Terahertz metasurface equilibrium three-valued 2-9-line decoder based on graphene and strontium titanate

Abstract

The invention discloses a terahertz metasurface equilibrium three-valued 2-9 line decoder based on graphene and strontium titanate, and belongs to the technical field of terahertz communication modulation. The structure is composed of a gold substrate, a silicon dielectric layer, a strontium titanate dielectric layer with a circular opening, an annular silicon dielectric layer and an annular graphene pattern layer from bottom to top. Based on the principle of a metamaterial absorber, the graphene Fermi level is controlled through voltage, the physical property of strontium titanate is controlled through temperature, the 2-9 decoding function in the terahertz wave band is achieved, and excellent decoding performance is achieved. The work provides a new thought for the expansion of the terahertz information decoding quantity and the design of the terahertz multi-valued logic device.

Description

Technical Field

[0001] The present invention relates to the field of terahertz modulation technology, and specifically refers to a terahertz metasurface device with 2-line - 9-line decoding function and an operation scheme. Background Art

[0002] In recent years, researchers have used tunable materials such as graphene and vanadium dioxide to design metamaterial logic functional devices. For example, a terahertz metasurface 2 - 4 decoder based on a metamaterial absorber realizes the 2 - 4 decoding function by changing the terahertz wave incident polarization angle and the graphene Fermi level, and a terahertz metasurface 3 - 8 decoder designed based on this principle adds the vanadium dioxide state as the third input quantity on the basis of the two input quantities of the 2 - 4 decoder to realize the 3 - 8 decoding function in the terahertz band. These devices can realize their logic functions without changing their structural dimensions or internal doping, which is of great significance in practical applications. However, the above terahertz devices are only binary decoders, that is, binary logic devices.

[0003] With the development of terahertz communication technology, the demand for multi - valued logic functional devices has increased accordingly. Compared with binary logic devices, ternary logic devices can obtain more output quantities with fewer input quantities. Currently, a 1 - line - 3 - line decoder and a 2 - line - 9 - line decoder based on ternary memristors are known to regulate the output voltage results. However, there is no ternary decoding device in the terahertz band. Ternary decoding devices have more decoding information. To fill this technical gap and maximize the information decoding amount in a single chip, it is particularly important to develop a balanced ternary 2 - line - 9 - line decoder in the terahertz band. Summary of the Invention

[0004] To solve the above problems, the present invention discloses a terahertz metasurface balanced ternary 2 - line - 9 - line decoder based on graphene and strontium titanate.

[0005] The present invention is realized through the following technical solutions:

[0006] A terahertz metasurface balanced ternary 2 - line - 9 - line decoder based on graphene and strontium titanate, comprising a gold substrate 1, a silicon dielectric layer 2, a strontium titanate dielectric layer 3 with a circular opening, an annular silicon dielectric layer 2, and an annular graphene layer 4; the dielectric layer 2 is located on the upper surface of the substrate layer 1, the dielectric layer 3 is located on the upper surface of the dielectric layer 2, the annular dielectric layer 2 is located on the upper surface of the dielectric layer 3, and the layer 4 is located on the upper surface of the annular dielectric layer 2.

[0007] In the above solution, the thickness of the substrate 1 is 1μm; the thickness of the dielectric layer 2 is 4.5μm; the thicknesses of the dielectric layer 3 and the annular dielectric layer 2 are both 0.2μm; the thickness of the graphene layer 4 is 1nm.

[0008] In the above solution, the graphene layer conducts electricity by connecting electrodes, and the strontium titanate dielectric layer changes its temperature. This device can be used as a 2-9 decoder in the terahertz frequency band.

[0009] The above terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate can achieve the 2-9 decoding function; its characteristics are as follows:

[0010] For the nine input quantities X1X0 = -1, -1, -1, 0, -1, 1, 0, -1, 0, 0, 0, 1, 1, -1, 1, 0, and 1, 1 of this device, nine sequentially selected frequency points can generate separate resonance absorption peaks, achieving 2-9 decoding of actively selecting terahertz frequencies; and the decoding output threshold is defined as 90%, that is, the absorption rate above 90% is the decoding output result "1" (high absorption rate), and the absorption rate below 90% is the decoding output result "0" (low absorption rate); its characteristics are as follows:

[0011] When the decoding input of this structure is X1X0 = -1, -1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 100000000, that is, there is a high absorption rate at the selected frequency point 1, and low absorption rates at the selected frequency points 2, 3, 4, 5, 6, 7, 8, and 9.

[0012] When the decoding input of this structure is X1X0 = -1, 0, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 010000000, that is, there is a high absorption rate at the selected frequency point 2, and low absorption rates at the selected frequency points 1, 3, 4, 5, 6, 7, 8, and 9.

[0013] When the decoding input of this structure is X1X0 = -1, 1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 001000000, that is, there is a high absorption rate at the selected frequency point 3, and low absorption rates at the selected frequency points 1, 2, 4, 5, 6, 7, 8, and 9.

[0014] When the decoding input of this structure is X1X0 = 0, -1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000100000, that is, there is a high absorption rate at the selected frequency point 4, and low absorption rates at the selected frequency points 1, 2, 3, 5, 6, 7, 8, and 9.

[0015] When the decoding input of this structure is X1X0 = 0, 0, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000010000, that is, there is a high absorption rate at the selected frequency point 5, and low absorption rates at the selected frequency points 1, 2, 3, 4, 6, 7, 8, and 9.

[0016] When the decoding input of this structure is X1X0 = 0, 1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000001000, that is, the high absorption rate is at the selected frequency point 6, and the low absorption rates are at the selected frequency points 1, 2, 3, 4, 5, 7, 8, 9;

[0017] When the decoding input of this structure is X1X0 = 1, -1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000100, that is, the high absorption rate is at the selected frequency point 7, and the low absorption rates are at the selected frequency points 1, 2, 3, 4, 5, 6, 8, 9;

[0018] When the decoding input of this structure is X1X0 = 1, 0, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000010, that is, the high absorption rate is at the selected frequency point 8, and the low absorption rates are at the selected frequency points 1, 2, 3, 4, 5, 6, 7, 9;

[0019] When the decoding input of this structure is X1X0 = 1, 1, the decoding output is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000001, that is, the high absorption rate is at the selected frequency point 9, and the low absorption rates are at the selected frequency points 1, 2, 3, 4, 5, 6, 7, 8;

[0020] That is, as described above, by changing two input quantities of the metasurface structure, a 2 - 9 decoder in the terahertz band is obtained. The present invention has the characteristics of novel structure, large information decoding amount, flexible tunability, etc. Brief Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the unit structure of a terahertz metasurface balanced ternary 2 - line - 9 - line decoder based on graphene and strontium titanate.

[0022] Figure 2 It is a top view of the unit structure of a terahertz metasurface balanced ternary 2 - line - 9 - line decoder based on graphene and strontium titanate.

[0023] Figure 3 It is an absorption spectrum of a terahertz metasurface balanced ternary 2 - line - 9 - line decoder realizing the decoding function.

[0024] Figure 4 It is a function truth table of a terahertz metasurface balanced ternary 2 - line - 9 - line decoder based on graphene and strontium titanate. Detailed Embodiment

[0025] To describe the solution 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 conjunction with embodiments. The following embodiments are only some of the embodiments shown, rather than all embodiments.

[0026] An embodiment of a terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate is as Figure 1 shown. A gold substrate 1 with a thickness of 1 μm is covered with a silicon dielectric layer 2 with a thickness of 4.5 μm. Then, a strontium titanate dielectric layer 3 with a circular opening (radius R1 = 2 μm) and a thickness of 0.2 μm is laid on the upper surface of the dielectric layer 2. Immediately afterwards, a circular silicon dielectric layer 2 with a thickness of 0.2 μm (inner diameter R1 = 2 μm, outer diameter R2 = 3 μm) is laid along the outer diameter of the circular opening of the dielectric layer 3. Finally, a graphene layer 4 with a thickness of 1 nm and the same pattern is plated on the upper surface of the circular silicon dielectric layer 2; in this example, the dielectric constant of silicon is 11.9; the unit period structure is P = 6.4 μm.

[0027] In the structure of a terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate, the graphene can change its Fermi level by applying a bias voltage, thereby changing its dielectric constant, and strontium titanate can change its dielectric constant by changing the temperature; the above two materials can respectively cause different degrees of blue shift of the resonance absorption peak frequency point with the increase of the Fermi level and temperature.

[0028] An embodiment of a terahertz metasurface balanced ternary 2-line - 9-line decoder to achieve 2 - 9 decoding is as Figure 3 shown. At this time, the decoding input quantity X1 is the Fermi level of graphene. It is defined that when the Fermi level is 0.9 eV, it is the logic input "-1", when the Fermi level is 1.1 eV, it is the logic input "0", and when the Fermi level is 1.3 eV, it is the logic input "1"; the decoding input quantity X0 is the temperature of strontium titanate. It is defined that when the temperature is 300 K, it is the logic input "-1", when the temperature is 350 K, it is the logic input "0", and when the temperature is 400 K, it is the logic input "1"; through the comprehensive control of voltage and temperature, 2 - 9 decoding can be performed at nine frequency points of Y0, Y1, Y2, Y3, Y4, Y5, Y6, Y7, Y8.

[0029] In this embodiment, for 2 - 9 decoding, it is defined that when the absorption rate at a certain terahertz frequency point is higher than 90%, it is the logic output state "1", and when the absorption rate at a certain terahertz frequency point is lower than 90%, it is the logic output state "0".

[0030] As Figure 3As shown, when the input is X1X0 = -1, -1, that is, the Fermi level of graphene is 0.9 eV and the temperature of strontium titanate is 300 K, the absorption rate at the frequency point Y0 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 100000000;

[0031] As Figure 3 shown, when the input is X1X0 = -1, 0, that is, the Fermi level of graphene is 0.9 eV and the temperature of strontium titanate is 350 K, the absorption rate at the frequency point Y1 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 010000000;

[0032] As Figure 3 shown, when the input is X1X0 = -1, 1, that is, the Fermi level of graphene is 0.9 eV and the temperature of strontium titanate is 400 K, the absorption rate at the frequency point Y2 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 001000000;

[0033] As Figure 3 shown, when the input is X1X0 = 0, -1, that is, the Fermi level of graphene is 1.1 eV and the temperature of strontium titanate is 300 K, the absorption rate at the frequency point Y3 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000100000;

[0034] As Figure 3 shown, when the input is X1X0 = 0, 0, that is, the Fermi level of graphene is 1.1 eV and the temperature of strontium titanate is 350 K, the absorption rate at the frequency point Y4 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000010000;

[0035] As Figure 3 shown, when the input is X1X0 = 0, 1, that is, the Fermi level of graphene is 1.1 eV and the temperature of strontium titanate is 400 K, the absorption rate at the frequency point Y5 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000001000;

[0036] As Figure 3As shown, when the input is X1X0 = 1, -1, that is, the Fermi level of graphene is 1.3 eV and the temperature of strontium titanate is 300 K, the absorption rate at the frequency point Y6 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000100;

[0037] As Figure 3 shown, when the input is X1X0 = 1, 0, that is, the Fermi level of graphene is 1.3 eV and the temperature of strontium titanate is 350 K, the absorption rate at the frequency point Y7 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000010;

[0038] As Figure 3 shown, when the input is X1X0 = 1, 1, that is, the Fermi level of graphene is 1.3 eV and the temperature of strontium titanate is 400 K, the absorption rate at the frequency point Y8 is higher than 90%, and the absorption rates at the other eight frequency points are all lower than 90%. That is, the decoding output at this time is Y0Y1Y2Y3Y4Y5Y6Y7Y8 = 000000001;

[0039] A terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate can achieve the 2 - 9 decoding function of multi-valued logic through the above implementation method, that is, convert two-bit ternary input signals (a total of 9 combinations) into single-channel activation in 9 output channels. Traditional electronic decoders are realized through transistor logic gates, while terahertz metamaterials rely on the collaborative regulation of electromagnetic resonant units, which is innovative in design.

[0040] As Figure 4 shown is the truth table of the device to achieve the 2 - 9 decoding function. Through the corresponding formula calculation, the maximum modulation depth MD = 97.60%, the minimum extinction ratio ER = 1.05 dB, and the maximum insertion loss IL = 0.21 dB of the decoder. This device has excellent decoding performance.

[0041] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate, characterized in that: First, a dielectric layer 2 is laid on the upper surface of the substrate 1, a dielectric layer 3 with a circular opening is laid on the upper surface of 2, then an annular dielectric layer 2 is laid on the upper surface of 3, and finally a graphene layer 4 with the same pattern as the annular dielectric layer 2 is plated on the upper surface of the annular dielectric layer 2; the substrate 1 is gold with a thickness of 1 μm; the dielectric layer 2 and the annular dielectric layer 2 are both silicon with a dielectric constant of 11.9, and their thicknesses are 4.5 μm and 0.2 μm respectively; the dielectric layer 3 with a circular opening is strontium titanate with a thickness of 0.2 μm; the thickness of the graphene layer 4 is 1 nm; the side length of the unit structure is P = 6.4 μm.

2. The terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate according to claim 1, characterized in that: The inner circle opening radius of the dielectric layer 3 with a circular opening is R1 = 2 μm, and the inner and outer diameters of the annular dielectric layer 2 and the annular graphene layer 4 are R1 = 2 μm and R2 = 3 μm respectively; the overall pattern is an axisymmetric figure in the top view.

3. The terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate according to claim 1, characterized in that: The 2-line - 9-line decoder is a multi-valued logic device with 2 decoding inputs, namely the Fermi level X1 of graphene and the temperature X0 of strontium titanate. The input states are "-1", "0", and "1", that is, 9 decoding input quantities X1X0 = -1, -1, -1,0, -1,1, 0, -1, 0,0, 0,1, 1, -1, 1,0, and 1,1; through the principle of the metamaterial absorber, 9 narrowband absorption peaks at different frequencies in the terahertz frequency band can be obtained, that is, 9 decoding outputs Y0Y1Y2Y3Y4Y5Y6Y7Y8.

4. The terahertz metasurface balanced ternary 2-line - 9-line decoder based on graphene and strontium titanate according to claim 1, characterized in that: By comprehensively controlling the two dimensions of the Fermi level of graphene and the temperature of strontium titanate, this device can be used as a 2 - 9 decoder in the terahertz band. The maximum modulation depth of the decoder is MD = 97.60%, the minimum extinction ratio is ER = 1.05 dB, and the maximum insertion loss is IL = 0.21 dB.

Images