Terahertz full-band active tuning multifunctional metamaterial wave absorber

Abstract

The invention relates to the technical field of terahertz metamaterial multifunctional wave absorbing devices, in particular to a terahertz full-band active tuning multifunctional metamaterial wave absorbing device. A single periodic structure sequentially comprises a metal substrate layer 1, a first dielectric layer 2, a graphene layer 3, a second dielectric layer 4, a third dielectric layer 5 and a vanadium dioxide layer 6 from bottom to top, the vanadium dioxide layer 6 is composed of a cross-shaped vanadium dioxide layer and four square ring vanadium dioxide layers with the same size, and the terahertz full-band active tuning multifunctional metamaterial wave absorber is formed through a periodic composite array. Based on the electrical adjustability (Fermi level modulation) of graphene and the phase change characteristic (temperature modulation) of vanadium dioxide, the absorption bandwidth with the 0.1-10THz full-band absorptivity larger than 92% and the 0.1-11.9 THz full-coverage active tuning are achieved, and the 11.8 THz absorption bandwidth with the 0.1-11.9 THz absorptivity larger than 90% and the 11.1 THz absorption bandwidth with the 0.1-11.2 THz absorptivity larger than 95% after tuning are achieved. And meanwhile, dynamic tuning in an absorption peak range from 2% to 100% is met, and the switching function of the reflector and the absorber is realized. In addition, the device adopts a central symmetry structure, and has polarization insensitivity and wide-angle absorption. Wide application prospects are shown in the frontier fields of national defense safety (radar stealth technology), advanced manufacturing (terahertz nondestructive testing), optical sensing and the like, and a new technical approach is provided for development of terahertz functional devices.

Description

(1) Technical Field

[0001] The present invention relates to a terahertz full-band actively tunable multifunctional metamaterial absorber, which can be used for the development of terahertz metamaterial absorbing devices, showing broad application prospects in such cutting-edge fields as national defense security (radar stealth technology), advanced manufacturing (terahertz non-destructive testing), and optical sensing, and providing a new technical approach for the development of terahertz functional devices. (2) Background Art

[0002] The terahertz wave has a frequency range of 0.1 to 10 THz and a wavelength range of approximately 3 to 0.03 mm, lying between microwaves and infrared waves. It is an electromagnetic wave band with excellent properties and has broad application prospects in such fields as communication, imaging, and sensing.

[0003] With the in-depth development of metamaterial research, it can precisely control physical properties such as amplitude, phase, frequency, and polarization in the terahertz band, breaking through the functional limitations of traditional materials. In recent years, the rapid progress of micro-nano processing technology has provided a new technical approach for the development of integrated multifunctional micro-nano photon devices, and related research has been scientifically verified in such fields as terahertz metamaterial absorbers, terahertz stealth, imaging technology, and biosensing.

[0004] Since the first perfect absorber was designed based on metamaterials, the door to the application research and exploration of absorbers has been opened. The efficient absorption and tuning of electromagnetic waves through metamaterial structures have great application value in the terahertz field.

[0005] Terahertz metamaterial absorbers have the advantages of strong absorption ability, thin thickness, and light weight. However, current terahertz metamaterial multifunctional absorbers are difficult to achieve the problems of terahertz full-band absorption bandwidth and full-band range active tuning, and there is still a large gap, which will be greatly restricted in applications.

[0006] Currently, many solutions have been proposed. Through in-depth research, it is found that terahertz multifunctional metamaterial absorbers based on the electro-tunable property of graphene (Fermi level modulation) and the phase change property of vanadium dioxide (temperature modulation) can achieve a wide absorption working bandwidth and a wide tunable range, etc., and have attracted wide attention in such fields as terahertz technology and nano-optics, becoming a research hotspot for scholars at home and abroad.

[0007] Vanadium dioxide has phase change properties and excellent electrical conductivity. When the temperature rises, the conductivity can change from 20 S / m to 2×10 5 S / m, and at a temperature of about 340 K, it changes from an insulating state to a metallic state, and the state is reversible. Therefore, vanadium dioxide can be used as the tunable material for this absorber.

[0008] Graphene has unique electrical and optical properties. The conductivity of graphene can be dynamically adjusted by electrically controlling the Fermi level, and dynamic tunability can also be achieved by changing the carrier relaxation time of graphene. Therefore, graphene can also be used as a tunable material for this absorber.

[0009] A terahertz full-band actively tunable multifunctional metamaterial absorber proposed in the present invention is based on the electro-tunability of graphene (Fermi level modulation) and the phase change characteristics of vanadium dioxide (temperature modulation), and has excellent absorption tuning performance (high absorption rate, full-band working bandwidth, full-coverage tunability) and practical characteristics (compact structure, light weight, easy processing), realizing the integration of the multifunctionality of terahertz metamaterial devices. It provides a new perspective and method for the research of terahertz multifunctional metamaterial devices, and shows great potential in application fields such as terahertz imaging, biomedicine, national defense and military industry, and advanced manufacturing. (III) Summary of the Invention

[0010] Aiming at the problems that the current absorber has a complex structure and it is difficult to achieve the terahertz full-band absorption bandwidth and full-band range active tuning, the present invention provides a terahertz full-band actively tunable multifunctional metamaterial absorber.

[0011] The described is a terahertz full-band actively tunable multifunctional metamaterial absorber. Its characteristics are: from the bottom to the upper layer, it successively includes a metal substrate layer 1, a first dielectric layer 2, a graphene layer 3, a second dielectric layer 4, a third dielectric layer 5, and a vanadium dioxide layer 6 composed of a cross and 4 square rings of vanadium dioxide with the same size. The terahertz full-band actively tunable multifunctional metamaterial absorber is formed by a centrosymmetric periodic composite array.

[0012] The period P of the unit structure of the described terahertz full-band actively tunable multifunctional metamaterial absorber is P = 25 μm; the thickness h1 of the metal substrate layer 1 is h1 = 0.2 μm; the thickness h2 of the first dielectric layer 2 is h2 = 4 μm; the thickness h3 of the graphene layer 3 is h3 = 0.34 nm; the thickness h4 of the second dielectric layer 4 is h4 = 4 μm; the thickness h5 of the third dielectric layer 5 is h5 = 0.15 μm; the thickness h6 of the vanadium dioxide layer 6 is h6 = 0.07 μm.

[0013] The material of the described metal substrate layer 1 is gold, and the conductivity is 4.561e 7 S / m. This metal serves as a reflection layer, which can ensure that all incident electromagnetic waves are reflected.

[0014] The dielectric constants of the described first dielectric layer 2 and the third dielectric layer 5 are both ε = 2.35. The materials of the dielectric layers are both cyclic olefin copolymer (Topas). Topas is a copolymer with high transparency, high heat resistance, good extrusion moldability and thermoformability, and has excellent optical properties, and can be used as the material of the terahertz absorber.

[0015] The described terahertz full-band actively tunable multifunctional metamaterial absorber is characterized in that: the length and width of the graphene layer 3 are both 25 μm. The conductivity of the graphene layer 3 can be expressed by the Kubo formula:

[0016] σ gra =σ intra +σ inter (1)

[0017]

[0018]

[0019] where, k B is the Boltzmann constant, is the reduced Planck constant, T is the Kelvin temperature, ω is the angular frequency, E f is the Fermi level, and τ is the graphene carrier relaxation time.

[0020] When the Fermi level E f = 0.4 eV, the graphene carrier relaxation time τ = 0.1 ps, and the conductivity of the vanadium dioxide layer σ = 2×10 5 S / m, an absorption bandwidth with an absorption rate greater than 92% in the full band from 0.1 to 10 THz is achieved.

[0021] When the Fermi level E f = 0.8 eV, the graphene carrier relaxation time τ = 0.1 ps, and the conductivity of the vanadium dioxide layer σ = 2×10 5 S / m is tuned to the Fermi level E f = 0 eV, the graphene carrier relaxation time τ = 1 ps (only here τ = 1 ps, and elsewhere without emphasis, τ = 0.1 ps by default), and the conductivity of the vanadium dioxide layer σ = 2×10 S / m, a tunable absorption bandwidth of 10 THz from the absorption rate of the blue curve greater than 90% to the absorption rate of the green curve less than 2.5% in the range of 1.9 to 11.9 THz is achieved, and at the same time, a dynamic tuning from 2% to 100% of the absorption peak is satisfied, realizing the function of switching between the reflector and the absorber.

[0022] The dielectric constant of the second dielectric layer 4 is ε = 1.1, and the material of the dielectric layer is polymethacrylimide (PMI). PMI is a lightweight, closed-cell rigid foam plastic with excellent mechanical properties, heat distortion temperature, and chemical stability, and has superior optical properties, and can be used as the material of the terahertz absorber.

[0023] The described vanadium dioxide layer 6 is composed of 4 hollow square-ring vanadium dioxides of the same size and a cross-shaped vanadium dioxide. The length l1 of the cross-shaped vanadium dioxide is 10 μm, and the width w1 is 3.5 μm; the outer length l2 of the outer hollow square-ring vanadium dioxide is 8.5 μm, and the width w2 is 1.5 μm. Its dielectric constant is described by the Drude model in the THz band, and the formula is:

[0024]

[0025] In the formula, ε ∞ = 12 is the dielectric constant at infinite frequency, ω p (σ) is the plasmon frequency, σ is the conductivity, and γ = 5.75×10 13 rad / s is the collision frequency. The relationship between ω p and σ is:

[0026]

[0027] In the formula, ω p (σ 0 ) = 1.4×10 15 rad / s, σ 0 = 3×10 5 S / m.

[0028] The conductivity σ of the absorber vanadium dioxide layer 6 is 2×10 5 S / m. After achieving an absorption bandwidth with an absorption rate greater than 92% in the entire THz band from 0.1 to 10 THz, when changing the Fermi level of the graphene layer 3 to E f = 0.25 eV, E f = 0.4 eV, and E f = 0.8 eV in three states, a total absorption bandwidth of 11.8 THz with an absorption rate greater than 90% from 0.1 to 11.9 THz and a total absorption bandwidth of 11.1 THz with an absorption rate greater than 95% from 0.1 to 11.2 THz are achieved through tuning. Due to the presence of the metal layer 1, the present invention can achieve the switching between the absorber and the reflector in a relatively wide frequency range. In addition, the device adopts a centrosymmetric structure, having polarization insensitivity and wide-angle absorption.

[0029] Specifically, the absorber realizes a red-shaded absorption bandwidth with an absorption rate greater than 99% from 0.1 to 1.3 THz when the Fermi level of the graphene layer 3 is switched to E f = 0.25 eV; when tuned to E f = 0.4 eV, a blue-shaded absorption bandwidth with an absorption rate greater than 97% from 1.3 to 7.7 THz is achieved; when further tuned to E fWhen it is 0.8 eV, the green shaded absorption bandwidth with an absorption rate greater than 90% from 7.7 to 11.9 THz and an absorption rate greater than 95% from 7.7 to 11.2 THz is achieved, thus realizing a total absorption bandwidth of 11.8 THz with an absorption rate greater than 90% from 0.1 to 11.9 THz and a total absorption bandwidth of 11.1 THz with an absorption rate greater than 95% from 0.1 to 11.2 THz.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. For the graphene layer 3 of the absorber, the Fermi level E f = 0.4 eV, the carrier relaxation time τ of graphene = 0.1 ps, and the conductivity σ of the vanadium dioxide layer = 2×10 5 S / m, an absorption bandwidth with an absorption rate greater than 92% in the full frequency band from 0.1 to 10 THz is achieved.

[0032] 2. For the graphene layer 3 of the absorber, the Fermi level E f = 0.8 eV, the carrier relaxation time τ of graphene = 0.1 ps, and when the conductivity σ of the vanadium dioxide layer is tuned to 2×10 5 S / m, the Fermi level E of the graphene layer 3 f = 0 eV, the carrier relaxation time τ of graphene = 1 ps, and when the conductivity σ of the vanadium dioxide layer is 2×10 S / m, a tunable absorption bandwidth of 10 THz is achieved, where the absorption rate of the blue curve from 1.9 to 11.9 THz is greater than 90% and is tuned to less than 2.5% of the green curve. At the same time, it satisfies the dynamic tuning from 2% to 100% of the absorption peak, realizing the function of switching between the reflector and the absorber.

[0033] 3. The conductivity σ of the vanadium dioxide layer 6 of the absorber is 2×10 5 S / m. When the Fermi level of the graphene layer 3 is changed to E f = 0.25 eV, E f = 0.4 eV, and E f = 0.8 eV in three states, after achieving an absorption bandwidth with an absorption rate greater than 92% in the full terahertz frequency band from 0.1 to 10 THz, through tuning, a total absorption bandwidth of 11.8 THz with an absorption rate greater than 90% from 0.1 to 11.9 THz and a total absorption bandwidth of 11.1 THz with an absorption rate greater than 95% from 0.1 to 11.2 THz are achieved. Due to the presence of the metal layer 1, the invention realizes the switching between the absorber and the reflector within the working bandwidth. In addition, the device adopts a centrosymmetric structure, having polarization insensitivity and wide-angle absorption. (IV) BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. The accompanying drawings in the following description are only one embodiment of the present invention. All other examples obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0035] Figure 1 It is a schematic diagram of the unit structure of the present invention.

[0036] Figure 2 It is a top view of the present invention.

[0037] Figure 3 For the present invention under perpendicular incidence of electromagnetic waves, the Fermi level E of graphene layer 3 f = 0.4 eV, the carrier relaxation time τ of graphene is 0.1 ps, and the conductivity σ of the vanadium dioxide layer is 2×10 5 S / m. The schematic diagram of the absorption bandwidth with an absorption rate greater than 92% in the full frequency band from 0.1 to 10 THz is simulated by the simulation software CST STUDIOSUITE 2020.

[0038] Figure 4 It is the Fermi level E of graphene layer 3 of the absorber of the present invention f = 0.8 eV, the carrier relaxation time τ of graphene is 0.1 ps, and the conductivity σ of the vanadium dioxide layer is 2×10 5 S / m is tuned to the Fermi level E of graphene layer 3 f = 0 eV, the carrier relaxation time τ of graphene is 1 ps, and the conductivity σ of the vanadium dioxide layer is 2×10 S / m. The schematic diagram of the tunable absorption bandwidth of 10 THz in total, from the absorption rate of the blue curve greater than 90% to the absorption rate of the green curve less than 2.5% in the range of 1.9 to 11.9 THz is simulated by the simulation software CST STUDIOSUITE 2020, while satisfying the dynamic tuning of 2% to 100% of the absorption peak, and realizing the switching function of the reflector and the absorber.

[0039] Figure 5 It is the conductivity σ of vanadium dioxide layer 6 of the absorber of the present invention is 2×10 5 S / m, and the Fermi level of graphene layer 3 is changed to E f = 0.25 eV, E f = 0.4 eV, E fWhen in three states of =0.8eV, after simulating with the simulation software CST STUDIO SUITE 2020 to achieve an absorption bandwidth greater than 92% for the entire terahertz frequency band from 0.1 to 10 THz, through tuning, a total absorption bandwidth of 11.8 THz with an absorption rate greater than 90% from 0.1 to 11.9 THz is achieved, and a schematic diagram of a total absorption bandwidth of 11.1 THz with an absorption rate greater than 95% from 0.1 to 11.2 THz is shown. (V) Specific implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other examples obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] A schematic diagram of a terahertz full-band actively tunable multifunctional metamaterial absorber proposed by the present invention is shown in Figure 1 , which successively includes a metal substrate layer 1, a first dielectric layer 2, a graphene layer 3, a second dielectric layer 4, a third dielectric layer 5, and a vanadium dioxide layer 6 composed of a cross shape and 4 square rings of the same size of vanadium dioxide from bottom to top. The terahertz full-band actively tunable multifunctional metamaterial absorber is formed by a centrosymmetric periodic composite array. The thickness h1 of the metal substrate layer 1 is 0.2 μm; the thickness h2 of the first dielectric layer 2 is 4 μm; the thickness h3 of the graphene layer 3 is 0.34 nm; the thickness h4 of the second dielectric layer 4 is 4 μm; the thickness h5 of the third dielectric layer 5 is 0.15 μm; the thickness h6 of the vanadium dioxide layer 6 is 0.07 μm.

[0042] Figure 1 As shown, the material of the metal substrate layer 1 is gold, and the conductivity is 4.561e 7 S / m. This metal serves as a reflective layer to ensure that all incident electromagnetic waves are reflected. The dielectric constants of the first dielectric layer 2 and the third dielectric layer 5 are both ε = 2.35, and the materials of the dielectric layers are both cyclic olefin copolymer (Topas). Topas is a transparent, hard amorphous thermoplastic copolymer with excellent optical properties and is suitable for advanced terahertz applications. The length and width of the graphene layer 3 are both 25 μm. The dielectric constant of the second dielectric layer 4 is ε = 1.1, and the material of the dielectric layer is polymethacrylimide (PMI). PMI is a lightweight, closed-cell rigid foam plastic with excellent mechanical properties, heat distortion temperature, and chemical stability, and is widely used as an ideal core layer material for high-performance sandwich structure composite materials.

[0043] Figure 2is the top view of the present invention. The period P of the unit structure of the ultra-wideband tunable multi-functional terahertz absorber is 25 μm. The vanadium dioxide layer 6 is composed of 4 hollow square-ring vanadium dioxides of the same size and a cross-shaped vanadium dioxide. The length l1 of the cross-shaped vanadium dioxide is 10 μm, and the width w1 is 3.5 μm; the outer length l2 of the peripheral hollow square-ring vanadium dioxide is 8.5 μm, and the width w2 is 1.5 μm.

[0044] The principle of the present invention is as follows:

[0045] The calculation formula for the absorber absorption rate is:

[0046] A(ω) = 1 - R(ω) - T(ω) (6)

[0047] R(ω) = |S 11 | 2 (7)

[0048] T(ω) = |S 21 | 2 (8)

[0049] In the formula, A(ω) is the absorption rate, R(ω) is the reflectivity, T(ω) is the transmittance, S 21 is the transmission coefficient, and S 11 is the reflection coefficient.

[0050] The metal substrate layer 1 serves as the substrate of the entire unit structure. When its thickness is greater than the skin depth of the electromagnetic wave, the electromagnetic wave cannot pass through, making the transmittance of the entire unit structure 0. Therefore, the above formula (6) can be simplified to:

[0051] A(ω) = 1 - R(ω) (9)

[0052] Therefore, for the absorption rate of the absorber, only its reflectivity needs to be considered.

[0053] Figure 3 is the Fermi level E f of the graphene layer 3 of the absorber, with E = 0.4 eV, the carrier relaxation time τ of graphene = 0.1 ps, and the conductivity σ of the vanadium dioxide layer = 2×10 5 S / m, achieving an absorption bandwidth with an absorption rate greater than 92% in the full frequency band from 0.1 to 10 THz.

[0054] Figure 4 is the Fermi level E f of the graphene layer 3 of the absorber, with E = 0.8 eV, the carrier relaxation time τ of graphene = 0.1 ps, and the conductivity σ of the vanadium dioxide layer = 2×10 5 S / m tuned to the Fermi level E fWhen the Fermi level of the graphene is \(E = 0eV\), the carrier relaxation time of the graphene \(\tau=1ps\), and the conductivity of the vanadium dioxide layer \(\sigma = 2\times10S / m\), a tunable absorption bandwidth of 10THz from an absorption rate greater than 90% of the blue curve to an absorption rate less than 2.5% of the green curve is achieved, while satisfying the dynamic tuning of the absorption peak from 2% to 100%, realizing the switching function between the reflector and the absorber.

[0055] Figure 5 The conductivity of the vanadium dioxide layer 6 of the absorber is \(\sigma = 2\times10\) 5 S / m, and the Fermi level of the graphene layer 3 is changed to \(E\) f \(= 0.25eV\), \(E\) f \(= 0.4eV\), \(E\) f \(= 0.8eV\) in three states. After achieving an absorption bandwidth with an absorption rate greater than 92% in the entire terahertz frequency band from 0.1 to 10THz, a total absorption bandwidth of 11.8THz with an absorption rate greater than 90% from 0.1 to 11.9THz is achieved through tuning, and a total absorption bandwidth of 11.1THz with an absorption rate greater than 95% from 0.1 to 11.2THz is achieved. Due to the presence of the metal layer 1, the present invention can realize the switching between the absorber and the reflector in a relatively wide frequency range. In addition, the device adopts a centrosymmetric structure, having polarization insensitivity and wide-angle absorption.

[0056] In summary, the present invention proposes a terahertz full-band active tuning multifunctional metamaterial absorber, realizing the integration of the multifunctionality of terahertz metamaterial devices. Through the precise adjustment of the electrically controlled Fermi level and carrier relaxation time of the graphene layer, combined with the temperature-controlled conductivity modulation of the vanadium dioxide layer, an absorption bandwidth with an absorption rate greater than 92% in the entire frequency band from 0.1 to 10THz, full-coverage active tuning from 0.1 to 11.9THz are achieved, and a total absorption bandwidth of 11.8THz with an absorption rate greater than 90% from 0.1 to 11.9THz and a total absorption bandwidth of 11.1THz with an absorption rate greater than 95% from 0.1 to 11.2THz after tuning are achieved. At the same time, the dynamic tuning in the range of 2% to 100% of the absorption peak is satisfied, realizing the switching function between the reflector and the absorber.

[0057] It should be noted that although the above is a preferred embodiment of the present invention, this is not a limitation of the present invention. Therefore, the present invention is not limited to the above specific embodiments. Without departing from the principle of the present invention, all or part of the processes of the above embodiments implemented by those skilled in the art under the inspiration of the present invention and equivalent changes made according to the claims of the present invention are regarded as within the protection scope of the present invention.

Claims

1. A terahertz full-band actively tuned multifunctional metamaterial absorber, characterized by: From bottom to top, it includes a metal substrate layer 1, a first dielectric layer 2, a graphene layer 3, a second dielectric layer 4, a third dielectric layer 5, and a vanadium dioxide layer 6 composed of a cross-shaped and four square vanadium dioxide rings of the same size. The terahertz full-band actively tuned multifunctional metamaterial absorber is formed through a centrally symmetric periodic composite array.

2. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1 is characterized by: The absorber unit structure period P=25μm; the thickness of the metal substrate layer 1 is h1=0.2μm; the thickness of the first dielectric layer 2 is h2=4μm; the thickness of the graphene layer 3 is h3=0.34nm; the thickness of the second dielectric layer 4 is h4=4μm; the thickness of the third dielectric layer 5 is h5=0.15μm; the thickness of the vanadium dioxide layer 6 is h6=0.07μm.

3. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1 is characterized by: The material of the metal substrate layer 1 is gold, and the electrical conductivity is 4.561e 7 S / m, is the reflective layer that ensures that all incident electromagnetic waves are reflected.

4. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1 is characterized by: The dielectric constants of the first dielectric layer 2 and the third dielectric layer 5 are both ε=2.35, and the materials of the dielectric layers are both polyethylene cycloolefin copolymer (Topas). Topas is a transparent, hard amorphous thermoplastic copolymer with excellent optical properties and is suitable for advanced terahertz applications.

5. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1 is characterized by: The length and width of the graphene layer 3 are both 25 μm.

6. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1, characterized in that: The dielectric constant of the second dielectric layer 4 is ε=1.1, and the material of the dielectric layer is polymethacrylimide (PMI). PMI is a lightweight, closed-cell rigid foam plastic with excellent mechanical properties, heat deformation temperature and chemical stability, and is widely used as an ideal core layer material for high-performance sandwich structure composite materials.

7. The terahertz full-band actively tuned multifunctional metamaterial absorber according to claim 1 is characterized by: The vanadium dioxide layer 6 is composed of 4 hollow square vanadium dioxide rings of the same size and a cross-shaped vanadium dioxide, the cross-shaped vanadium dioxide has a length of l1 = 10 μm and a width of w1 = 3.5 μm; the outer length of the outer hollow square vanadium dioxide ring is l2 = 8.5 μm and a width of w2 = 1.5 μm.

8. According to claim 1, a terahertz full-band active tuning multifunctional metamaterial absorber is based on graphene electrical tunability (Fermi level modulation) and vanadium dioxide phase change characteristics (temperature modulation), achieving an absorption bandwidth with an absorption rate of more than 92% in the full band from 0.1 to 10 THz, full coverage active tuning from 0.1 to 11.9 THz, and achieving a total absorption bandwidth of 11.8 THz with an absorption rate of more than 90% from 0.1 to 11.9 THz and a total absorption bandwidth of 11.1 THz with an absorption rate of more than 95% from 0.1 to 11.2 THz after tuning. At the same time, dynamic tuning of the absorption peak range from 2% to 100% is satisfied to realize the switching function of reflector and absorber. In addition, the device adopts a central symmetric structure, with polarization insensitivity and wide-angle absorption.

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