CN211826580U

CN211826580U - Metamaterial selective wave absorber with high reflection in visible light and high absorption in middle infrared

Info

Publication number: CN211826580U
Application number: CN201921817432.6U
Authority: CN
Inventors: 李玉涟; 李林植; 郭力
Original assignee: Shanghai Maritime University
Current assignee: Shanghai Maritime University
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2020-10-30
Anticipated expiration: 2029-10-28

Abstract

The invention discloses a metamaterial selective wave absorber with high reflection in visible light and high absorption in middle infrared, and relates to the technical field of functional optical metamaterials. The wave absorbing body is divided into three layers, wherein the upper layer is a silicon dioxide pyramid body (1), the middle layer is a silicon dioxide film (2), and the lower layer is a metal film substrate (3). The upper silicon dioxide pyramid body (1), the middle silicon dioxide film (2) and the lower metal film substrate (3) form a basic unit, and the basic unit is distributed in an array period on an x-y horizontal plane. The reflectivity of the metamaterial wave absorber at a visible light waveband of 0.6-4.5 microns is larger than 0.9, and the absorptivity of the metamaterial wave absorber at a mid-infrared waveband of 8-30 microns is larger than 0.9.

Description

Metamaterial selective wave absorber with high reflection in visible light and high absorption in middle infrared

Technical Field

The invention relates to the technical field of functional optical metamaterials and application thereof, in particular to a selective wave absorber of a metamaterial, which has high reflection characteristic in a visible light band and high absorption characteristic in a middle infrared band.

Background

A metamaterial is an artificial composite structure and material with extraordinary physical properties that natural materials do not have. It can break through the limit of natural material and form artificial structure material with special electromagnetic characteristic. By adjusting the microstructure of the material, one can create a selective metamaterial structure with high absorption or high reflection for a specific waveband. The metamaterial can be applied to the electromagnetic field, the optical field, the acoustic theory and the thermal theory at present, and the industries comprise the communication industry, the medical industry, the aerospace industry, the military industry and the integrated circuit board (IC) industry, such as infrared radars, wave-absorbing materials, textile coatings and the like. In recent years, radiation refrigeration has attracted wide attention in the field of energy conservation as a passive, efficient and reproducible method for reducing energy consumption. The principle of realizing radiation refrigeration can be simplified into high reflection of electromagnetic waves in visible light bands and high absorption of electromagnetic waves in mid-infrared bands. Therefore, the metamaterial wave absorber with high reflection on visible light and high absorption on electromagnetic waves in mid-infrared bands is designed, and the metamaterial wave absorber has great significance for development of radiation refrigeration technology. Meanwhile, the metamaterial structure body can also be used in the fields of sensor detection, nonlinear optics, electromagnetic stealth technology and the like.

At present, relevant researchers have proposed many wave-absorbing structures of metamaterials, but these structures have some disadvantages: tunable broadband absorption cannot be realized, or the absorption bandwidth is not easy to adjust, or the proposed structure is formed by stacking multiple layers of different materials, so that the preparation is complex and the cost is high. Aiming at the problems, the invention designs the metamaterial broadband wave absorber with a simple structure, only one material is etched, the preparation is simple, the economy is considerable, the ultra-wideband absorption that the reflectivity at a visible light wave band is more than 90 percent and the absorptivity at a middle infrared wave band is more than 90 percent is realized, and the radiation cooling under the direct irradiation of the sun can be realized. The structure has robustness, the change (increase or decrease) of the structure size in a certain range has little influence on the emission and absorption performance of the metamaterial wave absorber, and the requirement on the process is reduced.

The metamaterial wave absorber structure provided by the invention overcomes the problems of complex structure, narrow absorption bandwidth, poor absorption effect and difficult preparation in the prior art, and has wide application prospect.

Disclosure of Invention

In order to realize the purposes of high reflection in a visible light wave band and high absorption in a middle infrared wave band, the invention comprises the following contents:

a three-dimensional metamaterial selective wave absorber with high reflection at a visible light band and high absorption at a middle infrared band is divided into three layers, wherein the upper layer is a silicon dioxide pyramid body (1), the middle layer is a silicon dioxide film (2), and the lower layer is a metal film substrate (3). The upper silicon dioxide pyramid body (1), the middle silicon dioxide film (2) and the lower metal film substrate (3) form a basic unit, the basic unit is distributed in an array period on an x-y horizontal plane, and a three-dimensional structure top view and a schematic diagram of the basic unit are shown in figure 1. Wherein the thickness of the silicon dioxide pyramid body (1)

Width w of its top in x direction_ux1-4 μm, width w in y direction_uy1-4 μm, and a width w of the bottom in the x-direction _lx5 to 20 μm, and a width w in the y direction_ly5-20 μm, the interval i between the silica pyramids is 0-5 μm, and the thickness h of the silica film (2)_s0 to 40 μm, and a metal thin film substrate (3) having a film thickness h_AuThe respective structural parameters are indicated at corresponding positions in fig. 1 and 2, where the respective structural parameters are 0.05 to 5 μm. Within the range, the height of the silicon dioxide pyramid body (1) is changed

Width w of the top_uxAnd w_uyWidth of bottom w_lxAnd w_lyChanging the interval i between the silicon dioxide pyramids (1) and the thickness h of the silicon dioxide film (2)_sChanging the film thickness h of the metal film substrate (3)_AuHigh reflection in the visible band and high absorption in the mid-infrared band can also be achieved.

The metal film substrate (3) is made of any one of metal gold, silver, copper, tungsten and aluminum, the silicon dioxide pyramid body (1) can be replaced by aluminum oxide or glass, and the silicon dioxide film (2) can be replaced by aluminum oxide or glass.

Changing the thickness of each silicon dioxide pyramid body (1) in the designed metamaterial structure

Width w of the top_uxAnd w_uyWidth of bottom w_lxAnd w_lyAnd the parameters such as the interval i and the like, and the structural sizes of different silicon dioxide pyramids (1) can be slightly different, so that the influence on the reflection, transmission and absorption performances of the metamaterial wave absorber is small.

The spectral absorption range of the metamaterial structure designed by the invention is as follows: the reflectance in the visible wavelength range of 0.6 to 4.5 microns is greater than 0.9 and the absorbance in the mid-infrared range of 8 to 30 microns is greater than 0.9.

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

1. the upper layer and the middle layer of the metamaterial wave absorber provided by the invention only use the same material, and compared with the traditional multilayer complex structure, the metamaterial wave absorber provided by the invention has the advantages that the complexity of the structure is reduced to a great extent, so that the preparation process is relatively simple, and meanwhile, the better absorption and reflection effects are kept.

2. Compared with the structure proposed in the prior art, the metamaterial wave absorber provided by the invention well inhibits the absorption of electromagnetic waves with wave bands of 0.6 micrometer to 4.5 micrometers, and achieves near-perfect broadband absorption of electromagnetic waves with wave bands of 8 micrometers to 30 micrometers.

3. The materials used by the metamaterial wave absorber provided by the invention are conventional materials which are easy to obtain, are cheap and easy to realize, and are considerable in economy.

Drawings

FIG. 1 is a top plan view of a three-dimensional structure x-y of a metamaterial wave absorber of the present invention.

FIG. 2 is a side view in the x-z plane of the metamaterial absorber structure of the present invention.

FIG. 3 is a schematic diagram of an absorption spectrum of a metamaterial wave absorber structure according to an embodiment of the invention.

FIG. 4 is a schematic diagram of an absorption spectrum of a metamaterial wave absorber structure in accordance with a second embodiment of the present invention.

FIG. 5 is a schematic diagram of an absorption spectrum of a metamaterial wave absorber structure in the third embodiment of the invention.

FIG. 6 is a schematic diagram of an absorption spectrum of a metamaterial wave absorber structure according to the present invention in the fourth embodiment.

FIG. 7 is a schematic diagram of an absorption spectrum of a metamaterial wave absorber structure in the fifth embodiment of the invention.

Detailed Description

The present invention will be further described with reference to the following detailed description and the accompanying drawings, but the present invention is not limited to the following embodiments. Those skilled in the art will readily modify the following examples and apply the general principles to other examples without the use of inventive faculty. Therefore, it is intended that all such modifications and improvements within the scope of the invention be covered by the claims appended hereto.

Example one

Thickness of the silica pyramid (1) under parallel wave incidence

Its top width w_ux＝w _uy1 micron, base width w_lx＝w_ly8 [ mu ] m, spacing i [ mu ] m, thickness h of silicon dioxide film (2)_sThe material for the metal film substrate (3) is gold with a thickness h of 1 μm _Au1 micron. The absorption spectrum of the proposed metamaterial absorber is shown in fig. 3, and it can be seen that the reflectivity is greater than 0.9 at 0.6 to 4.5 microns and the absorptivity is greater than 0.9 at 8 to 30 microns.

Example two

Thickness of the silica pyramid (1) under parallel wave incidence

Its top width w_ux＝w _uy1 micron, base width w_lx＝w_ly7.5 micrometers, with an interval i of 0.5 micrometers, and a thickness h of the silicon dioxide film (2)_sThe material for the metal film substrate (3) is gold with a thickness h of 8 μm _Au2 microns. The absorption spectrum of the proposed metamaterial wave absorber is shown in fig. 4, and it can be seen that the reflectivity from 0.6 micrometer to 4.5 micrometer is also greater than 0.9, and the absorptivity from 8 micrometer to 30 micrometer is also greater than 0.9, so that the parameters such as the structure size of the metamaterial wave absorber are changed, and high reflection of electromagnetic waves with the incidence range from 0.6 micrometer to 4.5 micrometer and high absorption of electromagnetic waves with the incidence range from 8 micrometer to 30 micrometer can be realized as long as basic units consisting of the upper silicon dioxide pyramid body (1), the middle silicon dioxide film (2) and the lower metal film substrate (3) are distributed in an array period on the x-y horizontal plane.

EXAMPLE III

Thickness of the silica pyramid (1) under parallel wave incidence

Its top width w_ux＝w_uy1.2 μm, base width w_lx＝w_ly8 microns, with an interval i of 0 microns, thickness h of the silicon dioxide film (2)_sThe material for the metal film substrate (3) is gold with a thickness h of 1 μm _Au1 micron. The absorption spectrum of the proposed metamaterial absorber is shown in fig. 5. It can be seen from this that, by reducing the structural size of the inventive metamaterial absorber to a certain range, the absorption of the long wavelength band of the electromagnetic wave is slightly affected, the absorption rate is reduced near 15 micrometers, but the absorption rate is still greater than 0.8, and the reflection effect on the short wavelength band is very small, so this example is used to illustrate that when the structural size of the proposed metamaterial absorber is changed, the purpose of high reflection in the visible light band and high absorption in the mid-infrared band can be achieved.

Example four

Thickness of the silica pyramid (1) under parallel wave incidence

Its top width w_ux1.2 μm, w _uy1 micron, base width w_lx7.5 μm, w_ly7 microns, with an interval i of 0.5 microns, thickness h of the silicon dioxide film (2)_sThe material for the metal film substrate (3) is gold with a thickness h of 2 μm _Au1 micron. The absorption spectrum of the proposed metamaterial absorber is shown in fig. 6, and it can be seen that the reflectivity is greater than 0.9 from 0.6 microns to 4.5 microns and the absorptivity is greater than 0.9 from 8 microns to 30 microns. The example is used for explaining that when the top width and the bottom width of the silicon dioxide pyramid body (1) are different from each other, the absorption performance of the metamaterial wave absorber structure is slightly influenced, and the purposes of high reflection in a visible light wave band and high absorption in a middle infrared wave band can be achieved.

EXAMPLE five

Under parallel wave incidence, the silicon dioxide material is changed into aluminum oxide (Al)₂O₃) The aluminum oxide pyramid body has a thickness of 54 μm and a top width w_ux＝w _uy1 micron, base width w_lx＝w_ly7.5 microns, 0.5 micron apart, and the thickness h of the aluminum oxide film (2)_sThe gold material for the metal thin film substrate (3) was replaced by a silver material, and the thickness thereof was 2 μm. The absorption spectrum of the proposed metamaterial absorber is shown in fig. 7, and it can be seen that the absorbance at 0.6 to 5 microns is less than 0.1, and the absorbance at 9.2 to 26.5 microns is greater than 0.9. This example illustrates that the materials that make up the absorber of metamaterials do not substantially change their high reflectivity to the visible solar band and high absorption to the mid-infrared band when varied from the ranges described above.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A metamaterial selective absorber highly reflective in visible and highly absorptive in mid-infrared comprising: three layer construction, the upper strata is silica pyramid body (1), and the middle level is silica film (2), and the lower floor is metal film substrate (3), its characterized in that: the upper silicon dioxide pyramid body (1), the middle silicon dioxide film (2) and the lower metal film substrate (3) form a basic unit, and the basic unit is distributed in an array period on an x-y horizontal plane.

2. The selective wave absorber of the metamaterial according to claim 1, wherein the selective wave absorber comprises a transparent material and a transparent material, and the transparent material comprises: thickness of silicon dioxide pyramid body (1)

Width w of its top in x direction_ux1-4 μm, width w in y direction_uy1-4 μm, and a width w of the bottom in the x-direction_lx5 to 20 μm, and a width w in the y direction_ly5-20 μm, the interval between the silicon dioxide pyramids is 0-5 μm, and the thickness h of the silicon dioxide film (2)_s0 to 40 μm, and a metal thin film substrate (3) having a film thickness h_AuThe height of the silica pyramid (1) can be changed within the above range, i.e., 0.05 to 5 μm

3. The selective wave absorber of the metamaterial according to claim 1, wherein the selective wave absorber comprises a transparent material and a transparent material, and the transparent material comprises: the material of the metal film substrate (3) is any one of metal gold, silver, copper, tungsten and aluminum, the material of the silicon dioxide pyramid body (1) can be changed into aluminum oxide or glass, and the material of the silicon dioxide film (2) can be changed into aluminum oxide or glass.