Dual-layer transmission-type terahertz huygens metasurface modulation method and metasurface

Abstract

The application discloses a kind of double-layer transmission type terahertz huggins super surface regulation methods and super surface, it is related to electromagnetic wave and novel artificial electromagnetic material field, the method includes: obtaining the arm length parameter of cross structure and Jerusalem cross structure of super surface, and phase result simulation operation is carried out based on arm length parameter, according to simulation result determines super surface phase division permit;The distribution of discrete phase setting value on super surface is analyzed using super surface phase division permit and data analysis modeling technology, and based on distribution result, super surface terahertz beam focusing regulation processing is handled.The double-layer transmission type terahertz huggins super surface regulation method and super surface of the present application, innovatively combine phase change material, so that the originally single-function super surface unit can exhibit different characteristics in different states, and compared with single super surface unit structure, a very meaningful exploration is carried out on the dynamic terahertz beam regulation mode, and the regulation efficiency is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electromagnetic waves and new artificial electromagnetic materials, in particular to a double-layer transmission type terahertz Huygens super surface regulation method and super surface. BACKGROUND

[0002] Terahertz waves are widely used in natural science due to their excellent properties, such as high-speed wireless communication, imaging sensing, biomedicine, astronomy, and universe, and with the increasing demand of practical application, single-function terahertz super surface cannot meet the requirements. In order to dynamically modulate the terahertz beam by the super surface, the super surface can be combined with materials with adjustable properties, such as liquid crystal, vanadium dioxide, and semiconductor material, to form a tunable super surface. By applying voltage, temperature, light, and other excitations to change the properties of the material, the dynamic modulation of the super surface can be realized.

[0003] Vanadium dioxide has both metal-insulator properties, and the properties change with temperature, and the response in the terahertz frequency band is good, so it is also a common phase change material for designing dynamically tunable terahertz super surface. The existing technology based on the three-state conversion super surface of vanadium dioxide has a double-opened circular ring unit structure, which realizes the switching of two perfect absorptions to one reflection and one transmission at 1.89 terahertz and 2.67 terahertz frequencies, and is not sensitive to the incident angle. Meanwhile, there is also a "double-faced god" super surface based on vanadium dioxide, which realizes different focusing and imaging functions of terahertz beams by adjusting the temperature of the super surface to incident terahertz waves in front and back directions at 1 terahertz.

[0004] In addition, the coupled mode theory is a theory for studying the general law of coupling between two or more electromagnetic wave modes from the perspective of dynamics. The transmission matrix of the resonant system can be obtained from the dynamic equation of the resonant mode and the dynamic condition satisfying the equation, so that the response state of the resonant system to electromagnetic waves can be analyzed. The coupled mode theory is widely used in mode analysis of super surface, and the Huygens phenomenon appears when the magnetic resonance and electric resonance of the super surface are orthogonal, and the equivalent magnetic impedance and electric admittance on the super surface are the same, which appears the high transmission and large phase shift phenomenon.

[0005] For the Huygens super surface, it can be understood that the near-field coupling and far-field coupling of two resonant modes satisfy a certain degree of strong coupling or weak coupling, and the two resonant modes are degenerate, and the high transmission and large phase shift phenomenon appears. However, the Huygens super surface unit structure with high transmission characteristics in the prior art has a single function, so that the super surface unit cannot exhibit different characteristics in different states.

[0006] At present, there is no effective solution to the problems in the related art. SUMMARY

[0007] In view of the problems in the prior art, the present application provides a double-layer transmission type terahertz Huygens super surface regulation method and a super surface to overcome the above technical problems existing in the prior art.

[0008] To this end, the present application adopts the following specific technical solutions:

[0009] In the first aspect, the present application provides a double-layer transmission type terahertz Huygens super surface regulation method, which comprises:

[0010] Obtaining the arm length parameters of the cross structure and the Jerusalem cross structure of the super surface, and performing phase result simulation operation based on the arm length parameters, and determining the phase distribution of the super surface according to the simulation result;

[0011] Using the super surface phase distribution and data analysis modeling technology to analyze the distribution of the discrete phase setting value on the super surface, and performing super surface terahertz beam focusing regulation processing based on the distribution result.

[0012] Preferably, obtaining the arm length parameters of the cross structure and the Jerusalem cross structure of the super surface, and performing phase result simulation operation based on the arm length parameters, and determining the phase distribution of the super surface according to the simulation result comprises:

[0013] Obtaining the arm length parameters of the cross structure and the Jerusalem cross structure of the super surface, and collecting the terminal length of the Jerusalem cross structure;

[0014] Keeping the terminal length unchanged according to the simulation operation requirement, adjusting the arm length parameter, analyzing the phase change of the super surface based on the adjustment and simulation result, and judging the transmission coefficient amplitude according to the phase change;

[0015] Keeping the Jerusalem cross structure arm length parameter unchanged according to the simulation operation requirement, adjusting the cross structure arm length parameter and the terminal length, analyzing the phase change of the super surface based on the adjustment and simulation result, and judging the transmission coefficient amplitude according to the phase change;

[0016] According to the phase change and the super lens, analyzing the optical path of the electromagnetic wave at each position of the super surface to any position, using the optical path result to analyze the focal length obtained by the focusing state, and setting the phase distribution requirement relationship of the super surface based on the focal length and Fermat's principle.

[0017] Preferably, the phase distribution requirement relationship is:

[0018] ;

[0019] In the formula, φ ( x , y ) represents the phase distribution, x and yrespectively represent the transverse center distance and the longitudinal center distance of any point on the metasurface to the metasurface, λ represents the wavelength of the incident electromagnetic wave in free space, f represents the focal length, Δ φ ma represents the correction phase.

[0020] Preferably, the distribution of the discrete phase setting values on the metasurface is analyzed by using the metasurface phase distribution and data analysis modeling technology, and the metasurface terahertz beam focusing regulation and control processing is based on the distribution result, including:

[0021] The focal length, the wavelength of the incident electromagnetic wave in free space, the metasurface period, and the array size are set, and the code is written by using the data analysis modeling technology and the metasurface phase distribution requirements;

[0022] The distribution of the discrete phase threshold values on the metasurface is analyzed by using the code and the set values, and the theoretical distribution of the discrete phase is obtained based on the distribution;

[0023] The simulation metasurface structure is constructed at the same position in the electromagnetic field simulation software, and the simulation metasurface structure is translated to the position corresponding to the theoretical distribution of the discrete phase by using the data analysis modeling technology and the electromagnetic field simulation software, so that the constructed hyperlens array is obtained;

[0024] The beam focusing is analyzed according to the hyperlens array and the electromagnetic field simulation software, and the phase range is adjusted based on the analysis result to regulate and control the metasurface terahertz beam focusing.

[0025] Preferably, the beam focusing is analyzed according to the hyperlens array and the electromagnetic field simulation software, and the phase range is adjusted based on the analysis result to regulate and control the metasurface terahertz beam focusing, including:

[0026] The double electric and double magnetic boundary conditions are set in the electromagnetic field simulation software based on the hyperlens array, the line polarization plane wave is set in the waveguide port for simulation operation, and the beam focusing of the beam transmitted through the hyperlens array is observed;

[0027] According to the arm length of the Jerusalem cross structure and the cross structure of the metasurface, the phase range is expanded by using the adjusted arm length, and the number of simulation metasurface structures is changed based on the expansion result of the phase range;

[0028] The hyperlens array is generated again by using the increased result, and the beam focusing is analyzed by combining the electromagnetic field simulation software, so that the regulation and control of the metasurface terahertz beam focusing is completed.

[0029] In the second aspect, the application provides a double-layer transmission type terahertz Huygens metasurface regulation method, which includes:

[0030] Obtaining the ambient temperature of the metasurface, changing the vanadium dioxide properties based on the ambient temperature result, connecting the Jerusalem cross structure to form the Huygens condition according to the state result, and regulating the transmission state of the metasurface;

[0031] Initializing the conductivity of the vanadium dioxide, analyzing the action state of the vanadium dioxide based on the conductivity, combining the action state with the numerical simulation technology, determining the switching trend of the projection and reflection states of the metasurface, and performing the metasurface regulation operation.

[0032] Preferably, initializing the conductivity of the vanadium dioxide, analyzing the action state of the vanadium dioxide based on the conductivity, combining the action state with the numerical simulation technology, determining the switching trend of the projection and reflection states of the metasurface, and performing the metasurface regulation operation includes:

[0033] Initializing the conductivity of the vanadium dioxide, judging the transmission state of the metasurface, and recording the transmission coefficient amplitude and the absorption amplitude of the metasurface as the action state of the vanadium dioxide based on the transmission state;

[0034] Based on the numerical simulation technology, gradually increasing the conductivity of the vanadium dioxide, and judging the transmission change trend of the metasurface in the increasing process, and analyzing the transmission coefficient amplitude and the absorption amplitude by using the transmission change trend;

[0035] According to the analysis result and the transmission change trend, the switching trend of the projection and reflection states of the metasurface is determined, and the conductivity of the vanadium dioxide is changed to perform the metasurface regulation operation.

[0036] Preferably, when the conductivity of the vanadium dioxide is 0 Siemens, the reflection and absorption amplitudes of the metasurface are both 0.2, and the projection coefficient amplitude is 0.9;

[0037] When the conductivity of the vanadium dioxide is 1.1*10 5 Siemens, the reflection and absorption amplitudes of the metasurface are both less than 0.2, and the projection coefficient amplitude is greater than 0.9;

[0038] When the conductivity of the vanadium dioxide is 2*10 4 Siemens, the reflection and absorption amplitudes of the metasurface are both 0.25, and the projection coefficient amplitude is 0.8.

[0039] In a third aspect, the present application provides a double-layer transmission type terahertz Huygens metasurface, which is composed of a cross structure, an ultraviolet quartz substrate, a Jerusalem cross structure and vanadium dioxide.

[0040] Preferably, the thickness of the ultraviolet quartz substrate is 150 microns, and the thickness of the vanadium dioxide is 200 nanometers.

[0041] The present application has the following advantages:

[0042] 1. The double-layer transmission type terahertz Huygens super surface regulation method and super surface provided by the application innovatively combine phase change materials, so that the originally single-function super surface unit can exhibit different characteristics in different states, and compared with the single super surface unit structure, the dynamic terahertz beam regulation mode is explored very meaningfully, and the regulation efficiency is increased.

[0043] 2. The application adds vanadium dioxide at the bottom terminal of the super surface unit, can realize high modulation depth conversion of beam transmission and reflection through temperature control, and realizes the terahertz beam focusing effect with a focal length of 2 cm of 2-bit and 3-bit pixels through the design of different geometric sizes and relative positions of the structure. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0045] Figure 1 is a flow chart according to the first embodiment of the embodiment of the application;

[0046] Figure 2 is a phase change diagram obtained by changing the first embodiment according to the embodiment of the application; I c

[0047] Figure 3 is a phase change diagram obtained by changing the first embodiment according to the embodiment of the application; I 0

[0048] Figure 4 is a 2-bit ideal discrete phase distribution diagram of the super lens according to the first embodiment of the embodiment of the application;

[0049] Figure 5 is a front structure diagram of the 2-bit super lens according to the first embodiment of the embodiment of the application;

[0050] Figure 6 is a back structure of the 2-bit super lens according to the first embodiment of the embodiment of the application;

[0051] Figure 7 is a simulation beam distribution diagram after the beam is projected through the super lens array under the condition of 2-bit according to the first embodiment of the embodiment of the application;

[0052] Figure 8 is a simulation beam distribution diagram after the beam is projected through the super lens array under the condition of 3-bit according to the first embodiment of the embodiment of the application;​​

[0053] Figure 9 is a measured beam distribution diagram after the beam is projected through the meta-lens array according to the 2-bit case in embodiment one of the present application;

[0054] Figure 10 is a measured beam distribution diagram after the beam is projected through the meta-lens array according to the 3-bit case in embodiment one of the present application;

[0055] Figure 11 is a flow chart of embodiment two according to the present application;

[0056] Figure 12 is a simulation spectrum diagram when the electrical conductivity is 0 Siemens according to embodiment two of the present application;

[0057] Figure 13 is a simulation spectrum diagram when the electrical conductivity is 1.1x10 5 Siemens according to embodiment two of the present application;

[0058] Figure 14 is a simulation spectrum diagram when the electrical conductivity is 2x10 4 Siemens according to embodiment two of the present application;

[0059] Figure 15 is a structural schematic diagram of a double-layer transmission type terahertz Huygens super surface according to an embodiment of the present application;

[0060] Figure 16 is a front view of a double-layer transmission type terahertz Huygens super surface according to an embodiment of the present application;

[0061] Figure 17 is a back view of a double-layer transmission type terahertz Huygens super surface according to an embodiment of the present application.

[0062] In the figure:

[0063] 1, cross structure; 2, ultraviolet quartz substrate; 3, Jerusalem cross structure; 4, vanadium dioxide. DETAILED DESCRIPTION

[0064] To further illustrate the embodiments, the present application provides drawings, which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can be used to explain the operating principle of the embodiments in conjunction with the related description of the specification. With reference to these contents, those skilled in the art should understand other possible implementations and advantages of the present application.

[0065] According to an embodiment of the present application, a double-layer transmission type terahertz Huygens super surface regulation method and super surface are provided.

[0066] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0067] Example 1

[0068] See also Figure 1 According to a double-layer transmissive terahertz Huygens metasurface control method according to an embodiment of the present invention, the control method includes:

[0069] Step S101: obtaining arm length parameters of the cross structure 1 and the Jerusalem cross structure 3 of the metasurface, performing a phase result simulation operation based on the arm length parameters, and determining the metasurface phase resolution according to the simulation results;

[0070] Step S102: Analyze the distribution of discrete phase setting values ​​on the metasurface using metasurface phase analysis and data analysis modeling technology, and perform metasurface terahertz beam focusing control processing based on the distribution results.

[0071] In this embodiment, when obtaining the arm length parameters of the cross structure 1 and the Jerusalem cross structure 3 of the metasurface, and performing a phase result simulation operation based on the arm length parameters, and determining the phase separation of the metasurface according to the simulation results, the arm length parameters of the cross structure 1 and the Jerusalem cross structure 3 of the metasurface can be obtained, and the terminal length of the Jerusalem cross structure 3 can be collected; the terminal length is kept unchanged according to the simulation operation requirements, the arm length parameters are adjusted, the phase change of the metasurface is analyzed based on the adjustment and simulation results, and the transmission coefficient amplitude is judged according to the phase change; the arm length parameters of the Jerusalem cross structure 3 are kept unchanged according to the simulation operation requirements, the arm length parameters and the terminal length of the cross structure 1 are adjusted, the phase change of the metasurface is analyzed based on the adjustment and simulation results, and the transmission coefficient amplitude is judged according to the phase change; the optical path of the electromagnetic wave from each position of the metasurface to any position is analyzed according to the phase change and the superlens, the focusing state is analyzed using the optical path result to obtain the focal length, and the phase separation requirement relationship of the metasurface is set based on the focal length and the Fermat principle.

[0072] In the embodiment, when analyzing the distribution of the discrete phase setting values on the metasurface based on the super surface phase distribution and data analysis modeling technology, setting the focal length and the wavelength of the incident electromagnetic wave in free space, the metasurface period and the array size, and writing code by using the data analysis modeling technology and the super surface phase distribution requirements, analyzing the distribution of the discrete phase threshold on the metasurface by using the code and the set values, obtaining the theoretical distribution of the discrete phase based on the distribution, constructing the simulation metasurface structure at the same position in the electromagnetic field simulation software, and translating the simulation metasurface structure to the position corresponding to the theoretical distribution of the discrete phase by using the data analysis modeling technology and the electromagnetic field simulation software, the constructed metasurface lens array is obtained, the beam focusing is analyzed according to the metasurface lens array and the electromagnetic field simulation software, and the phase range is adjusted based on the analysis result to perform the metasurface terahertz beam focusing regulation and control processing.

[0073] In the embodiment, when the beam focusing is analyzed according to the metasurface lens array and the electromagnetic field simulation software, the phase range is adjusted based on the analysis result to perform the metasurface terahertz beam focusing regulation and control processing, the double electric and magnetic boundary conditions can be set in the electromagnetic field simulation software based on the metasurface lens array, the line polarization plane wave is set in the waveguide port for simulation operation, and the beam focusing of the beam transmitted through the metasurface lens array is observed, the arm length of the cross structure 1 and the Jerusalem cross structure 3 of the regulation and control metasurface is used to expand the phase range, the number of simulation metasurface structures is changed based on the expansion result of the phase range, the metasurface lens array is generated again by using the increase result, the beam focusing is analyzed in combination with the electromagnetic field simulation software, and the regulation and control processing of the metasurface terahertz beam focusing is completed.

[0074] As can be seen from the transmission coefficient of the metasurface unit, the phase change of the high transmission amplitude at the high transmission position reaches 360 degrees due to the two resonance couplings of the Huygens phenomenon, and therefore, by changing the size parameters and relative positions of the unit structure, a lens with a focal length of 2 cm and 2-bit and 3-bit pixels can be realized.

[0075] As Figure 2 and Figure 3 shown, it needs to be explained that, in the embodiment, by changing the size parameters of the metasurface unit structure, a continuous phase change can be obtained, and the structure parameters that determine the phase change mainly include the arm length of the cross structure 1 I a ( Figure 2 ), the arm length of the Jerusalem cross structure 3 I 0( Figure 3 ), the terminal length I c ( Figure 3 ), the arm length of the Jerusalem cross structure 3 I c= 236 microns unchanged, the other two parameters are changed, the phase change is-292 degrees to-562 degrees, and the transmission coefficient amplitude is kept above 0.75, as shown in Figure 2 I 0 = 543 microns unchanged, the other two parameters are changed, the phase change is-360 degrees to-605 degrees, and the transmission coefficient amplitude is kept above 0.6, as shown in Figure 3

[0076] Table 1 Phase structure parameters

[0077]

[0078] The basic principle of the superlens is that the continuous change of the super surface phase makes the optical path of the electromagnetic wave passing through each position of the super surface to a certain position on the super surface the same, thereby achieving the purpose of focusing. According to Fermat's principle, the super surface phase function needs to satisfy the following relationship:

[0079]

[0080] In the formula, φ x y x y , respectively, represent the phase function, z λ , respectively, represent the transverse center distance and longitudinal center distance of any point on the super surface to the super surface. It is assumed that the center of the super surface is located in the plane of f = 0, which is simplified to three-dimensional space distance, φ ma , represents the wavelength of the incident electromagnetic wave in free space,

[0081] , represents the focal length, and Figures 4 to 6 f , respectively, represent the corrected phase. λ p When the focal length Figure 4 ​​​​​​​​​​As shown in the discrete phase theoretical distribution, four phase metasurface unit structures are first established at the same position in CST, and then these four structures are translated to the positions corresponding to the discrete phase theoretical distribution through Matlab-CST joint simulation to complete the construction of the metalens array, as shown in Figure 5 and Figure 6 As shown, after obtaining the super lens array, in CST, set the double electric and double magnetic boundary conditions, set the linearly polarized plane wave at the waveguide port, and simulate and observe the situation after the beam passes through the super lens array after the power flow field monitor, as shown Figure 7 As shown, it can be found that the focus of the setting z = 20mm, the beam is clearly focused. z =15 and 25mm, the beam does not focus, but z = 0~15mm, the beam is slightly focused. The reason for this phenomenon is that the discrete phase is set too little, resulting in an insufficient phase distribution and a slight focusing of the beam at nearby locations.

[0082] In order to improve this phenomenon and enhance the focusing quality, it is necessary to increase the number of discrete phases and the corresponding phase range. I c The maximum phase range obtained by changing the dimensions of the other two structures is 270°. Since the relative position of the two structures can also affect the coupling state, the phase of the high transmission can be changed. By simulating the relative position change of the two structures (translation and rotation), it is found that when the centers of the two structures are x and y Directional offset 15 μm When , the phase range can be expanded to 315°, and then 4 more structures can be found on the basis of the original 2-bit structure to form a 3-bit structure. The added 4 structural parameters are shown in Table 2, and then the additional 4 structural parameters of the 3-bit lens are formed under the original 2-bit situation. Because the relative position change of the two structures will also affect the coupling state, according to the simulation of the relative position change (translation), it is found that when the centers of the two mechanisms are x and y When the direction is shifted by 15 microns, the phase range can be expanded.

[0083] Table 2 Structure table after modification

[0084]

[0085] like Figure 7 and Figure 8 As shown, based on the above embodiment, 2-bit and 3-bit pixel metalenses are designed. It can be found that the two designs have different focal lengths. z = 20 mm, the beam is clearly focused,z =15 and 25 mm, compared with 2-bit lens, 3-bit lens has no focusing phenomenon in the area close to the metasurface z =0-15 mm, the focusing phenomenon is obviously improved, compared with the energy density at the focal point, even it can be said that the focusing phenomenon in this area disappears, 3-bit metasurface can complete the high-quality terahertz beam focusing function.

[0086] As shown in Figure 9 With Figure 10 , respectively, the actual measured focusing of 2bit and 3bit at different positions, the designed focal point z =20 mm, both lenses have good focusing effect, in z =25 mm, both lenses do not focus, in z =15 mm, 2bit lens has slight focusing, 3bit lens has no focusing function, which is consistent with the simulation, indicating that 3bit lens can complete the focusing function of the set focal point with higher quality.

[0087] Embodiment two

[0088] Please refer to Figure 11 , according to another embodiment of the present application, a double-layer transmission type terahertz Huygens metasurface regulation method is also provided, the regulation method comprises:

[0089] Step S201, obtaining the environmental temperature of the metasurface, changing the properties of vanadium dioxide 4 based on the environmental temperature result, connecting Jerusalem cross structure 3 to form Huygens condition according to the state result, and regulating the transmission state of the metasurface;

[0090] Step S202, initializing the conductivity of vanadium dioxide 4, analyzing the action state of vanadium dioxide 4 based on the conductivity, combining the action state with numerical simulation technology, determining the switching trend of the projection and reflection state of the metasurface, and performing metasurface regulation operation.

[0091] In this embodiment, when initializing the conductivity of vanadium dioxide 4, analyzing the action state of vanadium dioxide 4 based on the conductivity, combining the action state with numerical simulation technology, determining the switching trend of the projection and reflection state of the metasurface, and performing metasurface regulation operation, the conductivity of vanadium dioxide 4 can be initialized, the transmission state of the metasurface is judged, and the transmission coefficient amplitude and absorption amplitude of the metasurface are recorded based on the transmission state as the action state of vanadium dioxide 4; based on numerical simulation technology, gradually increase the conductivity of vanadium dioxide 4, and judge the transmission change trend of the metasurface in the increasing process, analyze the transmission coefficient amplitude and absorption amplitude by using the transmission change trend; according to the analysis result and the transmission change trend, determine the switching trend of the projection and reflection state of the metasurface, and change the conductivity of vanadium dioxide 4 by using the switching trend to perform metasurface regulation operation.

[0092] It should be explained that by changing the properties of vanadium dioxide 4 through temperature, the Huygens condition for coupling between the two structures is destroyed. At the same frequency, at low temperatures, vanadium dioxide 4 behaves in an insulating state, with no effect on the unit structure, and the metasurface still maintains the Huygens phenomenon of high transmission for incident terahertz waves. At higher temperatures, vanadium dioxide 4 exhibits metallic properties, connecting the adjacent Jerusalem cross structure 3 and changing the resonant properties of the structure, thereby destroying the conditions for the Huygens phenomenon with the other cross structure 1. The high transmission disappears, and the metasurface exhibits a high reflection phenomenon for incident terahertz waves, which is the opposite of high transmission.

[0093] like Figures 12 to 14 As shown, (Magnitude represents amplitude, Transmission represents transmission, Reflection represents reflection, Absorption represents absorption, Frequency represents frequency, THz represents terahertz, and Phase represents phase) In the embodiment of the present invention, by changing the conductivity of the phase change material vanadium dioxide 4, the switching between the projection and reflection states can be achieved. When the conductivity is 0 Siemens, at the communication window frequency of 0.22 THz, the corresponding Figure 12 In the transmission state shown in the figure, the transmission coefficient amplitude reaches 0.9, and the reflection and absorption amplitudes are both 0.2. As the conductivity increases, the transmittance gradually decreases and the reflectivity increases. When the conductivity increases to 1.1×105 Siemens, the corresponding Figure 13 In the high reflection state shown, the transmission and absorption amplitudes are both below 0.2, while the reflection coefficient amplitude reaches above 0.9; in addition, when the conductivity is 2×104 Siemens, the corresponding Figure 14 While the metasurface remains highly reflective at 0.22 THz, it is found that at 0.19 THz, both the transmission and reflection coefficients are around 0.25, while the absorption coefficient reaches 0.8, indicating that the metasurface absorbs the incident terahertz beam. This demonstrates that the metasurface can transition between transmission and reflection at the same frequency, achieving a transition between transmission, absorption, and reflection within a certain bandwidth.

[0094] See also Figures 15 to 17 According to another embodiment of the present invention, a double-layer transmissive terahertz Huygens metasurface is provided. The metasurface consists of a cross structure 1, an ultraviolet quartz substrate 2, a Jerusalem cross structure 3 and vanadium dioxide 4. Specifically, the thickness of the ultraviolet quartz substrate 2 is 150 microns, the thickness of the vanadium dioxide 4 is 200 nanometers, the cross structure 1 is located on the top of the ultraviolet quartz substrate 2, the Jerusalem cross structure 3 is located at the bottom of the ultraviolet quartz substrate 2, and the vanadium dioxide 4 is located at the terminal of the Jerusalem cross structure 3.

[0095] With the above technical scheme of the present application, the double-layer transmission type terahertz Huygens super surface regulation method and super surface proposed by the present application innovatively combine phase change materials, so that the originally single-function super surface unit can exhibit different characteristics in different states, and compared with the single super surface unit structure, a very meaningful exploration is made on the dynamic terahertz beam regulation method, and the regulation efficiency is increased. The present application adds vanadium dioxide 4 at the bottom terminal of the super surface unit, which can realize high modulation depth conversion of beam transmission and reflection through temperature control, and through the design of different geometric sizes and relative positions of the structure, the terahertz beam focusing effect of 2-bit and 3-bit pixels with a focal length of 2 cm is realized.

[0096] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for regulating a double-layer transmission terahertz Huygens super surface, the super surface is composed of a cross structure, an ultraviolet quartz substrate, a Jerusalem cross structure and vanadium dioxide, the cross structure is located at the top of the ultraviolet quartz substrate, the Jerusalem cross structure is located at the bottom of the ultraviolet quartz substrate, and the vanadium dioxide is located at the terminal of the Jerusalem cross structure, characterized in that, The regulation method comprises: Obtaining the arm length parameters of the cross structure and Jerusalem cross structure of the super surface, and performing phase result simulation operation based on the arm length parameters, and determining the super surface phase distribution according to the simulation result; Using the super surface phase distribution and data analysis modeling technology to analyze the distribution of the discrete phase setting value on the super surface, and performing super surface terahertz beam focusing regulation processing based on the distribution result; Using the super surface phase distribution and data analysis modeling technology to analyze the distribution of the discrete phase setting value on the super surface, and performing super surface terahertz beam focusing regulation processing based on the distribution result comprises: Setting the focal length and the wavelength of the incident electromagnetic wave in free space, and the super surface period and array size, and using data analysis modeling technology and super surface phase distribution to write code; Using the code and the set value to analyze the distribution of the discrete phase threshold on the super surface, and obtaining the discrete phase theoretical distribution based on the distribution; In the same position of the electromagnetic field simulation software, the simulation super surface structure is constructed, and the simulation super surface structure is translated to the position corresponding to the discrete phase theoretical distribution by using the data analysis modeling technology and the electromagnetic field simulation software, so that the super lens array is constructed; According to the super lens array and the electromagnetic field simulation software, the beam focusing situation is analyzed, and the phase range is adjusted based on the analysis result to perform super surface terahertz beam focusing regulation processing; The super surface terahertz beam focusing regulation processing based on the analysis result of the phase range comprises: Based on the super lens array, double electric and magnetic boundary conditions are set in the electromagnetic field simulation software, the waveguide port is set as linear polarization plane wave for simulation operation, and the beam focusing situation of the beam transmitted through the super lens array is observed; According to the arm length of the cross structure and Jerusalem cross structure of the regulation super surface, the phase range is expanded by using the regulated arm length, and the number of simulation super surface structures is changed based on the phase range expansion result; The super lens array is generated again by using the increase result, and the beam focusing situation is analyzed in combination with the electromagnetic field simulation software, so that the super surface terahertz beam focusing regulation processing is completed.

2. The method according to claim 1, wherein, The super surface terahertz beam focusing regulation processing based on the analysis result of the phase range comprises: Obtaining the arm length parameters of the cross structure and Jerusalem cross structure of the super surface, and collecting the terminal length of the Jerusalem cross structure; According to the simulation operation requirement, the terminal length is kept unchanged, the arm length parameter is adjusted, the phase change of the super surface is analyzed based on the adjustment and simulation result, and the transmission coefficient amplitude is judged according to the phase change; According to the simulation operation requirement, the Jerusalem cross structure arm length parameter is kept unchanged, the cross structure arm length parameter and the terminal length are adjusted, the phase change of the super surface is analyzed based on the adjustment and simulation result, and the transmission coefficient amplitude is judged according to the phase change; According to the phase change and the super lens, the optical path of the electromagnetic wave at each position of the super surface to any position is analyzed, the focal length is obtained by using the optical path result, and the phase distribution requirement relationship of the super surface is set based on the focal length and Fermat principle.

3. The method of claim 2, wherein the method is a dual-layer transmission-type terahertz Huygens super surface modulation method. The phase division requirement relationship is: ； wherein, φ x y denotes the phase distribution, x and y denote the transverse and longitudinal center distance of a point on the metasurface to the metasurface, respectively, λ denotes the wavelength of the incident electromagnetic wave in free space, f denotes the focal length, and φ na denotes the correction phase.​​ 4. A double-layer transmission type terahertz Huygens super surface regulation method, the super surface is composed of a cross structure, an ultraviolet quartz substrate, a Jerusalem cross structure and vanadium dioxide, the cross structure is located at the top of the ultraviolet quartz substrate, the Jerusalem cross structure is located at the bottom of the ultraviolet quartz substrate, and the vanadium dioxide is located at the terminal of the Jerusalem cross structure, characterized in that, The regulation method comprises: Obtain the environmental temperature of the metasurface, change the vanadium dioxide properties based on the environmental temperature result, connect the Jerusalem cross structure according to the state result to form the Huygens condition, and regulate the transmission state of the metasurface; Initialize the conductivity of vanadium dioxide, analyze the action state of vanadium dioxide based on the conductivity, combine the action state with numerical simulation technology, determine the switching trend of the projection and reflection states of the metasurface, and perform the metasurface regulation operation.

5. The method of claim 4, wherein the method is a two-layer transmission-type terahertz Huygens super surface modulation method. The initialization of the conductivity of vanadium dioxide, the analysis of the action state of vanadium dioxide based on the conductivity, the combination of the action state with numerical simulation technology, the determination of the switching trend of the projection and reflection states of the metasurface, and the performance of the metasurface regulation operation comprise: Initialize the conductivity of vanadium dioxide, judge the transmission state of the metasurface, and record the transmission coefficient amplitude and the absorption amplitude of the metasurface based on the transmission state as the action state of vanadium dioxide; Based on the numerical simulation technology, gradually increase the conductivity of vanadium dioxide, and judge the transmission change trend of the metasurface in the increasing process, analyze the transmission coefficient amplitude and the absorption amplitude by using the transmission change trend; According to the analysis result and the transmission change trend, determine the switching trend of the projection and reflection states of the metasurface, change the conductivity of vanadium dioxide by using the switching trend, and perform the metasurface regulation operation.

6. The method of claim 5, wherein the method is a two-layer transmission-type terahertz Huygens super surface modulation method. When the conductivity of vanadium dioxide is 0 Siemens, the reflection and absorption amplitudes of the metasurface are both 0.2, and the projection coefficient amplitude is 0.

9. The conductivity of the vanadium dioxide is 1.1*10 5 In the Siemens time, the reflection and absorption amplitudes of the super surface are less than 0.2, and the projection coefficient amplitude is greater than 0.

9. The conductivity of the vanadium dioxide is 2*10 4 The reflection and absorption amplitudes of the super surface are both 0.25, and the projection coefficient amplitude is 0.8.

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