CN212783820U

CN212783820U - Broadband-adjustable terahertz wave absorber based on vanadium dioxide phase-change material

Info

Publication number: CN212783820U
Application number: CN202022308742.4U
Authority: CN
Inventors: 朱乐梅; 郎婷婷; 陈怡萍; 王可欣; 项晶晶
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2021-03-23
Anticipated expiration: 2030-10-16

Abstract

The utility model discloses an adjustable terahertz of broadband is wave-absorbing ware now based on vanadium dioxide phase change material. The wave absorber has three layers, namely, vanadium dioxide (VO) with periodic 'return holes' from top to bottom in sequence₂) A layer, a Polyimide (PI) layer, and a metal substrate layer; VO (vacuum vapor volume)₂Determines the absorption capacity of the absorber, either by optical excitation or thermal control of the VO₂The absorption rate of the terahertz wave absorber is adjustable through the phase change; the wave absorber of the utility model canTo achieve wide bandgap absorption when VO₂When the conductivity is 30000S/m, the bandwidth with the absorptivity of more than 90 percent reaches 1THz, and simultaneously, the flexible regulation and control of the absorptivity of 0.5-4THz can be realized, along with VO₂The wave absorber has the advantages that the conductivity is reduced, the absorption peak value can be reduced from 99% to 18%, the wave absorber is simple in structure and convenient to process and produce, and application values can be played in the fields of stealth, detection, communication and the like.

Description

Broadband-adjustable terahertz wave absorber based on vanadium dioxide phase-change material

Technical Field

The utility model discloses electromagnetic wave absorbs technical field, relates to an adjustable ripples ware that inhales based on vanadium dioxide phase change material.

Background

Metamaterial (MM for short) refers to an artificial medium with some extraordinary physical properties, the working wavelength of which is much larger than the unit size, and electromagnetic properties which conventional materials do not have can be obtained through reasonable structure and parameter design such as dielectric constant and magnetic permeability, and the unprecedented potential of the Metamaterial in the aspect of manipulating electromagnetic waves draws wide attention. With the continuous and deepened research on the metamaterial, the metamaterial wave absorber has more and more important application values in the fields of stealth, detection, communication and the like, and the effect of the wave absorber in a frequency selection system cannot be ignored. However, most of tuning of the wave absorber at present is to adjust and control the structural parameters thereof by changing, and belongs to passive adjustment and control, and the wave absorbing performance of the wave absorber cannot be changed after preparation, so that the wave absorber is lack of universality. For example, in a patent of a utility model entitled terahertz metamaterial wave absorber based on a structure shaped like a Chinese character 'tu', a periodic unit of the wave absorber is a typical metal-medium-metal structure, although perfect absorption is realized at a peak value, an absorption frequency band is narrow, response to terahertz waves is fixed and unchangeable, and an absorption amplitude or a frequency band can not be adjusted, so that the terahertz device can not adapt to the development of requirements in practice and is limited.

The wave absorber with fixed frequency response cannot meet the actual application requirements, so that materials with special properties are applied to metamaterial structures to manufacture tunable wave absorbers, such as graphene, vanadium dioxide, strontium titanate and the like. Vanadium dioxide (VO)₂) As a common phase change material, with an increase in ambient temperature, at a phase change temperature (340K) or so, the internal crystal structure and the forbidden band width change significantly, and a transition from an insulating state to a conductive metal state can be realized. Vanadium dioxide can achieve dielectric state transition through optical excitation or thermal control, so that the vanadium dioxide-based absorber can change temperature, illumination and electricityAnd field and other external factors regulate and control the absorption performance of the suction filter. For example, a tunable wave absorber design based on vanadium dioxide material published by daonana dynamically tunes an absorption spectrum by controlling external temperature, and simultaneously can change the structural parameters to optimize the wave absorbing performance, but the problem of wide band gap absorption is not considered, so that the wave absorber cannot meet the complex requirements of actual integration, cannot meet the perfect absorption of electromagnetic waves in practice, cannot realize the complete controllability of an absorption band, and still has great difficulty from theory to application. For example, the invention patent of a frequency band transfer wave absorber based on mercury thermal expansion and cold contraction regulation is characterized in that a top-layer cross-shaped glass cavity is connected with a bottom-layer mercury tank through a cylindrical through hole, the wave absorbing performance is adjusted by changing the form of mercury in the structure through controlling the temperature, the wave absorber realizes multiband absorption, but the frequency band is narrow, the adjusting speed is low and inflexible, and the wave absorber is difficult to prepare.

Disclosure of Invention

Aiming at the defects and the current research situation in the prior art, the utility model provides an adjustable wave absorber based on a vanadium dioxide phase-change material.

In order to realize the purpose, the utility model adopts the technical scheme that:

the utility model provides a terahertz wave absorber is adjustable in broadband based on vanadium dioxide phase change material which characterized in that: VO from top to bottom₂A layer (1), a PI layer (2) and a metal substrate layer (3); VO (vacuum vapor volume)₂The layer (1) is in a periodic 'return hole' structure, the PI layer (2) is a loss medium, and the metal substrate layer (3) is made of metal gold; VO (vacuum vapor volume)₂The crystal structure of the layer (1) is changed near the phase transition temperature (340K), the forbidden bandwidth is reduced along with the rise of the temperature, the forbidden bandwidth can be transited from an insulating phase to a metal phase, and the forbidden bandwidth macroscopically shows the change of the electric conductivity; VO in metallic phase₂The probability of the electron absorption energy in the layer (1) to jump from the valence band to the conduction band is increased, and strong resonance can be generated with the incident terahertz wave in the process to generate a strong absorption phenomenon, so that VO (volatile organic compounds)₂The electrical properties of the layer (1) determine the broadband absorption capacity of the absorber, either by optical excitation or thermal control of the VO₂Phase change of layer (1)The terahertz wave absorber with adjustable absorption rate can be realized.

A terahertz wave absorber is adjustable now in broadband based on vanadium dioxide phase change material, its characterized in that: VO (vacuum vapor volume)₂The thickness of the layer (1) is c 2 μm, the frame width of the loop-shaped hole is w 2 μm, and the frame side length is l 40 μm; the thickness of the PI layer (2) is 20 mu m, and the length of the periodic side is 50 mu m; the thickness of the metal substrate layer (3) is 0.2 mu m.

A terahertz wave absorber is adjustable now in broadband based on vanadium dioxide phase change material, its characterized in that: the wave absorber works at 0.5-4 THz; VO of wave absorber₂The electrical conductivity of the layer (1) is temperature dependent, when VO₂When in metal state, the conductivity can reach 2 x 10⁵S/m, when in an insulating state, the relative dielectric constant is 12, and the conductivity is 0S/m; the PI layer (2) is a loss medium, the dielectric constant is 2.88, and the loss tangent angle is 0.03; the conductivity of the metal substrate layer (3) gold is 4.09 multiplied by 10⁷S/m。

The wave absorber of the utility model can be prepared by the following method: firstly, sputtering a metal substrate layer (3) on a quartz wafer by a magnetron sputtering method, then preparing a PI layer (2) by addition polymerization of a polymer, and then preparing a pure vanadium target and O by a magnetron sputtering technology₂Deposition of VO in gas mixtures₂Finally, preparing the 'returning hole' VO by a photoetching process₂A layer (1).

The utility model has the advantages that:

the wave absorber breaks the limitation of regulating and controlling the wave absorbing performance of the wave absorber by changing the structural parameters of the wave absorber, and uses vanadium dioxide (VO)₂) The wave absorber is constructed by materials and electromagnetic metamaterials, and the problem can be well solved by changing external environmental conditions such as light intensity, temperature, electric field and the like.

The wave absorber is arranged on the temperature control platform and changes the vanadium dioxide (VO)₂) The temperature of the absorber can be regulated and controlled.

The wave absorber of the utility model can realize the frequency band movement by changing the structural parameters, can be applied to solar energy management when moving to the visible light wave band, and can absorb the infrared radiation to realize invisibility when moving to the infrared wave band; the wave absorber can convert changes such as external temperature into changes of terahertz wave absorption rate, can monitor temperature in real time, and is applied to the sensing field.

Wave-absorbing ware can realize wide band gap and absorb, simple structure, be convenient for process into production.

Drawings

Fig. 1 is a schematic diagram of a three-dimensional structure of the adjustable wave absorber of the present invention.

Fig. 2 is a top view of the unit structure of the adjustable wave absorber of the present invention.

Fig. 3 is a graph showing the absorption curves of the adjustable wave absorber of the present invention at different conductivities.

Detailed Description

The invention will be further explained and explained with reference to the drawings.

As shown in fig. 1, a broadband-adjustable terahertz wave absorber based on a vanadium dioxide phase-change material is characterized in that: VO from top to bottom₂A layer (1), a PI layer (2) and a metal substrate layer (3); VO (vacuum vapor volume)₂The layer (1) is a periodic 'return-type hole' structure, the PI layer (2) is a loss medium, and the metal substrate layer (3) is made of metal gold. The wave absorber of the utility model can be prepared by the following method: firstly, sputtering a metal substrate layer (3) on a quartz wafer by a magnetron sputtering method, then preparing a PI layer (2) by addition polymerization of a polymer, and then preparing a pure vanadium target and O by a magnetron sputtering technology₂Deposition of VO in gas mixtures₂Finally, preparing the 'returning hole' VO by a photoetching process₂A layer (1); VO (vacuum vapor volume)₂The crystal structure of the layer (1) is changed near the phase transition temperature (340K), the forbidden bandwidth is reduced along with the rise of the temperature, the forbidden bandwidth can be transited from an insulating phase to a metal phase, and the forbidden bandwidth macroscopically shows the change of the electric conductivity; VO in metallic phase₂The probability of the electron absorption energy in the layer (1) to jump from the valence band to the conduction band is increased, and strong resonance can be generated with the incident terahertz wave in the process to generate a strong absorption phenomenon, so that VO (volatile organic compounds)₂The electrical properties of the layer (1) determine the broadband absorption capacity of the absorber, either by optical excitation or thermal control of the VO₂The phase change of the layer (1) can realize a terahertz wave absorber with adjustable absorption rate; VO (vacuum vapor volume)₂The thickness of the layer (1) is 2 μm, the thickness of the PI layer (2) is 20 μm, and the thickness of the metal substrate layer (3) is 0.2 μm.

VO, as shown in FIG. 2₂The width w of the frame of the loop hole of the layer (1) is 2 μm, and the side length l of the frame is 40 μm; the period side of the PI layer (2) is p equal to 50 mu m.

As shown in FIG. 3, when the electrical conductivity of the obtained vanadium dioxide is 1S/m, 1000S/m, 3000S/m, 5000S/m, 10000S/m, 30000S/m, respectively, different absorption curves are obtained by CST simulation calculation, and it can be seen that when VO is obtained₂When the material has the conductivity of 30000S/m, the bandwidth with the absorptivity of more than 90 percent reaches 1THz, and ideal ultra-wideband absorption is realized; and simultaneously, the wave absorber can realize the flexible regulation and control of the absorption rate of 0.5-4THz along with VO₂The conductivity is reduced, and the absorption peak can be reduced from 99% to 18%.

Claims

1. The utility model provides a terahertz wave absorber is adjustable in broadband based on vanadium dioxide phase change material which characterized in that: VO from top to bottom₂A layer (1), a PI layer (2) and a metal substrate layer (3); VO (vacuum vapor volume)₂The layer (1) is in a periodic 'return hole' structure, the PI layer (2) is a loss medium, and the metal substrate layer (3) is made of metal gold; VO (vacuum vapor volume)₂The crystal structure of the layer (1) is changed near the phase transition temperature (340K), the forbidden bandwidth is reduced along with the rise of the temperature, the forbidden bandwidth can be transited from an insulating phase to a metal phase, and the forbidden bandwidth macroscopically shows the change of the electric conductivity; VO in metallic phase₂The probability of the electron absorption energy in the layer (1) to jump from the valence band to the conduction band is increased, and strong resonance can be generated with the incident terahertz wave in the process to generate a strong absorption phenomenon, so that VO (volatile organic compounds)₂The electrical properties of the layer (1) determine the broadband absorption capacity of the absorber, either by optical excitation or thermal control of the VO₂The phase change of the layer (1) can realize a terahertz wave absorber with adjustable absorption rate.

2. The broadband adjustable terahertz wave absorber based on the vanadium dioxide phase change material as claimed in claim 1, is characterized in that: VO (vacuum vapor volume)₂The thickness of the layer (1) is c 2 μm, the frame width of the loop-shaped hole is w 2 μm, and the frame side length is l 40 μm; the thickness of the PI layer (2) is 20 mu m, and the length of the periodic side is 50 mu m; the thickness of the metal substrate layer (3) is 0.2 mu m.

3. The broadband adjustable terahertz wave absorber based on the vanadium dioxide phase change material as claimed in claim 1, is characterized in that: the wave absorber works at 0.5-4 THz; VO of wave absorber₂The electrical conductivity of the layer (1) is temperature dependent, when VO₂When in metal state, the conductivity can reach 2 x 10⁵S/m, when in an insulating state, the relative dielectric constant is 12, and the conductivity is 0S/m; the PI layer (2) is a loss medium, the dielectric constant is 2.88, and the loss tangent angle is 0.03; the conductivity of the metal substrate layer (3) gold is 4.09 multiplied by 10⁷S/m。