Broadband-adjustable wave absorber based on metasurface

Abstract

The utility model belongs to the technical field of electromagnetic regulation and control, and particularly relates to a broadband-adjustable wave absorber based on a super-structure surface. The wave absorber sequentially comprises a vanadium dioxide resonance pattern layer, a silicon dioxide dielectric layer and an Au film bottom plate layer from top to bottom. The exterior of the vanadium dioxide resonance pattern layer is a square, the side length of the square is l1, the width of the square is l1-l2, parts with the length of l2 are excavated from the upper side and the lower side of the square, and parts with the length of l3 are excavated from the left side and the right side of the square; the middle part of the vanadium dioxide resonance pattern layer is a square, the side length of the square is a, the width of the square is a-b, the inner layer is a cross and a rectangle, the length of the cross is 14, the length of the rectangle is w4, and the width of the rectangle is w5; the thickness of the silicon dioxide dielectric layer is h2, the width of the silicon dioxide dielectric layer is p, and the dielectric constant of silicon dioxide is 3.8; the thickness of the Au film bottom plate layer is h1, and the width of the Au film bottom plate layer is p. The wave absorber adopts a unit cell boundary condition in the x direction and the y direction, and adopts an open add space boundary condition in the z direction.

Description

Technical Field

[0001] This application belongs to the field of electromagnetic control technology, and in particular relates to a broadband tunable absorber based on a metasurface. Background Technology

[0002] Significant progress has been made in the design of terahertz broadband absorbers, which can effectively absorb electromagnetic waves over a wide frequency band, solving the problem of narrow absorption bandwidth. However, most designs cannot achieve controllability, or can only be passively controlled, thus limiting their widespread use in practical applications.

[0003] To address this issue, a terahertz-tunable broadband metasurface absorber was designed. First, vanadium dioxide, a reversible insulating and conductive phase-change material, was selected for the structural design, utilizing its temperature phase-change characteristics to achieve dynamically tunable absorption. Second, the absorption mechanism of the designed broadband metasurface absorber was analyzed in depth using impedance matching theory and electric field distribution, and the accuracy of the design was verified using an equivalent circuit model. Finally, the influence of structural parameters, incident angle, and polarization angle on the absorption performance was presented. Due to its advantages of polarization insensitivity and wide-angle absorption, the designed terahertz-tunable metasurface absorber can be widely used in high-performance devices such as modulators and optoelectronic switches. Utility Model Content

[0004] The purpose of this application is to provide a broadband tunable absorber based on a metasurface, aiming to solve the problem that existing metasurface-based absorbers cannot be tunable. The broadband tunable absorber based on a metasurface is configured as follows:

[0005] The absorber consists of, from top to bottom, a vanadium dioxide resonant pattern layer, a silicon dioxide dielectric layer, and an Au film substrate layer.

[0006] The outer part of the vanadium dioxide resonant pattern layer is a square with a side length of l1 and a width of l1-l2. A portion of length l2 is removed from the top and bottom sides of the square, and a portion of length l3 is removed from the left and right sides of the square.

[0007] The middle part of the vanadium dioxide resonant pattern layer is a square with a side length of a and ab width. The inner layer is a cross shape plus a rectangle with a cross length of l4 and a rectangle length of w4 and width of w5.

[0008] The silicon dioxide dielectric layer has a thickness of h2 and a width of p, and the dielectric constant of the silicon dioxide is 3.8.

[0009] The Au membrane substrate layer has a thickness of h1 and a width of p.

[0010] The absorber uses unit cell boundary conditions in the x and y directions and open add space boundary conditions in the z direction. Attached Figure Description

[0011] Figure 1 This is a side view of an absorber structure according to an embodiment of this application;

[0012] Figure 2 This is a top view of an absorber structure according to an embodiment of this application;

[0013] Figure 3 Absorption, reflectance, and transmittance curves of vanadium dioxide with an electrical conductivity of 2×10⁵ S / m are provided in one embodiment of this application.

[0014] Figure 4 This application provides the absorption rate of vanadium dioxide at different electrical conductivities in one embodiment.

[0015] Figure 5 The electric field distribution at 7.35 THz is shown in one embodiment of this application.

[0016] Figure 6 The effect of the incident angle of E-mode on the absorption rate;

[0017] Figure 7 The effect of different polarization angles on absorption rate. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0019] like Figure 1-2 As shown, the structure of the broadband tunable absorber based on metasurface is as follows:

[0020] The absorber consists of, from top to bottom, a vanadium dioxide resonant pattern layer, a silicon dioxide dielectric layer, and an Au film substrate layer.

[0021] The outer part of the vanadium dioxide resonant pattern layer is a square with a side length of l1 and a width of l1-l2. A portion of length l2 is removed from the top and bottom sides of the square, and a portion of length l3 is removed from the left and right sides of the square.

[0022] The middle part of the vanadium dioxide resonant pattern layer is a square with a side length of a and ab width. The inner layer is a cross shape plus a rectangle with a cross length of l4 and a rectangle length of w4 and width of w5.

[0023] The silicon dioxide dielectric layer has a thickness of h2 and a width of p, and the dielectric constant of the silicon dioxide is 3.8.

[0024] The Au membrane substrate layer has a thickness of h1 and a width of p.

[0025] The absorber uses unit cell boundary conditions in the x and y directions and open add space boundary conditions in the z direction.

[0026] The values ​​of the parameters are as follows: p = 19 μm, l1 = 18 μm, l2 = 16 μm, l3 = 4 μm, l4 = 4 μm, w4 = 0.3 μm, l5 = 2 μm, w5 = 0.6 μm, a = 7 μm, b = 5.5 μm, h1 = 0.2 μm, h2 = 5 μm, h3 = 0.25 μm.

[0027] like Figure 3 As shown, this absorber can achieve an absorption rate of over 90% in the range of 4.73-10.02THz, with an absorption bandwidth of 5.29THz and a relative bandwidth of 71.73%. The absorption rate at the resonant frequency of 7.35THz is 99.63%, achieving a near-perfect absorption effect.

[0028] like Figure 4 As shown, when the conductivity of vanadium dioxide is 2 × 10² S / m (insulating state), the absorption rate is less than 3.3% across the entire frequency band. The absorption rate can be dynamically adjusted from 3.3% to nearly 100% as the conductivity changes by five orders of magnitude. This means the designed absorber has a dual function of switching between reflector and absorber, and can achieve different effects according to different application requirements, demonstrating strong practicality and flexibility.

[0029] like Figure 5 As shown, the electric field is mainly concentrated at both ends of the vertically open resonant ring, as well as the upper and lower parts of the Jerusalem structure and the four vertices of the square ring. This indicates that the absorbing resonant point is mainly caused by the electric dipole resonance excitation generated by the vertically open resonant ring structure, the upper and lower parts of the Jerusalem structure, and the four vertices of the square ring.

[0030] like Figure 6 As shown, in TE polarization mode, as the incident angle increases, the absorption rate gradually decreases, the relative bandwidth narrows and a blue shift occurs, but overall it can still maintain a broadband absorption effect of 30° (absorption rate > 90%).

[0031] like Figure 7As shown in the figure, the resonant frequency and absorption intensity of the absorber do not change significantly with the increase of the polarization angle, indicating that the absorber has good polarization insensitivity characteristics. This is mainly attributed to the high central symmetry of the designed absorber unit, which allows electromagnetic waves with different polarization angles to generate strong resonance when incident perpendicularly on the absorber.

[0032] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A broadband tunable absorber based on a metasurface, characterized in that, Its composition is as follows: The broadband tunable absorber based on metasurface consists of, from top to bottom, a vanadium dioxide resonant pattern layer, a silicon dioxide dielectric layer, and an Au film substrate layer. The outer surface of the vanadium dioxide resonant pattern layer is a square, with a side length of [missing information]. l 1, width is l 1- l 2. A length of [length missing] was cut out from the top and bottom sides of the square. l Part 2, with a length of [missing information] cut out from the left and right sides of the square. l Part 3; The central portion of the vanadium dioxide resonant pattern layer is a square, with a side length of a and a width of a-. b， The inner layer is a cross shape plus a rectangle, with the cross length being l4 and the rectangle length being w4 and width being w5; The silicon dioxide dielectric layer has a thickness of h2 and a width of p, and the dielectric constant of the silicon dioxide is 3.

8. The Au membrane substrate layer has a thickness of h1 and a width of p; The absorber uses unit cell boundary conditions in the x and y directions and open add space boundary conditions in the z direction; Each parameter values ​​are as follows: p =19 μm, l 1=18 μm, l 2=16 μm, l 3=4 μm, l 4=4 μm, w 4=0.3 μm, l 5=2 μm, w 5=0.6 μm, a= 7 μm, b =5.5 μm, h 1=0.2 μm, h 2=5 μm, h 3=0.25 μm.

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