Vanadium dioxide material-based transmission-type temperature-control band-stop-switchable terahertz modulator

Abstract

The invention discloses a transmission-type temperature-control band-stop-switchable terahertz modulator based on a vanadium dioxide material, which adopts a double-layer structural design and comprises a polyimide substrate at the bottom layer and a metal patch structure consisting of metal and vanadium dioxide at the upper layer, the surfaces of the metal patches are periodically arranged in a chessboard form to form unit cell periods; the periodic thickness of a single unit cell is 200 nm, the unit structure is a square with the side length of 120 microns, the side length of each metal patch is 10 microns, the thickness of each metal patch is 200 nm, and the thickness of the polyimide substrate is 5 microns; the method can be widely applied to various practical application scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz band metasurface functional devices, and in particular to a transmission-type temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material. Background Art

[0002] With the rapid development of terahertz technology, the terahertz band (0.1–10 THz) has gradually become a research hotspot in the fields of electronics and photonics due to its wide applications in communications, imaging, remote sensing, medical diagnosis, and security detection. In particular, how to effectively control the propagation characteristics of terahertz waves in high-frequency radar, terahertz imaging, and stealth technology has become a key factor in improving system performance.

[0003] In the design of terahertz devices, band-stop filters are an important functional device. Their main function is to isolate signals in a specific frequency band to prevent interference signals from affecting the normal operation of the system. Traditional band-stop filters mostly use a fixed frequency design and cannot dynamically adjust the frequency response according to demand, which has great limitations in many dynamic application scenarios. For example, radar systems need to effectively isolate interference signals from multi-band signals, but current band-stop filters often cannot adapt to changes in frequency bands or fluctuations in the working environment.

[0004] In order to solve the above problems, temperature-controlled or electrically-controlled adjustable band-stop filters have gradually become one of the research hotspots. By adjusting the spectral response of the device through the phase change characteristics of the material or the external control signal, the band-stop characteristics can be dynamically adjusted under different working environments, thereby achieving flexible management and precise control of the spectrum. This type of adjustable band-stop filter can not only effectively reduce signal interference, but also improve the performance and reliability of the system, especially in high-frequency and high-power applications.

[0005] At present, most common tunable band-stop filter designs rely on semiconductor materials or microwave technology, which usually require complex external control circuits and high processing precision. However, with the emergence of new functional materials, especially materials with significant phase change properties such as vanadium dioxide (VO2), filters based on phase change materials have gradually shown their unique advantages. Vanadium dioxide has phase change properties between dielectric and metallic states under temperature changes, and its conductivity changes dramatically during the phase change process, which can effectively regulate the transmission characteristics of electromagnetic waves. Therefore, the temperature-controlled band-stop filter based on vanadium dioxide can not only provide excellent band-stop performance, but also achieve dynamic frequency band selection through temperature control.

[0006] Despite this, most of the existing vanadium dioxide-based terahertz filters have the following shortcomings: first, the frequency band selectivity is not high enough to meet the needs of high-precision frequency band isolation; second, the phase change process of the material is limited by the temperature change range, and the phase change speed is slow, and it cannot respond quickly to changes in the external environment; third, most filter designs are only optimized for fixed terahertz frequency bands, and it is difficult to adapt to complex application scenarios that dynamically adjust the frequency band. Summary of the invention

[0007] Purpose of the invention: The purpose of the present invention is to provide a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material, which can achieve broadband stopband regulation by precisely controlling the phase change process of the material and provide a highly selective and fast-response filtering effect in high-frequency applications.

[0008] Technical solution: The transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material described in the present invention is composed of a double-layer structure, the bottom layer is a polyimide substrate, and the upper layer is a metal patch composed of metal and vanadium dioxide. The surface of the metal patch is periodically arranged with a checkerboard-style unit structure; the unit structure is a unit cell period.

[0009] Furthermore, the unit cell period thickness is t_metal = 200 nm, and the single unit structure is a square with a side length of P = 120 um.

[0010] Furthermore, each patch has a side length of p = 10 um and a thickness of 200 nm, and the thickness of the substrate is t_sub = 5 um.

[0011] The design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material described in the present invention comprises the following steps: (1) Designing a double-layer structure, including: a bottom layer of a polyimide substrate and an upper layer of a metal patch composed of metal and vanadium dioxide; (2) Designing the surface of the metal patch to have a unit structure that is periodically arranged in a checkerboard pattern, where the unit structure is one unit cell period; (3) The unit cell period is designed to have a thickness of t_metal = 200 nm and a single unit structure of a square with a side length of P = 120 um; (4) The side length of each patch is p = 10 um, the thickness is 200 nm, and the thickness of the substrate is t_sub = 5 um; (5) By regulating the phase change of vanadium dioxide through temperature, the transmission and blocking properties of electromagnetic waves can be flexibly adjusted.

[0012] Furthermore, in step (5), a change in the actual ambient temperature of 20°C to 87°C corresponds to a change in the conductivity of vanadium dioxide of 200 S / m to 200,000 S / m.

[0013] Furthermore, when vanadium dioxide is in a low-temperature dielectric state, the covered frequency range is 0.1 THz to 2.5 THz.

[0014] Furthermore, when vanadium dioxide enters the high-temperature metallic state, its 3dB bandwidth range covers 0.367-2.043THz, with a total bandwidth of 1.676 THz. The center frequency of the stopband is located at 1.205 THz, with a relative center frequency of 139.1%, and the steepness of the upper and lower edges of the stopband reaches 67 dB / THz and 38 dB / THz, respectively.

[0015] Furthermore, the relative dielectric constant of the polyimide dielectric layer is set to ε PI = 3.5 + 0.0027i, vanadium dioxide is calculated using the Drude model, the high-frequency dielectric constant is set to 12, and the collision frequency in the Drude model is set to rad / s, the plasma frequency is calculated as follows: ; in, Indicates that vanadium dioxide has a certain conductivity The plasma frequency under Indicates the conductivity in the current state; is the normalized reference conductivity.

[0016] The application method of the transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material described in the present invention is applied to a radome. The transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material is combined with the structure of the radome and integrated into the surface or internal structure of the radome through the flexibility and processability of the material, namely the dynamic regulation of vanadium dioxide. The broadband stopband performance allows the radome to form a shielding effect within the range of interference signals outside the operating frequency band, while maintaining low-loss transmission characteristics for the out-of-band operating frequency band.

[0017] An electronic device described in the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, the design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material described in any one of the items is implemented.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: by changing the ambient temperature and utilizing the reversible phase change characteristics of vanadium dioxide, the device exhibits a high-efficiency transmission characteristic of 0.1-2.5 THz in the low-temperature dielectric state, and exhibits an ultra-wideband stopband characteristic of 0.367-2.043 THz in the high-temperature metallic state, thereby realizing flexible conversion of broadband functions. This characteristic not only enriches the means of terahertz regulation, but also provides more possibilities for the research and application of the THz metasurface field; the transmission-type temperature control design is simple and efficient, and the device is actively controlled through the phase change characteristics of vanadium dioxide, further improving flexibility, and can be widely used in a variety of practical application scenarios; the device exhibits a passband characteristic of 0.1-2.5 THz when vanadium dioxide is in the low-temperature dielectric state; when vanadium dioxide is in the high-temperature metallic state, it exhibits an ultra-wideband stopband characteristic of 0.367-2.043 THz; under low-temperature conditions, the actively regulated device exhibits high-efficiency transmission characteristics, and under high-temperature conditions, it exhibits broadband high-efficiency band-stop filtering characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention and a partially enlarged schematic diagram of a unit; Figure 2 It is a schematic diagram of the unit structure size marking of the present invention; Figure 3 The terahertz metasurface structure of the present invention realizes the effect of high-efficiency ultra-wideband band-stop filtering and transmission function switching: when vanadium dioxide is in a high-temperature metallic state (conductivity is 200000S / m), its filtering characteristics are as follows: Figure 3 As shown in (a), it exhibits a significant high-efficiency band-stop filtering effect and is polarization-independent (it exhibits the same spectral response for both TE and TM linearly polarized incidents). When vanadium dioxide is in a low-temperature dielectric state (conductivity is 200S / m), the transmittance is as follows: Figure 3 (b) Figure 4 It is a trend diagram of the transmittance variation of the terahertz metasurface structure of the present invention with temperature, wherein the conductivity ranges from 200 S / m to 200000 S / m; Figure 5 The terahertz metasurface structure of the present invention realizes the effect of high-efficiency ultra-wideband band-stop filtering and transmission function switching (in dB form): when vanadium dioxide is in a high-temperature metallic state, the obtained broadband stop band has a 3dB bandwidth of 0.367-2.043THz, a bandwidth of 1.676THz, a center frequency of 1.205THz, and a relative center frequency of 139.1%; Figure 6 It is a schematic diagram of the application of the flexible switchable band-stop filter of the present invention and the radome. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0021] Example 1 Switchable band-stop terahertz filter device A transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material, consisting of a double-layer structure, the bottom layer is a polyimide substrate, the upper layer is a metal patch composed of metal and vanadium dioxide, and the surface of the metal patch is periodically arranged with a checkerboard-style unit structure; the unit structure is a unit cell period. The unit cell period thickness is t_metal = 200 nm, and the single unit structure is a square with a side length of P = 120 um. Each patch has a side length of p = 10 um and a thickness of 200 nm, and the thickness of the substrate is t_sub = 5 um The embodiment of the present invention utilizes the metal double-layer metasurface structure design and phase change characteristics based on vanadium dioxide material to propose a transmissive, temperature-controllable broadband filtering terahertz modulation device. The device can realize multiple functions under different temperature conditions: at room temperature (that is, when vanadium dioxide is in a dielectric state), it exhibits efficient transmission performance for linearly polarized incident terahertz waves; when the temperature rises and exceeds the critical temperature of phase change (that is, when vanadium dioxide enters a metallic state), the metasurface structure exhibits broadband filtering characteristics, thereby realizing functional conversion under temperature control.

[0022] In an embodiment of the present invention, electromagnetic full-wave simulation software is used to simulate the electromagnetic response characteristics of the switchable band-stop terahertz filter metasurface structure. In the simulation, the boundary conditions in the x and y directions are set to periodic, while the boundary conditions in the z direction are open (open, add space). A linearly polarized electromagnetic wave is injected through the Waveguide Port port to propagate along the z-axis direction and vertically incident on the top structure of the metasurface from the +z direction. The simulation frequency range is 0.1-2.5 THz, and the time domain TLM mode is used for simulation. At the same time, the structure exhibits polarization-independent characteristics, that is, for terahertz incident waves of different linear polarizations, its electromagnetic response characteristics remain consistent.

[0023] Example 2 Calculation of performance of flexible switchable band-stop filter metasurface Combine the following Figure 2-5 , calculation formula The scheme in Example 1 is further introduced, as described below: 1. The transmissive temperature-controlled switchable band-stop terahertz filter terahertz modulation device proposed in the embodiment of the present invention has a unit structure with a periodic size of 120 μm × 120 μm, adopts a double-layer metasurface structure design mode, and is composed of the following parts: Bottom dielectric layer: Made of 5 μm thick polyimide material, it provides excellent dielectric properties and ensures the structural stability and transmission characteristics of the metasurface.

[0024] Top structure layer: composed of metal aluminum and vanadium dioxide, with a thickness of 200 nm. The top structure is designed to have a checkerboard structure, which can achieve flexible regulation of the terahertz band through periodic arrangement.

[0025] 2. When simulation software is used for simulation analysis in the embodiment of the present invention, the relative dielectric constant of the polyimide dielectric layer is set to ε PI = 3.5 + 0.0027i, vanadium dioxide is calculated using the Drude model, the high-frequency dielectric constant is set to 12, and the collision frequency in the Drude model is set to rad / s, the plasma frequency is calculated as follows: ; in, Indicates that vanadium dioxide has a certain conductivity The plasma frequency under Indicates the conductivity in the current state; is the normalized reference conductivity.

[0026] In the simulation, the conductivity of vanadium dioxide is changed to simulate the actual phase change process of vanadium dioxide material with temperature change in actual application. The actual ambient temperature change of 20 ℃ to 87 ℃ corresponds to the conductivity change of vanadium dioxide of 200 S / m to 200000 S / m.

[0027] When vanadium dioxide is in a low-temperature dielectric state, it exhibits a high transmittance region covering a frequency range of 0.1 THz to 2.5 THz, showing excellent transmission performance.

[0028] When vanadium dioxide enters the high-temperature metallic state, a broadband stopband with excellent performance is formed. Its 3dB bandwidth covers 0.367-2.043 THz, and the total bandwidth reaches 1.676 THz, showing extremely wide frequency coverage. The center frequency of the stopband is located at 1.205 THz, and the relative center frequency is 139.1%, reflecting that the stopband has a high spectrum utilization rate. In addition, the edge characteristics of the stopband are particularly outstanding, and the steepness of the upper and lower edges reaches 67 dB / THz and 38 dB / THz respectively.

[0029] The stopband characteristics of the embodiment of the present invention are closely related to the phase change behavior of vanadium dioxide, and can be used as a manifestation of the transmittance "switch" mechanism: by regulating the phase change of vanadium dioxide through temperature, the transmission and blocking performance of electromagnetic waves can be flexibly adjusted. This phase change "switch" not only enhances the ability of the material in electromagnetic wave regulation, but also demonstrates its potential for wide application in dynamic spectrum management and THz devices. The high steepness of the embodiment of the present invention not only ensures the effective isolation of the stopband from the non-working frequency band, but also improves the accuracy of the frequency band selectivity, making it have important application potential in THz device design.

[0030] Example 3 Application of flexible switchable band-stop filter radar cover Combine the following Figure 6 The scheme in Example 2 is further introduced, as described below: When vanadium dioxide enters the metallic state at high temperature, its phase change characteristics not only make the band-stop filter exhibit excellent broadband characteristics, but also show significant performance improvement in radome applications. Traditional radome design needs to avoid external signal interference and mutual interference between multiple frequency bands while achieving electromagnetic wave transmission. The flexible switchable band-stop filter in the present invention achieves precise blocking of specific frequency bands through dynamic regulation of vanadium dioxide, while maintaining good transmittance in other frequency bands.

[0031] Specifically, in the application scenario of the radome, the filter can be combined with the structure of the radome and integrated into the surface or internal structure of the radome through the flexibility and processability of the material. Its broadband stopband performance allows the radome to form a shielding effect within the range of interference signals outside the working frequency band, while maintaining low-loss transmission characteristics for the out-of-band working frequency band. This differentiated processing not only improves the signal reception quality of the radar system, but also effectively reduces the impact of stray signals on the system.

[0032] In addition, the flexible properties of the present invention make it suitable for radomes of different shapes and materials, such as radomes with curved surfaces or complex geometric structures. By introducing a "switch" mechanism, it realizes dynamic adjustment, and can adjust the stopband characteristics in real time according to different environments and mission requirements, thereby meeting the adaptability of multiple tasks and multiple scenarios. Compared with traditional static designs, the flexible band-stop filter of the present invention can flexibly switch states through thermal control means, thereby achieving a balance between the stealth and anti-interference performance of the radome. In this process, the phase change "switch" effect of the vanadium dioxide material provides an efficient adjustment means, enabling the radome to automatically optimize its electromagnetic performance according to actual needs.

[0033] The application of the present invention in the field of radomes not only provides a solution for suppressing interference signals in a wide frequency range, but also provides a new idea for the design of high-performance and intelligent radomes in the future.

[0034] The above-mentioned flexible switchable band-stop filter metasurface has a simple structural design, a reasonable structural size design, and low precision requirements for processing equipment, and can be processed using existing micro-nano processing technology.

Claims

1. A transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material, characterized in that: It consists of a double-layer structure, with the bottom layer being a polyimide substrate and the upper layer being a metal patch composed of metal and vanadium dioxide. The surface of the metal patch is periodically arranged with a checkerboard-style unit structure; the unit structure is a unit cell period.

2. The transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 1, characterized in that: The unit cell period thickness is t_metal=200 nm, and the single unit structure is a square with a side length of P=120 um.

3. The transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 1, characterized in that: Each patch has a side length of p = 10 um and a thickness of 200 nm, and the thickness of the substrate is t_sub = 5 um.

4. A design method for a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material, characterized in that: The following steps are involved: (1) Designing a double-layer structure, including: a bottom layer of a polyimide substrate and an upper layer of a metal patch composed of metal and vanadium dioxide; (2) Designing the surface of the metal patch to have a unit structure that is periodically arranged in a checkerboard pattern, where the unit structure is one unit cell period; (3) The unit cell period is designed to have a thickness of t_metal = 200 nm and a single unit structure of a square with a side length of P = 120 um; (4) The side length of each patch is p = 10 um, the thickness is 200 nm, and the thickness of the substrate is t_sub = 5 um; (5) By regulating the phase change of vanadium dioxide through temperature, the transmission and blocking properties of electromagnetic waves can be flexibly adjusted.

5. The design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 4, characterized in that: In step (5), the actual ambient temperature changes from 20°C to 87°C, which corresponds to a change in the conductivity of vanadium dioxide of 200 S / m to 200,000 S / m.

6. The design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 5, characterized in that: When vanadium dioxide is in a low-temperature dielectric state, the covered frequency range is 0.1 THz to 2.5 THz.

7. The design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 5, characterized in that: When vanadium dioxide enters the high-temperature metallic state, its 3dB bandwidth range covers 0.367-2.043 THz, with a total bandwidth of 1.676 THz. The center frequency of the stopband is located at 1.205 THz, with a relative center frequency of 139.1%. The steepness of the upper and lower edges of the stopband reaches 67 dB / THz and 38 dB / THz, respectively.

8. The design method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to claim 4, characterized in that: The relative dielectric constant of the polyimide dielectric layer is set to ε PI = 3.5 + 0.0027i, vanadium dioxide is calculated using the Drude model, the high-frequency dielectric constant is set to 12, and the collision frequency in the Drude model is set to rad / s, the plasma frequency is calculated as follows: ； in, Indicates that vanadium dioxide has a certain conductivity The plasma frequency under Indicates the conductivity in the current state; is the normalized reference conductivity.

9. An application method of a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material, characterized in that: Applied to radomes, the transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material is combined with the structure of the radome and integrated into the surface or internal structure of the radome through the flexibility and processability of the material, namely the dynamic regulation of vanadium dioxide. The broadband stopband performance allows the radome to form a shielding effect within the range of interference signals outside the operating frequency band, while maintaining low-loss transmission characteristics for the out-of-band operating frequency band.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into a processor, the method for designing a transmissive temperature-controlled switchable band-stop terahertz modulator based on vanadium dioxide material according to any one of claims 4 to 7 is implemented.

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