surface when the wave is incident at 0-70 degrees in the TM mode and the TE mode is shown in fig. 5 and 6. It can be seen from the figure that the incident electromagnetic wave of the wave absorber provided by the invention in the TM mode and the TE mode has good angle-independent absorption characteristics in the range of 0-50 degrees, and the absorptivity can be kept above 90%. Therefore, the super-surface wave absorber with the double frequency bands and the high absorption rate has good performance.

Claims

1. The utility model provides a graphite alkene super surperficial dual-band terahertz wave absorber, its characterized in that: the super-surface wave absorber is composed of a plurality of wave absorber units, wherein each wave absorber unit is composed of a bottom metal film (1), a middle medium layer (2) and a top graphene film (3), the bottom metal film (1), the middle medium layer (2) and the top graphene film (3) are sequentially arranged from bottom to top, the bottom metal film (1) is an all-metal film, the top graphene film (3) is patterned single-layer graphene, and the geometric center of the patterned single-layer graphene, the geometric center of the middle medium layer (2) and the geometric center of the bottom metal film (1) are on the same straight line.

2. The graphene super-surface dual-band terahertz wave absorber according to claim 1, characterized in that: the cross section of each wave absorber unit is square, and the side length P of each wave absorber unit is 2.1 microns.

3. The graphene super-surface dual-band terahertz wave absorber according to claim 1, characterized in that: the thickness d of the bottom layer metal film (1) is 0.5 micrometer and is made of one of gold, silver, copper or aluminum.

4. The graphene super-surface dual-band terahertz wave absorber according to claim 1, characterized in that: the intermediate dielectric layer (2) is silicon dioxide, the thickness t of the intermediate dielectric layer is 3.6 microns, and the relative dielectric constant is 3.9.

5. The graphene super-surface dual-band terahertz wave absorber according to claim 1, characterized in that: patterning the single-layer graphene structure; the pattern consists of four rhombuses with completely identical geometric shapes and a disc; the four rhombuses are arranged in a vertical mirror symmetry mode and a left mirror symmetry mode and a right mirror symmetry mode; one vertex angle of two vertex angles corresponding to the four rhombus long diagonal lines is right opposite to the middle points of four edges of the middle medium layer, and the vertex angle of the other vertex angle, the geometric center of the disc, the geometric center of the middle medium layer (2) and the geometric center of the bottom metal film (1) are on the same straight line.

6. The graphene super-surface dual-band terahertz wave absorber according to claim 5, characterized in that: the two diagonal lengths L1 and L2 of the diamond are 1.0 micron and 0.7 micron respectively, and the radius r of the disc is 0.2 micron.