CN116300147A - VO-based 2 Current modulation terahertz device and system of metamaterial - Google Patents

Abstract

The invention provides a VO-based system ₂ And a current modulation terahertz device, a terahertz wave modulation system and an information encryption system of the metamaterial. Wherein, current modulation terahertz device includes: a substrate transparent to terahertz waves; VO formed on substrate ₂ A layer; formed at VO ₂ A microresonator on the layer; the microresonator includes: formed at VO ₂ The layer is used for loading bias current, and a current positive terminal and a current negative terminal which are bilaterally symmetrical; formed at VO ₂ On the layer, the inner sides of the current positive electrode end and the current negative electrode end are bilaterally symmetrical, N is more than or equal to 2, and M is more than or equal to 2; the resonance units are in a split ring structure with LC resonance modes, M resonance units in each row are sequentially connected in series, and two ends of the N rows of resonance units are respectively connected to a current positive terminal and a current negative terminalAnd extreme ends. Compared with the modes of laser irradiation, voltage regulation, traditional thermal control and the like, the invention has the advantages of simple operation, easier integration with the current integrated circuit technology and the like.

Description

Current-modulated terahertz devices and systems based on VO2 and metamaterials

technical field

The invention relates to the field of metamaterials and terahertz functional devices, in particular to a current modulation terahertz device based on _VO2 and metamaterials, a terahertz wave modulation system, and an information encryption system.

Background technique

Metamaterials obtain many unusual properties, such as negative refraction, perfect lens, superlens and invisibility, etc., by designing a periodic unit structure to achieve a special response to electromagnetic waves. However, these metamaterials are passive because their optical response cannot be changed dynamically after fabrication.

Vanadium dioxide (VO ₂ ), as a phase change material, exhibits insulator-metal transition (IMT) behavior at near room temperature. During the phase transition, _VO undergoes a reversible resistance change between the high-temperature metallic tetragonal phase and the low-temperature insulating monoclinic phase. Conductivity can vary by several orders of magnitude, accompanied by thermal hysteresis. These excellent properties make _VO materials suitable for many promising applications, such as smart windows, optical switches, and phase-change memories.

However, the thermal control of _VO2 and metamaterial-based devices requires the use of expensive and bulky heating equipment, which brings inconvenience to the operation of experiments and further loses the opportunity to develop into integrated devices.

Contents of the invention

(1) Technical problems to be solved

In view of this, the present invention intends to at least partially solve one of the above technical problems.

(2) Technical solutions

In order to achieve the above purpose, according to the first aspect of the present invention, a current modulation terahertz device based on _VO2 and metamaterials is provided, including: a substrate transparent to terahertz waves; a _VO2 layer formed on the substrate; A microresonator formed on the VO ₂ layer; the microresonator includes: formed on the VO ₂ layer for loading bias current, left and right symmetrical current positive terminals and current negative terminals; current positive terminals formed on the VO ₂ layer The inner side of the negative terminal of the sum current, left and right symmetrical, N×M resonant units arranged in an array, N≥2, M≥2; wherein, the resonant unit has a split ring structure with LC resonance mode, and the M resonant units in each row are sequentially connected in series , the two ends of the resonant units in the N rows are respectively connected to the positive current terminal and the negative current terminal.

In some embodiments of the present invention, in the horizontal direction, the resonant unit is symmetrical up and down, including: a closed ring; a left extension arm and a right extension arm passing through the left and right sides of the closed ring respectively; the left side of the left extension arm is connected The positive current terminal or the right extension arm of the last resonance unit; the right side of the right extension arm is connected to the left extension arm or the current negative terminal of the next resonance unit; a rectangular opening area is formed between the left and right extension arms.

In some embodiments of the present invention, it includes: formed on the _VO2 layer, S×T microresonators arranged in an array, S≥2, T≥2; for each microresonator, N×M resonant units The structural parameters are the same, and N=M; the period p of the resonant unit is between 40 μm and 60 μm; the closed ring is a closed square ring, and its side length l is between 30 μm and 40 μm; the line width w is between 3 μm and 6 μm Between; the line width of the left and right extension arms is the same as that of the closed loop; the height h of the rectangular opening area is between 5 μm and 15 μm, and the width g is between 2 μm and 8 μm.

In some embodiments of the present invention, the thickness of the VO ₂ layer is between 5 nm˜100 nm.

In some embodiments of the present invention, the bias current loaded by the positive current terminal and the negative current terminal to the inner N rows of resonant units is between 0-0.7A.

In some embodiments of the present invention, in the thickness direction, the resonance unit includes: an adhesive metal layer formed on the VO2 layer; a conductive layer formed on the adhesive metal layer, and the thickness of the adhesive metal layer is between 5nm and 100nm , the thickness of the conductive metal layer is between 100nm and 300nm, and the closed ring and the left and right extension arms are formed by the adhesive metal layer and the conductive metal layer.

In some embodiments of the present invention, in the horizontal direction, the period of the resonant unit is 50 μm; the side length l of the closed loop is 36 μm, and the line width w is 4 μm; the height h of the rectangular opening area between the left and right extension arms is 10 μm .

In some embodiments of the present invention, in the vertical direction, the substrate is a sapphire substrate; the _VO2 layer has a thickness of 10 nm; the adhesive metal layer is a chromium film with a thickness of 20 nm; the conductive metal layer is a gold film with a thickness of 200 nm .

In some embodiments of the present invention, the current modulated terahertz device is used as a terahertz wave active modulator or an information encryption memory.

In order to achieve the above object, according to the second aspect of the present invention, a terahertz wave modulation system is provided, including: the above current modulation terahertz device, which serves as a terahertz wave active modulator; a bias current source, two of which terminal is connected to the current positive terminal and the current negative terminal of the microresonator in the terahertz wave active modulator; wherein, the bias current source loads the encoded current carrying the encoded information to the current positive terminal of the microresonator in the terahertz wave active modulator extreme and negative current to adjust the terahertz wave transmittance of the microresonator.

In some embodiments of the present invention, the coded information carried in the terahertz wave transmittance is 2-bit information code; the terahertz wave modulation system is defined as follows: when the terahertz wave transmittance is greater than or equal to the transmittance threshold, Carry binary code "1"; when it is less than the transmittance threshold, carry binary code "0".

In some embodiments of the present invention, the terahertz wave active modulator includes: S×T micro-resonators arranged in an array, S≥2, T≥2, for each micro-resonator, N×M resonance units The structural parameters are the same; for different micro-resonators, the structural parameters of the internal resonant units are different, and the bias current source can provide different bias currents for different micro-resonators.

In order to achieve the above object, according to the third aspect of the present invention, an information encryption system is provided, including: the current modulation terahertz device as above, which is used as an information encryption memory; the microresonator is used as a pixel of the information encryption memory; wherein, The structural parameters of the microresonator in the information encryption memory carry encrypted information, and the specific terahertz wave frequency and the specific bias current loaded to the positive and negative terminals of the current of the microresonator are used as the key, wherein the specific The terahertz wave frequency is selected among the resonant peaks or resonant valleys of the microresonator.

In some embodiments of the present invention, the information encryption memory includes: S×T microresonators arranged in an array, S≥2, T≥2, each microresonator serves as a pixel forming the information encryption memory, for each For microresonators, the structural parameters of N×M resonant units are the same; for different microresonators, the structural parameters of the internal resonant units are different; in the information encryption system, the corresponding relationship between terahertz wave transmittance and color is preset; The encrypted information carried is expressed as the corresponding color obtained from the transmittance of the terahertz wave under the condition of a specific terahertz wave frequency and a specific bias current; the encrypted information carried by the information encryption memory is expressed as a color block composed of S×T pixels Arranged and combined graphics, the graphics are expressed as letters, numbers and/or symbols; on the decryption side, the information encryption system also includes: a decryption module, which is used to apply specific biases to each micro-resonator in the information encryption memory current, and irradiate the information encryption memory with a terahertz wave of a specific frequency; the color demodulation module is set at the back end of the optical path of the information encryption memory, and is used to encrypt the information according to the preset corresponding relationship between the terahertz wave transmittance and the color The terahertz wave transmittance of each pixel in the memory is decrypted into the corresponding color, and the color blocks of S×T pixels are arranged and combined to form a graph.

(3) Beneficial effects

It can be seen from the above technical solutions that the present invention has at least one of the following beneficial effects compared with the prior art:

(1) The present invention symmetrically arranges the current positive terminal and the current negative terminal on both sides of the microresonator, and heats the _VO2 material below by the electric field generated when the bias current passes through the microresonator. The structure of the microresonator results in a highly localized phase transition of _VO2 and a distribution of electrical current filaments attached to the microresonator, so that the design can ensure that the bias current flows through each resonator to generate relatively The consistent heating effect can be used to control the resonance spectral response of the terahertz wave and adjust the transmission spectral line by using the difference in the gap.

Compared with the control method using laser irradiation, the present invention is more conducive to the integration with the current mainstream technology of integrated circuits, and at the same time avoids the interference between the laser light source and the terahertz wave source.

Compared with the voltage regulation method, the present invention adopts the current modulation method, and the experiment proves that the current regulation is more direct and effective, and the current can be used as an additional modulation parameter to expand the application range of the device. At the same time, it is more conducive to the combination with the current integrated circuit technology.

Compared with the traditional modulation method of thermally controlling the phase transition of VO ₂ , the present invention abandons the bulky external heater and adopts a flexible electrical control method, which reduces the complexity of actual operation and provides convenience for the development of integrated devices.

Compared with the modulation method in which the _VO2 layer and the lower layer material form a pn junction to heat the _VO2 material, the present invention utilizes the metal properties of the metamaterial to generate Joule heat after electrification, and heats the _VO2 layer, thereby changing the _VO2 material The electrical conductivity is lower, the terahertz wave transmittance is reduced, the process is more direct and effective, the energy consumption is lower, and at the same time, the impact of doping the base material on other components of the integrated circuit is reduced.

Compared with using _VO2 powder to form the phase change material region only at the opening of the split ring, the present invention has the following advantages. First, the whole piece of _VO2 layer made by epitaxial growth has higher crystallinity and better consistency Good, so that the reliability of the device is higher; second, the overall coating process is more controllable, the production cost is lower, and it is more conducive to industrial production; third, it is more conducive to the integration with the current mainstream technology of integrated circuits.

(2) Compared with the asymmetric resonant unit in the prior art, no matter in the present invention, the symmetrical arrangement of the positive current terminal and the negative current terminal in the microresonator, the array arrangement of the resonant unit, and the internal structure of the resonant unit are all set as Symmetrical arrangement. Compared with the asymmetric resonant unit in the prior art, such a symmetrical arrangement makes the electrical and thermodynamic characteristics of the whole device more stable.

(3) Each microresonator is an array of split-ring resonant unit structures with different subwavelength sizes fabricated on the same substrate and independently controlled by applying an external current. The difference in threshold current and resonance response required by each microresonator enables the microresonator to be used as a space-selective terahertz modulator according to actual needs.

(4) The split-ring structure with LC resonance mode is used to construct the microstructure of the terahertz metasurface layer. The LC resonance mode makes the spectral line show a sharp line shape with a high quality factor. This line shape has a high sensitivity to the external field response, which can enhance the response of the terahertz wave to the conductivity change during the phase transition of _VO2 , and improve the line shape of the spectrum curve. Modulation sensitivity upon phase transition of _VO2 .

(5) In the terahertz metasurface microstructure, the internal gap size of the resonant unit structure is 8, 6, 4, and 2 μm respectively; among them, the microresonator with the smallest gap has the strongest response LC resonance mode, so it shows in the frequency spectrum It shows the sharpest resonance valley line shape, and shows the greatest sensitivity in the phase change modulation of _VO2 . When fully modulated, the reduction of the gap reduces the operating current of the device from 0.62A to 0.38A, which effectively reduces the operating threshold of the device.

(6) Based on the high modulation depth and hysteresis characteristics exhibited by current-modulated terahertz devices, a terahertz wave modulation system based on transmission spectrum was developed. Based on the rewritable characteristics and non-volatile multi-level conductance states of different electromagnetisms, multiple microresonator arrays can realize rewritable functions, and can output any combination of output binary codes, which is a promising solution for photonic memory and solar energy. The development of Hertzian communication devices presents exciting opportunities.

(7) Using the separated transmittance hysteresis loops generated by arrays of different resonant unit structures, an information encryption system with frequency-selectable and dynamically adjustable color pattern display is further provided in the terahertz frequency band. Through the preset terahertz wave transmission The corresponding relationship between frequency and color, using current and terahertz wave frequency as the decryption key can realize information encryption and multi-image reproduction.

Description of drawings

FIG. 1A is a three-dimensional schematic diagram of a current-modulated terahertz device according to an embodiment of the present invention.

FIG. 1B is a cross-sectional view of the current-modulated terahertz device shown in FIG. 1A .

FIG. 2 is a schematic diagram of a resonance unit of each of the four resonators in the current-modulated terahertz device shown in FIG. 1A .

FIG. 3A , FIG. 3B , FIG. 3C , and FIG. 3D are respectively the terahertz transmission spectrum curves of the four resonators of the current-modulated terahertz device shown in FIG. 1A under current modulation.

FIG. 4 is a diagram of the surface current and electric field distribution at the first resonance valley of the fourth resonator with an internal gap g=2 in the current-modulated terahertz device shown in FIG. 1A .

FIG. 5 is a comparison diagram of the modulation depth of the transmittance at the first resonance valley of the second, third, and fourth microresonators in the current-modulated terahertz device shown in FIG. 1A as a function of current.

Fig. 6 is a schematic diagram of the conversion and output of the continuous frequency spectrum of the four microresonators varying with the current into digital information in the current-modulated terahertz device of the present invention.

FIG. 7 is a schematic diagram of the multi-state characteristics of the transmittance realized by the terahertz wave modulation system and the binary codes corresponding to the multi-states according to the embodiment of the present invention.

8A and 8B are schematic diagrams of the flexible arbitrary encoding function realized by the fourth resonator in the terahertz wave modulation system shown in FIG. 7 by using programmable current pulses.

Fig. 9A demonstrates a schematic diagram of an information encryption memory composed of four micro-resonators.

Fig. 9B is a schematic diagram of color display changing with current at wrong decryption key - 0.87 and 1.01 THz.

FIG. 9C is a schematic diagram of implementing information decryption and image reproduction using various terahertz wave frequencies and bias currents as decryption keys.

Detailed ways

In the present invention, a technical solution is proposed that utilizes Joule heat generated by current to modulate the _VO2 layer, and utilizes the phase transition characteristics of _VO2 to realize related functions. Compared with laser irradiation, voltage regulation, traditional thermal control, etc. Simple, easier to integrate with current integrated circuit technology and other advantages.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific implementation methods and with reference to the accompanying drawings.

1. Current-modulated terahertz devices

In the first exemplary embodiment of the present invention, a current-modulated terahertz device based on _VO2 and metamaterials is provided, which is sensitive to external fields by optimizing the modulation method and designing the microstructure of the metasurface layer The spectral line shape improves the consistency and stability of the entire device, and increases the compatibility with current integrated circuit technology.

FIG. 1A is a three-dimensional schematic diagram of a current-modulated terahertz device according to an embodiment of the present invention. FIG. 1B is a cross-sectional view of the current-modulated terahertz device shown in FIG. 1A . As shown in Figure 1A and Figure 1B, the current modulation terahertz device of this embodiment includes:

Substrates transparent to terahertz waves;

a VO _layer formed on the substrate;

Four microresonators arranged in a 2× ₂ array were formed on the VO layer by etching.

The current-modulated terahertz device of this embodiment will be described in detail below, especially the VO ₂ layer and the microresonator, which are the key parts of the present invention.

In this embodiment, the substrate is a 430 μm thick sapphire substrate (Sapphire), which is transparent to terahertz waves. The sapphire substrate has the advantages of mature technology, low cost and good transparency. In addition to the sapphire substrate, the present invention can also use other substrates that match the lattice parameters of the VO ₂ material to make the VO ₂ layer.

In this embodiment, a VO ₂ layer is grown on a substrate by a pulsed laser deposition (PLD) method. The _VO2 layer has a thickness of 10nm and is tiled over the entire substrate, not just in the resonator region. Those skilled in the art should understand that, in addition to PLD, other thin film epitaxial deposition methods can also be used. In addition, in other embodiments of the present invention, the thickness of the VO ₂ layer is between 5nm and 100nm, and the present invention can also be realized.

The test results show that the _VO2 layer epitaxially grown on the sapphire substrate in this embodiment has high-quality epitaxy and a relatively smooth surface, and the resistance has a sudden change of three orders of magnitude near the transition temperature, which provides a large contrast and greater stability.

It should be noted that in the prior art, there is a technical solution for forming the phase-change material region by coating the opening of the split ring with _VO2 powder. Compared with it, the present invention has the following advantages. First, the entire _VO2 layer made by epitaxial growth has higher crystallinity and better consistency, so that the reliability of the device is higher; second, the overall coating The controllability of the process is better, the production cost is lower, and it is more conducive to industrial production; third, it is more conducive to the integration with the current mainstream technology of integrated circuits.

Please continue to refer to FIG. 1 , in this embodiment, a metasurface layer microstructure consisting of four microresonators is fabricated on the _VO2 layer by etching. Four microresonators 2×2 are evenly distributed on the VO ₂ layer, and the distance between each microresonator in the horizontal and vertical directions is 2mm. For the convenience of description, the upper left, upper right, lower left, and lower right resonators are respectively named: the first resonator, the second resonator, the third resonator, and the fourth resonator.

Those skilled in the art should understand that in the present invention, each microresonator is an array of split-ring resonant unit structures with different subwavelength sizes fabricated on the same substrate, and is independently controlled by applying an external current. The difference in threshold current and resonance response required by each microresonator enables the microresonator to be used as a spatially selective terahertz wave active modulator according to actual needs.

In other embodiments of the present invention, the current-modulated terahertz device may include S×T independent micro-resonators, S≥2, T≥2, and S and T may be the same or different. In this embodiment, S=T=3.

For each microresonator, it includes: formed on the VO ₂ layer for loading bias current, left and right symmetrical current positive terminals and current negative terminals, connected to the bias current source (Bias Current); formed on VO ₂ On the layer, on the inner side of the current positive terminal and the current negative terminal, there are 3×3 resonant units arranged in an array. Among them, the 3×3 resonant units of each microresonator are connected by gold wires and connected to the positive current terminal and negative current terminal on the left and right sides to form a path, so as to realize independent current modulation. In other words, each microresonator acts as an independent current modulation unit.

In other embodiments of the present invention, the resonant unit array constituting the micro-resonator may include N×M units, N≥2, M≥2, and N and M may be the same or different. Preferably, in order to reduce the detected anisotropy as much as possible, the number of unit structures in the transverse and longitudinal directions is the same, ie N=M. In addition, preferably, in order to ensure the detection signal strength, the area covered by the unit structure array should be equal to or larger than the covered area of the terahertz wave in the terahertz time-domain spectroscopy system.

As shown in Figure 1A, in this embodiment, the resonant unit has a split ring structure with LC resonance mode, and the three resonant units in each row are connected in series in sequence, and the two ends of the resonant units in the three rows are respectively connected to the positive terminal of the current and the current negative extreme. FIG. 2 is a schematic diagram of a resonance unit of each of the four resonators in the current-modulated terahertz device shown in FIG. 1A .

Among them, (A), (B), (C), and (D) are the resonant units in the first, second, third, and fourth microresonators in FIG. 1A . The resonant unit in this embodiment will be introduced below with reference to FIG. 1A , FIG. 1B and FIG. 2 .

Referring to FIG. 1B , in the thickness direction, the resonant unit includes: a chromium layer formed on the VO ₂ layer; and a gold layer formed on the chromium layer. Wherein, the thickness of the chromium layer is 20nm, and the thickness of the gold layer is 200nm. Among them, the role of the chromium layer is mainly to ensure the adhesion of the gold layer on the substrate. The chromium and gold layers are etched to form the planar structure of the resonant unit.

It should be clear to those skilled in the art that the chromium film can also be replaced by other bonding metal materials that can provide high adhesion, such as titanium, etc.; the gold microstructure can also be replaced by other similar metal materials, such as: silver, copper wait. In addition, the thickness of the chromium thin film and the gold microstructure can also be adjusted according to needs. Preferably, the thickness of the chromium thin film is between 5nm and 100nm. The thickness of the gold thin film is between 100nm and 300nm.

In this embodiment, the structures of the resonant units in the four microresonators are the same, and the only difference lies in the size g of the split gap. Please refer to Figure 1A and Figure 2, in the horizontal direction, the resonance unit is symmetrical up and down, including: a closed square ring; a left extension arm and a right extension arm passing through the left and right sides of the closed square ring; The left side of the left extension arm is connected to the positive terminal of the current or the right extension arm of the previous resonance unit; the right side of the right extension arm is connected to the left extension arm of the next resonance unit or the negative terminal of the current; the left, A rectangular open area is formed between the right extension arms.

Specifically, in this embodiment, the period p of the resonant unit is between 40 μm and 60 μm; the side length l of the closed square ring is between 30 μm and 40 μm; the line width w is between 3 μm and 6 μm; The line width of the left and right extension arms is the same as that of the closed square ring; the height h of the rectangular opening area is between 5 μm and 15 μm, and the width g is between 2 μm and 8 μm. The period of the resonance unit is 50 μm; the side length l of the closed square ring is 36 μm, the line width w is 4 μm; the height h of the rectangular opening area between the left and right extension arms is 10 μm.

Those skilled in the art should understand that although this embodiment is described by taking a closed square ring as an example, in other embodiments of the present invention, closed ring forms such as a closed circular ring and a closed rectangular ring may also be used. At the same time, the structural parameters of the closed loop, such as side length, line width, opening size, etc., can also be adjusted as needed.

It should be noted that, in order to enhance the sensitivity of the spectral line shape of the current-modulated terahertz device in this embodiment to the _VO2 phase change, the values of the parameter g of the resonance unit in the four resonators determined in the experiment after adjusting the resonance response are respectively: 8, 6, 4, 2 μm.

The current modulation terahertz device of this embodiment is set up in this way because the phase transition of _VO2 is highly localized and the distribution of the electrical current filaments attached to the microresonator, so that the design can ensure that the bias current flows through each A relatively consistent heating effect can be produced when a microresonator is used, and the difference in the gap can be used to realize the manipulation of the resonant spectral response of the terahertz wave and the adjustment of the transmission spectral line.

Further, the present invention adopts the split ring structure with LC resonance mode to construct the microstructure of the terahertz metasurface layer. The LC resonance mode makes the spectral line show a sharp line shape with a high quality factor. This line shape has a high sensitivity to the external field response, which can enhance the response of the THz wave to the conductivity change during the phase transition of _VO2 , and improve the line shape of the spectrum curve to VO2. Modulation sensitivity at phase transitions.

In addition, it can be seen from the above structure that, compared with the asymmetric resonant unit in the prior art, no matter the symmetrical arrangement of the positive current terminal and the negative current terminal in the microresonator in the present invention, the array arrangement of the resonant unit, the inside of the resonant unit The structures are all arranged symmetrically. Compared with the asymmetric resonant unit in the prior art, such a symmetrical arrangement makes the electrical and thermodynamic characteristics of the whole device more stable.

Fig. 3A, Fig. 3B, Fig. 3C and Fig. 3D are respectively the transmission spectrum curves of the first, second, third and fourth micro-resonators in the current-modulated terahertz device shown in Fig. 1 as a function of the applied current. Wherein, the abscissa is frequency (Frequency), and the unit is terahertz (THz); the ordinate is transmittance (Transmission). As shown in FIG. 3A , there is no obvious resonance absorption in the transmission spectrum under static state (I=0A). When I gradually increases, the amplitude transmittance begins to decrease and drops to the lowest value as a whole when the current value is large enough. As the current decreases to 0A, the transmittance spectrum returns to the state of static current again, indicating that VO ₂ The resistance change is reversible. At the same time, in Fig. 3A, under the modulation of small current, the changes of the spectral lines are not obvious.

In order to improve the sensitivity of the micro-resonator to electric control response, the present invention conducts systematic research on the design of the unit structure of the surface resonator. Fix the external wiring structure in the resonance unit structure, and only reduce the gap size g value to tune the impedance and reduce the loss, so as to obtain a resonance line shape with high quality factor and narrow bandwidth in the frequency spectrum. When the value of g in the resonant unit structure is reduced to 6, 4, and 2 μm, the corresponding electrical tuning transmission spectra measured by experiments are shown in Fig. 3B, Fig. 3C and Fig. 3D. The figure shows that with the decrease of g, both the resonant frequency and amplitude in the frequency spectrum have changed, and the resonant frequency in the static state has moved to the low frequency while producing a sharper linear resonance.

Fig. 4 shows the surface current and electric field distribution diagram of the fourth resonator at the first resonance valley. The fact that the current is a circular current indicates that the microresonator has an LC resonance mode, and the electric field is mainly localized at the gap with a strong intensity.

It is worth noting that when the value of the internal gap size g in the resonant unit structure decreases, the changes of the spectral lines at small current values also become sensitive, and the terahertz transmission amplitude of the fourth resonator decreases rapidly with the increase of current . In order to show more strongly that the microresonator with sharp linear resonance increases the response to the modulation current, the modulation depth of the resonance amplitude of the second, third and fourth microresonators at the first resonance valley is extracted as a function of the current value changes, as shown in Figure 5. The results show that the saturation current of LC resonance modulation drops from 0.32A to 0.22A with the decrease of g. This shows that by reducing the internal gap size of the resonant unit structure, the response of the terahertz wave to the conductivity change during the phase transition of VO2 has been successfully enhanced, the sensitivity of the spectral curve to the control of small currents has been improved, and the operating current has been reduced.

In the present invention, the positive current terminal and the negative current terminal are arranged symmetrically on both sides of the microresonator, and the _VO2 material below is heated by the electric field generated when the bias current passes through the microresonator. The structure of the microresonator results in a highly localized phase transition of _VO2 and a distribution of electrical current filaments attached to the microresonator, so that the design can ensure that the bias current flows through each resonator to generate relatively The consistent heating effect can be used to control the resonance spectral response of the terahertz wave and adjust the transmission spectral line by using the difference in the gap.

As can be seen from the above description, the present invention symmetrically arranges the current positive terminal and the current negative terminal on both sides of the microresonator, and heats the _VO2 material below by the electric field generated when the bias current passes through the microresonator. The structure of the microresonator results in a highly localized phase transition of _VO2 and the distribution of electrical current filaments attached to the microresonator. This design can ensure that the bias current is relatively consistent when flowing through each resonator. The heating effect of the terahertz wave can also be realized by using the difference in the gap to control the resonant spectral response of the terahertz wave and adjust the transmission spectral line. The following describes the differences and advantages of the current modulation terahertz device of the present invention compared with the _VO2 regulation method in the prior art:

(1) Compared with the control method using laser irradiation, the present invention is more conducive to the integration with the mainstream technology of current integrated circuits, and at the same time avoids the interference between the laser light source and the terahertz wave source.

(2) Compared with the voltage regulation method, the present invention adopts the current modulation method, and the experiment proves that the current regulation is more direct and effective, and the current can be used as an additional modulation parameter to expand the application range of the device. At the same time, it is more conducive to the combination with the current integrated circuit technology.

(3) Compared with the modulation method in which the VO ₂ layer and the lower layer material form a pn junction to heat the VO ₂ material, the present invention uses the metallic properties of the metamaterial to generate Joule heat after electrification, and heats the VO ₂ layer, thereby changing The electrical conductivity of the VO ₂ material reduces the transmittance of terahertz waves, the process is more direct and effective, and the energy consumption is lower. At the same time, it reduces the impact of doping the base material on other components of the integrated circuit.

(4) Compared with the traditional modulation method of thermally controlling the phase transition of _VO2 , the present invention abandons the bulky external heater and adopts a flexible electric control method, which reduces the complexity of actual operation and provides a great advantage for the development of integrated devices convenient.

(5) Compared with utilizing _VO2 powder to only form the phase change material region at the opening of the split ring, the present invention has the following advantages, first, the whole piece of _VO2 layer made by epitaxial growth has higher crystallinity, The consistency is better, so the reliability of the device is higher; second, the overall coating process is more controllable, the production cost is lower, and it is more conducive to industrial production; third, it is more conducive to the integration with the current mainstream integrated circuit technology .

In this embodiment, the four microresonators correspond to different transmission spectral line shapes in the experimentally measurable frequency range (0.25-2.25THz). Based on this, the function of converting continuous spectral information into digital information is developed. Specifically Two applications are proposed: terahertz wave active modulator, information encryption memory.

2. Terahertz wave modulation system

In a second exemplary embodiment of the present invention, a terahertz wave modulation system is provided. Please refer to Figure 1A, the terahertz wave modulation system of this embodiment includes:

The current-modulated terahertz device as described above, which acts as an active modulator of terahertz waves;

A bias current source, both ends of which are connected to the current positive terminal and the current negative terminal of the microresonator in the terahertz wave active modulator;

Wherein, the bias current source loads the coded current carrying coded information to the current positive terminal and the current negative terminal of the micro-resonator in the terahertz wave active modulator, so as to regulate the terahertz wave transmission of the micro-resonator Overrate.

In this embodiment, it is defined that (1) when the transmittance in the spectrum is greater than 0.3, the output is a digital signal "1"; (2) when the transmittance in the spectrum is less than 0.3, the output is a digital signal "0". In this way, the continuous spectrum can be separated by 0.25THz, and 8 binary codes can be used to represent the transmittance within the spectrum range. And referring to the international ASCII code, 8 binary codes are combined into corresponding digital information. The digital signal outputs corresponding to the spectral lines of the four microresonators under different current modulation states are shown in the upper left corner of Fig. 6 . When no current is applied, the _VO2 thin film is in an insulating state, and the signal conversion and output of the four microresonators correspond to the four curves from top to bottom respectively. For example: for the first microresonator, the transmittance exceeds 0.3 within 0.5-2.0THz, so this frequency band is represented by 6 binary codes 1, while the transmittance of other frequency bands is less than 0.3, so it is represented by 0, so The numerical signal corresponding to the entire frequency band is "01111110", and the coded information corresponding to the output of the reference international ASCII code is the symbol "~"; the figure also shows the coded information output of the other three microresonators in static state, all of which realize continuous Conversion and output of spectral information to digital information.

Changing the magnitude of the applied bias current can change the shape of the transmitted spectrum, thereby changing the coded output information. In Fig. 6, as directed by the direction of the arrow, the encoded output information of the four microresonators when the current is raised to 0.34A and 0.7A until the VO ₂ film is completely metallic, and then the bias current is reduced to 0.34A are shown. It can be found that with the change of the applied current, the output information of the same microresonator varies with the change of the transmission spectrum. During the entire current modulation process, the first resonator outputs two types of symbol information, the second resonator outputs three types of symbol information, and the third and fourth resonators with smaller g values output four types of symbol information. In the insulating and metallic states, the spectral line shape of each microresonator is significantly affected by the current modulation, and they all output different coded information.

It is worth noting that when the current stops at 0.34A twice, the microresonator presents different encoding information due to the inherent hysteresis of VO ₂ . Based on this, the arbitrary encoding function of the current-modulated terahertz device is developed.

In this embodiment, the arbitrary encoding function is realized by selecting a frequency with a monotonous change and a large transmittance amplitude modulated with the current. FIG. 7 is a schematic diagram of the multi-state characteristics of the transmittance realized by the terahertz wave modulation system and the binary codes corresponding to the multi-states according to the embodiment of the present invention. In Fig. 7, the transmittance of the four microresonators at 1.425THz is first extracted, and the change curve of the whole process of current regulation is drawn, which corresponds to the longest cycle curve in the figure. It can be seen that the transmittance of different microresonators responds differently to the applied current, and the structural design brings the difference in the terahertz electromagnetic response to the resonator and also makes the hysteresis loop adjustable. From top to bottom, corresponding to the decrease of the g value of the internal gap of the unit structure, the working current value of the microresonator moves to the direction of small current. At the same time, the current value I _h corresponding to the maximum hysteresis of each microresonator (vertical dotted line in Fig. 7) was found. The transmittance difference under this current is the largest, which is more conducive to signal distinction and state reading. Obviously, I _h also decreases with the decrease of the gap, and the I _h values corresponding to the decrease of the gap are 0.45, 0.34, 0.3 and 0.26A, respectively. Further, in order to realize the multi-state memory function of VO ₂ , the applicant applied current circulation curves with different terminal current values to the microresonator, and realized three corresponding circulation curves with clearly visible transmittance changes, as shown in Figure 7. The three complete circular curves in each microresonator are represented; corresponding to four different transmittances at _Ih , they are defined as the four states of _VO2 , and are coded with 2-bits "00, 01, 10, 11" states are represented by .

In this embodiment, the applicant applies a programmable series of pulse currents to the fourth resonator to realize the demonstration of any encoding function. As shown in Figure 8A, the I _h value of 0.26A is used as the "read" current input in the process of obtaining the transmittance state, and the "write" and "erase" inputs are realized by applying different short pulse currents. The "write" input is set to 0.5A with a pulse width of 4s, and the "erase" input is set to 0A with a pulse width of 10s. First, to realize the information "|" output by the binary code of the fourth resonator in Figure 6 when there is no current at 0A, it is only necessary to apply the programmable pulse sequence in the upper figure of Figure 8A to the resonator, where the "write" current If the encoding is 0.29-0.5-0.5-0A, the binary sequence "01111100" and its corresponding encoding can be obtained, which is the same as the result in Figure 6; in addition, any encoding of other sequences can be performed, as shown in Figure 8B, where the current The sequence is 0-0.5-0.35-0A, and the same output information can be obtained when the current in Figure 6 drops to 0.34A. It is worth noting that this device can not only repeat the full-spectrum fixed encoding in its own structure in Figure 6, but also realize arbitrary 2-bit information encoding and transmission functions through the design and application of pulse sequences.

Those skilled in the art should understand that for an active terahertz wave modulator containing S×T microresonators, S≥2, T≥2, for each microresonator, the structure of N×M resonant units The parameters are the same; for different micro-resonators, the structural parameters of the internal resonance units are different, and the bias current source can provide different bias currents for different micro-resonators. Through the method of this embodiment, various modulation options can be provided.

It can be seen that in the present invention, based on the rewritable characteristics and different electro-induced non-volatile multi-level conductance states, multiple microresonator arrays can realize rewritable functions, and can output binary codes in any combination. , providing exciting opportunities for the development of photonic memory and terahertz communication devices.

3. Information encryption system

According to the third aspect of the present invention, an information encryption system is also provided. The information encryption system of the embodiment of the present invention includes:

The current modulation terahertz device as described above is used as an information encryption memory; the micro-resonator is used as a pixel of the information encryption memory;

Wherein, the structural parameters of the micro-resonator in the information encryption memory carry encrypted information, and a specific terahertz wave frequency and a specific bias current loaded to the positive current terminal and the negative current terminal of the micro-resonator are used as keys. Preferably, a specific terahertz wave frequency as a key is selected among resonant peaks or resonant valleys of said microresonator.

For the information encryption memory, it includes: S'×T' micro-resonators, each micro-resonator is used as a pixel of the information encryption memory, and for each micro-resonator, the structural parameters of the N×M resonance units are the same ; For different microresonators, the structural parameters of the internal resonant unit are different. It should be noted that here, S' and T' are used to represent the number of rows and columns of microresonators in the information encryption memory, respectively, in order to compare with the number of rows of microresonators in the current-modulated terahertz device shown in Figure 1A. =2 and the number of columns T=2 are different and have no other meaning.

In the information encryption system, the corresponding relationship between the terahertz wave transmittance and the color is preset; the encrypted information carried by the pixel is represented by the transmission rate of the terahertz wave under the condition of a specific terahertz wave frequency and a specific bias current. The corresponding color obtained at a higher rate; the encrypted information carried by the information encryption memory is presented as a graphic formed by the arrangement and combination of color blocks of S'×T' pixels, and the graphic is a form of expression of letters, numbers and/or symbols.

Fig. 9A demonstrates a schematic diagram of an information encryption memory composed of four micro-resonators. In the medium information encryption memory shown in Fig. 9A, using four different gap sizes (g) of the microresonator - the first resonator, the second resonator, the third resonator, the fourth resonator, the distinguishable hysteresis The spatial arrangement design of the array device is carried out, which expands its application in the field of dynamic display that is still lacking in the terahertz range.

In FIG. 9A, each square corresponds to a pixel, that is, a microresonator. Numbers 1, 2, 3, and 4 represent the positions of the above-mentioned first, second, third, and fourth microresonators in the information encryption memory respectively, and the gray scale indicates that at a frequency of 1.425THz, the bias current value increases from 0A to 0.34A When , the transmittance of each microresonator corresponds to the pseudo-color grayscale.

In this embodiment, the color is displayed as a false color. The encryption principle is: use the "Colormap" option in the function drawing software Origin to associate the terahertz wave transmittance value of the pixel with the pseudo color, use the range of the value to correspond to the range of the color, and finally use the color to express the transmittance, so that The colors of the microresonators at special terahertz frequencies are combined into letter patterns, and each microresonator is arranged as a pixel unit of the information encryption memory, and the composed letter patterns are encrypted information.

In FIG. 9A, S'=16, T'=16. The encrypted information of 16×16 pixels, the letters “EROI”, is formed by four microresonators. It is worth noting that the grayscale at this time is only to show the encryption process more clearly. In the real operation, only the device composed of 16×16 microresonators can be seen in this step, and there is no grayscale display, but this When the letter information has been encrypted, the information already exists in the memory.

On the decryption side, the information encryption system further includes: a decryption module, which is used to respectively apply a specific bias current to each micro-resonator in the information encryption memory, and irradiate the information encryption memory with a terahertz wave; a color demodulation module, It is arranged at the back end of the optical path of the information encryption memory, and is used to convert the terahertz wave transmittance of each pixel in the information encryption memory to Decrypt it into the corresponding color, and arrange and combine the color blocks of S'×T', that is, 16×16 pixels, to form a graphic.

In this embodiment, the decryption module selects 3 frequencies, which are the LC resonance valley (1.01THz) in the fourth resonator and the two side resonance peaks (0.87THz and 1.425THz) for dynamic display and decryption demonstration. Current-dependent transmittance is represented in pseudo-color.

Figure 9B shows the graphical displays at 0.87 and 1.01 THz, respectively. When the _VO2 film is in the insulating state with no applied current, the transmittance of the four microresonators at 0.87THz is similar and the chromatic aberration is small. At 1.01 THz, only the fourth resonator has very low transmittance due to the resonance valley, which will lead to a huge difference in color display compared with the other three microresonators. However, when the current is applied to 0.7 A, it can be observed that the images at these two frequencies are almost the same in dark blue, because in the metallic state, the transmittance of all hybrid microresonators is significantly attenuated by the _VO2 film. It can be seen that Fig. 9B shows the dynamic imaging at different frequencies and different current values. But it is worth noting that, because the frequency and current values are not the key to decrypt, the graphics shown are not encrypted letter information "EROI". It can be seen that as long as one of the frequency of the terahertz wave and the bias current does not match, the encrypted information cannot be decrypted.

FIG. 9C is a schematic diagram of implementing information decryption and image reproduction using various terahertz wave frequencies and bias currents as decryption keys. As shown in Figure 9C, the functionality of this array at a frequency of 1.425 THz is demonstrated. In the initial state of 0A, the transmittance of the four microresonators is the highest, but the difference is not large, the result is displayed in red (state Ⅰ), and the information of the encrypted letter pattern cannot be seen, and the decryption cannot be realized. When the current increases to 0.34A, the pattern is consistent with the encrypted letter information "EROI" (state II), indicating that under the terahertz wave frequency and the bias current, the decryption process has been completed, and the information stored in the encrypted memory has been successfully reproduced. The letter information in , successfully decrypted. In order to more clearly demonstrate the importance of the bias current as a key, the bias current was further increased to 0.7A, and it was found that the letter information was hidden in the blue background (state III), and the decryption could not be completed. In addition, if the bias current is used as the key, the decryption cannot be completed if the order of application is wrong. For example, when the bias current selection starts from the maximum current of 0.7A and gradually decreases to 0.34A, although the current value is the same, the graphic display is quite different from that in state II, and the displayed information is that the letter information is converted into a red highlighted "FPCL" (state IV), decryption failed. Importantly, this opens up new avenues for using the bias current as a decryption key, using current-modulated terahertz devices to realize information encryption, and realizing multi-color dynamic display in terahertz imaging.

It can be seen that in the present invention, the separate transmittance hysteresis loops generated by arrays of different resonant unit structures are used to further provide an information encryption system for displaying frequency-selectable and dynamically adjustable color patterns in the terahertz frequency band, using current and terahertz The wave frequency can be used as the decryption key to realize information encryption and multi-image reproduction.

So far, the embodiments of the present invention have been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the present invention.

It should be noted that, for some implementations, if they are not the key content of the present invention and are well known to those of ordinary skill in the art, they are not described in detail in the accompanying drawings or in the text of the specification. It can be understood with reference to relevant prior art. It should be understood that these examples are provided only to enable the invention to satisfy legal requirements, and the invention can be embodied in many different forms, and should not be construed as being limited to the above examples.

In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them, for example:

(1) The size of the resonant unit structure in the microresonator can be finely adjusted;

(2) The spacing of each unit cell in the resonant unit array can be set as required;

(3) In current-modulated terahertz devices, the thickness of the substrate and _VO2 layer can be finely tuned.

In summary, the present invention provides a current-modulated terahertz device based on _VO2 and metamaterials, which enhances the linearity of the _VO2 phase by improving the structure of the resonant unit, the plane layout of the resonator, and the modulation method. The response to the change of conductivity during the change process, reduce the working current of the current modulation terahertz device, and develop the application of the terahertz wave modulation system and information encryption system, which provides a new method for building a change platform with _VO2 integrated devices , has a good application prospect.

It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", "inside", "outside" and so on, only It is the direction of referring to the accompanying drawings, and is not used to limit the protection scope of the present invention. Throughout the drawings, the same elements are indicated by the same or similar reference numerals. Moreover, the shape and size of each component in the figure do not reflect the actual size and proportion, but only illustrate the content of the embodiment of the present invention. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms according to specific situations.

Unless expressly indicated to the contrary, the numerical parameters in the specification and claims of the present invention may be approximations, which can be changed according to the content of the present invention. Specifically, all numbers indicating composition content, reaction conditions, etc. in the specification and claims should be understood as being modified by the word "about" in all cases, and the meaning expressed refers to including In some embodiments a variation of ±10%, in some embodiments a variation of ±5%, in some embodiments a variation of ±1%, in some embodiments a variation of ±0.5%.

Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.

The ordinal numbers used in the specification and claims, such as "first", "second", "third", "main", "secondary", as well as Arabic numerals, letters, etc., are used to modify corresponding elements or steps. It is only used to clearly distinguish one element (or step) with a certain name from another element (or step) with the same name, it does not mean that the element (or step) has any ordinal number, nor Represents the sequence of an element (or step) with another element (or step).

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, in order to streamline the present disclosure and to facilitate an understanding of one or more of the various inventive aspects, various features of the invention are sometimes grouped together in a single embodiment, figure, or in its description. This method of invention, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, various inventive aspects lie in less than all features of a single foregoing embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

The specific embodiments described above have described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. VO-based ₂ And a metamaterial current-modulated terahertz device, characterized by comprising: a substrate transparent to terahertz waves; VO formed on the substrate ₂ A layer; formed at the VO ₂ A microresonator on the layer;

the microresonator includes: formed at the VO ₂ The layer is used for loading bias current, and a current positive terminal and a current negative terminal which are bilaterally symmetrical; formed at the VO ₂ N multiplied by M resonant units are arranged in an array manner, wherein N is more than or equal to 2, and M is more than or equal to 2;

the resonant units are in a split ring structure with LC resonant modes, M resonant units in each row are sequentially connected in series, and two ends of the N rows of resonant units are respectively connected to the current positive terminal and the current negative terminal.

2. The current-modulated terahertz device according to claim 1, characterized in that the resonance unit is symmetrical up and down in a horizontal direction, comprising: a closed loop; a left extension arm and a right extension arm respectively penetrating through the left side and the right side of the closed loop;

The left side of the left extension arm is connected with the current positive end or the right extension arm of the last resonance unit; the right side of the right extension arm is connected with the left extension arm of the next resonance unit or the current negative electrode end; a rectangular opening area is formed between the left extension arm and the right extension arm.

3. The current-modulated terahertz device of claim 2, comprising: formed at the VO ₂ S multiplied by T micro resonators arranged in an array manner on the layer, wherein S is more than or equal to 2, and T is more than or equal to 2;

for each microresonator, the structural parameters of n×m resonant cells are the same, and n=m;

the period p of the resonance unit is between 40 and 60 mu m; the closed ring is a closed square ring, and the side length l of the closed square ring is between 30 and 40 mu m; the line width w is between 3 μm and 6 μm; the line width of the left and right extension arms is the same as that of the closed loop; the rectangular opening area has a height h of 5 μm to 15 μm and a width g of 2 μm to 8 μm.

4. The current-modulated terahertz device of claim 3, characterized in that,

the VO is ₂ The thickness of the layer is between 5nm and 100 nm; and/or

The bias current loaded by the N rows of resonance units at the inner side is between 0 and 0.7A at the current positive end and the current negative end; and/or

In the thickness direction, the resonance unit includes: formed at VO ₂ An adhesive metal layer on the layer; a conductive layer formed on the adhesive metal layer, theThe thickness of the adhesive metal layer is between 5nm and 100nm, the thickness of the conductive metal layer is between 100nm and 300nm, and the adhesive metal layer and the conductive metal layer form the closed ring and the left and right extension arms.

5. The current-modulated terahertz device of claim 4, characterized in that,

in the horizontal direction, the period of the resonance unit is 50 μm; the side length l of the closed ring is 36 mu m, and the line width w is 4 mu m; the height h of the rectangular opening area between the left extension arm and the right extension arm is 10 mu m; and/or

In the vertical direction, the substrate is a sapphire substrate; the VO is ₂ The thickness of the layer was 10nm; the viscous metal layer is a chromium film, and the thickness of the viscous metal layer is 20nm; the conductive metal layer is a gold film, and the thickness of the conductive metal layer is 200nm.

6. The current-modulated terahertz device according to claim 1, characterized in that the current-modulated terahertz device functions as a terahertz wave active modulator or an information encryption memory.

7. A terahertz wave modulation system, characterized by comprising:

The current-modulated terahertz device as set forth in any one of claims 1 to 5, which functions as a terahertz-wave active modulator;

a bias current source, two ends of which are connected to a current positive terminal and a current negative terminal of a micro resonator in the terahertz wave active modulator;

the bias current source loads coding current carrying coding information to a current positive end and a current negative end of a micro resonator in the terahertz wave active modulator so as to regulate and control the terahertz wave transmittance of the micro resonator.

8. The terahertz wave modulation system according to claim 7, wherein,

the encoded information carried in the terahertz wave transmittance is 2-bit information encoding; the terahertz wave modulation system is defined as follows: when the transmittance of the terahertz waves is larger than or equal to a transmittance threshold value, carrying a binary code of 1; when the transmittance is smaller than the threshold value, carrying binary code '0'; and/or

The terahertz wave active modulator includes: s multiplied by T micro resonators arranged in an array, wherein S is more than or equal to 2, T is more than or equal to 2, and for each micro resonator, the structural parameters of N multiplied by M resonance units are the same; the structural parameters of the internal resonant cells are different for different microresonators, and the bias current source can provide different bias currents for different microresonators.

9. An information encryption system, comprising:

the current-modulated terahertz device as set forth in any one of claims 1 to 5, which serves as an information encryption memory; the microresonator serves as a pixel of an information encryption memory;

the structural parameters of the micro resonator in the information encryption memory bear encryption information, specific terahertz wave frequency and specific bias currents loaded to the positive end and the negative end of the current of the micro resonator are used as keys, and the specific terahertz wave frequency used as the keys is selected from resonance peaks or resonance valleys of the micro resonator.

10. The information encryption system of claim 9, wherein,

the information encryption memory includes: s multiplied by T micro resonators arranged in an array, wherein S is more than or equal to 2, T is more than or equal to 2, each micro resonator is used as a pixel for forming an information encryption memory, and the structural parameters of N multiplied by M resonance units are the same for each micro resonator; the structural parameters of the internal resonance units of the micro-resonators are different;

in the information encryption system, presetting a corresponding relation between the transmittance of terahertz waves and the color; the encryption information carried by the pixels is represented as corresponding colors obtained by terahertz wave transmittance under the conditions of specific terahertz wave frequency and specific bias current; the encryption information carried by the information encryption memory is represented as a graph formed by arranging and combining color blocks of S multiplied by T pixels, and the graph is taken as a representation form of letters, numbers and/or symbols;

On the decryption side, the information encryption system further includes: a decryption module for applying a specific bias current to each micro resonator in an information encryption memory, respectively, and irradiating the information encryption memory with terahertz waves of a specific frequency; the color demodulation module is arranged at the rear end of the light path of the information encryption memory and is used for decrypting the terahertz wave transmittance of each pixel in the information encryption memory into a corresponding color according to the corresponding relation between the preset terahertz wave transmittance and the color, and arranging and combining color blocks of S multiplied by T pixels to form a graph.

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