Vanadium dioxide-based ultra-wideband-multi-frequency switchable terahertz absorber

Abstract

The invention discloses an ultra wide band-multi-frequency switchable terahertz absorber based on vanadium dioxide, and belongs to the technical field of terahertz waves. The ultra-wideband-multi-frequency switchable terahertz absorption unit is of a multi-layer structure and is sequentially provided with an upper patterned VO2 layer, an upper SiO2 dielectric layer, a lower VO2 layer, a middle patterned gold layer, a lower SiO2 dielectric layer and a bottom gold layer which are attached to one another from top to bottom; the upper patterned VO2 layer is disc-shaped, and a square annular slit is formed in the disc-shaped upper patterned VO2 layer; the middle patterned gold layer comprises an inner circular ring, an outer circular ring and an open square ring which are sequentially arranged at intervals from inside to outside, and an opening of the open square ring is formed in the middle of each edge. According to the ultra wide band-multi-frequency switchable terahertz absorber based on vanadium dioxide, the designed absorber can adjust the conductivity of vanadium dioxide through temperature control so as to realize switching from ultra wide band absorption to multi-frequency absorption.

Description

Technical Field

[0001] The invention relates to the technical field of terahertz waves, and in particular to an ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide. Background Art

[0002] Terahertz (THz) waves are a band between microwaves and infrared bands. With the rapid development of THz detection technology, the exploration and application of THz-related fields has become one of the current research hotspots. Due to its unique band range, THz has the characteristics of strong penetration, low radiation intensity, and rich spectrum resources. However, due to the lack of natural materials with electromagnetic matching in nature, research in the THz field has been stagnant. However, the emergence of metamaterials has effectively solved this problem. Therefore, the combination of metamaterials and THz waves will have great application prospects in wireless communications, sensing, medical imaging and other fields.

[0003] Since Landy first proposed the perfect absorber based on electromagnetic metamaterials in 2008, more and more researchers have proposed different types of terahertz absorbers based on metamaterials, with bandwidths ranging from narrowband, broadband to ultra-wideband, peak numbers ranging from single frequency, dual frequency to multi-frequency, and functions ranging from single absorption, adjustable absorption amplitude to adjustable working frequency. Various terahertz absorbers have been designed to meet the needs under different conditions. In the existing technology, most terahertz absorbers are not easy to change in size and performance after they are manufactured. Therefore, active materials are introduced into the design of the absorber to make it tunable and multifunctional to increase its application range. Finally, how to design a terahertz absorber with a wider working bandwidth and achieve the second function of the absorber with a simple switching method is a challenge in designing a multifunctional terahertz absorber.

[0004] Therefore, it is necessary to provide an ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide. Summary of the invention

[0005] The purpose of the present invention is to provide an ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide to solve the problem of achieving the second function of the absorber by a simple switching method.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide, wherein the ultra-wideband-multi-frequency switchable terahertz absorption unit is a multi-layer structure, and upper patterned VO layers that are bonded to each other are sequentially arranged from top to bottom. 2 Layer, upper SiO 2 Dielectric layer, lower VO 2layer, middle layer patterned gold layer, lower layer SiO 2 Dielectric layer and bottom gold layer;

[0008] Wherein, the upper patterned VO 2 The layer is in the shape of a disk, a square annular slit is arranged inside the disk, and the four corners of the square annular slit intersect with the disk and are provided with notches;

[0009] The middle layer patterned gold layer comprises an inner circular ring, an outer circular ring and an open square ring which are sequentially arranged from the inside to the outside, and the opening of the open square ring is arranged at the middle position of each edge;

[0010] The upper SiO 2 The dielectric layer, the lower VO 2 layer, the lower SiO 2 The side lengths of the dielectric layer and the bottom gold layer are equal to the period length of the ultra-wideband-multi-frequency switchable terahertz absorption unit. 2 The side lengths of the patterned gold layer and the intermediate layer are both smaller than the period length of the ultra-wideband-multi-frequency switchable terahertz absorption unit.

[0011] Furthermore, the upper patterned VO 2 The radius of the layer is 12μm-16μm, the width of the square ring slit is 0.5μm-2.5μm, and the side length is 22μm; the upper patterned VO 2 The thickness of the layer is 0.02 μm - 0.2 μm.

[0012] Furthermore, the side length of the open square ring is 32μm, the width of the square ring is 0.5μm-2μm, and the opening width of the open square ring is 1μm-3μm; the outer diameter of the outer ring is 10μm-12μm, and the inner diameter is 9μm; the outer diameter of the inner ring is 5μm-7μm, and the inner diameter is 4μm; the thickness of the middle layer patterned gold layer is 1μm-3μm.

[0013] Furthermore, the upper SiO 2 The thickness of the dielectric layer is 4μm-8μm, and the lower VO 2 The thickness of the layer is 0.5 μm. 2 The thickness of the dielectric layer is 4 μm-8 μm, the thickness of the bottom gold layer is 0.2 μm; the thickness of the upper SiO 2 The dielectric layer, the lower VO 2 layer, the lower SiO 2 The side lengths of the dielectric layer and the bottom gold layer are both 33 μm.

[0014] Furthermore, the upper patterned VO 2layer and the lower VO 2 The electrical conductivity of the layer in the insulating phase is 20 S / m, and the electrical conductivity in the metallic phase is 200,000 S / m.

[0015] Furthermore, the upper SiO 2 The dielectric layer and the lower SiO 2 The relative dielectric constant of the dielectric layer is 2.13.

[0016] Furthermore, the bottom gold layer is made of gold with an electrical conductivity of 4.56×10 7 S / m.

[0017] Furthermore, the ultra-wideband-multi-frequency switchable terahertz absorber includes M*N multi-layer structures of the ultra-wideband-multi-frequency switchable terahertz absorption units, and the M*N multi-layer structures of the ultra-wideband-multi-frequency switchable terahertz absorption units are distributed in M*N two dimensions, wherein M and N are both positive integers.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention is based on an ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide. The designed absorber can achieve switching from ultra-wideband absorption to multi-frequency absorption by adjusting the conductivity of vanadium dioxide through temperature control. When the conductivity of vanadium dioxide is 200000S / m, the absorber is in the range of 3.9-9.3THz, and the absorption bandwidth of 90% absorption rate is 5.4THz. When the conductivity of vanadium dioxide is 20S / m, the absorber exhibits multi-frequency absorption, and there are 4 absorption peaks with an absorption rate of more than 90%, which are at 3.94THz, 7.06THz, 7.7THz and 9.16THz, respectively, and the absorption rate at 9.9THz is 82%.

[0020] 2. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide of the present invention is polarization-insensitive and maintains excellent absorption performance under different polarization angles and a wide incident angle of 0°-80°.

[0021] 3. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide of the present invention can tune the position and absorption intensity of the absorption peak in the multi-frequency absorption mode to a certain extent by changing the structural parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The periodic structure of the ultra-wideband-multi-frequency switchable terahertz absorption unit based on vanadium dioxide provided in Example 1 of the present invention;

[0023] Figure 2 A schematic diagram of the unit structure of an ultra-wideband and multi-frequency switchable terahertz absorber based on vanadium dioxide provided in Example 1 of the present invention;

[0024] Figure 3 A front view of the structure of an ultra-wideband and multi-frequency switchable terahertz absorption unit based on vanadium dioxide provided in Example 1 of the present invention;

[0025] Figure 4 The upper patterned VO of the ultra-wideband-multi-frequency switchable terahertz absorption unit based on vanadium dioxide provided in Example 1 of the present invention 2 Top view of the layer;

[0026] Figure 5 A top view of a patterned gold layer in the middle layer of the ultra-wideband-multi-frequency switchable terahertz absorption unit based on vanadium dioxide provided in Example 1 of the present invention;

[0027] Figure 6 The absorption spectrum of the ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide in the metallic phase provided in Example 1 of the present invention;

[0028] Figure 7 The absorption spectrum of the ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide in the insulating phase provided in Example 1 of the present invention;

[0029] Figure 8 The real part and imaginary part of the relative impedance of the ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide in the metallic phase provided in Example 1 of the present invention;

[0030] Fig. 9 The real part and imaginary part of the relative impedance of the ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide in the insulating phase provided in Example 1 of the present invention;

[0031] Fig.10 The absorption spectra of the ultra-wideband-multi-frequency switchable terahertz absorber with the conductivity of vanadium dioxide at 20, 200, 2000, 20000, and 200000 S / m provided in Example 1 of the present invention;

[0032] Fig.11 The electric field distribution of the ultra-wideband-multi-frequency switchable terahertz absorber provided in Example 1 of the present invention at a frequency of 8 THz and a vanadium dioxide conductivity of 200,000 S / m;

[0033] Fig.12 The electric field distribution of the ultra-wideband-multi-frequency switchable terahertz absorber provided in Example 1 of the present invention at a frequency of 3.94 THz and a vanadium dioxide conductivity of 20 S / m;

[0034] Fig.13The electric field distribution of the ultra-wideband-multi-frequency switchable terahertz absorber provided in Example 1 of the present invention at a frequency of 7.7 THz and a vanadium dioxide conductivity of 20 S / m;

[0035] Fig.14 Absorption spectra of the ultra-wideband-multi-frequency switchable terahertz absorber with a vanadium dioxide conductivity of 200,000 S / m provided in Example 1 of the present invention under different incident angles of TE waves;

[0036] Fig.15 The absorption spectra of the ultra-wideband-multi-frequency switchable terahertz absorber with a vanadium dioxide conductivity of 20 S / m provided in Example 1 of the present invention under different incident angles of TE waves.

[0037] Among them: 1. Upper patterned VO 2 2. Upper SiO 2 Dielectric layer; 3. Lower layer VO 2 layer; 4, middle layer patterned gold layer; 5, lower layer SiO 2 Dielectric layer; 6. Bottom gold layer. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] The present invention provides an ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide, such as Figure 1 As shown, it includes M*N multi-layer structures of ultra-wideband-multi-frequency switchable terahertz absorption units, and the M*N multi-layer structures of ultra-wideband-multi-frequency switchable terahertz absorption units are distributed in M*N two dimensions, wherein M and N are both positive integers.

[0040] Each multi-layer ultra-wideband-multi-frequency switchable terahertz absorption unit includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 The dielectric layer 5 and the bottom gold layer 6 are six layers of materials that are bonded to each other.

[0041] Upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length.

[0042] Among them, the upper patterned VO2 Layer 1 is disc-shaped with a square annular slit inside. The radius R of the disc is 12μm-16μm, the slit width d is 0.5μm-2.5μm, and the slit side length c is fixed at 22μm. The upper layer is patterned VO 2 The thickness of layer 1 is t 6 It is 0.02μm-0.2μm.

[0043] The middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is fixed at 32 μm, the square ring width b is 0.5 μm-2 μm, and the opening width w is 1 μm-3 μm. The outer diameter r of the outer circular ring is 1 10μm-12μm, inner diameter r 2 Fixed at 9μm, the outer diameter of the inner ring r 3 5μm-7μm, inner diameter r 4 The thickness of the middle patterned gold layer 4 is fixed at 4 μm. 3 1μm-3μm.

[0044] Upper SiO 2 The thickness of dielectric layer 2 is t 5 4μm-8μm, lower VO 2 The thickness of layer 3 is t 4 0.5μm, the lower layer SiO 2 The thickness t of the dielectric layer 5 2 The thickness of the bottom gold layer 6 is 4μm-8μm. 1 0.2μm. The upper layer SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths P of the dielectric layer 5 and the bottom gold layer 6 are both 33 μm.

[0045] Upper patterned VO 2 Layer 1 and lower VO 2 The conductivity of layer 3 in the insulating phase is 20S / m, and the conductivity in the metallic phase is 200000S / m. 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13. The material of the bottom gold layer 6 is gold, and the conductivity is 4.56×10 7 S / m.

[0046] The present invention is an ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide. The designed absorber can achieve switching from ultra-wideband absorption to multi-frequency absorption by adjusting the conductivity of vanadium dioxide through temperature control. When the conductivity of vanadium dioxide is 200000S / m, the absorber is in the range of 3.9-9.3THz, and the absorption bandwidth of 90% absorption rate is 5.4THz. When the conductivity of vanadium dioxide is 20S / m, the absorber exhibits multi-frequency absorption, and there are 4 absorption peaks with absorption rates above 90%, which are respectively at 3.94THz, 7.06THz, 7.7THz and 9.16THz, and the absorption rate at 9.9THz is 82%.

[0047] The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide of the present invention is polarization insensitive and maintains excellent absorption performance under different polarization angles and a wide incident angle of 0°-80°.

[0048] Example 1

[0049] like Figure 1 As shown, the ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide in this embodiment includes 3*3 ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure. The number of ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure does not affect the overall absorption performance. Each ultra-wideband-multi-frequency switchable terahertz absorber unit with a multi-layer structure includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 Dielectric layer 5 and bottom gold layer 6.

[0050] In this embodiment, the upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length, and the specific parameters are as follows.

[0051] In this embodiment, the upper patterned VO 2 The disk radius R of the layer is 15 μm, the slit width d is 1 μm, the slit side length c is 22 μm, and the thickness t 6 0.05μm.

[0052] The middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is 32 μm, the square ring width b is 1 μm, and the opening width w is 2 μm. The outer diameter r of the outer circular ring is 1is 10μm, the inner diameter of the outer ring is r 2 is 9μm, the outer diameter of the inner ring is r 3 is 5μm, the inner diameter of the inner ring is r 4 The thickness of the patterned gold layer 4 in the middle layer is t 3 is 2μm.

[0053] Upper SiO 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13, and its thickness t 5 and t 2 The bottom gold layer 6 is made of gold with an electrical conductivity of 4.56×10 7 S / m, thickness t 1 It is 0.2μm, and the side lengths P of the dielectric layer and the reflective layer are both 33μm.

[0054] VO 2 In the metallic phase, the conductivity is 200000S / m, the absorber is in the range of 3.9-9.3THz, and the absorption bandwidth of 90% absorption rate is 5.4THz. 2 In the insulating phase, the conductivity is 20S / m, and the absorber exhibits multi-frequency absorption. There are four absorption peaks with an absorption rate of more than 90%, which are located at 3.94THz, 7.06THz, 7.7THz and 9.16THz respectively.

[0055] The periodic structure of the absorber in this embodiment is as follows Figure 1 The unit structure diagram is shown in Figure 2 As shown, it contains six layers of structure, from top to bottom, the upper layer patterned VO 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 The dielectric layer 5 and the bottom gold layer 6. The front view of the unit structure is as follows Figure 3 As shown, the upper patterned VO 2 The thickness of layer 1 is t 6 0.05μm, upper SiO 2 The thickness of dielectric layer 2 is t 5 6μm, lower VO 2 The thickness of layer 3 is t 4 The thickness of the patterned gold layer 4 in the middle layer is 0.5 μm. 3 2μm, the lower layer SiO 2 The thickness t of the dielectric layer 5 2 is 5 μm, the thickness of the bottom gold layer 6 is t 1 0.2μm.

[0056] Upper patterned VO2 The top view of layer 1 and the middle layer patterned gold layer 4 is as shown Figure 4 and Figure 5 As shown, patterned VO 2 The disk radius R of the layer is 15 μm, the slit width d is 1 μm, and the slit side length c is 22 μm. The patterned gold layer consists of an open square ring, an outer ring, and an inner ring. The side length a of the open square ring is 32 μm, the square ring width b is 1 μm, and the opening width w is 2 μm. The outer diameter r of the outer ring 1 is 10μm, the inner diameter of the outer ring is r 2 is 9μm, the outer diameter of the inner ring is r 3 is 5μm, the inner diameter of the inner ring is r 4 is 4μm.

[0057] The absorption spectra of vanadium dioxide absorbers in the metallic phase and insulating phase are as follows Figure 6 and Figure 7 As shown. When VO 2 When in the metallic phase (conductivity of 200,000 S / m), the structure exhibits ultra-wideband absorption, with an absorption rate of more than 90% in the range of 3.9-9.3 THz and an absorption bandwidth of 5.4 THz. 2 When in the insulating phase (conductivity is 20S / m), the structure exhibits multi-frequency absorption. Five absorption peaks can be observed in the entire terahertz range. There are four absorption peaks with absorption rates above 90%, namely 3.94THz (98%), 7.06THz (96%), 7.7THz (98%) and 9.16THz (94%). The absorption rate at 9.9THz is 82%.

[0058] The real and imaginary parts of the absorber relative impedance of vanadium dioxide in the metallic phase and the insulating phase are as follows: Figure 8 and Fig. 9 As shown. When VO 2 When the conductivity is 200000S / m, it can be seen that in the corresponding high absorption rate frequency range, the solid line indicates that the real part of the impedance Re(z) approaches 1, and the dotted line indicates that the imaginary part of the impedance Im(z) approaches 0. At this time, the equivalent impedance of the absorber is approximately equal to the equivalent impedance of free space. 2 When the conductivity is 20S / m, the real part Re(z) of the equivalent impedance at the frequency corresponding to the absorption peak is close to 1, and the imaginary part Im(z) is close to 0. The absorber achieves impedance matching at 3.94THz, 7.06THz, 7.7THz and 9.16THz, thereby achieving a multi-frequency high absorption effect with an absorption rate of more than 90%.

[0059] VO 2 The absorption spectra of the absorber at different conductivities are shown in Figure 2. Fig.10 As shown. VO can be controlled by controlling the temperature2 The conductivity can be controlled to adjust the absorption rate of the absorber. 2 When in the metallic phase with higher conductivity, the designed absorber exhibits ultra-broadband absorption. 2 When in the insulating phase, the absorber can achieve multi-frequency high absorption in the terahertz band.

[0060] The electric field distribution of the absorber at a frequency of 8 THz and a vanadium dioxide conductivity of 200,000 S / m is as follows: Fig.11 As shown, the electric field distribution of the absorber at frequencies of 3.94 THz and 7.7 THz and a vanadium dioxide conductivity of 20 S / m is shown in Fig.12 and Fig.13 As shown. Fig.11 It can be seen that the electric field energy is mainly concentrated in the upper VO 2 Between the edge of the disk and the slits of the inner square pattern, there is almost no energy distribution in the square ring and circular ring gold layers in the middle layer, and the energy is mainly distributed in the upper three layers. Therefore, the ultra-wideband absorption is mainly achieved by the upper three layers, and the lower VO 2 The first layer blocks most of the terahertz waves from entering the lower three layers, so there is almost no energy distribution in the lower three layers. Fig.12 It can be seen that the electric field energy of the absorption peak at 3.94 THz is mainly concentrated on the upper and lower edges of the outer ring and the opening of the square ring, and the energy is mainly distributed near the patterned gold layer in the middle layer. Fig.13 It can be seen that the electric field energy of the absorption peak at 7.7 THz is mainly concentrated on the upper and lower edges and the opening of the square ring. Therefore, different parts of the patterned gold layer absorb terahertz energy at different frequencies, thus forming multi-frequency absorption.

[0061] When VO 2 When the conductivity is 200000S / m and 20S / m respectively, the effect of the incident angle on the absorptivity is as follows: Fig.14 and Fig.15 As shown. When the incident angle is in the wide angle range of 0°-80°, the absorber can maintain a high absorption rate in the corresponding frequency range and at the corresponding frequency point. The designed terahertz absorber has excellent wide-angle absorption characteristics.

[0062] Example 2

[0063] The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide in this embodiment includes 3*3 ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure, and each ultra-wideband-multi-frequency switchable terahertz absorber unit with a multi-layer structure includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO2 Dielectric layer 5 and bottom gold layer 6.

[0064] In this embodiment, the upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length.

[0065] In this embodiment, the upper patterned VO 2 Layer 1 is disc-shaped with a square ring slit inside. The radius R of the disc is 16 μm, the width d of the slit is 1.5 μm, the side length c of the slit is 22 μm, and the upper patterned VO 2 The thickness of layer 1 is t 6 It is 0.08μm.

[0066] The middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is 32 μm, the square ring width b is 0.5 μm, and the opening width w is 1.5 μm. The outer diameter r of the outer circular ring is 1 10.5μm, inner diameter r 2 Fixed at 9μm, the outer diameter of the inner ring r 3 5.5μm, inner diameter r 4 The thickness of the middle patterned gold layer 4 is fixed at 4 μm. 3 is 1.5μm.

[0067] Upper SiO 2 The thickness of dielectric layer 2 is t 5 5μm, lower layer VO 2 The thickness of layer 3 is t 4 0.5μm, lower SiO 2 The thickness t of the dielectric layer 5 2 is 6 μm, the thickness of the bottom gold layer 6 is t 1 The side length P is 33 μm.

[0068] Upper patterned VO 2 Layer 1 and lower VO 2 The conductivity of layer 3 in the insulating phase is 20S / m, and the conductivity in the metallic phase is 200000S / m. 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13. The material of the bottom gold layer 6 is gold, and the conductivity is 4.56×10 7 S / m.

[0069] Example 3

[0070] The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide in this embodiment includes 3*3 ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure, and each ultra-wideband-multi-frequency switchable terahertz absorber unit with a multi-layer structure includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 The dielectric layer 5 and the bottom gold layer 6. Among them, the upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length.

[0071] In this embodiment, the upper patterned VO 2 Layer 1 is disc-shaped with a square ring slit inside. The radius R of the disc is 14 μm, the width d of the slit is 2 μm, the side length c of the slit is 22 μm, and the upper patterned VO 2 Layer 1 thickness t 6 0.02μm.

[0072] In this embodiment, the middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is 32 μm, the square ring width b is 1.5 μm, and the opening width w is 1 μm. The outer diameter r of the outer circular ring is 1 11μm, inner diameter r 2 Fixed at 9μm, the outer diameter of the inner ring r 3 6μm, inner diameter r 4 Fixed to 4 μm. The thickness of the middle patterned gold layer 4 is t 3 1μm.

[0073] Upper SiO 2 The thickness of dielectric layer 2 is t 5 4μm, lower layer VO 2 The thickness of layer 3 is t 4 0.5μm, lower SiO 2 The thickness t of the dielectric layer 5 2 is 7 μm, the thickness of the bottom gold layer 6 is t 1 The side length P is 33 μm.

[0074] Upper patterned VO 2 Layer 1 and lower VO 2The conductivity of layer 3 in the insulating phase is 20S / m, and the conductivity in the metallic phase is 200000S / m. 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13. The material of the bottom gold layer 6 is gold, and the conductivity is 4.56×10 7 S / m.

[0075] Example 4

[0076] The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide in this embodiment includes 3*3 ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure, and each ultra-wideband-multi-frequency switchable terahertz absorber unit with a multi-layer structure includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 Dielectric layer 5 and bottom gold layer 6.

[0077] Among them, the upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length.

[0078] In this embodiment, the upper patterned VO 2 Layer 1 is disc-shaped with a square ring slit inside. The radius R of the disc is 13 μm, the width d of the slit is 2.5 μm, the side length c of the slit is 22 μm, and the upper patterned VO 2 Layer 1 thickness t 6 0.02μm.

[0079] In this embodiment, the middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is 32 μm, the square ring width b is 2 μm, and the opening width w is 2.5 μm. The outer diameter r of the outer circular ring is 1 11.5μm, inner diameter r 2 Fixed at 9μm, the outer diameter of the inner ring r 3 6.5μm, inner diameter r 4 Fixed to 4 μm. The thickness of the middle patterned gold layer 4 is t 3 is 2.5μm.

[0080] Upper SiO 2 The thickness of dielectric layer 2 is t 5 4μm, lower layer VO2 The thickness of layer 3 is t 4 0.5μm, lower SiO 2 The thickness t of the dielectric layer 5 2 is 8 μm, the thickness of the bottom gold layer 6 is t 1 The side length P is 33 μm.

[0081] Upper patterned VO 2 Layer 1 and lower VO 2 The conductivity of layer 3 in the insulating phase is 20S / m, and the conductivity in the metallic phase is 200000S / m. 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13. The material of the bottom gold layer 6 is gold, and the conductivity is 4.56×10 7 S / m.

[0082] Example 5

[0083] The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide in this embodiment includes 3*3 ultra-wideband-multi-frequency switchable terahertz units with a multi-layer structure, and each ultra-wideband-multi-frequency switchable terahertz absorber unit with a multi-layer structure includes an upper patterned VO arranged in sequence from top to bottom. 2 Layer 1, upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, middle layer patterned gold layer 4, lower layer SiO 2 Dielectric layer 5 and bottom gold layer 6.

[0084] Among them, the upper SiO 2 Dielectric layer 2, lower VO 2 Layer 3, lower layer SiO 2 The side lengths of the dielectric layer 5 and the bottom gold layer 6 are equal and are the period length of the absorption unit. 2 The side lengths of layer 1 and the middle patterned gold layer 4 are slightly smaller than the period length.

[0085] In this embodiment, the upper patterned VO 2 Layer 1 is disc-shaped with a square ring slit inside. The radius R of the disc is 12 μm, the slit width d is 2.5 μm, the slit side length c is 22 μm, and the upper patterned VO 2 The thickness of layer 1 is t 6 0.02μm.

[0086] In this embodiment, the middle layer patterned gold layer 4 is composed of an open square ring, an outer circular ring and an inner circular ring. The side length a of the open square ring is 32 μm, the square ring width b is 1 μm, and the opening width w is 3 μm. The outer diameter r of the outer circular ring is 1 12μm, inner diameter r2 Fixed at 9μm, the outer diameter of the inner ring r 3 7μm, inner diameter r 4 The thickness of the middle patterned gold layer 4 is fixed at 4 μm. 3 is 3μm.

[0087] Upper SiO 2 The thickness of dielectric layer 2 is t 5 6μm, lower layer VO 2 The thickness of layer 3 is t 4 0.5μm, lower SiO 2 The thickness t of the dielectric layer 5 2 is 5 μm, the thickness of the bottom gold layer 6 is t 1 The side length P is 33 μm.

[0088] Upper patterned VO 2 Layer 1 and lower VO 2 The conductivity of layer 3 in the insulating phase is 20S / m, and the conductivity in the metallic phase is 200000S / m. 2 Dielectric layer 2 and lower SiO 2 The relative dielectric constant of the dielectric layer 5 is 2.13. The material of the bottom gold layer 6 is gold, and the conductivity is 4.56×10 7 S / m.

[0089] The present invention is based on the ultra-wideband-multi-frequency switchable terahertz absorber of vanadium dioxide. 2 The insulating-metal phase transition characteristics of VO can be achieved by controlling the temperature. 2 The control of the conductivity can further realize the regulation of the absorber's absorption rate, so that it has a switchable function from ultra-wideband absorption to multi-frequency absorption. The ultra-wideband-multi-frequency switchable terahertz absorber of the present invention has a switchable function and good absorption performance, and has potential application value.

[0090] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide, characterized in that: The ultra-wideband-multi-frequency switchable terahertz absorption unit is a multi-layer structure, which is sequentially provided with an upper patterned VO2 layer, an upper SiO2 dielectric layer, a lower VO2 layer, an intermediate patterned gold layer, a lower SiO2 dielectric layer and a bottom gold layer which are bonded to each other from top to bottom; The upper patterned VO2 layer is in the shape of a disk, a square ring slit is arranged inside the disk, and the four corners of the square ring slit intersect with the disk and are provided with notches; The middle layer patterned gold layer comprises an inner circular ring, an outer circular ring and an open square ring which are sequentially arranged from the inside to the outside, and the opening of the open square ring is arranged at the middle position of each edge; The side lengths of the upper SiO2 dielectric layer, the lower VO2 layer, the lower SiO2 dielectric layer and the bottom gold layer are equal to the period length of the ultra-wideband-multi-frequency switchable terahertz absorption unit, and the side lengths of the upper patterned VO2 layer and the middle patterned gold layer are smaller than the period length of the ultra-wideband-multi-frequency switchable terahertz absorption unit.

2. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The radius of the upper patterned VO2 layer is 12 μm-16 μm, the width of the square ring slit is 0.5 μm-2.5 μm, and the side length is 22 μm; the thickness of the upper patterned VO2 layer is 0.02 μm-0.2 μm.

3. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The side length of the open square ring is 32μm, the width of the square ring is 0.5μm-2μm, and the opening width of the open square ring is 1μm-3μm; the outer diameter of the outer ring is 10μm-12μm, and the inner diameter is 9μm; the outer diameter of the inner ring is 5μm-7μm, and the inner diameter is 4μm; the thickness of the middle layer patterned gold layer is 1μm-3μm.

4. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The thickness of the upper SiO2 dielectric layer is 4μm-8μm, the thickness of the lower VO2 layer is 0.5μm, the thickness of the lower SiO2 dielectric layer is 4μm-8μm, and the thickness of the bottom gold layer is 0.2μm; the side lengths of the upper SiO2 dielectric layer, the lower VO2 layer, the lower SiO2 dielectric layer and the bottom gold layer are all 33μm.

5. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The electrical conductivity of the upper patterned VO2 layer and the lower VO2 layer in the insulating phase is 20 S / m, and the electrical conductivity in the metallic phase is 200000 S / m.

6. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The relative dielectric constant of the upper SiO2 dielectric layer and the lower SiO2 dielectric layer is 2.

13.

7. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The bottom gold layer is made of gold, and its conductivity is 4.56×10 7 S / m.

8. The ultra-wideband-multi-frequency switchable terahertz absorber based on vanadium dioxide according to claim 1, characterized in that: The ultra-wideband-multi-frequency switchable terahertz absorber comprises M*N multi-layer structures of the ultra-wideband-multi-frequency switchable terahertz absorption units, and the M*N multi-layer structures of the ultra-wideband-multi-frequency switchable terahertz absorption units are distributed in M*N two dimensions, wherein M and N are both positive integers.

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