CN112928492B - Tunable optical transparent broadband metamaterial wave absorber based on water layer - Google Patents
Tunable optical transparent broadband metamaterial wave absorber based on water layer Download PDFInfo
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- CN112928492B CN112928492B CN202110095170.2A CN202110095170A CN112928492B CN 112928492 B CN112928492 B CN 112928492B CN 202110095170 A CN202110095170 A CN 202110095170A CN 112928492 B CN112928492 B CN 112928492B
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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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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/006—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
- H01Q15/0066—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces said selective devices being reconfigurable, tunable or controllable, e.g. using switches
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Abstract
The invention provides a tunable optical transparent metamaterial wave absorber based on a water layer, and belongs to the field of optical transparent and electromagnetic wave absorption shielding materials. The metamaterial wave absorber is composed of a plurality of structural units which are periodically arranged, and each structural unit sequentially comprises an upper layer transparent resonance structure, a second layer transparent dielectric substrate and a lower layer transparent reflection layer from top to bottom; water layers are arranged between the second layer of transparent medium substrate and the lower layer of transparent reflecting layer and in the second layer of transparent medium substrate; a water injection pipe and a water outlet pipe are inserted in the water layer and used for adjusting the thickness of the water layer; the upper transparent resonance structure is a symmetrical structure and comprises a cross and a plurality of concentric rings; the upper transparent resonance structure and the lower transparent reflection layer are made of transparent conductive materials. The invention has excellent broadband electromagnetic wave absorption function in a radar wave band (1-18 GHz), the absorption rate can reach more than 90%, the electromagnetic wave absorption performance can further control the tuning of a water layer through a water injection pipe and a water outlet pipe, and meanwhile, the invention can keep higher transmittance in visible and infrared bands and has very high application prospect.
Description
Technical Field
The invention relates to the technical field of electromagnetic wave absorption and novel artificial electromagnetic materials, in particular to a tunable optical transparent broadband metamaterial wave absorber based on a water layer.
Background
With the development of television, broadcasting, microwave technology and wireless communication technology, electromagnetic pollution not only causes interference to precise electronic instruments and equipment, but also has non-negligible negative effects on human health. Electromagnetic shielding is therefore widely used to isolate sources of electromagnetic pollution from sophisticated electronic equipment and human habitats. In many fields, the electromagnetic shielding material needs to maintain excellent visible and infrared high transmittance in addition to excellent ability to absorb or shield microwaves and radio waves, such as high-end medical equipment observation windows, shielding members for precision communication equipment, ultra-fine monitoring equipment observation windows, optical windows for aircraft and aeronautical weapons, advanced optical instrument windows, and the like. These precision instruments and devices are extremely sensitive to external electromagnetic interference, which requires transparent electromagnetic shielding to maintain high transmission of visible light and infrared light, and requires excellent electromagnetic shielding performance. At present, most of electromagnetic shielding materials mainly reflect electromagnetic waves, and the reflected electromagnetic waves cause secondary electromagnetic pollution in space, thereby complicating the electromagnetic environment of the space. The most desirable electromagnetic shielding material is one that completely absorbs incident electromagnetic waves and maintains good optical transmittance in the visible and infrared bands.
In recent years, the appearance of metamaterials brings a new design idea for transparent electromagnetic wave-absorbing materials. The metamaterial (metamaterial) is formed by arranging periodic sub-wavelength structural units, and electromagnetic parameters such as equivalent dielectric constant, equivalent magnetic permeability, refractive index and the like of the metamaterial can be realized by artificially designing the structural units, so that special properties which are not possessed by natural materials are realized. The metamaterial wave absorber is a composite wave absorbing material consisting of a metamaterial structure and a medium substrate. The metamaterial wave absorber realizes impedance matching with a free space through electromagnetic resonance, so that incident waves almost have no reflection and enter the metamaterial to be lost, and perfect wave absorbing performance is realized.
At present, most metamaterial wave absorbers have narrow absorption band width, or are not optically transparent in visible and infrared bands, or once the structural parameters of the metamaterial wave absorbers are processed and prepared, the wave absorbing performance is fixed and unchanged, and the metamaterial wave absorbers cannot be tuned through external conditions or control, so that the metamaterial wave absorbers are limited to be flexibly applied to the field of optical windows of medical use, civil use, military use and the like.
For example, although the technical solutions proposed in the patents (CN 202020117851.5, CN201810192399.6 and CN 200810236471.7) achieve broadband wave-absorbing performance, the metamaterial wave absorbers are prepared from opaque materials, which are difficult to maintain high permeability in visible and even infrared light bands, and limit the development and application of the metamaterial wave absorbers in the field of optical windows; patent (CN 201610721042.3) proposes a transparent broadband metamaterial wave absorber, but it belongs to a non-tunable metamaterial structure, and does not introduce a material or structure with tunable function, and once the structure is processed, its absorption capacity for electromagnetic waves is fixed, and it cannot tune its electromagnetic wave absorbing performance through external conditions. The prior technical scheme realizes broadband electromagnetic absorption and tunable wave absorption performance in a microwave band, realizes visible and infrared high permeability at the same time, and has certain technical difficulty.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problems in the prior art, realize the integration of multiple functions and simultaneously realize the microwave broadband absorption, tunable wave-absorbing performance and high optical permeability of visible and infrared bands, the invention provides a tunable optical transparent broadband metamaterial wave absorber based on a water layer.
The technical scheme of the invention is as follows:
a tunable optical transparent broadband metamaterial wave absorber based on a water layer comprises a plurality of structural units which are periodically arranged, wherein each structural unit sequentially comprises an upper layer transparent resonance structure, a second layer transparent dielectric substrate and a lower layer transparent reflection layer from top to bottom; the transparent reflective film is characterized in that water layers are arranged between the second layer of transparent medium substrate and the lower layer of transparent reflective layer and in the second layer of transparent medium substrate.
And a water injection pipe and a water outlet pipe are inserted in the water layer and used for adjusting the thickness of the water layer.
The upper transparent resonant structure is a symmetrical pattern and comprises a cross and a plurality of concentric rings.
The upper transparent resonance structure and the lower transparent reflection layer are plated on the transparent medium substrate and are made of transparent conductive materials, and the upper transparent resonance structure and the lower transparent reflection layer can be prepared by means of photoetching, laser stripping, chemical etching and the like.
The transparent conductive material is one or more of Indium Tin Oxide (ITO), zinc oxide (ZnO), a graphene film, a micro-metal grid or a metal nanowire.
The second layer of transparent medium substrate is made of one or more of glass, fluoride infrared glass, zinc sulfide, organic glass, transparent polymer, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET) or polyvinyl chloride (PVC).
The material of the water layer is one or more of distilled water, deionized water, ultrapure water, saline water or other transparent liquid.
The upper layer transparent resonant structure, the second layer transparent medium substrate and the lower layer transparent reflecting layer are formed by hot pressing through an optical transparent adhesive.
When the thickness of the water layer reaches the maximum allowable value, the broadband electromagnetic wave-absorbing performance can be realized; the thickness of the water layer reaches the minimum value, namely the thickness is zero, and the narrow-band electromagnetic wave absorption performance can be realized.
Compared with the prior art, the invention has the beneficial effects that:
1) The structure is simple, the processing technology is mature, and the preparation is easy;
2) Compared with the traditional wave absorber, the wave absorber can realize broadband absorption at the microwave band of the 1-18GHz radar, and the absorption rate can reach more than 90%.
3) The preparation material adopted by the invention is transparent in visible and infrared wave bands, and can keep high permeability in the visible and infrared wave bands;
4) The invention can control the thickness of the water layer through the water injection pipe and the water outlet pipe, can realize active tuning of the electromagnetic wave absorption performance of the water layer, and realizes the conversion of the narrow-band-wide-band electromagnetic wave absorption function.
Drawings
FIG. 1 is a schematic diagram of a tunable optical transparent broadband metamaterial wave absorber based on a water layer according to the invention.
FIG. 2 is a side view of a tunable optical transparent broadband metamaterial wave absorber based on a water layer according to the present invention.
FIG. 3 is a three-dimensional schematic of a single building block in the present invention.
Fig. 4 is a side view of a single structural unit in the present invention.
Fig. 5 is a schematic diagram of an upper transparent resonant structure of a single structural unit in the present invention.
FIG. 6 is a schematic front view of a tunable optical transparent broadband metamaterial wave absorber based on a water layer according to the present invention.
FIG. 7 is an absorption rate simulation result of the tunable optical transparent broadband metamaterial wave absorber based on the water layer according to the invention under the condition of different water layer thicknesses when the incident electromagnetic wave is normally incident.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.
Example 1: a tunable optical transparent broadband metamaterial wave absorber based on a water layer comprises a plurality of structural units which are arranged periodically, and is shown in figure 1. Each structural unit sequentially comprises an upper layer transparent resonant structure 1, a second layer transparent dielectric substrate 2 and a lower layer transparent reflecting layer 4 from top to bottom; the transparent reflective film is characterized in that a water layer 3 is arranged between the second layer of transparent medium substrate 2 and the lower layer of transparent reflective layer 4 and in the second layer of transparent medium substrate 2. A water injection pipe 5 and a water outlet pipe 6 are inserted into the water layer 3 to adjust the thickness of the water layer 3, as shown in fig. 2. The upper transparent resonant structure 1 in this example is a symmetrical pattern comprising a cross and three concentric rings, with the side length of the cross being equal to the diameter of the smallest ring, as shown in fig. 5. The materials used by the upper transparent resonance structure 1 and the lower transparent reflection layer 4 are Indium Tin Oxide (ITO) deposited on polyethylene terephthalate (PET), and the upper transparent resonance structure 1 is prepared by a laser photoetching process. The material used for the second layer of transparent dielectric substrate 2 is polymethyl methacrylate (PMMA). The material of the water layer 3 is distilled water. And the upper layer transparent resonant structure 1, the second layer transparent medium substrate 2 and the lower layer transparent reflecting layer 4 are formed by hot pressing through an optical transparent adhesive.
A tunable optical transparent broadband metamaterial wave absorber based on a water layer utilizes a designed structure to realize impedance matching with a free space through electromagnetic resonance, and further realizes the absorption effect on incident electromagnetic waves in a wide band. The structural parameters (including the types and sizes of materials) of the upper transparent resonant structure 1, the second dielectric substrate 2, the water layer 3 and the lower transparent reflective layer 4 can be reasonably adjusted. In addition, the thickness of water in the water layer 3 can be controlled through the water injection pipe 5 and the water outlet pipe 6, and the tuning of the wave-absorbing performance and the resonant frequency of the structure is further realized.
As shown in fig. 3, the structural unit is square, let the side length of the structural unit be p, and the thickness of the first layer of transparent resonant structure be h 1 The thickness of the second layer of transparent dielectric substrate 2 is h 2 Total thickness of the water layer 3 (including the thickness of water when not filled and the thickness of the remaining air layer, wherein the thickness of water is h Water ) Is h Air+Water The thickness of the lower transparent reflecting layer is h 3 . As shown in fig. 5, the radii of the three circular rings in the upper transparent resonant structure 1 are respectively set to r 1 ，r 2 ，r 3 The side length of the cross is 2r 1 The width of the cross and all rings is w. The sheet resistance of Indium Tin Oxide (ITO) used as the material of the upper transparent resonant structure 1 is set to be R 1 . The sheet resistance of Indium Tin Oxide (ITO) used as the lower transparent reflective layer 4 is set to be R 2 . The parameters in this example are specifically set as p =12mm 1 ＝0.175mm，h 2 ＝3.8mm，h Air+Water ＝1.2mm，0mm≤h Water ≤1.2mm，h 3 ＝0.175mm，r 1 ＝3.8mm，r 2 ＝4.5mm，r 3 ＝5.5mm，w＝100μm，R 1 ＝18Ω/sq，R 2 =15 Ω/sq, wherein h Water Is variable, tunable. As shown in fig. 7, under normal incidence conditions, h Water When different values are taken, the absorption performance and the resonant frequency are different, and when the thickness h of the water layer is equal to Water When the thickness of the metamaterial absorber is 1.2mm and the maximum value is allowed, the metamaterial absorber realizes broadband absorption at 4.9-17.1GHz, and the absorption rate reaches over 90%. When the thickness of the water layer is h Water And when the thickness is not less than 0mm, the metamaterial wave absorber only has a single resonance peak, so that narrow-band absorption is realized. In addition, the prepared material is optically transparent, so that the metamaterial wave absorber can maintain high optical transmittance in visible light and even near infrared bands.
The foregoing has described and explained the broad features and general principles of the present invention, as well as the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the examples, and the first example and the description are only for illustrating the principle of the present invention, and the broadband absorption and tunable wave-absorbing performance of electromagnetic waves in different bands can be realized by performing equal-scale amplification or reduction on the size of the present invention. Without departing from the spirit and scope of the invention, it is intended that all changes and modifications within the spirit and scope of the invention be embraced by the appended claims, e.g., by enabling a skilled person to modify the parameters set forth above to accommodate different operating bands or to modify the parameters involved to make them different in structure and performance from the examples set forth herein. The scope of the invention is defined by the claims and their equivalents.
Claims (7)
1. A tunable optical transparent broadband metamaterial wave absorber based on a water layer comprises a plurality of structural units which are periodically arranged, wherein each structural unit sequentially comprises an upper layer transparent resonance structure, a second layer transparent dielectric substrate and a lower layer transparent reflection layer from top to bottom; the transparent reflective film is characterized in that water layers are arranged between the second layer of transparent medium substrate and the lower layer of transparent reflective layer and in the second layer of transparent medium substrate;
a water injection pipe and a water outlet pipe are inserted in the water layer and used for adjusting the thickness of the water layer;
the conversion of the narrow-band-wide-band electromagnetic absorption function is realized by controlling the thickness of the water layer: when the thickness of the water layer reaches the maximum value allowed, the broadband electromagnetic wave-absorbing performance is realized; when the thickness of the water layer reaches the minimum value, namely the thickness is zero, the narrow-band electromagnetic wave-absorbing performance is realized.
2. The tunable optical transparent broadband metamaterial wave absorber based on water layer as claimed in claim 1, wherein the upper transparent resonant structure is a symmetrical pattern comprising a cross and a plurality of concentric rings.
3. The tunable optical transparent broadband metamaterial wave absorber based on water layer as claimed in claim 1, wherein the upper transparent resonant structure and the lower transparent reflective layer are plated on the surface of the transparent dielectric substrate, are made of transparent conductive materials, and are prepared by means of photolithography, laser lift-off, chemical etching and the like.
4. The tunable optical transparent broadband metamaterial wave absorber based on the water layer as claimed in claim 3, wherein the transparent conductive material is one or more of Indium Tin Oxide (ITO), zinc oxide (ZnO), graphene film, micro metal mesh grid or metal nanowire.
5. The tunable optical transparent broadband metamaterial wave absorber based on the water layer as claimed in claim 1 or 2, wherein the material of the second layer of transparent dielectric substrate is one or more of glass, fluoride infrared glass, zinc sulfide, organic glass, transparent polymer, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET) or polyvinyl chloride (PVC).
6. The tunable optical transparent broadband metamaterial wave absorber based on the water layer as claimed in claim 1 or 2, wherein the material of the water layer is one or more of distilled water, deionized water, ultrapure water, saline water or other transparent liquid.
7. The tunable optical transparent broadband metamaterial wave absorber based on water layer as claimed in any one of claims 1 to 6, wherein the upper transparent resonant structure, the second transparent dielectric substrate and the lower transparent reflective layer are formed by hot pressing with an optical transparent adhesive.
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| CN113555695B (en) * | 2021-07-14 | 2022-07-05 | 东南大学 | Ku-waveband high-transparency flexible dynamic frequency modulation wave-absorbing surface structure and preparation method thereof |
| CN113540812B (en) * | 2021-07-16 | 2022-08-23 | 北京理工大学 | S, C and X-band flexible transparent electromagnetic confusion metamaterial stealth device |
| CN113993366B (en) * | 2021-11-02 | 2023-03-21 | 西安电子科技大学 | Magnetic control reconfigurable silver nanowire electromagnetic shielding film and preparation method thereof |
| CN114054112B (en) * | 2021-12-02 | 2022-09-13 | 北京大学 | Micro-fluidic technology-based medium-adjustable wave-absorbing metamaterial and performance regulation and control device thereof |
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