CN107544103B

CN107544103B - Dual-band terahertz wave absorber based on graphene

Info

Publication number: CN107544103B
Application number: CN201610480681.5A
Authority: CN
Inventors: 肖丙刚; 古明月
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2016-06-28
Filing date: 2016-06-28
Publication date: 2020-08-18
Anticipated expiration: 2036-06-28
Also published as: CN107544103A

Abstract

The invention discloses a graphene-based dual-band terahertz wave absorber, belongs to wave absorbing devices in the technical field of terahertz, and utilizes the surface plasma characteristic of graphene. The wave absorbing device is a two-dimensional periodic structure, and the structure of the wave absorbing device is as follows: the metal strip (1) is composed of gold, an aluminum oxide dielectric layer (2), a graphene absorption layer (3), a polymethyl methacrylate (PMMA) dielectric layer (4), a silicon dioxide substrate layer (5) and a reflecting layer gold (6) at the bottom. The absorption spectrum of the graphene to the terahertz waves is calculated and simulated mainly through a finite element method, the structure of the wave absorption device is optimized, and an ideal absorption effect is obtained. The invention has simple structure and easy processing; and due to the special optical characteristics of the graphene, the position of an absorption peak can be adjusted through a doping mode.

Description

Dual-band terahertz wave absorber based on graphene

Technical Field

The invention relates to a graphene-based dual-band terahertz wave absorber, and belongs to the field of application of graphene materials in terahertz wave bands.

Background

Terahertz waves are electromagnetic waves with frequencies between 0.1THz and 10THz, and have partial characteristics of the two wave bands between millimeter waves and infrared rays. With the application of terahertz technology in communication, imaging, sensing and other aspects, great attention is paid to terahertz technology. At present, few materials can be applied to the band in the nature, an effective terahertz source and a detector are mainly lacked, in order to improve the detection efficiency and sensitivity of a terahertz detection device in recent years, researchers begin to put the research on terahertz wave absorbing materials at a crucial position, wherein the research on terahertz wave absorbing materials based on metamaterials is an important direction, and the materials can act on the terahertz band by changing the size of a structural unit, so that the terahertz wave absorbing materials are used as the terahertz wave absorbing device.

The wave-absorbing material is a material which can convert electromagnetic waves incident on the surface of the material into heat energy or other forms of energy, and can reduce the transmission and reflection of the electromagnetic waves, thereby realizing the absorption of the electromagnetic waves. The structure of the typical wave absorbing device at present is a sandwich type: the top layer is a periodic metamaterial pattern, the middle layer is a layer of non-metallic dielectric material, and the bottom layer is an opaque metal plane. The position of the absorption peak and the absorption efficiency are adjusted by adjusting the size of the unit structure, so that the adjustability is difficult to realize once the unit structure is fixed in the experiment. In the terahertz waveband, the imaginary part of the dielectric constant of metal used as a common surface plasma material is very large, so that the surface plasma cannot be directly supported, and the application of the surface plasma in the terahertz wave absorption aspect is limited.

Compared with a traditional metal wave absorber, the terahertz wave absorber based on the graphene has the advantages that the structure is simple, the processing is easy, and the property of the graphene can be adjusted through an external voltage. The real part of the relative dielectric constant of the graphene is negative in the terahertz waveband, so that the graphene shows the property of metal in the terahertz waveband and supports surface plasmon polariton. The graphene serving as a new material has the characteristics shown in the terahertz wave band, so that the graphene becomes a hotspot for research on wave-absorbing materials.

Disclosure of Invention

The invention designs a dual-band terahertz wave absorber based on graphene, and provides a terahertz wave absorbing device which is simple in structure and easy to adjust.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the dual-band terahertz wave absorber based on graphene is of a two-dimensional periodic six-layer structure and comprises the following components from top to bottom: a layer of metal strip, an aluminum oxide strip, a graphene strip, a layer of polymethyl methacrylate, a layer of silicon dioxide, and a bottommost metal reflective layer.

The dual-band terahertz wave absorbing device in the technical scheme is based on graphene materials and can be manufactured by a graphite oxide reduction method, and the processing of the device further comprises photoetching and etching technologies. The invention uses graphene strips as an absorption medium, and the chemical potential of the graphene strips can be changed by means of doping.

The beneficial effects of the invention are as follows:

1. the terahertz wave absorption device can realize high-efficiency absorption of terahertz waves, and the absorption efficiency of a single frequency band is close to 100%.

2. By adjusting the chemical potential of the graphene, a dual-band absorption effect can be obtained, and the absorption efficiency is over 90%.

3. The position of the absorption peak of the device can be adjusted not only by geometric parameters but also by an external voltage method.

4. The wave absorbing device adopts a two-dimensional periodic structure, has a simple and compact structure and is convenient for large-scale integration.

Drawings

FIG. 1 is a schematic diagram of the structural elements of the present invention.

FIG. 2 is a diagram of the absorption pattern with w =7 μm and μ varying from 1.5eV to 1.8eV

FIG. 3 is the diagram of the absorption pattern of the structure with chemical potential μ =1.5eV and w of 7.2 μm

The above pictures contain:

1: a metal material of gold; 2: aluminum oxide; 3, graphene; 4: polymethyl methacrylate;

5: silicon dioxide; 6: metallic material gold

m=t=0.5μm；b=210nm；g=1nm；h=85nm；d=3μm；s=10.75μm；

Detailed Description

Fig. 1 is a graphene-based dual-band terahertz wave absorber. The metal reflecting film is composed of gold with a period P and a thickness t as a reflecting substrate, a layer of silicon dioxide medium with a thickness d is superposed on the gold, the dielectric constant of the silicon dioxide medium is set to be 4, a layer of polymethyl methacrylate with a thickness h is superposed on the silicon dioxide, the dielectric constant of the polymethyl methacrylate medium is set to be 2.3, a layer of graphene strip with a width w is superposed on the polymethyl methacrylate to be used as an absorbing layer, the thickness of the graphene strip is g, a layer of aluminum oxide strip with a thickness b is superposed on the graphene, the dielectric constant of the aluminum oxide strip is 3.5, and the top layer is made of metal material gold with a thickness m. The thickness of gold is far larger than the skin depth of gold in the terahertz wave band, so the gold material can be regarded as PEC.

One of the most important properties of graphene is electrical tunability, so that the absorption effect of graphene on terahertz waves under different chemical potentials is analyzed, and as can be seen from fig. 2, when the chemical potential is changed from 1.5eV to 1.8eV, a dual-band absorption peak appears, and when the chemical potential is 1.5eV, both absorption peaks are greater than 90%; meanwhile, when other parameters are kept unchanged, the chemical potential is 1.5eV, and the width of a strip is 7.2 μm, a relatively ideal dual-band absorption peak appears, and the absorption efficiency is above 90%, as shown in FIG. 3.

Claims

1. Graphite alkene based on double-frequency-band terahertz wave absorber, its characterized in that: a layer of gold is used as a reflecting substrate layer, a layer of silicon dioxide substrate layer, a layer of polymethyl methacrylate, a layer of graphene strip absorbing layer, a layer of aluminum oxide strip dielectric layer and a top layer of gold strip layer; wherein, from the gold reflection stratum basale of bottom layer to the gold stripe band layer of top layer, specific every layer thickness respectively is: 0.5um, 3um, 85nm, 1nm, 210nm, 0.5um, and the length of the corresponding three layers of strip layers is: 7um, 7 um.