CN110854546A - Graphene-adjustable dual-band metamaterial absorber - Google Patents
Graphene-adjustable dual-band metamaterial absorber Download PDFInfo
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- CN110854546A CN110854546A CN201911264479.9A CN201911264479A CN110854546A CN 110854546 A CN110854546 A CN 110854546A CN 201911264479 A CN201911264479 A CN 201911264479A CN 110854546 A CN110854546 A CN 110854546A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/007—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with means for controlling the absorption
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Abstract
The invention provides a graphene adjustable dual-band metamaterial absorber. The metamaterial absorber is composed of a plurality of absorber units, each 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 metamaterial absorber provided by the invention has the characteristics of high absorptivity, tunable frequency, wide incident angle and polarization insensitivity, and has very high engineering application value.
Description
Technical Field
The invention relates to the technical field of optical characteristics, in particular to a graphene-adjustable dual-band metamaterial absorber.
Background
High efficiency absorption of light energy, especially perfect absorption, is desirable because perfect absorption can be applied in many fields, for example: imaging, sensing, stealth, detection, etc. The choice of suitable materials is a very important issue to achieve perfect absorption of the device. The metamaterial is an artificial electromagnetic material which is periodically arranged. The electromagnetic properties of the material can be controlled by adjusting the geometric shape, size, distribution and other forms of the structure, so that a plurality of novel characteristics such as negative refraction, perfect lens, super absorption and the like can be obtained. Since Landy et al designed and proposed the first perfect metamaterial absorber in 2008, the perfect metamaterial absorber developed rapidly and showed various absorbers. Generally, absorbers can be divided into two main types according to different application requirements: narrow band absorbers and wide band absorbers. The narrow-band absorber is mainly applied to the fields of sensing, imaging, detection and the like, and the wide-band absorber is mainly applied to the fields of solar energy collection, thermal radiation, stealth and the like. Unfortunately, some of these approaches have encountered challenging problems. For example, in most cases, the position of the absorption peak is adjusted by changing the structural parameters of the metamaterial. However, in practical applications, this method requires a remanufacturing structure to change the size of the metamaterial absorber and further adjust the frequency of the absorption peaks, which wastes both time and material, and is not desirable from a practical standpoint. Therefore, the active tuning of the absorption peak frequency is realized by a simple and effective method, which is a problem to be solved urgently at present.
The invention has the advantages of simple structure, high absorptivity, tunability and the like.
Disclosure of Invention
The invention aims to provide a graphene adjustable dual-band metamaterial absorber.
The purpose of the invention is realized as follows: the metamaterial absorber is composed of a plurality of absorber units, each absorber unit is composed of a bottom metal thin film (1), a middle medium layer (2) and a top graphene thin film (3), the bottom metal thin film (1), the middle medium layer (2) and the top graphene thin film (3) are sequentially arranged from bottom to top, the bottom metal thin film (1) is an all-metal thin film, the top graphene thin 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 thin film (1) are located on the same straight line.
Each absorber unit is square in cross-section with a side length of 1.7 microns.
The thickness d of the bottom layer metal film (1) is 0.5 micron 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.
The top graphene film (3) is patterned single-layer graphene, a symmetrical cross-shaped hole is dug in the center of the symmetrical cross-shaped single-layer graphene, and the geometric center of the cross-shaped single-layer graphene coincides with the geometric center of the dug cross-shaped hole.
The long side L1 of cross-shaped graphene is 1.6 microns, the short side W1 is 0.6 microns, the long side L2 of the dug cross-shaped hole is 0.9 microns, and the short side W2 is 0.1 microns.
Compared with the prior art, the invention has the following remarkable advantages:
1. the top layer of the metamaterial absorber is made of cross-shaped graphene, the metamaterial absorber is simple and compact in structure, perfectly symmetrical and easy to realize, and the metamaterial absorber can have the polarization insensitivity;
2. the metamaterial absorber provided by the invention can realize two absorption peaks in a frequency range of 6-18 THz, and both have nearly perfect absorption rate;
3. the dielectric constant of the graphene is changed by applying bias voltage, so that the graphene can correspond to different resonance frequencies corresponding to different bias voltages, and voltage frequency modulation absorption can be realized.
4. When the incidence angle is increased, good absorption effect can still be maintained.
Drawings
FIG. 1: the invention is a three-dimensional structure schematic diagram.
FIG. 2: the unit structure of the present invention is a plan view.
FIG. 3: the invention provides an absorption spectrogram under different graphene Fermi energy levels.
FIG. 4: absorption spectrum diagram of each angle at 0-50 degree incidence under TM mode.
FIG. 5: absorption spectrum diagram of each angle when incident at 0-50 degree under TE mode.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1-2, a graphene adjustable dual-band metamaterial absorber includes a plurality of absorption units continuously arranged along a plane. The absorber unit comprises a bottom metal film (1), a middle dielectric layer (2) and a top graphene film (3) which are sequentially arranged from bottom to top, wherein the bottom metal film (1), the middle dielectric 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 a cross-shaped microstructure, and the geometric center of the cross-shaped microstructure, 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 absorption units are continuously arranged along a plane, the bottom metal film 1 and the middle lossy medium 2 are connected into a whole, and the top graphene films (3) are mutually isolated, so that each absorption unit works independently.
As an example, the dimensional parameters of the three-layer structure of each absorbent unit are as follows: lattice period P is 1.7 microns; the long side L1 of the cross-shaped graphene is 1.6 micrometers, the short side W1 is 0.6 micrometers, the long side L2 of the dug cross-shaped hole is 0.9 micrometers, and the short side W2 is 0.1 micrometers; 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 dual-frequency tunable metamaterial absorber described in this embodiment is defined as a ═ 1-R-T, where R is the reflectance and T is the 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 Fermi level of the graphene is controlled by controlling the external voltage (bias voltage), so that the optical response of the graphene is changed, the resonance frequency of the cross-shaped microstructure based on the graphene is further changed, and the frequency-modulated metamaterial absorber is realized. Because the cross-shaped microstructure is insensitive to horizontal and vertical polarization, the device can realize large-angle absorption.
The simulation result of this embodiment under normal incidence of electromagnetic waves is shown in fig. 3, and the simulation result is calculated by the CST MicrowaveStudio software. As can be seen from the figure, when the bias voltage required for the fermi levels of 0.6 ev, 0.7 ev, 0.8 ev, 0.9 ev and 1.0 ev is applied to the graphene thin film (3), it can be seen that the absorption peak is shifted and the absorption rate is slightly changed but still maintained above 90% as the fermi level is changed by the bias voltage. This shows that the fermi level of the graphene can be controlled by controlling the applied voltage (bias voltage), so that the optical response of the graphene is changed, and the resonance frequency of the cross-shaped microstructure is changed, thereby realizing frequency modulation.
In this example, the absorption spectra at various angles at 0 ° to 50 ° incidence in the TM mode and the TE mode are shown in fig. 4 and 5. It can be seen from the figure that the incident electromagnetic wave in TM mode and TE mode of the absorber proposed by the present invention has good angle-independent absorption characteristics in the range of angle 0 ° to 50 °, and the absorption rate can be kept above 90%. Therefore, the tunable metamaterial absorber with dual frequency bands and high absorptivity has good performance.
Claims (8)
1. The utility model provides a graphite alkene adjustable dual-band metamaterial absorber which characterized in that: the metamaterial absorber is composed of a plurality of absorber units, each absorber unit is composed of a bottom metal thin film (1), a middle medium layer (2) and a top graphene thin film (3), the bottom metal thin film (1), the middle medium layer (2) and the top graphene thin film (3) are sequentially arranged from bottom to top, the bottom metal thin film (1) is an all-metal thin film, the top graphene thin 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 thin film (1) are located on the same straight line.
2. The graphene adjustable dual-band metamaterial absorber of claim 1, wherein: each absorber unit is square in cross-section with a side length P of 1.7 microns.
3. The graphene adjustable dual-band metamaterial absorber of claim 1, wherein: 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 adjustable dual-band metamaterial absorber of claim 1, wherein: 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 adjustable dual-band metamaterial absorber of claim 1, wherein: the top graphene film (3) is patterned single-layer graphene, a symmetrical cross-shaped hole is dug in the center of the symmetrical cross-shaped single-layer graphene, and the geometric center of the cross-shaped single-layer graphene coincides with the geometric center of the dug cross-shaped hole.
6. The graphene adjustable dual-band metamaterial absorber of claim 5, wherein: the long side L1 of cross-shaped graphene is 1.6 microns, the short side W1 is 0.6 microns, the long side L2 of the dug cross-shaped hole is 0.9 microns, and the short side W2 is 0.1 microns.
7. The graphene adjustable dual-band metamaterial absorber of claim 1, wherein: the invention works in the frequency band of 6 THz-18 THz.
8. The graphene adjustable dual-band metamaterial absorber of claim 1, wherein: the surface conductivity of the graphene has active adjustability, so that the chemical potential energy of the graphene can be changed, and the high absorption function can be realized in different frequency bands.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111883935A (en) * | 2020-09-03 | 2020-11-03 | 浙江科技学院 | Terahertz wave absorber based on graphene metamaterial |
| CN112003024A (en) * | 2020-07-13 | 2020-11-27 | 清华大学 | Temperature-controlled two-dimensional omnidirectional metal-medium composite stealth device and manufacturing method thereof |
| CN112864634A (en) * | 2021-01-08 | 2021-05-28 | 宁波大学 | Perfect absorption incident angle adjustable electromagnetism absorbing structure |
| CN113488776A (en) * | 2021-05-07 | 2021-10-08 | 维沃移动通信有限公司 | Super surface structure |
| CN113764897A (en) * | 2021-09-01 | 2021-12-07 | 中国计量大学 | Broadband microwave absorber based on single-layer graphene auxiliary metamaterial |
| EP3975679A1 (en) * | 2020-09-24 | 2022-03-30 | Rockwell Collins, Inc. | System and method for shielding attenuation of electromagnetic interference emissions |
| CN115313059A (en) * | 2022-09-01 | 2022-11-08 | 中国人民解放军空军工程大学 | Polarization insensitive electromagnetic anti-reflection super surface under extreme incident angle |
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2019
- 2019-11-29 CN CN201911264479.9A patent/CN110854546A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112003024A (en) * | 2020-07-13 | 2020-11-27 | 清华大学 | Temperature-controlled two-dimensional omnidirectional metal-medium composite stealth device and manufacturing method thereof |
| CN112003024B (en) * | 2020-07-13 | 2022-02-18 | 清华大学 | Temperature-controlled two-dimensional omnidirectional metal-medium composite stealth device and manufacturing method thereof |
| CN111883935A (en) * | 2020-09-03 | 2020-11-03 | 浙江科技学院 | Terahertz wave absorber based on graphene metamaterial |
| CN111883935B (en) * | 2020-09-03 | 2022-05-20 | 浙江科技学院 | Terahertz wave absorber based on graphene metamaterial |
| EP3975679A1 (en) * | 2020-09-24 | 2022-03-30 | Rockwell Collins, Inc. | System and method for shielding attenuation of electromagnetic interference emissions |
| US11575211B2 (en) | 2020-09-24 | 2023-02-07 | Rockwell Collins, Inc. | System and method for shielding attenuation of electromagnetic interference emissions |
| CN112864634A (en) * | 2021-01-08 | 2021-05-28 | 宁波大学 | Perfect absorption incident angle adjustable electromagnetism absorbing structure |
| CN112864634B (en) * | 2021-01-08 | 2022-11-15 | 宁波大学 | Perfect absorption incident angle adjustable electromagnetism absorbing structure |
| CN113488776A (en) * | 2021-05-07 | 2021-10-08 | 维沃移动通信有限公司 | Super surface structure |
| CN113764897A (en) * | 2021-09-01 | 2021-12-07 | 中国计量大学 | Broadband microwave absorber based on single-layer graphene auxiliary metamaterial |
| CN115313059A (en) * | 2022-09-01 | 2022-11-08 | 中国人民解放军空军工程大学 | Polarization insensitive electromagnetic anti-reflection super surface under extreme incident angle |
| CN115313059B (en) * | 2022-09-01 | 2023-09-08 | 中国人民解放军空军工程大学 | Electromagnetic anti-reflection super surface under polarization insensitive extreme incidence angle |
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