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

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

A dual-band terahertz absorber with a graphene metasurface

technical field

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

Background technique

Terahertz waves are the electromagnetic spectrum in the spectral range between the microwave and infrared bands. Terahertz waves have some unique properties: First, terahertz waves, like microwaves, have strong penetrating power to many non-polar substances, such as cartons, plastics, and cloth, so terahertz waves can detect hidden objects; The wavelength of hertz waves is shorter than that of microwaves, so that terahertz waves have higher spatial resolution in imaging; third, the photon energy of terahertz waves is relatively low (1THz ~ 4meV) and will not cause damage to biological tissues. Compared with terahertz waves, X-rays have photon energies in the keV range, which may cause genetic damage to biological tissues and skin cancer. 4. Since the vibrational and rotational energy levels of macromolecules are mostly in the terahertz band, their spectral information can be obtained by terahertz time-domain spectroscopy, and their material structures and properties can be analyzed and identified by their characteristic frequencies.

It is because of these properties that terahertz waves are used in communications (broadband communication), radar, electronic countermeasures, electromagnetic weapons, astronomy, medical imaging (label-free genetic inspection, imaging at the cellular level), non-destructive testing, security inspection (biochemical Inspection) and other fields have important applications. Terahertz imaging technology and terahertz spectroscopy technology thus constitute the two main key technologies for terahertz applications. In recent years, THz wave generation and THz wave detection have been recognized as two key issues restricting the development of THz technology. The absorption and energy capture of terahertz waves are the basis for realizing terahertz detection, and they are also the core issues of terahertz wave calibration, regulation, conversion and application. Therefore, the research and development of terahertz technology will be beneficial to the development of terahertz technology. However, the existing ones generally have disadvantages such as complex structure, low absorption rate, large structure size, and difficulty in integration. In view of the above shortcomings, the present invention designs a dual-frequency terahertz with the advantages of dual-frequency absorption, high absorption rate, wide incident angle, simple structure, and easy integration.

SUMMARY OF THE INVENTION

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

The object of the present invention is achieved as follows: the metasurface wave absorber is composed of a plurality of wave absorber units, and the wave absorber unit is composed of a bottom metal film (1), an intermediate dielectric layer (2) and The top graphene film (3) is composed, and the bottom metal film (1), the intermediate medium layer (2) and the top graphene film (3) are bonded to each other. The bottom metal film (1) is an all-metal film, the top graphene film (3) is a patterned single-layer graphene, and the geometric center of the patterned single-layer graphene and the geometric center of the intermediate dielectric layer (2) And the geometric center of the underlying metal film (1) is on a straight line.

The cross section of each unit is square, and its side length P is 2.1 μm.

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

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

The single-layer graphene structure is patterned; the pattern is composed of four rhombus with identical geometric shapes and a disk; the four rhombus are arranged in a mirror-symmetrical manner of up and down, left and right; the four rhombus One of the two vertices corresponding to the long diagonal is exactly at the midpoint of the four sides of the intermediate dielectric layer, and the vertex of the other vertex corresponds to the geometric center of the disc and the geometry of the intermediate dielectric layer (2). The center and the geometric center of the underlying metal film (1) are on a straight line.

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

Compared with the prior art, the present invention has the following significant advantages:

1. The top layer of the metasurface absorber adopts a patterned single-layer graphene, which is simple, compact, perfectly symmetrical, easy to implement, and can also be polarized insensitive;

2. The metasurface wave absorber proposed by the present invention can realize two absorption peaks in the frequency range of 6-16 THz, and both have almost perfect absorption rates;

3. When the incident angle is in the range of 0° to 50°, the present invention can still maintain a good absorption effect.

Description of drawings

Figure 1: Schematic diagram of the three-dimensional structure of a dual-band terahertz absorber based on graphene metasurfaces.

Figure 2: Main schematic diagram of a dual-band terahertz absorber based on graphene metasurfaces.

Figure 3: Schematic bottom view of a dual-band terahertz absorber based on a graphene metasurface.

Figure 4: Graph of the performance of a dual-band terahertz absorber based on graphene metasurfaces.

Figure 5: Performance diagram of the graphene metasurface-based dual-band terahertz absorber at 0°-70° incidence in TM mode.

Figure 6: Performance diagram of a dual-band terahertz absorber based on graphene metasurface at 0°-70° incidence in TE mode.

Detailed ways

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

As shown in Figures 1-3, a dual-band terahertz wave absorber with a graphene metasurface includes a plurality of wave absorbing units continuously arranged along a plane. The absorber unit is composed of a bottom metal film (1), an intermediate dielectric layer (2) and a top graphene film (3) arranged in sequence from bottom to top, the bottom metal film (1), the intermediate dielectric layer (2) and the top layer The graphene films (3) are adhered to each other. The bottom metal film (1) is an all-metal film, the top graphene film (3) is a patterned single-layer graphene, and the geometric center of the patterned single-layer graphene and the geometric center of the intermediate dielectric layer (2) And the geometric center of the underlying metal film (1) is on a straight line.

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

As an example, the size parameters of the three-layer structure of each wave absorbing unit are as follows: lattice period P=2.1 μm, the top graphene film (3) is a patterned single-layer graphene, and the patterned single-layer graphite The alkene is composed of four rhombus with identical geometric shapes and a disc; the two diagonal lengths L1 and L2 of the rhombus are 1.0 microns and 0.7 microns respectively, and the radius r of the disc is 0.2 microns; the The thickness of the top graphene film (3) is 1 nanometer; the bottom metal film (1) shown is gold, and its thickness d is 0.5 μm; the middle dielectric layer (2) shown is silicon dioxide, and its thickness t is 3.6 microns, and the relative dielectric constant is 3.9.

The absorptivity of the dual-band terahertz wave absorber of a graphene metasurface described in this embodiment is defined as A=1-R-T, where R is the reflectivity and T is the transmittance. To maximize absorptivity, reflectivity and transmittance are required to be as small as possible over the entire frequency range. The bottom layer of the wave absorbing unit designed by the present invention is an all-metal film (1), electromagnetic waves cannot be transmitted, and the transmittance is close to zero, so the calculation formula of the absorption rate can be simplified as A=1-R.

The simulation result of this embodiment under the normal incidence of electromagnetic waves is shown in FIG. 4 , and the simulation result is calculated by CST MicrowaveStudio software. It can be seen from the figure that when the supply voltage is applied between the graphene layer and the base metal layer, at 10.39THz and 12.40, the absorption rate of the pair of terahertz is above 99.45%, achieving dual-band high absorption rate.

Figure 5 and Figure 6 show the performance of the graphene metasurface-based dual-band terahertz wave absorber in the TM mode and the TE mode in this example at an incidence of 0° to 70°. It can be seen from the figure that the wave absorber proposed by the present invention has good angle-independent absorption characteristics of incident electromagnetic waves in the TM mode and TE mode in the angle range of 0° to 50°, and the absorption rate can be maintained at 90° %above. It can be seen that this embodiment is a dual-band, high absorption rate metasurface wave absorber with good performance.

Claims (6)

1. a dual-band terahertz wave absorber of graphene metasurface, it is characterized in that: this metasurface wave absorber is made up of a plurality of absorber units, and the absorber unit is by the bottom metal that is arranged successively from bottom to top The film (1) is composed of an intermediate dielectric layer (2) and a top graphene film (3), and the bottom metal film (1), the intermediate dielectric layer (2) and the top graphene film (3) are bonded to each other, and the described The bottom metal film (1) is an all-metal film, and the top graphene film (3) is a patterned monolayer graphene, the geometric center of the patterned monolayer graphene, the geometric center of the intermediate dielectric layer (2) and the bottom layer The geometric center of the metal thin film (1) is on a straight line. 2. the dual-band terahertz wave absorber of a kind of graphene metasurface according to claim 1, is characterized in that: the cross section of described each wave absorber unit is all square, and its side length P is 2.1 microns . 3. the dual-band terahertz wave absorber of a kind of graphene metasurface according to claim 1, is characterized in that: the thickness d of described bottom metal film (1) is 0.5 micron, is composed of gold, silver, copper or Made of one of aluminum. 4. the dual-band terahertz wave absorber of a kind of graphene metasurface according to claim 1, is characterized in that: intermediate dielectric layer (2) is silicon dioxide, and its thickness t is 3.6 microns, and relative dielectric constant is 3.9. 5. the dual-band terahertz wave absorber of a kind of graphene metasurface according to claim 1, is characterized in that: described single-layer graphene structure is patterned; Described pattern is composed of four geometric shapes completely The same rhombus and a disc are formed; the four rhombus are arranged in a mirror-symmetrical manner up and down and left and right; one of the two apex angles corresponding to the long diagonal lines of the four rhombus is opposite to the middle medium layer. The midpoint of the four sides and the vertex of the other vertex are on a straight line with the geometric center of the disk, the geometric center of the intermediate dielectric layer (2), and the geometric center of the underlying metal film (1). 6. the dual-band terahertz wave absorber of a kind of graphene metasurface according to claim 5, is characterized in that: two diagonal lengths L1 and L2 of rhombus are respectively 1.0 microns and 0.7 microns, and the The radius r is 0.2 microns.

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