Tunable broadband terahertz band absorber

Abstract

A tunable broadband terahertz band absorber disclosed by the present invention is composed of a bottom reflection layer, a dielectric isolation layer and a resonance pattern layer, the dielectric isolation layer is located between the bottom reflection layer and the resonance pattern layer, the resonance pattern layer is a vanadium dioxide layer, and the pattern of the resonance pattern layer comprises a disc and a plurality of isosceles right triangles. The isosceles right triangles are located on the periphery of the disc and are spaced from the disc, a plurality of grooves are formed in the disc, and the depth of each groove is equal to the thickness of the vanadium dioxide layer. According to the invention, the vanadium dioxide pattern is simple and easy to integrate, and has unique absorption response, the absorption rate is dynamically regulated and controlled from 1.2% to 99%, when the conductivity of vanadium dioxide is 2 * 10 < 5 > S / m, the absorption of terahertz waves by the absorber in the range of 3.88-10.3 THz exceeds 90%, the absolute bandwidth is 6.42 THz, and the relative bandwidth reaches 90.4%.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, specifically to a tunable broadband terahertz band absorber. Background Technology

[0002] Terahertz (THz) bands, typically referring to electromagnetic waves with frequencies ranging from 0.1 to 10 THz, lie in the spectral region between infrared and millimeter waves. They possess many unique physical properties and have wide applications in communication, sensing, and imaging. Given the urgent need for higher transmission rates in future wireless communications, the THz band, with its vast available bandwidth, is considered a key technology for next-generation high-speed communication. However, the lack of materials in nature that can efficiently interact with terahertz waves severely restricts the research and application of THz functional devices. To address this issue, researchers have begun to focus on artificial electromagnetic metasurfaces. The electromagnetic response of metasurfaces originates from their intricate subwavelength-scale structural design, rather than the intrinsic properties of the constituent materials, enabling the realization of special electromagnetic phenomena unobservable in natural materials. Based on this, various high-performance THz functional devices have been developed, such as filters, modulators, and absorbers.

[0003] Among various terahertz functional devices based on metasurfaces, absorbers have attracted much attention due to their broad application prospects in electromagnetic compatibility, target stealth technology, sensing, and photoelectric detection. However, existing metasurface absorber designs typically rely on a single resonant effect, resulting in generally narrow operating bandwidths. Early methods employing multilayer dielectric stacking structures to extend bandwidth are not only complex and costly to manufacture, but their absorption characteristics also become fixed and unchanging once fabricated, lacking dynamic tunability and making them difficult to adapt to varying application requirements. To overcome these inherent limitations, integrating active materials into metasurface designs has become an effective and important research strategy. Among these, vanadium dioxide (VO2), a phase change material, stands out due to its unique insulator-metal phase transition (IMT) characteristics. VO2 undergoes a significant conductivity jump (up to several orders of magnitude) at a critical temperature of approximately 341 K, making it highly sensitive to external thermal, electrical, and optical stimuli. Utilizing this reversible IMT characteristic of VO2, the untunability of traditional devices can be overcome, enabling improvements in the absorption bandwidth extension and dynamic control of absorption amplitude in terahertz metasurface absorbers.

[0004] However, although current research has explored the integration of vanadium dioxide materials into metasurfaces to broaden absorption bandwidth and dynamically control absorption amplitude, the following technical limitations remain: existing vanadium dioxide-based tunable terahertz metamaterial absorbers generally suffer from limited absorption bandwidth, relatively simple control methods, relatively complex structures, and insufficient stability in polarization and incident angles, leaving room for improvement in practical applications. In particular, most structures primarily achieve on / off adjustment of absorption intensity, making it difficult to simultaneously optimize absorption bandwidth, absorptivity, and control depth. Furthermore, the limited coupling efficiency between the VO2 layer and the metal resonant unit constrains the overall electromagnetic energy absorption level.

[0005] Therefore, this patent application is filed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a tunable broadband terahertz absorber, particularly a tunable broadband terahertz absorber based on vanadium dioxide. Through optimization of the structure and energy coupling method, the absorption bandwidth and tunability are improved to a certain extent, while maintaining a relatively simple structural form and good polarization and incident angle stability. This provides a feasible design approach for improving the performance of VO2-based absorbers. The absorber obtained by this invention features a wide operating bandwidth, high absorption efficiency, and continuously adjustable absorption amplitude.

[0007] This invention is achieved using the following technical solution:

[0008] A tunable broadband terahertz band absorber comprises a bottom reflective layer, a dielectric isolation layer, and a resonant pattern layer. The dielectric isolation layer is located between the bottom reflective layer and the resonant pattern layer. The resonant pattern layer is a vanadium dioxide layer. The pattern of the resonant pattern layer includes a disk and multiple isosceles right triangles. The multiple isosceles right triangles are located around the disk and are spaced apart from the disk. Multiple grooves are formed on the disk, and the depth of each groove is equal to the thickness of the vanadium dioxide layer.

[0009] In this invention, the bottom reflective layer, the dielectric isolation layer, and the resonant pattern layer are closely bonded together, which has the advantages of simple vanadium dioxide patterning and easy integration. Furthermore, by utilizing the characteristic that the conductivity of vanadium dioxide increases with increasing temperature and the state changes from insulating to metallic, the absorption rate can be dynamically controlled from 1.2% to 99%.

[0010] As a preferred design, four isosceles right triangles are arranged at the four right angles of the disk, and the groove is an elliptical groove.

[0011] As a preferred design, four slots are provided, and the four slots are evenly distributed in a ring along the inner circle of the disk.

[0012] In this invention, the vanadium dioxide pattern is a composite structure consisting of a disk with four elliptical grooves and four isosceles right triangles. The four isosceles triangles are located at the four corners of the pattern, and the disk is located at the center of the structure. The bottom reflective layer, the dielectric isolation layer, and the resonant pattern layer all have square cross-sections. The entire absorber has fourfold rotational symmetry and is insensitive to the polarization of incident electromagnetic waves.

[0013] As a preferred design, the dielectric isolation layer is a polydimethylsiloxane layer, and the bottom reflective layer is a gold film layer.

[0014] As a preferred design, the absorber has a structural period of 28~32µm.

[0015] As a preferred design, the vanadium dioxide layer has a thickness of 0.01~0.11 μm and an electrical conductivity of 200 S / m~2×10⁻⁶. 5 S / m.

[0016] As a preferred design, the dielectric constant of the vanadium dioxide material used in the resonant pattern layer can be represented by the Drude model in the terahertz band, and its formula is as follows:

[0017]

[0018] Among them, the high-frequency dielectric constant of vanadium dioxide =12; Oscillation frequency =5.75 × 10 13 rad / s, The plasma frequency. For electrical conductivity, ω is the angular frequency, and i is the imaginary unit;

[0019] ω p and The relationship is:

[0020] ;

[0021] in, = 3×10 5 S / m, =1.45 × 10 5 rad / s.

[0022] As a preferred design, the thickness of the bottom reflective layer is 0.1~0.5µm, and the conductivity is 4.56×10⁻⁶. 7 S / m;

[0023] And / or, the thickness of the dielectric isolation layer is 6~10µm, and its dielectric constant is 1.72.

[0024] The thickness of the bottom reflective layer is much greater than the skin thickness of the terahertz wave, resulting in a transmittance of 0 for the absorber structure.

[0025] As a preferred design, the radius of the disk is 8~12µm.

[0026] As a preferred design, the short half-axis of the groove has a length of 1.3~1.7um, the long half-axis has a length of 2.1~2.9um, and the leg length of the isosceles triangle is 6~9um.

[0027] This invention improves the structure of the resonant pattern layer and, by leveraging the characteristics of vanadium dioxide, optimizes the structure and energy coupling method, thereby improving the absorption bandwidth and tuning capability while maintaining a relatively simple structural form and good polarization and incident angle stability.

[0028] The advantages and beneficial effects of this invention compared to the prior art are:

[0029] 1. The vanadium dioxide tunable broadband terahertz absorber proposed in this invention has the characteristics of simple vanadium dioxide patterning, easy integration, and unique absorption response, which improves the shortcomings of the complex structure design of existing absorbers.

[0030] 2. The present invention proposes a vanadium dioxide tunable broadband terahertz absorber, which utilizes the characteristic that the conductivity of vanadium dioxide increases with increasing temperature to achieve the transition from an insulating state to a metallic state, thereby achieving dynamic control of the absorption rate from 1.2% to 99%.

[0031] 3. The vanadium dioxide tunable broadband terahertz absorber proposed in this invention has fourfold rotational symmetry, thus exhibiting insensitivity to the polarization of incident electromagnetic waves.

[0032] 4. The present invention proposes a tunable broadband terahertz absorber of vanadium dioxide, wherein the conductivity of vanadium dioxide is 2×10⁻⁶. 5 At a conductivity of 200 S / m, the absorber exhibits over 90% absorption of terahertz waves in the range of 3.88-10.3 THz, with an absolute bandwidth of 6.42 THz and a relative bandwidth of 90.4%. At 8.86 THz, the absorption rate is 0.99. With a vanadium dioxide conductivity of 200 S / ms, the absorption rate at 8.86 THz is 0.012, achieving a modulation depth of 98.79% through the phase transition characteristic of vanadium dioxide. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0034] Figure 1 This is a schematic diagram of the top layer pattern of a vanadium dioxide terahertz tunable broadband absorber provided in an embodiment of the present invention.

[0035] Figure 2 A side view of a vanadium dioxide terahertz tunable broadband absorber provided in an embodiment of the present invention.

[0036] Figure 3 The vanadium dioxide-based terahertz tunable broadband absorber provided in this embodiment of the invention has a conductivity of 2×10⁻⁶. 5 A graph showing the absorptivity and reflectivity at S / m.

[0037] Figure 4 This invention provides an absorption rate curve of a vanadium dioxide terahertz tunable broadband absorber as the conductivity changes.

[0038] Figure 5 The normalized impedance curve of a vanadium dioxide terahertz tunable broadband absorber is provided for an embodiment of the present invention.

[0039] Figure 6 The above is a contour plot of the absorption rate of a vanadium dioxide-based terahertz tunable broadband absorber at different polarization angles, provided as an embodiment of the present invention.

[0040] Figure 7 The diagram shows the absorption rate curves of a vanadium dioxide terahertz tunable broadband absorber under different incident angles in TE wave mode, as provided in an embodiment of the present invention.

[0041] Figure 8 The diagram shows the absorption rate curves of a vanadium dioxide terahertz tunable broadband absorber under different incident angles in TM wave mode, as provided in an embodiment of the present invention.

[0042] The markings and the components they represent in the attached diagram are as follows:

[0043] 1-Bottom reflective layer, 2-Dielectric isolation layer, 3-Resonant pattern layer, 301-Disk, 302-Isosceles right triangle, 303-Groove. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0045] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0046] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] In the description of this invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0048] Example 1:

[0049] The vanadium dioxide tunable broadband terahertz absorber (BTMA) designed in this embodiment is a periodic 3D structure, consisting of a bottom reflective layer 1, a dielectric isolation layer 2, and a resonant pattern layer 3 from top to bottom, with each layer tightly bonded together.

[0050] The bottom reflective layer 1 is a gold film, but it can also be made of metals such as Cu or Al. Its thickness h1 is 0.2 μm, and its conductivity is 4.56 × 10⁻⁶. 7 S / m. Because the thickness of the bottom reflective layer 1 is much greater than the skin depth of the terahertz wave, complete reflection can be achieved when the terahertz wave is incident on its surface.

[0051] The intermediate dielectric isolation layer 2 is made of polydimethylsiloxane with a dielectric constant ε1 = 1.72. The thickness h2 is 8 μm with a dielectric constant of 1.72.

[0052] Both the bottom reflective layer 1 and the dielectric isolation layer 2 have square cross-sections.

[0053] like Figure 1 As shown, the top layer of the absorber unit is a composite structure consisting of a disk 301 with four elliptical grooves 303 and four isosceles right triangles 302. Its overall cross-section adopts a square structure, with the four isosceles right triangles 302 located at the four corners of the square, the disk 301 located at the center of the structure, and the four elliptical grooves 303 arranged in a ring array along the inner circle of the disk 301.

[0054] like Figure 1 As shown, the disk radius r = 10 μm, the minor semi-axis a = 1.5 μm, the major semi-axis b = 2.5 μm of the elliptical groove, the isosceles side length d = 8.79 μm of the four isosceles right triangles 302, and the side length of the front cross-section of the resonant pattern layer 3 is the structural period p = 30 μm of the absorber.

[0055] The entire resonant pattern layer 3 is made of vanadium dioxide, with electrical conductivities of 200 S / m in its insulating state and 2 × 10⁻⁶ S / m in its metallic state. 5 S / m, the thickness of the entire vanadium dioxide patterned layer is h3 = 0.05um. For example... Figure 2 The side view is shown in the image.

[0056] Furthermore, in this embodiment, the dielectric constant of the vanadium dioxide material in the terahertz band can be represented by the Drude model, and its formula can be expressed as:

[0057]

[0058] The high-frequency dielectric constant of vanadium dioxide in the formula =12; Oscillation frequency =5.75 × 10 13 rad / s, The plasma frequency. For electrical conductivity, ω is the angular frequency, and i is the imaginary unit.

[0059] ω p and The relationship is:

[0060] ;

[0061] in, = 3×10 5S / m, =1.45 × 10 5 rad / s.

[0062] Example 2:

[0063] The vanadium dioxide tunable broadband terahertz absorber (BTMA) designed in this embodiment is a periodic 3D structure, consisting of a bottom reflective layer 1, a dielectric isolation layer 2, and a resonant pattern layer 3 from top to bottom, with each layer tightly bonded together.

[0064] The bottom reflective layer 1 is a gold film with a thickness h1 of 0.5 μm and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m. Because the thickness of the bottom reflective layer 1 is much greater than the skin depth of the terahertz wave, complete reflection can be achieved when the terahertz wave is incident on its surface.

[0065] The intermediate dielectric isolation layer 2 is made of polydimethylsiloxane with a dielectric constant ε1 = 1.72. The thickness h2 is 6 μm with a dielectric constant of 1.72.

[0066] Both the bottom reflective layer 1 and the dielectric isolation layer 2 have square cross-sections.

[0067] like Figure 1 As shown, the top layer of the absorber unit is a composite structure consisting of a disk 301 with four elliptical grooves 303 and four isosceles right triangles 302. Its overall cross-section adopts a square structure, with the four isosceles right triangles 302 located at the four corners of the square, the disk located at the center of the structure, and the four elliptical grooves distributed in a ring array along the inner circle of the disk.

[0068] like Figure 1 As shown, the disk radius r = 12 μm, the minor semi-axis a = 1.3 μm, the major semi-axis b = 2.9 μm of the elliptical groove, the isosceles side length d = 6 μm of the four isosceles right triangles 302, and the side length of the front cross section of the resonant pattern layer 3 is the structural period p = 28 μm of the absorber.

[0069] The entire resonant pattern layer 3 is made of vanadium dioxide, with electrical conductivities of 200 S / m in its insulating state and 2 × 10⁻⁶ S / m in its metallic state. 5 S / m, the thickness of the entire vanadium dioxide patterned layer is h3 = 0.11um. For example... Figure 2 The side view is shown in the image.

[0070] Example 3:

[0071] To verify the performance of the terahertz absorber designed in this invention, the ultra-wideband terahertz absorber was analyzed using the finite element method in the electromagnetic simulation software CST. Periodic boundary conditions were set in the x and y axes, and an open boundary condition was set in the z-axis direction to simulate an infinite periodic array. In the simulation, the incident electromagnetic wave was divided into transverse electric (TE) and transverse magnetic (TM) waves, where the electric field of the TE wave is parallel to the y-axis and the magnetic field is parallel to the x-axis; the electric field of the TM wave is parallel to the x-axis and the magnetic field is parallel to the y-axis. Assuming that the electromagnetic wave is incident perpendicularly to the surface of the absorber structure along the z-axis, according to electromagnetic theory, the absorptivity of the absorber is given by the following formula:

[0072] ;

[0073] Where the reflectivity R(ω) = |S11| 2 And transmittance T(ω) = |S21| 2 Since the thickness of the underlying metallic reflective layer is much greater than the maximum skin thickness of terahertz waves, the transmittance is close to zero. Therefore, the absorptivity equation can be simplified to:

[0074] .

[0075] The absorptivity and reflectivity curves of the tunable broadband terahertz absorber designed in this invention are shown in the figure below. Figure 3 As shown. By Figure 3 It can be seen that when VO2 is in the metallic state (σ = 2 × 10), 5 When the electromagnetic wave is incident perpendicularly along the -z direction (S / m), the polarization direction is the x-axis.

[0076] Further simulations and calculations were performed on the absorption and reflection spectra of the broadband terahertz metamaterial absorber designed in this invention. Figure 3 It can be seen that when VO2 is in the metallic state, the absorption rate of the absorber is greater than 90% in the frequency range of 3.88-10.3 THz, and perfect absorption is achieved at the frequency of f= 8.86 THz with a relative bandwidth of 90.4%.

[0077] like Figure 4 The figure shows the absorption rate curve of the absorber designed in this invention as the conductivity changes. Figure 4 It can be seen that when the conductivity of VO2 increases from 200 S / m to 2×10 5 At a current S / m, the absorption rate and absorption bandwidth of the absorber gradually increase. The absorption rate of the absorber can be dynamically adjusted from 1.2% to 99%, and the modulation depth reaches 98.79%. It can be seen that the absorption rate of the device can be controlled by adjusting the conductivity of VO2 to achieve the effect of absorption or reflection. Therefore, the device can switch between absorber and reflector functions.

[0078] Figure 5 The figure shows the normalized impedance curve of the designed broadband terahertz absorber. It can be observed from the figure that in the frequency range of 3.88–10.3 THz, the real part of the relative impedance is close to 1, and the imaginary part is close to zero. At this point, the equivalent impedance of the absorber is approximately the same as the impedance of free space, achieving impedance matching. This significantly reduces the reflection of incident electromagnetic waves from the absorber surface and maximizes the absorption of electromagnetic waves.

[0079] Figure 6 The diagram shows the absorption spectrum contours of terahertz waves under normal incidence conditions with polarization angles varying from 0° to 90°. Because the broadband terahertz absorber designed in this invention has a highly symmetrical surface resonance layer structure, its absorption rate and bandwidth frequency range remain constant with increasing polarization angle, exhibiting polarization insensitivity.

[0080] Figure 7 The figure shows the contour plot of the terahertz absorption spectrum of the absorber under TE polarization conditions, with the incident angle varying from 0° to 80°. As can be seen from the figure, when the incident angle of the TE-polarized wave varies from 0° to 30°, the absorber maintains over 90% absorption in the bandwidth of 3.88–10.3 THz. However, when the incident angle exceeds 30°, the absorption spectrum shows a blue shift, indicating a change in response. When the incident angle reaches 50°, the absorbance of the absorber remains above 80%. However, as the incident angle continues to increase, the absorption gradually decreases due to impedance mismatch.

[0081] Figure 8 As shown, when the incident angle is less than 50°, the absorber maintains more than 80% of its absorption performance under TM polarization. However, as the incident angle continues to increase, the absorptivity decreases sharply, the center frequency of the bandwidth exhibits a blue shift, and the bandwidth gradually narrows.

[0082] from Figure 7 and Figure 8 It can be seen that the resonant frequencies under both polarizations undergo a blue shift. This is mainly because the propagation of electromagnetic waves inside the absorber is disturbed by the change in the incident angle, and Lag scattering significantly affects the higher-order Fabry-Perot resonant modes.

[0083] Therefore, this invention discloses a tunable broadband terahertz absorber based on vanadium dioxide. From bottom to top, the absorber consists of a gold reflective layer, a polydimethylsiloxane dielectric isolation layer, and a vanadium dioxide resonant pattern layer. The vanadium dioxide pattern layer is a composite structure composed of a disk with four elliptical grooves and four isosceles right triangles. The triangles are located at the four corners of the pattern, and the disk is located in the center of the structure. This invention utilizes the characteristic that the conductivity of vanadium dioxide changes with external temperature to achieve a tunable terahertz absorber when the conductivity of VO2 is between 200 and 2 × 10⁻⁶.5 When varying within the S / m range, the absorbance of the absorber can be dynamically adjusted from 1.2% to 99%. When VO2 is in the metallic state, the absorbance can reach over 90% in the frequency range of 3.88-10.30 THz, with an absorption bandwidth of 6.42 THz and a modulation depth of 98.79%. Furthermore, the symmetry of the device surface pattern makes this terahertz ideal absorber device polarization insensitive. Simultaneously, the absorber also exhibits wide-angle absorption. This absorber possesses advantages such as simple structure, large adjustment range, high absorbance, and ultra-wide absorption bandwidth, showing potential applications in tunable bandwidth absorption devices, stealth devices, thermal detection, and terahertz switches.

[0084] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tunable broadband terahertz band absorber, characterized in that, It consists of a bottom reflective layer, a dielectric isolation layer, and a resonant pattern layer. The dielectric isolation layer is located between the bottom reflective layer and the resonant pattern layer. The resonant pattern layer is a vanadium dioxide layer. The pattern of the resonant pattern layer includes a disk and multiple isosceles right triangles. The multiple isosceles right triangles are located around the disk and are spaced apart from the disk. Multiple grooves are formed on the disk, and the depth of each groove is equal to the thickness of the vanadium dioxide layer.

2. A tunable broadband terahertz band absorber according to claim 1, characterized in that, Four isosceles right triangles are provided and located at the four right angles of the disk, and the groove is an elliptical groove.

3. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The disk has four slots, which are evenly distributed in a ring along the inner circle of the disk.

4. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The dielectric isolation layer is a polydimethylsiloxane layer, and the bottom reflective layer is a gold film layer.

5. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The structural period p of the absorber is 28~32um.

6. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The vanadium dioxide layer has a thickness of 0.01~0.11 μm and an electrical conductivity of 200 S / m~2×10⁻⁶. 5 S / m.

7. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The dielectric constant of the vanadium dioxide material used in the resonant pattern layer can be expressed in the terahertz band as: ； Among them, the high-frequency dielectric constant of vanadium dioxide =12; Oscillation frequency =5.75 × 10 13 rad / s, The plasma frequency. For electrical conductivity, ω is the angular frequency, and i is the imaginary unit; ω p and The relationship is: ； in, = 3×10 5 S / m, =1.45 × 10 5 rad / s.

8. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The thickness of the bottom reflective layer is 0.1~0.5 μm, and the conductivity is 4.56 × 10⁻⁶. 7 S / m; And / or, the thickness of the dielectric isolation layer is 6~10µm, and its dielectric constant is 1.

72.

9. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The radius of the disk is 8~12um.

10. A tunable broadband terahertz band absorber according to claim 1, characterized in that, The groove has a short semi-axis length of 1.3~1.7um, a long semi-axis length of 2.1~2.9um, and an isosceles triangle with a leg length of 6~9um.

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