CN107942418B - Terahertz dual-waveband absorber based on cross-shaped graphene material and application thereof - Google Patents
Terahertz dual-waveband absorber based on cross-shaped graphene material and application thereof Download PDFInfo
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Abstract
The invention discloses a terahertz double-waveband absorber based on a cross-shaped graphene material, which comprises a metal reflecting layer, a dielectric layer and a pattern layer which are sequentially arranged from bottom to top, wherein the pattern layer is composed of cross-shaped material structure units which are periodically arranged, each cross-shaped material structure unit is formed by connecting mutually vertical horizontal belts and vertical belts, the horizontal belts and the vertical belts are made of graphene, the lattice period d of each cross-shaped material structure unit is 3-5 mu m, the width a of each horizontal belt and the width b of each vertical belt are 0.6-1 mu m, and the length b of each horizontal belt and the length b of each vertical belt are 1.2-2 mu m. While providing applications thereof. The absorber provided by the invention has the advantages of simple pattern structure, no need of stacking multiple layers of materials and multiple resonators, easiness in integration, good stability, special electromagnetic response, high absorption rate, high sensitivity and flexibility in regulation and control.
Description
Technical Field
The invention belongs to the technical field of metamaterials and electromagnetic functions, and particularly relates to a terahertz double-waveband absorber based on a cross-shaped graphene material and application thereof.
Background
The terahertz wave generally refers to electromagnetic wave with frequency within the range of 0.1 THz-10 THz, and viewed from frequency, the wave band is located between millimeter wave and infrared ray and belongs to far infrared wave band; energetically, between electrons and photons. For a long time, due to the lack of research results and data on the terahertz wave band, people have little knowledge on the terahertz wave band, so that a phenomenon of terahertz blank is formed. Because terahertz waves are in a special area of transition from electronics to photonics, terahertz waves have many unique properties, such as broadband properties, transient properties, low energy properties, coherence and the like. The terahertz wave research also relates to the fields of physics, optoelectronics, material science and the like, and has wide application prospect and application value in the fields of imaging, medical diagnosis, environmental science, information, national security and basic physical research.
The electromagnetic metamaterial is an artificial composite structure or composite material with an extraordinary electromagnetic property which is not possessed by natural materials, and is characterized in that the physical dimensions of an artificial structure unit are optimally designed to realize the random regulation and control of electromagnetic wave and light wave performance, so that the extraordinary electromagnetic properties such as electromagnetic induction transparency, perfect lens, negative refractive index and the like are realized, a metamaterial device in a terahertz waveband has great application potential in the fields of sensing, imaging, electromagnetic stealth and the like, the development of the future society must be greatly influenced, and the research on the terahertz metamaterial device is gradually developed into a new technological strategic point of countries in the world. However, due to the resonance characteristics, such metamaterial absorbers typically operate in a single frequency band, and are mostly narrowband absorbing. Some broadband absorbers based on multilayer structures or multiple resonators are more complex and have a working region in the far infrared region and polarization dependence, which hinders their potential applications.
Disclosure of Invention
The invention aims to provide a terahertz dual-waveband absorber based on a cross-shaped graphene material, and simultaneously provides another invention aim of the terahertz dual-waveband absorber.
Based on the purpose, the invention adopts the following technical scheme:
the utility model provides a terahertz is two wave band absorbers now based on cross graphite alkene material, includes metal reflection stratum, dielectric layer and the pattern layer that from the bottom up set gradually, the pattern layer comprises the cross material constitutional unit that is periodic arrangement, every cross material constitutional unit is connected by mutually perpendicular's horizontal band and vertical band and is constituteed, and horizontal band and vertical band are made by graphite alkene, cross material constitutional unit's crystal lattice period d is 3-5 mu m, and every horizontal band and vertical band's width an is 0.6-1 mu m, long b is 1.2-2 mu m.
The thickness of the pattern layer is 1 nm.
The metal reflecting layer is a metal film made of a metal material with high conductivity, and the thickness of the metal reflecting layer is 200-300 mu m.
The metal material is gold, silver, aluminum or copper.
The dielectric constant of the dielectric layer is 3-5, and the thickness of the dielectric layer is 3-5 μm.
The dielectric layer is a silicon dioxide film.
The application of the terahertz dual-waveband absorber based on the cross-shaped graphene material is applied to sensing, optical filtering and detecting devices of electromagnetic waves.
Compared with the prior art, the invention has the following beneficial effects:
1) the absorber has the advantages of simple graph structure, no need of stacking multiple layers of materials and multiple resonators, easy integration, good stability, special electromagnetic response, high absorption rate, high sensitivity and flexible regulation, the position of an absorption peak can be controlled by regulating and controlling different graphene Fermi energy, and the position and the absorption intensity of the absorption peak are not changed along with the change of the polarization direction of incident light; by changing the refractive index of the dielectric layer, the absorption peak can have obvious blue shift, and FOM can be calculated to be up to 15.35 at most, so that the FOM can be used for sensing, optical filtering and detecting devices of electromagnetic waves;
2) the absorber provided by the invention has more adjustable conditions, is easy to search for the metamaterial with specific absorption frequency, specific response frequency band and specific structure thickness, and has wide application prospect in optical sensing, filtering and detecting devices.
Drawings
FIG. 1 is a schematic view of the overall structure of the absorber of the present invention;
FIG. 2 is a schematic diagram of a cross-shaped material structural unit in FIG. 1;
FIG. 3 is a numerical simulated absorption spectrum of the absorber of the present invention;
FIG. 4 is a graph showing the electric field intensity and surface current distribution at the resonance frequency of the absorber of the present invention, (a) and (c) are the electric field intensity and surface current distribution at the resonance frequency 1, and (b) and (d) are the electric field intensity and surface current distribution at the resonance frequency 2;
FIG. 5 is a graph of the absorption spectrum of an absorber unit of the present invention as a function of aspect ratio;
FIG. 6 is a graph showing the variation of absorption spectrum with polarization direction of the absorber unit of the present invention;
FIG. 7 is a graph of the trend of the absorption spectrum of the absorber unit of the present invention as a function of the Fermi energy of the graphene;
FIG. 8 is a graph showing the variation of the absorption spectrum of the absorber unit of the present invention with the refractive index of the dielectric layer.
Detailed Description
Example 1
A terahertz double-waveband absorber based on a cross-shaped graphene material is structurally shown in figures 1-3 and comprises a metal reflecting layer 1, a dielectric layer 2 and a pattern layer 3 which are sequentially arranged from bottom to top, wherein the metal reflecting layer 1 is made of a high-conductivity metal material (the conductivity is 4.7 multiplied by 10)7S/m), the thickness of the metal reflecting layer 1 is 200 μm, and the metal material is gold; the dielectric constant of the dielectric layer 2 is 3.9, the thickness of the dielectric layer 2 is 3.3 mu m, and the dielectric layer 2 is a silicon dioxide film; the pattern layer 3 is composed of cross-shaped material structure units which are periodically arranged, the thickness of the pattern layer 3 is 1nm, each cross-shaped material structure unit is formed by connecting mutually vertical horizontal bands and vertical bands, each horizontal band and each vertical band are made of graphene, the lattice period d of each cross-shaped material structure unit is 3 micrometers, the width a of each horizontal band and each vertical band is 0.6 micrometers, and the length b of each horizontal band and each vertical band is 2 micrometers.
The conductivity of graphene adopts an in-plane conductivity form of Drude model
Wherein E isFIs the Fermi energy of graphene with an intrinsic relaxation time τ ═ μ EF/eνF 2Fermi velocity vF＝106m/s, mu is the carrier mobility of the graphene.
The application of the terahertz dual-waveband absorber based on the cross-shaped graphene material is applied to sensing, optical filtering and detecting devices of electromagnetic waves.
Example 2
A terahertz double-waveband absorber based on a cross-shaped graphene material is structurally shown in figures 1-3 and comprises a metal reflecting layer 1, a dielectric layer 2 and a pattern layer 3 which are sequentially arranged from bottom to top, wherein the metal reflecting layer 1 is a metal film made of a high-conductivity metal material, the thickness of the metal reflecting layer 1 is 230 microns, and the metal material is silver; the dielectric constant of the dielectric layer 2 is 3.9, the thickness of the dielectric layer 2 is 3 microns, and the dielectric layer 2 is a silicon dioxide film; the pattern layer 3 is composed of cross-shaped material structure units which are periodically arranged, the thickness of the pattern layer 3 is 1nm, each cross-shaped material structure unit is formed by connecting mutually vertical horizontal bands and vertical bands, each horizontal band and each vertical band are made of graphene, the lattice period d of each cross-shaped material structure unit is 5 micrometers, the width a of each horizontal band and each vertical band is 0.8 micrometers, and the length b of each horizontal band and each vertical band is 1.4 micrometers.
The rest is the same as example 1.
Example 3
A terahertz double-waveband absorber based on a cross-shaped graphene material is structurally shown in figures 1-2 and comprises a metal reflecting layer 1, a dielectric layer 2 and a pattern layer 3 which are sequentially arranged from bottom to top, wherein the metal reflecting layer 1 is a metal film made of a high-conductivity metal material, the thickness of the metal reflecting layer 1 is 250 micrometers, and the metal material is aluminum; the dielectric constant of the dielectric layer 2 is 3.9, the thickness of the dielectric layer 2 is 5 microns, and the dielectric layer 2 is a silicon dioxide film; the pattern layer 3 is composed of cross-shaped material structure units which are periodically arranged, the thickness of the pattern layer 3 is 1nm, each cross-shaped material structure unit is formed by connecting mutually vertical horizontal bands and vertical bands, each horizontal band and each vertical band are made of graphene, the lattice period d of each cross-shaped material structure unit is 4 micrometers, the width a of each horizontal band and each vertical band is 1 micrometer, and the length b of each horizontal band and each vertical band is 1.8 micrometers.
The rest is the same as example 1.
Example 4
A terahertz double-waveband absorber based on a cross-shaped graphene material is structurally shown in figures 1-2 and comprises a metal reflecting layer 1, a dielectric layer 2 and a pattern layer 3 which are sequentially arranged from bottom to top, wherein the metal reflecting layer 1 is a metal film made of a high-conductivity metal material, the thickness of the metal reflecting layer 1 is 300 mu m, and the metal material is copper; the dielectric constant of the dielectric layer 2 is 3.9, the thickness of the dielectric layer 2 is 3.5 mu m, and the dielectric layer 2 is a silicon dioxide film; the pattern layer 3 is composed of cross-shaped material structure units which are periodically arranged, the thickness of the pattern layer 3 is 1nm, each cross-shaped material structure unit is formed by connecting mutually vertical horizontal bands and vertical bands, each horizontal band and each vertical band are made of graphene, the lattice period d of each cross-shaped material structure unit is 3.5 micrometers, the width a of each horizontal band and each vertical band is 0.7 micrometers, and the length b of each horizontal band and each vertical band is 2 micrometers.
The rest is the same as example 1.
Examples 5 to 7
In examples 5-7, the dimensions of the horizontal and vertical bands in each example were, in turn, respectively: the width a is 0.6 μm and the length b is 2 μm; the width a is 0.6 μm, and the length b is 1.5 μm; the width a was 0.6 μm and the length b was 1.2. mu.m. The rest is the same as example 1. Example 8 simulation calculation
The data of example 1 were calculated using three-dimensional finite element Multiphysics simulation software COMSOL Multiphysics. In the simulation, only one cross-shaped material structural unit is taken as an example. Infinite array structures are simulated by setting periodic boundary conditions in the x, y directions. The plane electromagnetic wave is incident perpendicular to the surface of the structure, the polarization directions of an electric field and a magnetic field are respectively along an x axis and a y axis, periodic boundary conditions are adopted in the x axis direction and the y axis direction, a perfect matching layer is used in the z direction to eliminate non-physical reflection at the boundary, grid division is carried out and set to be particularly refined, frequency domain scanning is carried out to calculate the change relation of transmission and reflectivity along with frequency, the numerical simulation absorption spectrum of an absorber is shown in figure 3, and therefore the absorption spectrum A is 1-T-R. The electric field profile and the surface current profile are shown in FIG. 4.
As can be seen from FIG. 3, the absorber is at resonant frequency 1 (6.25THz, abbreviated as mode f)1Below f1Here) of 96% at the resonant frequency 2 (14.5THz, simple mode f)2Below f2As here) had an absorption of 97%.
As can be seen from FIGS. 4(a) and (c), pattern f1Is generated by the surface response of a periodic structure or the interaction between adjacent unit structures and shows the resonance characteristic of a dipole; as shown in FIGS. 4(b) and (d), pattern f2Is generated by a pair of even-order sub-pairs (similar to a four-even-order sub-pair) with opposite phases. Thus mode f2Absorption peak ratio mode f1Has a higher FOM number.
Example 9 influence factor analysis
The data in example 1 are used as examples of other parameters, except for the changed parameters.
9.1 influence of the size of the Cross-shaped Material building Block
The widths a of the horizontal and vertical bands of the structural unit are kept constant, and the lengths b are changed, and in examples 5-7, the absorption spectrum has a change trend along with the length-width ratio, as shown in FIG. 5.
As can be seen from FIG. 5, the absorption peak of the absorber of the cross-shaped material structural unit is obviously changed along with the change of the length b, and the two absorption peaks are blue-shifted along with the increase of a: b, and the absorption intensity is reduced.
9.2 Effect of polarization Angle
The polarization direction of the electric field is initially along the y-axis and then rotates towards the x-axis, and the absorption spectrum of the cross-shaped material structural unit has a trend along with the polarization direction under different polarization angles (theta), as shown in fig. 6.
As is clear from fig. 6, the position of the absorption peak and the intensity of the absorption peak do not change, and this indicates that the cross-shaped material structural unit is not affected by the polarization direction of the electric field.
9.3 Effect of graphene Fermi energy
The absorption rate of the absorber of the present invention varied with different graphene fermi energies, as shown in fig. 7.
As can be seen from fig. 7, as the fermi energy of the graphene increases, the position of the absorption peak moves in the high-frequency direction, which also indicates that the cross-shaped material structural unit of the present invention has flexible adjustability, and the position of the absorption peak can be adjusted and controlled as needed.
9.4 influence of the refractive index of the dielectric layer
The absorption rate of the absorber of the present invention has a tendency to change when the refractive indexes of the dielectric layers are different, as shown in fig. 8.
As can be seen from fig. 8, as the refractive index of the dielectric layer increases, the position of the absorption peak shifts in the low frequency direction. The quality factor formula of the structure is as follows:
wherein △ f/Δ n is the magnitude of frequency generation per index of Refraction (RIU) change.
By calculation, the pattern f can be derived2The FOM of (b) was 15.35.
Claims (7)
1. The utility model provides a terahertz is two wave band absorbers based on cross graphite alkene material which characterized in that, includes metal reflection stratum, dielectric layer and the pattern layer that from the bottom up set gradually, the pattern layer comprises the cross material constitutional unit that is periodic arrangement, every cross material constitutional unit is connected by mutually perpendicular's horizontal band and vertical band and is constituteed, and horizontal band and vertical band are made by graphite alkene, cross material constitutional unit's lattice period d is 3-5 mu m, and every horizontal band and vertical band's width an is 0.6-1 mu m, long b is 1.2-2 mu m.
2. The terahertz dual-band absorber based on a cross-shaped graphene material of claim 1, wherein the pattern layer is 1nm thick.
3. The terahertz dual-band absorber based on the cross-shaped graphene material as claimed in claim 1, wherein the metal reflective layer is a metal thin film made of a high-conductivity metal material, and the thickness of the metal reflective layer is 200-300 μm.
4. The terahertz dual-band absorber based on a cross-shaped graphene material of claim 3, wherein the metal material is gold, silver, aluminum, or copper.
5. The terahertz dual-band absorber based on a cross-shaped graphene material of claim 1, wherein the dielectric layer has a dielectric constant of 3-5 and a thickness of 3-5 μ ι η.
6. The terahertz dual-band absorber based on a cross-shaped graphene material of claim 5, wherein the dielectric layer is a silicon dioxide thin film.
7. The use of the terahertz dual-band absorber based on a cross-shaped graphene material as claimed in claim 1, wherein the absorber is applied to a sensing, optical filtering and detecting device of electromagnetic waves.
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| CN108646325B (en) * | 2018-05-07 | 2019-09-20 | 厦门大学 | A kind of adjustable graphene wide angle Terahertz wave absorbing device of frequency |
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| CN112490678B (en) * | 2020-11-12 | 2022-11-01 | 云南师范大学 | VO-based2Broadband terahertz super-surface absorption unit and super-surface absorber |
| CN112739186B (en) * | 2020-12-22 | 2023-08-22 | 博微太赫兹信息科技有限公司 | Metamaterial wave-absorbing structure for enhancing absorption and reducing surface radiation |
| CN112909565B (en) * | 2021-01-20 | 2023-08-08 | 华南师范大学 | Multi-band absorber with mixed patterned metal-graphene super surface |
| CN113410648B (en) * | 2021-06-10 | 2022-07-15 | 上海交通大学 | Graphene-based passband switchable frequency selection surface and implementation method thereof |
| CN113741065B (en) * | 2021-09-09 | 2023-06-02 | 安徽大学 | Optical rotation and polarization adjustable square lattice super-surface resonator |
| CN114408912B (en) * | 2021-12-30 | 2023-05-02 | 电子科技大学 | Preparation method of graphene deflection terahertz zone plate with low reflection |
| CN116106263B (en) * | 2023-04-07 | 2023-06-16 | 成都甄识科技有限公司 | Super-surface local plasmon sensor with high sensitivity and high quality factor |
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| CN206558698U (en) * | 2016-06-28 | 2017-10-13 | 中国计量大学 | Broadband Terahertz wave absorbing device based on graphenic surface plasma |
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| CN105896098A (en) * | 2016-04-25 | 2016-08-24 | 中国工程物理研究院激光聚变研究中心 | Broadband THz metamaterial absorber based on multi-resonant absorption superposition |
| CN206558698U (en) * | 2016-06-28 | 2017-10-13 | 中国计量大学 | Broadband Terahertz wave absorbing device based on graphenic surface plasma |
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