3-8 decoder based on graphene and vanadium dioxide metamaterial

Abstract

The invention discloses a 3-8 decoder based on graphene and a vanadium dioxide metamaterial, and belongs to the technical field of terahertz communication modulation. The structure is composed of a gold substrate, a silicon dioxide dielectric layer, a graphene pattern layer on the top and inlaid vanadium dioxide. Based on the principle of a metamaterial absorber, the incident polarization angle of terahertz waves is changed and different bias voltages are given to graphene on the inner side through conversion between a vanadium dioxide metal state and an insulating state, and the 3-8 decoding function in the terahertz wave band is achieved. The work provides a new thought for decoding amount expansion of terahertz information and dynamic change of a device structure.

Description

Technical Field

[0001] The present invention relates to the field of terahertz modulation technology, and in particular to a terahertz metasurface device with a 3-8 decoding function and an operation scheme. Background Art

[0002] Terahertz decoders are important devices in the field of communication modulation. For the selection of terahertz frequency, the relatively new and efficient method is to make 2-bit encoders and 3-bit encoders based on the principles of graphene plasma induced transparency and graphene dual plasma induced transparency for frequency selection. In addition, researchers have developed a 2-4 decoder in the terahertz frequency band based on the principle of metamaterial absorbers, which can efficiently convert information. The above technologies have important research significance for the development of 6G wireless communication technology.

[0003] With the development of communication technology, the amount of information that chips need to process will also increase. For the 2-4 decoders that have been developed in the terahertz frequency band, the amount of information decoded is limited, and the decoding frequency range is limited. Therefore, it is particularly important to develop a decoder with a larger decoding amount and a wider decoding frequency range.

[0004] In order to overcome the above-mentioned deficiencies of the prior art, it is particularly important to develop a 3-8 decoder in the terahertz frequency band. Summary of the invention

[0005] In order to solve the above problems, the present invention discloses a 3-8 decoder based on graphene and vanadium dioxide metamaterials.

[0006] The present invention is achieved through the following technical solutions:

[0007] A 3-8 decoder based on graphene and vanadium dioxide metamaterials comprises a gold substrate 1, a silicon dioxide dielectric layer 2, a graphene layer 3 and a vanadium dioxide cuboid 4; the dielectric layer 2 is located on the upper surface of the substrate layer 1, the graphene layer 3 and the vanadium dioxide cuboid 4 are both located on the upper surface of the dielectric layer 2, the vanadium dioxide cuboid 4 is embedded between an inner layer 3 and an outer layer 3, and the inner layer 3 and the outer layer 3 are not directly connected.

[0008] In the above scheme, the overall structure of the substrate layer 1 and the dielectric layer 2 are both square when viewed from a normal top view; the top layers 3 and 4 are composed of graphene and vanadium dioxide, and the inner graphene pattern is composed of two rectangles of different sizes superimposed in the diagonal direction, followed by inlaying vanadium dioxide rectangles along the diagonal (the length is consistent with the width of the adjacent inner graphene pattern), followed by laying rectangular graphene along the diagonal (the length is consistent with the length of the adjacent vanadium dioxide rectangle), and finally laying semicircular graphene (the diameter is consistent with the length of the adjacent rectangular graphene pattern); the top layer is symmetrical about the diagonals of the two axes in the xoy plane.

[0009] In the above scheme, the thickness of the substrate 1 is 1 μm; the thickness of the dielectric layer 2 is 4 μm; the thickness of the graphene is 1 nm; and the thickness of the vanadium dioxide cuboid 4 is 0.26 μm.

[0010] In the above scheme, the inner graphene layer is conductive by coating the ion gel connected to the electrode, and the vanadium dioxide is converted between the insulating state and the metallic state. The device can be used as a 3-8 decoder.

[0011] The above-mentioned 3-8 decoder based on graphene and vanadium dioxide metamaterial can realize 3-8 decoding function; it is characterized by:

[0012] By changing the two states of vanadium dioxide, changing the two polarization angles of the incident terahertz wave, and applying two different gate voltages to the inner graphene layer, 8 input modes are formed, and then separate resonant absorption peaks can be generated at 8 sequentially selected frequency points, achieving 3-8 decoding of actively selecting terahertz frequency; the characteristics are:

[0013] When the decoding input of this structure is the "000" state, the decoding output is the "10000000" state, with high absorption rate at the selected frequency point 1 and low absorption rate at the selected frequency points 2, 3, 4, 5, 6, 7, and 8;

[0014] When the decoding input of this structure is in the "001" state, the decoding output is in the "01000000" state, with high absorption rate at the selected frequency point 2 and low absorption rate at the selected frequency points 1, 3, 4, 5, 6, 7, and 8;

[0015] When the decoding input of this structure is the "010" state, the decoding output is the "00100000" state, with high absorption rate at the selected frequency point 3 and low absorption rate at the selected frequency points 1, 2, 4, 5, 6, 7, and 8;

[0016] When the decoding input of this structure is in the "011" state, the decoding output is in the "00010000" state, with high absorption rate at the selected frequency point 4 and low absorption rate at the selected frequency points 1, 2, 3, 5, 6, 7, and 8;

[0017] When the decoding input of this structure is the "100" state, the decoding output is the "00001000" state, with high absorption rate at the selected frequency point 5 and low absorption rate at the selected frequency points 1, 2, 3, 4, 6, 7, and 8;

[0018] When the decoding input of this structure is the "101" state, the decoding output is the "00000100" state, with high absorption rate at the selected frequency point 6 and low absorption rate at the selected frequency points 1, 2, 3, 4, 5, 7, and 8;

[0019] When the decoding input of this structure is the "110" state, the decoding output is the "00000010" state, with high absorption rate at the selected frequency point 7 and low absorption rate at the selected frequency points 1, 2, 3, 4, 5, 6, and 8;

[0020] When the decoding input of the structure is in the "111" state, the decoding output is in the "00000001" state, with high absorption rate at the selected frequency point 8 and low absorption rate at the selected frequency points 1, 2, 3, 4, 5, 6, and 7;

[0021] That is, as described above, the present invention obtains a 3-8 decoder in the terahertz band by changing the three input quantities of the metasurface structure. In addition, the present invention uses vanadium dioxide as a conductor and an insulator to indirectly connect the inner and outer graphene (when connected, the inner and outer graphene are both applied with a bias voltage) or separate (when separated, the outer graphene cannot be applied with a bias voltage), thereby achieving the effect of dynamically changing the device structure. The present invention has the characteristics of novel structure, flexible tunability, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the unit structure of a 3-8 decoder based on graphene and vanadium dioxide metamaterials.

[0023] Figure 2 A top view of the unit structure of a 3-8 decoder based on graphene and vanadium dioxide metamaterials.

[0024] Figure 3 Absorption spectrum of 3-8 decoding realized for a 3-8 decoder based on graphene and vanadium dioxide metamaterials. DETAILED DESCRIPTION

[0025] In order to describe the solutions and advantages of the present invention in more detail, the present invention will be further explained below with reference to the accompanying drawings and in combination with embodiments. The following embodiments are only part of the embodiments, not all of the embodiments.

[0026] An implementation example of a 3-8 decoder based on graphene and vanadium dioxide metamaterials Figure 1 As shown, a silicon dioxide dielectric layer 2 with a thickness of 4 μm is laid on a gold substrate 1 with a thickness of 1 μm, and then a "fork"-shaped graphene layer 3 is plated on the upper surface of the dielectric layer 2, and then a vanadium dioxide rectangular block 4 (the length is consistent with the width of the adjacent inner graphene pattern) is inlaid along the diagonal line, followed by a rectangular graphene 3 (the length is consistent with the length of the adjacent vanadium dioxide rectangular block) plated along the diagonal line, and finally a semicircular graphene 3 (the diameter is consistent with the length of the adjacent rectangular graphene pattern) is plated, thereby separating the inner and outer graphene layers by the vanadium dioxide structure; the dielectric constant of silicon dioxide in this example is 3.9.

[0027] A top view of the unit structure of a 3-8 decoder based on graphene and vanadium dioxide metamaterials Figure 2 As shown, the whole is in a cross shape and is symmetrical about the diagonal of the square medium 2. The inner graphene is composed of two rectangles of different sizes rotated 45° and 135° around the center point of the square, and the semi-major axes of the small rectangle and the large rectangle are fixed to be a1=2μm and a2=2.5μm, respectively, and the widths of the large rectangle and the small rectangle are c1=3μm and c2=2μm, respectively; the width of the rectangular vanadium dioxide is d=0.5μm; the outer semicircular graphene layer 3 is composed of a semicircle and a rectangle, the radii of the large semicircle and the small semicircle are r1=1.5μm and r2=1μm, respectively, and the widths of the large rectangle and the small rectangle are b1=1μm and b2=0.7μm, respectively; the unit structure period P=10μm.

[0028] An implementation example of a 3-8 decoder based on graphene and vanadium dioxide metamaterials to implement 3-8 decoding Figure 3 As shown, at this time, the input quantity A2 is the state of vanadium dioxide. When vanadium dioxide is in a metallic state (conductivity is 200000 S / m), it is defined as a low logic input "0", and when it is in an insulating state (conductivity is 200 S / m), it is defined as a high logic input "1"; the input quantity A1 is the polarization angle of the incident terahertz wave, and is defined as a low logic input "0" when the polarization angle is 45°, and is defined as a high logic input "1" when it is 135°; the input quantity A0 is the Fermi level of graphene, and is defined as a low logic input "0" when the Fermi level is 0.7ev, and is defined as a high logic input "1" when it is 0.9ev, and 3-8 decoding can be performed at eight frequency points D1, D2, D3, D4, D5, D6, D7, and D8.

[0029] The decoding of this embodiment 3-8 defines that the absorption rate of a certain terahertz frequency point is higher than 50% as a logic output state "1"; and defines that the absorption rate of a certain terahertz frequency point is lower than 50% as a logic output state "0".

[0030] like Figure 3 As shown, when the input is A2A1A0=000, that is, vanadium dioxide is in a metallic state (at this time, gate voltage is applied to both the inner and outer graphene layers), the polarization angle is 45°, and the graphene Fermi level is 0.7ev, the absorption rate at the frequency point D1 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=10000000;

[0031] like Figure 3 As shown, when the input is A2A1A0=001, that is, vanadium dioxide is in a metallic state (at this time, gate voltage is applied to both the inner and outer graphene layers), the polarization angle is 45°, and the graphene Fermi level is 0.9ev, the absorption rate at the frequency point D2 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=01000000;

[0032] like Figure 3 As shown, when the input is A2A1A0=010, that is, vanadium dioxide is in a metallic state (at this time, gate voltage is applied to both the inner and outer graphene layers), the polarization angle is 135°, and the graphene Fermi level is 0.7ev, the absorption rate at the frequency point D3 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00100000;

[0033] like Figure 3 As shown, when the input is A2A1A0=011, that is, vanadium dioxide is in a metallic state (at this time, gate voltage is applied to both the inner and outer graphene layers), the polarization angle is 135°, and the graphene Fermi level is 0.9ev, the absorption rate at the frequency point D4 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00010000;

[0034] like Figure 3 As shown in the figure, when the input is A2A1A0=100, that is, vanadium dioxide is in an insulating state (at this time, only the inner graphene layer is applied with gate voltage), the polarization angle is 45°, and the graphene Fermi level is 0.7ev, the absorption rate at the frequency point D5 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00001000;

[0035] like Figure 3 As shown in the figure, when the input is A2A1A0=101, that is, vanadium dioxide is in an insulating state (at this time, only the inner graphene layer is applied with gate voltage), the polarization angle is 45°, and the graphene Fermi level is 0.9ev, the absorption rate at the frequency point D6 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00000100;

[0036] like Figure 3 As shown in the figure, when the input is A2A1A0=110, that is, vanadium dioxide is in an insulating state (at this time, only the inner graphene layer is applied with gate voltage), the polarization angle is 135°, and the graphene Fermi level is 0.7ev, the absorption rate at the frequency point D7 is higher than 50%, and the absorption rates of the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00000010;

[0037] like Figure 3 As shown, when the input is A2A1A0=111, that is, vanadium dioxide is in an insulating state (at this time, only the inner graphene layer is applied with gate voltage), the polarization angle is 135°, and the graphene Fermi level is 0.9ev, the absorption rate at the frequency point D8 is higher than 50%, and the absorption rates at the other seven frequency points are all lower than 50%, that is, the decoding output at this time is D1D2D3D4D5D6D7D8=00000001.

[0038] A 3-8 decoder based on graphene and vanadium dioxide metamaterials can realize the 3-8 decoding function through the above implementation. The corresponding formula is used to calculate the maximum modulation depth MD=99.67%, the minimum extinction ratio ER=17.7dB, and the maximum insertion loss IL=0.76dB of the decoder.

[0039] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A 3-8 decoder based on graphene and vanadium dioxide metamaterials, characterized in that: First, a layer of dielectric 2 is laid on the upper surface of substrate 1, and a "fork"-shaped graphene layer 3, an embedded vanadium dioxide cuboid 4, and a semicircular graphene layer 3 are plated on the upper surface of 2 from the inside to the outside; substrate 1 is gold with a thickness of 1μm; dielectric 2 is silicon dioxide with a dielectric constant of 3.9 and a thickness of 4μm; the conductivity of vanadium dioxide cuboid 4 is 200S / m or 200000S / m, and the thickness is 0.26μm; the side length P of the unit structure is 10μm.

2. A 3-8 decoder based on graphene and vanadium dioxide metamaterial according to claim 1, characterized in that: The inner "fork"-shaped graphene layer 3 is composed of two rectangles of different sizes, with the semi-major axes of the small rectangle and the large rectangle being a1=2μm and a2=2.5μm respectively, and the widths of the large rectangle and the small rectangle being c1=3μm and c2=2μm respectively; the width of the rectangular vanadium dioxide is d=0.5; the outer semicircular graphene layer 3 is composed of a semicircle and a rectangle, with the radii of the large semicircle and the small semicircle being r1=1.5μm and r2=1μm respectively, and the widths of the large rectangle and the small rectangle being b1=1μm and b2=0.7μm respectively; the top layer is symmetrical about the diagonals of the x-axis and the y-axis (assuming that the center position of the substrate 1 is the origin of the coordinate system).

3. The 3-8 decoder based on graphene and vanadium dioxide metamaterial according to claim 1, characterized in that: The ion gel acting as a conductor is coated only on the upper surface of the inner "fork"-shaped graphene layer 3 through the electrode.

4. The 3-8 decoder based on graphene and vanadium dioxide metamaterial according to claim 1, characterized in that: Through comprehensive control of three dimensions: vanadium dioxide state, terahertz wave polarization angle, and graphene Fermi level, the device can be used as a 3-8 decoder in the terahertz band. The maximum modulation depth of the decoder is MD=99.67%, the minimum extinction ratio is ER=17.7dB, and the maximum insertion loss is IL=0.76dB.

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