Vanadium dioxide-based terahertz broadband chiral absorber capable of being actively regulated and controlled
By designing a vanadium dioxide-based terahertz broadband chiral absorber, utilizing a structural unit composed of a Z-type gold structure and vanadium dioxide microdiscs, and combining temperature-controlled conductivity changes, high absorption of linearly polarized light and selective absorption of left and right circularly polarized light were achieved. This solves the problems of narrow absorption bandwidth and single function of existing chiral terahertz absorbers, and also provides temperature tunability.
Patent Information
- Application Number
- CN202511968253.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-02-27
AI Technical Summary
Existing chiral terahertz absorbers have a narrow absorption bandwidth and a relatively simple light absorption function.
A terahertz broadband chiral absorber based on vanadium dioxide is designed. By using a Z-shaped gold structure and a structural unit composed of four vanadium dioxide microdiscs, combined with temperature-controlled changes in the conductivity of vanadium dioxide, selective absorption of left and right circularly polarized light and broadband absorption are achieved.
It achieves high absorption of linearly polarized light, while selectively absorbing both left and right circularly polarized light. It has a wide absorption bandwidth and temperature tunability, overcoming the shortcomings of passive control in traditional devices.
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Figure CN121584271A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of terahertz metamaterial design technology. Background Technology
[0002] The terahertz (THz) band lies between microwave and infrared frequencies, ranging from 0.1 THz to 10 THz. It has attracted widespread attention due to its unique potential in imaging, communication, and spectroscopy. In recent years, terahertz absorbing materials have been extensively explored in electromagnetic stealth, detection, and sensing technologies. Chirality describes the inability of an object's structure and its mirror image to perfectly overlap through operations such as rotation and translation. When a chiral object interacts with electromagnetic waves, it produces different optical responses under left-handed and right-handed circularly polarized light, exhibiting an intensity or phase difference; this difference is called circular dichroism. However, naturally occurring chiral materials typically exhibit weak optical chirality; therefore, artificial chiral metamaterials provide an effective way to enhance and customize this response.
[0003] Chiral terahertz absorbers, which combine terahertz absorbers with chiral structures, integrate terahertz technology, metamaterials science, and chiral optics. Their high selectivity for circularly polarized light and sensitive chiral response make them have great application potential in information security and encrypted communication, chiral material sensing and detection, stealth technology, and electromagnetic control. However, existing chiral terahertz absorbers have narrow absorption bandwidth and relatively simple light absorption functions. Summary of the Invention
[0004] This invention aims to address the problems of narrow absorption bandwidth and limited light absorption function in existing chiral terahertz absorbers, and to provide a vanadium dioxide-based actively tunable broadband chiral terahertz absorber.
[0005] A vanadium dioxide-based actively tunable terahertz broadband chiral absorber consists of a reflective bottom layer, an intermediate dielectric layer, and a top layer, arranged from bottom to top.
[0006] The top layer is composed of an array of multiple structural units; each structural unit consists of a Z-shaped gold structure and four vanadium dioxide microdiscs.
[0007] The Z-shaped metal structure consists of a middle longitudinal arm, an upper horizontal arm, and a lower horizontal arm. The upper end of the middle longitudinal arm is perpendicularly connected to the lower edge of the upper horizontal arm, and the lower end of the middle longitudinal arm is perpendicularly connected to the upper edge of the lower horizontal arm.
[0008] The four vanadium dioxide micron disks are symmetrically arranged on the left and right sides of the middle longitudinal arm and are in contact with the left and right edges of the middle longitudinal arm.
[0009] The beneficial effects of this invention are:
[0010] This invention relates to an actively tunable terahertz broadband chiral absorber based on vanadium dioxide. Utilizing the phase transition process of vanadium dioxide from an insulating to a metallic state, it achieves a highly efficient, tunable absorber with chiral absorption characteristics. This absorber features actively temperature-tunable terahertz wave absorption and selective absorption of circularly polarized light, achieving circular dichroism and a wide absorption bandwidth. This overcomes the problems of narrow absorption bandwidth and limited light absorption function in existing chiral terahertz absorbers. While achieving high absorption of linearly polarized light, it also achieves selective absorption of circularly polarized light, overcoming the shortcomings of passive control in traditional devices. The amplitude and peak position can be adjusted at different temperatures.
[0011] (1) The unit structure designed in this invention is simple, with few layers, and is easy to process and manufacture. The above-mentioned active controllable terahertz broadband chiral absorber based on vanadium dioxide meets the application requirements for manufacturing highly sensitive optical sensors and photodetectors.
[0012] (2) The present invention proposes a vanadium dioxide-based terahertz broadband chiral absorber that can be actively tuned, which simultaneously satisfies the high absorption of linear polarization and circular polarization. The maximum absorption rate of linear polarization reaches 0.953, and the absorption rate of left-handed circular polarization reaches 0.995. It also achieves selective absorption of left-handed and right-handed circular polarized light. In addition, it has temperature tunability and broadband absorption characteristics, and has rich absorption functions.
[0013] As can be seen from the above, the terahertz broadband chiral absorber of the present invention has broadband absorption, dynamic tunability, circular dichroism, and high absorption characteristics for both linearly and circularly polarized light. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of a vanadium dioxide-based actively tunable terahertz broadband chiral absorber according to the present invention.
[0015] Figure 2 This is a schematic diagram of the structural unit of the present invention;
[0016] Figure 3 This represents the real part of the dielectric constant of vanadium dioxide calculated using the Drude model.
[0017] Figure 4 This represents the imaginary part of the dielectric constant of vanadium dioxide calculated using the Drude model.
[0018] Figure 5 The absorption spectra of the actively modulated terahertz broadband chiral absorbers based on vanadium dioxide in Examples 1 and 2 are shown.
[0019] Figure 6The temperature-dependent absorption spectrum of the vanadium dioxide-based actively modulated terahertz broadband chiral absorber in Example 1;
[0020] Figure 7 The absorption spectrum of left-handed circularly polarized light in Example 3 is based on a vanadium dioxide-based actively modulated terahertz broadband chiral absorber. l R represents the absorption rate of the device for left-handed circularly polarized light. ll R represents the reflection of left-handed circularly polarized light by the device after the incident light. rl The device reflects left-handed circularly polarized light after it is incident, converting the polarization to right-handed circularly polarized light.
[0021] Figure 8 The right-handed circularly polarized light absorption spectrum of the vanadium dioxide-based actively modulated terahertz broadband chiral absorber in Example 4 is shown in Figure A. r R represents the absorption rate of the device for left-handed circularly polarized light. rr R represents the reflection of right-handed circularly polarized light by the device after the light is incident on it. lr The device reflects right-handed circularly polarized light after it is incident, converting the polarization to left-handed circularly polarized light.
[0022] Figure 9 The absorption spectrum of left-handed circularly polarized light as a function of temperature in Example 3, based on a vanadium dioxide-based actively modulated terahertz broadband chiral absorber.
[0023] Figure 10 The absorption spectrum of right-handed circularly polarized light as a function of temperature in Example 4, based on a vanadium dioxide-based actively modulated terahertz broadband chiral absorber.
[0024] Figure 11 The circular dichroism spectra of the vanadium dioxide-based actively modulated terahertz broadband chiral absorbers in Examples 3 and 4 are shown. Detailed Implementation
[0025] Specific implementation method one, combined with Figure 1 and Figure 2 Detailed description: This embodiment is a vanadium dioxide-based actively tunable terahertz broadband chiral absorber, which consists of a reflective bottom layer, an intermediate dielectric layer and a top layer from bottom to top;
[0026] The top layer is composed of an array of multiple structural units; each structural unit consists of a Z-shaped gold structure and four vanadium dioxide microdiscs.
[0027] The Z-shaped metal structure consists of a middle longitudinal arm, an upper horizontal arm, and a lower horizontal arm. The upper end of the middle longitudinal arm is perpendicularly connected to the lower edge of the upper horizontal arm, and the lower end of the middle longitudinal arm is perpendicularly connected to the upper edge of the lower horizontal arm.
[0028] The four vanadium dioxide micron disks are symmetrically arranged on the left and right sides of the middle longitudinal arm and are in contact with the left and right edges of the middle longitudinal arm.
[0029] In this specific embodiment, the top layer is a chiral structure composed of Z-type metal and vanadium dioxide phase change material, which is periodically arranged in the x and y directions to form a metasurface microstructure. The device has the function of temperature-controlled absorption and can simultaneously meet the high absorption of linearly polarized and circularly polarized incident light.
[0030] This specific embodiment further regulates the conductivity of vanadium dioxide by adjusting the temperature, thereby controlling the frequency and position of the absorption peak and achieving dynamic regulation of the absorption peak value of the absorber.
[0031] This specific embodiment further regulates the conductivity of vanadium dioxide by adjusting the temperature, thereby changing the absorption rate of the absorber and achieving dynamic control of the absorber's absorption rate.
[0032] This specific embodiment achieves broadband selective absorption of left-handed and right-handed circularly polarized light by establishing a chiral structure. Within the working bandwidth, it maintains high absorption of left-handed circularly polarized light while keeping the absorption of right-handed circularly polarized light in a low absorption range.
[0033] The beneficial effects of this embodiment are:
[0034] This embodiment is based on a vanadium dioxide-based actively tunable terahertz broadband chiral absorber. Utilizing the phase transition process of vanadium dioxide from an insulating to a metallic state, it achieves a highly efficient, tunable absorber with chiral absorption characteristics. This absorber features actively temperature-tunable terahertz wave absorption and selective absorption of circularly polarized light, achieving circular dichroism. Furthermore, it boasts a wide absorption bandwidth, overcoming the problems of narrow absorption bandwidth and limited light absorption function found in existing chiral terahertz absorbers. While achieving high absorption of linearly polarized light, it also achieves selective absorption of circularly polarized light, overcoming the shortcomings of passive control in traditional devices. The amplitude and peak position can be adjusted at different temperatures.
[0035] (1) The unit structure designed in this embodiment is simple, with few layers, and is easy to process and manufacture. The above-mentioned active controllable terahertz broadband chiral absorber based on vanadium dioxide meets the application requirements for manufacturing highly sensitive optical sensors and photodetectors.
[0036] (2) The present embodiment proposes a vanadium dioxide-based terahertz broadband chiral absorber that can be actively tuned, which simultaneously satisfies the high absorption of linear polarization and circular polarization. The maximum absorption rate of linear polarization reaches 0.953, and the absorption rate of left-handed circular polarization reaches 0.995. It also achieves selective absorption of left-handed and right-handed circularly polarized light. In addition, it has temperature tunability and broadband absorption characteristics, and has rich absorption functions.
[0037] As can be seen from the above, the terahertz broadband chiral absorber of this embodiment has broadband absorption, dynamic tunability, circular dichroism, and high absorption characteristics for both linearly polarized and circularly polarized light.
[0038] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the reflective substrate is made of gold; and the thickness of the reflective substrate is ≥2μm. Everything else is the same as in Specific Implementation Method One.
[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the intermediate dielectric layer is made of silicon dioxide; and the thickness of the intermediate dielectric layer is 9μm~11μm. Everything else is the same as in Specific Implementation Method One or Two.
[0040] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the width b of the intermediate longitudinal arm is 5μm to 7μm, and the length a is 20μm to 25μm. Everything else is the same as in Specific Implementation Methods One to Three.
[0041] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the width d of both the upper and lower horizontal arms is 1.5μm to 2.5μm, and the length c is 5μm to 7.5μm. Everything else is the same as in Specific Implementation Methods One to Four.
[0042] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the radius r of the vanadium dioxide microdisc is 3μm to 4.5μm. Everything else is the same as in Specific Implementation Methods One to Five.
[0043] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the minimum distance w between the vanadium dioxide microdiscs on the same side is 3μm to 7μm. Everything else is the same as in Specific Implementation Methods One to Six.
[0044] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the minimum distance between the vanadium dioxide microdisc and the adjacent upper or lower horizontal arm is 0 μm to 1 μm. Everything else is the same as in Specific Implementation Methods One to Seven.
[0045] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the thickness of the Z-shaped gold structure and the four vanadium dioxide micron disks is 0.1 μm to 0.3 μm. Everything else is the same as in Specific Implementation Methods One to Eight.
[0046] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the periodic side length P of the structural unit along the x-direction is... x and the periodic side length P along the y directiony All are 30μm~32μm. Other details are the same as in specific embodiments one through nine.
[0047] The beneficial effects of the present invention are verified using the following embodiments:
[0048] Example 1:
[0049] A vanadium dioxide-based actively tunable terahertz broadband chiral absorber consists of a reflective bottom layer, an intermediate dielectric layer, and a top layer, arranged from bottom to top.
[0050] The top layer is composed of an array of multiple structural units; each structural unit consists of a Z-shaped gold structure and four vanadium dioxide microdiscs.
[0051] The Z-shaped metal structure consists of a middle longitudinal arm, an upper horizontal arm, and a lower horizontal arm. The upper end of the middle longitudinal arm is perpendicularly connected to the lower edge of the upper horizontal arm, and the lower end of the middle longitudinal arm is perpendicularly connected to the upper edge of the lower horizontal arm.
[0052] The four vanadium dioxide micron disks are symmetrically arranged on the left and right sides of the middle longitudinal arm and are in contact with the left and right edges of the middle longitudinal arm.
[0053] The reflective substrate is made of gold; the thickness of the reflective substrate is 2μm.
[0054] The intermediate dielectric layer is made of silicon dioxide; the thickness of the intermediate dielectric layer is 10 μm.
[0055] The width b of the intermediate longitudinal arm is 6μm and the length a is 21.2μm.
[0056] The width d of both the upper and lower cross arms is 1.9 μm, and the length c of both is 6.8 μm.
[0057] The radius r of the vanadium dioxide microdiscs is 3.7 μm.
[0058] The minimum distance w between vanadium dioxide microdiscs on the same side is 6 μm.
[0059] The minimum distance between the vanadium dioxide microdisc and the adjacent upper or lower horizontal arm is 0.2 μm.
[0060] The thickness of the Z-shaped gold structure and the four vanadium dioxide micron disks is 0.2 μm.
[0061] The periodic side length P of the structural unit along the x-direction x and the periodic side length P along the y direction y All are 30μm.
[0062] The incident light is linearly polarized along the x-direction.
[0063] Example 2: This example differs from Example 1 in that the thickness of the Z-shaped gold structure and the vanadium dioxide micron disk are changed to 0.1 μm, 0.15 μm, or 0.25 μm. Everything else is the same as in Example 1.
[0064] Example 3: This example differs from Example 1 in that the incident light is replaced with left-handed circularly polarized light. Everything else is the same as in Example 1.
[0065] Example 4: This example differs from Example 1 in that the incident light is replaced with right-handed circularly polarized light. Everything else is the same as in Example 1.
[0066] In the examples, the dielectric constant of vanadium dioxide can be described by the Drude model:
[0067] (1)
[0068] In the formula, and These are the high-frequency dielectric constant and the collision frequency, respectively; ω is the actual angular frequency. Plasma frequency; plasma frequency The relationship between conductivity and electrical conductivity is:
[0069] (2)
[0070] In the formula, For reference plasma frequency, For reference conductivity, This represents the actual conductivity.
[0071] Figure 3 This represents the real part of the dielectric constant of vanadium dioxide calculated using the Drude model. Figure 4 This represents the imaginary part of the dielectric constant of vanadium dioxide calculated using the Drude model. Figure 3 and Figure 4 The results of calculating the real and imaginary parts of the dielectric constant of vanadium dioxide at different conductivity levels from 2 THz to 8 THz using the Drude model are presented. The conductivity of vanadium dioxide changes significantly at different temperatures, meaning that the temperature change of vanadium dioxide can be represented by the change in conductivity. As can be seen from the figure, higher temperatures correspond to higher conductivity, with the real part of the dielectric constant of vanadium dioxide decreasing and the imaginary part increasing.
[0072] use Figure 3 and Figure 4 The calculation results were obtained through simulation. Figures 5 to 10 :
[0073] Figure 5The absorption spectra of the vanadium dioxide-based actively tunable terahertz broadband chiral absorbers in Examples 1 and 2 are shown. Examples 1 and 2 varied the thickness of the top Z-shaped gold structure and the vanadium dioxide microdisk, and the effect of the top layer thickness on the absorbance of the vanadium dioxide-based actively tunable terahertz broadband chiral absorber was discussed. The results were all based on the assumption that vanadium dioxide was in the metallic phase. Figure 5 It can be seen that the absorption rate is best when the thickness is 0.2 μm, reaching 0.953. However, the top layer structure of other thicknesses also maintains a good absorption effect, indicating that the top layer thickness has little effect on the absorption rate of the device. Furthermore, as the thickness increases, the absorption peak is accompanied by a slight red shift.
[0074] Figure 6 The temperature-dependent absorption spectrum of the vanadium dioxide-based actively tunable terahertz broadband chiral absorber in Example 1 is shown. By changing the conductivity of vanadium dioxide to correspond to its optical properties at different temperatures, the absorptivity at different temperatures was obtained. As can be seen from the figure, with increasing temperature, the absorptivity of the vanadium dioxide-based actively tunable terahertz broadband chiral absorber gradually increases and reaches stable broadband absorption in the range of 3 THz to 7 THz. The temperature and frequency range with an absorptivity greater than 0.9 was extracted using a coil, achieving temperature tunability.
[0075] Figure 7 The absorption spectrum of left-handed circularly polarized light in Example 3 is based on a vanadium dioxide-based actively modulated terahertz broadband chiral absorber. l R represents the absorption rate of the device for left-handed circularly polarized light. ll R represents the reflection of left-handed circularly polarized light by the device after the incident light. rl The reflection of left-handed circularly polarized light after incident radiation is converted to right-handed circularly polarized light by the device. The absorptivity of the incident light, which is actively tunable in a vanadium dioxide terahertz broadband chiral absorber, is obtained by changing the incident light from linearly polarized to left-handed circularly polarized light. Due to the impermeability of the bottom metal layer to terahertz waves, the reflectivity of the device for circularly polarized light is discussed; some left-handed circularly polarized light is converted to right-handed circularly polarized light after reflection. All research results are based on the case where vanadium dioxide is in the metallic phase. As shown in the figure, the vanadium dioxide-based actively tunable terahertz broadband chiral absorber reflects left-handed and right-handed circularly polarized light, and absorbs left-handed circularly polarized light. The absorptivity for left-handed circularly polarized light reaches 0.995, and the device maintains a high absorption effect for left-handed circularly polarized light throughout the 2.5THz~7THz broadband range.
[0076] Figure 8 The right-handed circularly polarized light absorption spectrum of the vanadium dioxide-based actively modulated terahertz broadband chiral absorber in Example 4 is shown in Figure A. rR represents the absorption rate of the device for left-handed circularly polarized light. rr R represents the reflection of right-handed circularly polarized light by the device after the light is incident on it. lr The reflection of right-handed circularly polarized light after incident radiation is converted to left-handed circularly polarized light by the device. By changing the incident light from linearly polarized to right-handed circularly polarized, the absorptivity of the vanadium dioxide-based actively tunable terahertz broadband chiral absorber for right-handed circularly polarized light is obtained. Due to the impermeability of the bottom metal layer to terahertz waves, we only need to discuss the reflectivity of the device for circularly polarized light; some right-handed circularly polarized light is converted to left-handed circularly polarized light after reflection. The research results are all based on the case where vanadium dioxide is in the metallic phase. As can be seen from the figure, the vanadium dioxide-based actively tunable terahertz broadband chiral absorber reflects left-handed circularly polarized light, reflects right-handed circularly polarized light, and absorbs right-handed circularly polarized light, with the absorption of right-handed circularly polarized light falling within the low absorption range.
[0077] Figure 9 The figure shows the absorption spectrum of left-handed circularly polarized light as a function of temperature in Example 3, based on a vanadium dioxide-based actively tunable terahertz broadband chiral absorber. By changing the conductivity of vanadium dioxide to correspond to its optical properties at different temperatures, and setting the incident light as left-handed circularly polarized light, the absorption rate of left-handed circularly polarized light at different temperatures was obtained. As can be seen from the figure, with increasing temperature, the absorption rate of left-handed circularly polarized light by the vanadium dioxide-based actively tunable terahertz broadband chiral absorber gradually increases and reaches stable broadband absorption, achieving temperature tunability.
[0078] Figure 10 The figure shows the absorption spectrum of right-handed circularly polarized light as a function of temperature in Example 4, based on a vanadium dioxide-based actively tunable terahertz broadband chiral absorber. By changing the conductivity of vanadium dioxide to correspond to its optical properties at different temperatures, and setting the incident light as right-handed circularly polarized light, the absorption rate of right-handed circularly polarized light at different temperatures was obtained. As can be seen from the figure, with increasing temperature, the absorption of right-handed circularly polarized light by the vanadium dioxide-based actively tunable terahertz broadband chiral absorber first increases and then decreases, achieving temperature tunability.
[0079] use Figure 9 and Figure 10 The sample values at temperatures of 313K, 340K, 341K, 343K, and 353K were substituted into formula (3) for calculation to obtain the results. Figure 11 The circular dichroism can be expressed as:
[0080] (3)
[0081] In the formula, A l and A rThese represent the absorption rates of the device for left-handed circularly polarized light and the absorption rates of the device for right-handed circularly polarized light, respectively.
[0082] Figure 11 The circular dichroism (CD) spectra of the vanadium dioxide-based actively tunable terahertz broadband chiral absorbers in Examples 3 and 4 are shown. Based on the difference in absorption of left- and right-circularly polarized light by the vanadium dioxide-based actively tunable terahertz broadband chiral absorber, a CD formula is defined. As can be seen in the figure, the CD of the vanadium dioxide-based actively tunable terahertz broadband chiral absorber gradually increases with increasing temperature and then stabilizes. At 353 K and 5.9 THz, the CD reaches its highest value of 0.421. Within the broadband calculation range of 2 THz to 7 THz, the device consistently maintains CD for both left- and right-circularly polarized light, achieving chiral absorption and temperature tunability.
Claims
1. A THz broadband chiral absorber based on active regulation of vanadium dioxide, characterized in that It is from bottom to top in turn is a reflective bottom layer, intermediate medium layer and top layer; The top layer is arranged by a plurality of structural unit arrays; the structural unit is composed of a Z-shaped gold structure and four vanadium dioxide microplates; The Z-shaped gold structure is composed of an intermediate longitudinal arm, an upper horizontal arm and a lower horizontal arm, the upper end of the intermediate longitudinal arm is connected with the lower side edge of the upper horizontal arm perpendicularly, and the lower end of the intermediate longitudinal arm is connected with the upper side edge of the lower horizontal arm perpendicularly. The four vanadium dioxide microplates are symmetrically arranged on the left and right sides of the intermediate longitudinal arm and are attached to the left and right side edges of the intermediate longitudinal arm.
2. The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, characterized in that The material of the reflective bottom layer is gold; the thickness of the reflective bottom layer is greater than or equal to 2 μm. 3.The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, wherein The material of the intermediate medium layer is silicon dioxide; the thickness of the intermediate medium layer is 9 μm to 11 μm. 4.The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, wherein The width b of the intermediate longitudinal arm is 5 μm to 7 μm, and the length a is 20 μm to 25 μm.
5. The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, characterized in that The width d of the upper horizontal arm and the lower horizontal arm is 1.5 μm to 2.5 μm, and the length c is 5 μm to 7.5 μm.
6. The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, characterized in that The radius r of the vanadium dioxide microplate is 3 μm to 4.5 μm.
7. The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, characterized in that The minimum distance w between the vanadium dioxide microplates on the same side is 3 μm to 7 μm. 8.The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, wherein The minimum distance between the vanadium dioxide microplate and the adjacent upper horizontal arm or lower horizontal arm is 0 μm to 1 μm. 9.The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, wherein The thickness of the Z-shaped gold structure and the four vanadium dioxide microplates is 0.1 μm to 0.3 μm. 10.The active tunable terahertz broadband chiral absorber based on vanadium dioxide according to claim 1, wherein The period side length P of the structural unit along the x direction x and the period side length P along the y direction y are both 30 μm~32 μm.