A terahertz tunable multifunctional device based on vanadium dioxide

Abstract

A terahertz tunable multifunctional device based on vanadium dioxide, which relates to a terahertz tunable multifunctional device. The terahertz tunable multifunctional device based on vanadium dioxide of the present invention is composed of four layers, which are, in order from the bottom layer to the top layer, a dielectric substrate layer, a vanadium dioxide layer, a dielectric layer, and a metal aluminum and vanadium dioxide hybrid resonant layer; the metal aluminum and vanadium dioxide hybrid resonant layer is composed of 4 N-type metals, metal strips, and 4 vanadium dioxide bands. Two N-type metals are respectively arranged on both sides of the metal strip, and the openings of the two N-type metals on the same side of the metal strip are opposite to each other. The vanadium dioxide bands are arranged at the openings of each N-type metal. The present invention provides a terahertz tunable multifunctional device based on vanadium dioxide. By adjusting the conductivity of vanadium dioxide through temperature, it is possible to achieve free switching between the two functions of broadband absorption and broadband electromagnetic induced transparency, as well as dynamic adjustment of absorption and transmission efficiency.

Description

Technical Field

[0001] The present invention relates to a terahertz tunable multifunctional device. Background Art

[0002] Terahertz (THz) waves refer to electromagnetic waves between microwaves and infrared light in the frequency range of 0.1 - 10 THz. Due to their unique optical properties, they have broad application prospects in fields such as broadband communication, biological imaging, and security detection. Metamaterials are artificial dielectric materials that can generate electromagnetic properties not possessed by many natural materials. In recent years, they have attracted much research interest and many novel electromagnetic phenomena have been obtained, such as perfect lenses, invisibility cloaks, and perfect absorbers. For terahertz metamaterial devices, researchers at home and abroad have designed many models, and simulations have verified the designs of functions such as electromagnetic induced transparency, absorbers, and phase modulation. However, most current metamaterial devices have relatively single functions, and their functions are difficult to tune according to requirements, which will limit their application scope. Therefore, the design of multifunctional tunable terahertz metamaterial devices has become a new research hotspot.

[0003] Currently, with the emergence of tunable materials such as vanadium dioxide (VO2) and graphene, new ideas have been provided for the design of tunable terahertz multifunctional devices. Among them, vanadium dioxide (VO2) is a typical reversible phase change material. It is in an insulating state at room temperature and changes to a metallic state when the temperature reaches 68°C. The phase change causes a change in the conductivity of VO2 by nearly four orders of magnitude, and VO2 can change back from the metallic state to the insulating state when the temperature drops. This phase change material can not only undergo phase change through thermal excitation, but also through various manipulation methods such as electrical excitation and optical pumping, which makes VO2 an ideal material for the design of tunable metamaterials. However, most previous studies have focused on single functions, and it is difficult to change their performance once the samples are fabricated. Therefore, it is necessary to further study multifunctional tunable metamaterial devices. Summary of the Invention

[0004] The present invention provides a terahertz tunable multifunctional device based on vanadium dioxide. By adjusting the conductivity of vanadium dioxide through temperature, it is possible to achieve free switching between two functions of broadband absorption and broadband electromagnetic induced transparency, as well as dynamic adjustment of absorption and transmission efficiencies.

[0005] The terahertz tunable multifunctional device based on vanadium dioxide of the present invention consists of a four-layer structure, which are, from the bottom layer to the top layer in sequence, a dielectric substrate layer, a vanadium dioxide layer, a dielectric layer, and a metal aluminum and vanadium dioxide hybrid resonance layer; the metal aluminum and vanadium dioxide hybrid resonance layer is composed of 4 N-type metals, metal strips and 4 vanadium dioxide bands. Two N-type metals are arranged on both sides of the metal strip, the openings of the two N-type metals on the same side of the metal strip are opposite to each other, and the vanadium dioxide bands are arranged at the openings of each N-type metal.

[0006] The principle and beneficial effects of the present invention are as follows:

[0007] In the present invention, the conductivity of vanadium dioxide can be changed between 10 and 200,000 S / m by various means such as light, temperature, and voltage. When the conductivity of vanadium dioxide is 10 S / m, vanadium dioxide is in an insulating phase, and vanadium dioxide, the dielectric substrate layer and the dielectric layer together constitute the substrate; the hybrid structure composed of the metal strip and 4 N-type metals in the metal aluminum and vanadium dioxide hybrid resonance layer serves as a resonance unit, where the metal strip serves as the bright mode and the 4 N-type metals serve as the dark mode. When an incident electromagnetic wave with linear polarization and polarization direction in the y direction perpendicularly irradiates the surface of the device, electromagnetic induced transparency (EIT) phenomenon will be generated by the coupling of bright and dark modes. When the conductivity of vanadium dioxide is 200,000 S / m, vanadium dioxide shows a metallic phase; since the thickness of the vanadium dioxide layer is greater than its maximum skin depth at terahertz frequencies, the transmittance of the device is almost 0 at this time. The top metal aluminum and vanadium dioxide hybrid resonance layer, the third layer dielectric layer and the second layer metallic phase vanadium dioxide layer together constitute an absorber structure. When an incident electromagnetic wave with linear polarization and polarization direction in the y direction perpendicularly irradiates the surface of the device, wave absorption function will be generated within a relatively wide frequency range. Therefore, by adjusting the conductivity of VO2, the switching between electromagnetic induced transparency and absorption functions can be carried out within a relatively wide frequency range, realizing the tunable characteristics of the device, and the function switching between broadband absorption and broadband electromagnetic induced transparency can be achieved through the regulation of the active tuning material; when the conductivity of VO2 is 10 S / m, the device generates an electromagnetic induced transparency peak in the range of 1.03 - 1.37 THz, and the transmittance is above 90%. When the conductivity of VO2 is 200,000 S / m, the device generates an absorption peak in the range of 0.9 - 1.8 THz, and the absorption rate is above 90%.

[0008] The present invention utilizes the phase change characteristics of vanadium dioxide to design a multi-layer nested structure with absorption and electromagnetic induction functions, and realizes good broadband absorption and electromagnetic induced transparency characteristics through methods such as reconstructing the top resonance unit with vanadium dioxide bands and adding the first layer dielectric substrate layer to increase the substrate thickness, providing a new idea for the design of multifunctional devices. Description of the Drawings

[0009] Figure 1It is a schematic structural diagram of the vanadium dioxide-based terahertz tunable multifunctional device in Embodiment 1;

[0010] Figure 2 It is a schematic structural diagram of the metal aluminum and vanadium dioxide hybrid resonant layer of the vanadium dioxide-based terahertz tunable multifunctional device in Embodiment 1;

[0011] Figure 3 It is the absorption curve when the device in Embodiment 1 is used as an absorber;

[0012] Figure 4 It is the transmission curve when the device in Embodiment 1 is used as an electromagnetically induced transparency device;

[0013] Figure 5 It is the electric field distribution diagram at different resonant frequencies in the broadband absorption mode;

[0014] Figure 6 It is the coupling mechanism diagram in the broadband electromagnetically induced transparency mode;

[0015] Figure 7 It is the change curve of the absorption rate when the conductivity of vanadium dioxide changes from 200000 S / m to 7000 S / m;

[0016] Figure 8 It is the change curve of the transmittance when the conductivity of vanadium dioxide changes from 10 S / m to 200000 S / m. Detailed implementation manners

[0017] The technical solution of the present invention is not limited to the following listed specific implementation manners, and also includes any reasonable combination between the specific implementation manners.

[0018] Detailed implementation manner one: The vanadium dioxide-based terahertz tunable multifunctional device in this implementation manner is composed of four layers, which are, from bottom to top, a dielectric substrate layer 1, a vanadium dioxide layer 2, a dielectric layer 3, and a metal aluminum and vanadium dioxide hybrid resonant layer; the metal aluminum and vanadium dioxide hybrid resonant layer is composed of 4 N-type metals 4, a metal strip 5, and 4 vanadium dioxide bands 6. Two N-type metals 4 are respectively arranged on both sides of the metal strip 5. The openings of the two N-type metals 4 on the same side of the metal strip 5 are opposite to each other. The vanadium dioxide band 6 is arranged at the opening of each N-type metal 4, and both ends of the vanadium dioxide band 6 are connected to the N-type metal 4.

[0019] This implementation manner has the following beneficial effects:

[0020] In this embodiment, the conductivity of vanadium dioxide can be changed between 10 and 200,000 S / m in various ways such as light, temperature, and voltage. When the conductivity of vanadium dioxide is 10 S / m, vanadium dioxide is in an insulating phase, and vanadium dioxide, dielectric substrate layer 1, and dielectric layer 3 together form a substrate; the hybrid structure composed of metal aluminum and metal strip 5 and four N-type metals 4 in the vanadium dioxide hybrid resonator layer serves as a resonant unit, where metal strip 5 serves as the bright mode and the four N-type metals 4 serve as the dark mode. When an incident electromagnetic wave with linear polarization and polarization direction in the y direction is perpendicularly incident on the surface of the device, electromagnetic induced transparency (EIT) phenomenon will be generated by the coupling of bright and dark modes. When the conductivity of vanadium dioxide is 200,000 S / m, vanadium dioxide exhibits a metallic phase; since the thickness of vanadium dioxide layer 2 is greater than its maximum skin depth at terahertz frequencies, the transmittance of the device is almost 0 at this time. The top-layer metal aluminum, vanadium dioxide hybrid resonator layer, third-layer dielectric layer 3, and second-layer metallic-phase vanadium dioxide layer 2 together form an absorber structure. When an incident electromagnetic wave with linear polarization and polarization direction in the y direction is perpendicularly incident on the surface of the device, an absorbing function will be generated within a relatively wide frequency range. Therefore, by adjusting the conductivity of VO2, the switching between electromagnetic induced transparency and absorption functions can be achieved within a relatively wide frequency range, realizing the tunable characteristics of the device, and the functional switching between broadband absorption and broadband electromagnetic induced transparency can be achieved by regulating the active tuning material; when the conductivity of VO2 is 10 S / m, the device generates an electromagnetic induced transparency peak in the range of 1.03 - 1.37 THz, and the transmittance is above 90%. When the conductivity of VO2 is 200,000 S / m, the device generates an absorption peak in the range of 0.9 - 1.8 THz, and the absorption rate is above 90%.

[0021] In this embodiment, the phase change characteristics of vanadium dioxide are utilized to design a multi-layer nested structure with absorption and electromagnetic induction functions, and good broadband absorption and electromagnetic induced transparency characteristics are achieved by reconstructing the top-layer resonant unit with vanadium dioxide bands and increasing the substrate thickness by adding the first-layer dielectric substrate layer, etc., providing a new idea for the design of multifunctional devices.

[0022] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the material of metal strip 5 is pure aluminum.

[0023] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the material of N-type metal 4 is pure aluminum.

[0024] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that the materials of dielectric substrate layer 1 and dielectric layer 3 are polydimethylsiloxane.

[0025] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that the thickness of the dielectric substrate layer 1 is 13 - 15 μm.

[0026] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that the thickness of the vanadium dioxide layer 2 is 0.19 - 0.21 μm.

[0027] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that the thickness of the dielectric layer 3 is 26 - 28 μm.

[0028] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that the widths of the N-type metal 4 and the metal strip 5 are both 4.9 - 5.1 μm.

[0029] Specific Embodiment 9: The difference between this embodiment and any one of Specific Embodiments 1 to 8 is that the thicknesses of the N-type metal 4, the metal strip 5, and the four vanadium dioxide strips 6 are all 0.19 - 0.21 μm.

[0030] Example 1

[0031] Combined with Figures 1 to 8 to illustrate this example, Figure 1 is a schematic structural diagram of a terahertz tunable multifunctional device based on vanadium dioxide in Example 1; Figure 2 is a top view of the structural diagram of the metal aluminum and vanadium dioxide hybrid resonance layer of the terahertz tunable multifunctional device based on vanadium dioxide in Example 1;

[0032] The terahertz tunable multifunctional device based on vanadium dioxide in this example consists of four layers of structures, which are, from bottom to top, a dielectric substrate layer 1, a vanadium dioxide layer 2, a dielectric layer 3, and a metal aluminum and vanadium dioxide hybrid resonance layer; the metal aluminum and vanadium dioxide hybrid resonance layer consists of four N-type metals 4, a metal strip 5, and four vanadium dioxide strips 6. Two N-type metals 4 are respectively arranged on both sides of the metal strip 5. The openings of the two N-type metals 4 on the same side of the metal strip 5 face each other, and the vanadium dioxide strip 6 is arranged at the opening of each N-type metal 4;

[0033] The material of the metal strip 5 is pure aluminum;

[0034] The material of the N-type metal 4 is pure aluminum;

[0035] The materials of the dielectric substrate layer 1 and the dielectric layer 3 are polydimethylsiloxane PDMS;

[0036] The thickness of the dielectric substrate layer 1 is 14 μm;

[0037] The thickness of the vanadium dioxide layer 2 is 0.2 μm;

[0038] The thickness of the dielectric layer 3 is 27 μm;

[0039] The widths of the N-type metal 4 and the metal strip 5 are both 5 μm;

[0040] The thicknesses of the N-type metal 4, the metal strip 5, and the four vanadium dioxide bands 6 are all 0.2 μm;

[0041] The length of the metal strip 5 is 83 μm, the length of the horizontal arm of the N-type metal 4 is 38 μm, and the length of the vertical arm is 32 μm;

[0042] Figure 3 is the absorption curve when the device of Example 1 is used as an absorber; from Figure 2 it can be obtained that the absorber generates a broadband absorption peak in the frequency band of 0.9 THz - 1.8 THz, and the absorption efficiency is above 90%. Figure 4 is the transmission curve when the device of Example 1 is used as an electromagnetically induced transparency device; from Figure 3 it can be obtained that the device shows a transparency peak in the frequency band of 1.03 - 1.37 THz, and the transmittance is above 90%. Figure 5 is the electric field distribution diagram at different resonant frequencies in the broadband absorption mode. Among them, (a) and (b) are the electric field distributions at 1 THz and 1.4 THz respectively. The electric field is mainly distributed on the metal strip and the vertical arm of the square ring structure close to the metal strip, and its resonance is generated by the mutual excitation of the two structures; while (c) and (d) are the electric field distributions at 1.67 THz and 1.8 THz respectively. Positive and negative charges are distributed on the upper and lower horizontal arms of the square ring structure, generating an electric dipole resonance. Therefore, the broadband absorption of the absorber is generated by the resonance at multiple frequency points. Figure 6 is the coupling mechanism diagram in the broadband electromagnetically induced transparency mode. Respectively, for the resonator b with an independent metal strip 5, the resonator c with a mouth-shaped structure composed of an N-type metal 4 and vanadium dioxide bands 6, and the resonator a in Example 1 composed of 4 N-type metals 4, metal strips 5, and 4 vanadium dioxide bands 6, the transmission curves of these three are simulated. From the results, it can be known that: the resonator b with an independent metal strip 5 generates an obvious plasma resonance at 1.27 THz and operates in the bright mode; the resonator c with a mouth-shaped structure composed of an N-type metal 4 and vanadium dioxide bands 6 does not generate resonance and operates in the dark mode; while after combining the two, the metal wire structure of the resonator a composed of 4 N-type metals 4, metal strips 5, and 4 vanadium dioxide bands 6 will be excited by the incident field, directly generating the corresponding plasma resonance, and generating a near-field coupling with the mouth-shaped structure, thereby exciting the resonance of the mouth-shaped structure, and finally resulting in the cancellation interference between the bright mode and the dark mode to generate a transparent window of 1.03 - 1.37 THz. Figure 7It is the curve of the change in the absorption rate when the conductivity of vanadium dioxide changes from 200000 S / m to 7000 S / m. For the device of Example 1, the absorption rate in the range of 0.9 THz - 1.8 THz can be adjusted from above 90% to below 30%. Figure 8 It is the curve of the change in the transmittance when the conductivity of vanadium dioxide changes from 10 S / m to 200000 S / m. For the device of Example 1, the transmittance in the range of 1.03 - 1.37 THz can be adjusted from above 90% to below 10%.

Claims

1. A terahertz tunable multifunctional device based on vanadium dioxide, characterized in that: The vanadium dioxide-based terahertz tunable multifunctional device consists of a four-layer structure, which from the bottom layer to the top layer are a dielectric substrate layer (1), a vanadium dioxide layer (2), a dielectric layer (3), and a metal aluminum and vanadium dioxide hybrid resonance layer; the metal aluminum and vanadium dioxide hybrid resonance layer is composed of 4 n-shaped metals (4), a metal strip (5), and 4 vanadium dioxide strips (6). Two n-shaped metals (4) are respectively arranged on both sides of the metal strip (5), the openings of the two n-shaped metals (4) on the same side of the metal strip (5) face each other, and the vanadium dioxide strip (6) is arranged at the opening of each n-shaped metal (4).

2. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, wherein: The material of the metal strip (5) is pure aluminum.

3. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, wherein: The material of the n-shaped metal (4) is pure aluminum.

4. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, wherein: The materials of the dielectric substrate layer (1) and the dielectric layer (3) are polydimethylsiloxane.

5. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, wherein: The thickness of the dielectric substrate layer (1) is 13 - 15 μm.

6. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, characterized in that: The thickness of the vanadium dioxide layer (2) is 0.19 - 0.21 μm.

7. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, characterized in that: The thickness of the dielectric layer (3) is 26 - 28 μm.

8. The terahertz tunable multifunctional device based on vanadium dioxide according to claim 1, characterized in that: The widths of the n-shaped metal (4) and the metal strip (5) are both 4.9 - 5.1 μm.

9. The vanadium dioxide-based terahertz tunable multifunctional device according to claim 1, characterized in that: The thicknesses of the n-shaped metal (4), the metal strip (5), and the 4 vanadium dioxide strips (6) are all 0.19 - 0.21 μm.

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