An active electromagnetic metasurface implementing programmable topological polaritonic waveguide

Abstract

The application relates to an active electromagnetic metasurface for realizing programmable topology polariton waveguide, which is composed of basic functional units combined with varactor diodes and periodically extended in a two-dimensional plane; the basic functional unit comprises two layers of dielectric, four layers of metal and a metallized via; by changing the applied bias voltage, reconfigurable topology transmission of magnetic polariton dispersion topology from ellipse to straight line and hyperbola can be realized; by means of wavefront characteristics under different dispersion topologies, adjustable field channeling and reconfigurable flat panel focusing functions and programmable topology polariton waveguide design can be realized. The application supports flexible propagation and guiding manipulation of surface waves, has the advantages of low dimension, real-time response, continuous controllability and high stability, provides an effective platform for active optoelectronic integrated circuit research, is beneficial to the design of planar integrated high-speed communication components, high-resolution imaging and high-sensitivity sensing and positioning systems, and has wide application prospects in the fields of near-field information processing and energy collection.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of artificial electromagnetic super-materials, and particularly relates to an active electromagnetic metasurface for realizing programmable topological polariton waveguide. BACKGROUND

[0002] Electromagnetic super-materials are a kind of structural array that is arranged on demand at a sub-wavelength scale by artificial atoms to regulate electromagnetic fields, which are inspired by the composition of natural materials. These artificial atoms usually have a unique electromagnetic response and can be implemented according to a specific arrangement (usually periodic arrangement) to exhibit unique properties beyond traditional natural materials. As a planarized electromagnetic super-material, electromagnetic metasurfaces are a new material construction paradigm that has attracted widespread attention in the scientific community and engineering fields. They can flexibly regulate the basic properties of electromagnetic waves, including amplitude, phase, dispersion, frequency and polarization, while also having the advantages of low loss, low profile, thinness, easy processing and easy integration. They have been widely used in planar integrated circuit research, advanced electromagnetic components and high-resolution imaging system design, etc.

[0003] Polaritons are a kind of "half-light-half-matter" quasi-particles formed by strong coupling between light and matter, which have the characteristics of high localization and have broad application prospects in the fields of optical sensing, imaging, information storage and ultra-sensitive detection. Due to their unique properties in manipulating the interaction between light and matter, polaritons have been extensively studied in low-dimensional materials, photonic crystals and super-materials. In recent years, hyperbolic polaritons in anisotropic materials have attracted widespread attention due to their unique optical properties, such as supporting strong electromagnetic field localization, enhanced spontaneous radiation and high-momentum photon modes.

[0004] The current progress of science and technology has put forward higher requirements for emerging electromagnetic devices. Due to the limited space resources in practical applications, the differences in application requirements of different scenarios, and other limitations, it has become an important concern in the research of metasurface electromagnetic devices to develop reconfigurable multifunctional integration and small-sized planar compact devices that can meet the needs of compatible applications. In recent years, the exploration of dynamic control of hyperbolic plasmons in the field of photonics and excitonics has promoted the research of reconfigurable topological transmission (the change of dispersion equal-frequency line from ellipse to hyperbola), which has great potential in developing future photonic integrated circuits, developing multifunctional plasmonic devices and high-speed communication applications, and is one of the important topics in the field of interface photonics. Currently, Moire rotation and Origami / Kirigami three-dimensional folding, etc. control the internal coupling of the structure through geometric deformation to manipulate plasmons, which has the disadvantages of slow response speed, low accuracy, poor robustness and difficulty in integrated design. On the other hand, due to the weak magnetic anisotropy response of natural hyperbolic materials, the dispersion control of electrically reconfigurable topological plasmons still focuses more on the exploration of electric anisotropy (with the help of molybdenum trioxide and hexagonal boron nitride materials), ignoring the exploration of magnetic anisotropy-related phenomena and their dynamic control. In fact, the exploration of related phenomena such as optical excitation of magnetic response and enhancement of magnetic transition can help further explore and understand the mechanism of light-matter interaction, and play an important role in the development of advanced electromagnetic components such as microwave quantum applications, magnetic emitters and topological microwave devices. In particular, the current exploration of reconfigurable topological transmission is almost limited to the exploration of the global dispersion characteristics of plasmons, and cannot realize the control of the local dispersion characteristics of the structure. In fact, the control of the local dispersion characteristics of plasmons can greatly improve the degree of freedom of surface wave excitation, propagation and guidance manipulation, and help the design of related functions and reconfigurable plasmonic devices, such as planar programmable topological plasmonic waveguides that can realize real-time transmission of surface wave energy flow on demand.

[0005] In summary, in order to further improve the flexibility and effectiveness of reconfigurable topological transmission, it is necessary to explore an effective solution for dynamically controlling the local dispersion characteristics of magnetic plasmons, while also having the characteristics of low dimensionality, easy integration, high-speed response, continuous controllability and high robustness. SUMMARY

[0006] The purpose of the present application is to overcome the above-mentioned problems, and provide an active electromagnetic metasurface for realizing programmable topology polariton waveguide. By loading a varactor tube on the basic functional unit of the electromagnetic metasurface, the bias voltage loaded can be adjusted, the dispersion characteristics of the basic functional unit can be controlled to realize topology reconfigurable magnetic polariton, so that the designed electrically reconfigurable metasurface supports the fast switching of the magnetic polariton dispersion equifrequency line on the ellipse, straight line and hyperbola, and realizes the adjustable field channeling function and reconfigurable flat lens design. In particular, by designing the feed line of the electromagnetic metasurface in the form of supporting unit control, the dispersion characteristics of each basic functional unit can be locally controlled, the topology state distribution of the basic functional unit of the metasurface can be independently tailored on demand, the programmable topology polariton waveguide design is realized, and the free and flexible design of the effective transmission path of the magnetic polariton is supported. Real-time fast switching.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: an active electromagnetic metasurface for realizing programmable topology polariton waveguide, which is composed of a basic functional unit loaded with a varactor diode periodically extended in a two-dimensional plane; the basic functional unit includes a vertically placed open resonant ring and a horizontally placed bottom plate feed line; the open resonant ring includes a first metal patch layer from front to back, a dielectric layer and a second metal patch layer, the first and second metal patch layers are connected by a metalized via, the first metal patch layer has magnetic anisotropy, and the varactor diode is connected across the two metal patch areas on both sides of the opening above the inner ring of the first metal patch layer; the bottom plate feed line includes a first metal patch layer from top to bottom, a dielectric layer and a second metal patch layer, and the bottom plate feed line includes two different design modes of whole plate control and unit control.

[0008] As a preferred, the first metal patch layer of the open resonant ring is a center-symmetric two-double-open metal ring geometric pattern; the metal wires at both ends of the metal ring opening can be straight lines, triangles or arrows.

[0009] As a preferred, the number of metal ring structures of the first metal patch layer of the open resonant ring is one, two or more; the ring is a square ring or a circular ring, and the inner line width of the square ring / circular ring is greater than the diameter of the metalized via.

[0010] As a preferred, the varactor diode is connected across the two metal patch areas on both sides of the opening above the inner ring of the first metal patch layer of the open resonant ring, connected with the second metal patch layer of the open resonant ring through the metalized via, and connected with the first metal patch layer of the bottom plate feed line; the isolation between the second metal patch layer of the open resonant ring and the first metal patch layer of the bottom plate feed line is realized by patch resistance.

[0011] As preferred, in the whole-board control design, the first and second metal patch layers of the bottom plate feed line are longitudinally continuous and laterally have a certain interval, and the metal strips are connected with the rectangular metal patches on both sides; the metal strips of the first and second metal patch layers are alternately connected laterally by the metalized via holes on the rectangular metal patches; the metal strips of the first and second metal patch layers of the bottom plate feed line are connected with the positive and negative poles of the direct current voltage source, respectively.

[0012] As preferred, in the unit control design, the annular metal structure is removed from the left side area of the first metal patch layer of the bottom plate feed line, and the annular metal structure is a square ring or a circular ring; the left metal pattern of the open resonant ring second metal patch layer is connected with the metal patch within the ring of the first metal patch layer of the bottom plate feed line, and the right metal pattern is connected with the metal patch area outside the ring of the first metal patch layer of the bottom plate feed line; the metal patch within the ring of the first metal patch layer of each basic functional unit of the bottom plate feed line is connected with the independent feed line of the second metal patch layer by the metalized via hole, and the isolation is realized by the patch resistance; the second metal patch layer of the bottom plate feed line is connected with the feed line of each unit, and different voltages are applied to the direct current voltage source, so as to realize the independent control of the bias voltage of the varactor diode loaded on each basic functional unit.

[0013] In the embodiment, when the super surface bottom plate feed line adopts the whole-board control design, the electromagnetic super surface supports the generation and propagation of hyperbolic magnetic polariton, and the reconfigurable topology transmission of the magnetic polariton is realized by applying different bias voltages, and the dispersion topology of the magnetic polariton is dynamically switched between the ellipse, the straight line and the hyperbola.

[0014] In the embodiment, when the super surface bottom plate feed line adopts the unit control design, the bias voltage V C1 is independently applied to the basic functional units in a specific area or on a path, so that the dispersion topology of the basic functional units in the specific area or on the path is a hyperbola, and the effective transmission of the magnetic polariton is supported; the bias voltage V C2 is applied to other basic functional units outside the specific area or path, so that the dispersion topology of the basic functional units is an ellipse, and the transmission of the magnetic polariton is inhibited.

[0015] Further, the programmable topology polariton waveguide design can be realized, the magnetic polariton transmission path supports free and flexible design, the same bias voltage V C1 is applied to the basic functional units within the effective transmission area or path of the magnetic polariton; the same bias voltage V C2 is applied to the basic functional units outside the effective transmission area or path of the magnetic polariton, where V C1 >V C2The magnetic plasmonic effective transmission path can be an "L" shape, an "S" shape, and an "Omega" shape, and the like, which contains a right-angle turn.

[0016] Further, the excitation source of the magnetic plasmon is a dipole antenna, which can be placed at any unit around or inside the active electromagnetic metasurface as needed; the number of excitation sources is one, two or more, and accordingly, the magnetic plasmonic effective transmission area or path can be one, two or more; by changing the bias voltage applied to the basic functional unit, the working frequency of the magnetic plasmon effectively transmitted in a specific area or path can be adjusted.

[0017] The active electromagnetic metasurface for realizing the programmable topology plasmonic waveguide provided by the application uses a varactor as a control device, and by changing the direct current bias voltage loaded on the varactor, the dispersion characteristics of each basic functional unit can be independently controlled, the topology state distribution of the basic functional unit of the metasurface can be flexibly tailored, and the surface wave energy flow can be transmitted and quickly switched as needed; compared with the prior art, the application has the following advantages:

[0018] (1) The reconfigurable metasurface for dynamically controlling the topology characteristics of the magnetic plasmon provided by the application supports the reconfigurable topology transmission of the magnetic plasmon dispersion equal-frequency line from an ellipse to a straight line and a hyperbola in a certain frequency range, the voltage-controlled varactor device has a fast response feature, the response time is significantly reduced compared with the Moire rotation and the Origami / Kirigami three-dimensional folding control mode, the switching time of the dispersion equal-frequency line can be controlled in the order of microseconds, and the repeatability and accuracy of the control can also be obviously improved.

[0019] (2) By means of the wave front characteristics under different dispersion topologies (collimation line and hyperbola), the application designs, realizes and verifies the adjustable field channelization and the dynamic surface wave function; the unit control design method is used for the electromagnetic metasurface bottom plate feed line, the dispersion characteristics of each basic functional unit can be independently controlled, the design of the planar programmable plasmonic circuit is realized, and the flexible design and on-demand switching of the transmission path of the magnetic plasmon in the two-dimensional plane are supported.

[0020] (3) The application originally proposes and experimentally presents the electrically tunable metasurface of the topology characteristics of the magnetic plasmon, and has the features of on-demand reconfigurable local dispersion characteristics, easy integration, continuous controllability, high robustness and high-speed response, and can be further developed in the planar photonic integrated circuit and high-speed communication components, and has a wide application prospect in high-resolution imaging, high-sensitivity near-field sensing and energy harvesting and the like applications.

[0021] (4) The design scheme provided by the application also has good scalability, in addition to the microwave band application shown in the embodiments, can be extended to millimeter wave and terahertz and other higher frequency bands, and the active control device can adopt millimeter wave semiconductor devices, liquid crystals and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a function schematic diagram of the metasurface of the embodiment of the application when the applied bias voltage changes, realizing the function of switching the magnetic plasmon transmission channel.

[0023] Figure 2 is a three-dimensional structure schematic diagram of a basic functional unit when the metasurface of the embodiment of the application adopts an integral plate control feed line design, a varactor diode is loaded on the first metal patch layer of the resonant ring of the basic functional unit, and adjustable capacitance load can be realized.

[0024] Figure 3 is a momentum space equi-frequency line distribution diagram of the first mode of the first Brillouin zone when the basic functional unit of the metasurface of the embodiment of the application adopts an integral plate control feed line design and the loaded capacitance values are (a) 0 pF, (b) 0.24 pF and (c) 0.48 pF.

[0025] Figure 4 is a momentum space equi-frequency line of the basic functional unit of the metasurface of the embodiment of the application at an observation frequency of 3.5 GHz under different loaded capacitance values, which are (a) an ellipse, (b) a straight line and (c) a hyperbola.

[0026] Figure 5 is a photo of (a) a test environment, (b) an excitation source and (c) a magnetic field probe of a processed sample when the metasurface of the embodiment of the application adopts an integral plate control feed line design.

[0027] Figure 6 is a reconfigurable metasurface near-field magnetic field distribution simulation result diagram of dynamically regulating the topological characteristics of magnetic plasmons when the metasurface of the embodiment of the application adopts an integral plate control feed line design, corresponding to (a) an elliptical topology (0 pF), (b) a straight line topology (0.24 pF) and (c) a hyperbolic topology (0.48 pF).

[0028] Figure 7 is a reconfigurable metasurface near-field magnetic field distribution test result diagram of dynamically regulating the topological characteristics of magnetic plasmons when the metasurface of the embodiment of the application adopts an integral plate control feed line design, corresponding to (a) an elliptical topology (0 pF), (b) a straight line topology (corresponding to a bias voltage of 8 V) and (c) a hyperbolic topology (corresponding to a bias voltage of 3.3 V).

[0029] Figure 8The magnetic field distribution test results of the super surface of the embodiment of the application in the implementation of the adjustable field channeling function at (a) 3.81 GHz, (b) 3.75 GHz and (c) 3.63 GHz frequencies when the super surface is designed by using the whole-board control feed line.

[0030] Figure 9 The magnetic field distribution test results of the super surface of the embodiment of the application in the implementation of the in-plane dynamic surface wave focusing function at (a) 3.92 GHz, (b) 3.79 GHz and (c) 3.64 GHz frequencies when the super surface is designed by using the whole-board control feed line.

[0031] Figure 10 The schematic diagram of the programmable topology plasmonic waveguide when the super surface of the embodiment of the application is designed by using the unit control feed line, wherein: the basic functional units in the propagation channel shown by the green area are designed in the transmission state to support the effective transmission of the magnetic plasmonic; the basic functional units outside the propagation channel shown by the orange area are designed in the cutoff state to inhibit the effective transmission of the magnetic plasmonic.

[0032] Figure 11 The three-dimensional structure schematic diagram of the basic functional unit when the super surface of the embodiment of the application is designed by using the unit control feed line.

[0033] Figure 12 The dispersion curves of the magnetic plasmonic propagating along the y direction in the first Brillouin zone in the first mode under the condition that the basic functional units have the load capacitance values of 0.2 pF and 1.3 pF respectively, and the simulation results of the near-field magnetic field distribution of the super surface under the condition that the load capacitance of the magnetic plasmonic is 0.2 pF (the dispersion topology is a hyperbola) and 1.3 pF (the dispersion topology is a hyperbola) when the super surface is designed by using the unit control feed line.

[0034] Figure 13 The (a) schematic diagram and (b) magnetic field distribution simulation results of the programmable topology plasmonic waveguide in the implementation of the "L" shaped transmission path in the embodiment of the application.

[0035] Figure 14 The (a) schematic diagram and (b) magnetic field distribution simulation results of the programmable topology plasmonic waveguide in the implementation of the "S" shaped transmission path in the embodiment of the application.

[0036] Figure 15 The (a) schematic diagram and (b) magnetic field distribution simulation results of the programmable topology plasmonic waveguide in the implementation of the "Ω" shaped transmission path in the embodiment of the application.

[0037] Figure 16 The (a) front view, (b) back view and (c) test environment photos of the bottom plate feed line when the super surface of the embodiment of the application is designed by using the unit control feed line.

[0038] Figure 17 are the test results of magnetic field distribution of the programmable topology polaritonic waveguide to realize (a) "L" shape, (b) "S" shape and (c) "Ω" shape three transmission paths in the embodiment of the application. DETAILED DESCRIPTION

[0039] The technical solutions of the application will be further described below in combination with the accompanying drawings and specific embodiments. It should be understood that the application can be implemented in various forms, and some exemplary and non-limiting embodiments shown in the accompanying drawings and described below are not intended to limit the application to the specific embodiments described.

[0040] Referring to Figure 1 The embodiment of the application discloses an active electromagnetic metasurface for realizing a programmable topology polaritonic waveguide, supporting reconfigurable propagation and guiding manipulation of magnetic polaritons. Specifically, the metasurface is fed by dipoles located at the bottom edge region, and by applying a bias voltage to each basic functional unit, the topology state thereof is independently regulated, and the desired effective transmission channel of the surface wave can be constructed as needed, supporting longitudinal, transverse and turning paths, etc. By changing the bias voltage distribution loaded on the basic functional units of the metasurface, flexible switching of the surface wave transmission path can be realized, with the characteristics of real-time response and high robustness.

[0041] The embodiments of the two electromagnetic metasurfaces involved in the application are specifically introduced, including the metasurfaces designed by the whole-board control feed line and the unit control feed line. For the metasurface designed by the whole-board control feed line, the positive electrodes of all the basic functional units loaded with varactor diodes are connected and grounded, so the bias voltage loaded is the same. When the bias voltage is regulated, the capacitance value of the varactor diode loaded on the metasurface will decrease (increase) with the increase (decrease) of the bias voltage, thereby changing the dispersion characteristics of the basic functional units, and reconfigurable topology transmission (continuous switching of the dispersion topology of magnetic polaritons between an ellipse, a straight line and a hyperbola) can be realized. By designing the feed line of the electromagnetic metasurface in the form of unit control and optimizing the size of the basic functional units accordingly, the dispersion characteristics of each basic functional unit can be independently regulated, and thus a programmable topology polaritonic waveguide can be realized.

[0042] The reconfigurable metasurface designed by the whole-board control feed line is composed of Figure 2The basic functional units shown are constituted in a periodic manner in an xy two-dimensional plane. Specifically, the metasurface basic functional unit includes two main parts of a vertically placed open resonant ring and a horizontally placed bottom plate feed line, the open resonant ring including a first metal patch layer from front to back, a dielectric layer, and a second metal patch layer; the bottom plate feed line including a feed line first metal patch layer from top to bottom, a feed line dielectric layer, and a feed line second metal patch layer. The first metal patch layer of the open resonant ring is a center-symmetrical two-open-loop geometric pattern, having significant magnetic anisotropy; the metal wires at both ends of the metal annular opening of the first metal patch layer can also be linear, triangular, or arrow-shaped structures; the annular structure of the first metal patch layer can be a square ring or a circular ring, and the inner line width of the square ring / circular ring is greater than the diameter of the metalized via; the first metal layer of each basic functional unit open resonant ring has a varactor tube connected to the metal patch area on both sides of the opening above the inner ring; the first and second metal patch layers of the open resonant ring are connected by a metalized via, and the second metal patch layer is connected to the first metal patch layer of the bottom plate feed line through an isolation resistor; the resistance value of the isolation resistor is 100kΩ, and can also be other suitable values; as shown in the figure, Figure 2 In the embodiment, the first and second metal patch layers of the bottom plate feed line are both longitudinally continuous and laterally spaced metal strips, and small rectangular metal patches are extended from both sides of the metal strips; the metal strips of the first and second metal patch layers of the bottom plate feed line are connected in a staggered manner by the rectangular metal patches; the metal strips of the first and second metal patch layers of the bottom plate feed line are connected to the positive and negative poles of a direct current voltage source, respectively, to provide a bias voltage; the metasurface is excited by a magnetic dipole antenna near the edge area at the bottom, and the feeding position can also be other positions of the metasurface, such as the top edge area of the metasurface.

[0043] Figure 2 The period p of the basic functional unit shown is x 13.8mm, p y 8mm, the metal layers of the open resonant ring and the bottom plate feed line are both copper foils with a thickness of 0.018mm, and the dielectric layers are both F4B type plates with a thickness t s 1mm, the dielectric constant of the dielectric layer of the open resonant ring is 2.2, and the dielectric constant of the dielectric layer of the bottom plate feed line is 3.0; the structural parameters of the first metal patch layer geometric pattern of the open resonant ring are L i 7.2mm, L o= 10.8mm, line width w = 0.4mm, metal ring opening gap width g = 0.2mm; the second metal patch layer of the open resonant ring, the width of the rectangular feed line a = 0.6mm, the width of the square patch b = 1.2mm; the first metal patch layer of the bottom plate feed line, the width of the rectangular metal strip s = 5.5mm, the width of the rectangular metal patch extending out of the two sides is 0.6mm, and the length is 1mm; the diameter of the metalized via is 0.3mm.

[0044] Based on the above basic functional unit design, the dispersion characteristics are simulated by using the commercial simulation calculation software CST Microwave Studio. Figure 3 The momentum space iso-frequency line distribution diagrams of the first mode of the first Brillouin zone are given under the conditions that the basic functional unit is loaded with capacitances of (a) 0pF, (b) 0.24pF and (c) 0.48pF, wherein the red dotted line represents the momentum space iso-frequency line at the observation frequency of 3.5GHz. x , k y , k The wave vectors of the magnetic polaritons propagating along the x and y directions are represented by kx and ky respectively. It can be seen that due to the in-plane anisotropy of the basic functional unit, the magnetic polaritons propagating along the y direction exhibit higher intrinsic frequency than the magnetic polaritons propagating along the x direction. When the loaded capacitance is fixed, for example, 0pF, the dispersion iso-frequency lines of the magnetic polaritons exhibit frequency-dependent topological states, which respectively present elliptical, straight and hyperbolic geometric characteristics as the frequency increases; as the loaded capacitance increases (decreases), the cut-off frequencies of the magnetic polaritons propagating along the x and y directions both exhibit a monotonous decreasing (increasing) trend, indicating that the dispersion characteristics of the basic functional unit can be regulated by changing the loaded variable capacitance.

[0045] Figure 4 The momentum space iso-frequency lines of the basic functional unit of the embodiment of the present application at the typical loaded capacitances (a) 0pF, (b) 0.24pF and (c) 0.48pF and the corresponding observation frequency of 3.5GHz are given, which are (a) an ellipse, (b) a straight line and (c) a hyperbola respectively. Here, when the loaded capacitance increases from 0pF to 0.48pF, the spatial iso-frequency line of the basic functional unit can realize continuous topological change from an ellipse to a hyperbola.

[0046] In this embodiment, sample processing and test verification are performed, Figure 5 The photos of (a) the test environment, (b) the excitation source and (c) the magnetic field probe of the prototype are given. Figure 6 and Figure 7 The near-field magnetic field distribution simulation and test results of the reconfigurable metasurface for dynamically regulating the topological characteristics of the magnetic polaritons in the embodiment of the present application are given respectively. The observation frequency is 3.5GHz.Figure 6 The first row of pictures can be found that when the magnetic plasmonic dispersion topology switches between (a) an ellipse (0pF), (b) a straight line (0.24pF) and (c) a hyperbola (0.48pF), the wave front of the magnetic plasmon respectively shows the characteristics of outward convex divergent propagation, non-diffractive propagation and inward concave convergent propagation; by Fourier transforming the near-field magnetic field distribution, the equal-frequency lines of the momentum space as shown in the second row of pictures are obtained, which correspondingly show the topological transmission phenomenon from an ellipse to a hyperbola, which is consistent with the geometric characteristics of the equal-frequency lines of the momentum space of the basic functional unit in Figure 6 Figure 4 Figure 7 The experimental test results shown in the figure show that the near-field magnetic field distribution and the corresponding geometric characteristics of the equal-frequency lines of the momentum space are highly consistent with the simulation results.

[0047] In the above results, 3.5GHz is selected as the observation frequency for presentation. In fact, the reconfigurable metasurface in this embodiment can also realize reconfigurable topological magnetic plasmons in a certain frequency range (not limited to point frequency) under different loaded capacitance values. With the wave front characteristics of magnetic plasmons under different topological states, we also further realize the function design related to the control and manipulation of near-field electromagnetic waves. By applying different bias voltages, we can continuously realize the field channeling phenomenon of magnetic plasmons (corresponding to collimating line dispersion topology) in a certain frequency band. Figure 8 The magnetic field distribution test results of realizing the adjustable field channeling function under different bias voltages at (a) 3.81GHz, (b) 3.75GHz and (c) 3.63GHz frequencies are given, and it can be seen that the magnetic field distribution also shows obvious non-diffractive transmission characteristics.

[0048] In addition, we can also realize the continuously adjustable hyperbolic dispersion equal-frequency line of the magnetic plasmon in a certain frequency band. In this topological state, the wave front of the magnetic plasmon shows the characteristics of inward concave convergent propagation, and when the magnetic plasmon continuously propagates from the metasurface to the space outside the metasurface, it will realize negative refraction at the interface between the metasurface and the air, and thus produce the phenomenon of electromagnetic focusing. Referring to Figure 9 , we take (a) 3.92GHz, (b) 3.79GHz and (c) 3.64GHz as examples to realize the frequency-adjustable surface wave focusing function by controlling the bias voltage design. The near-field magnetic field distribution in a certain space in front of the reconfigurable metasurface is tested and characterized, and a significant focal point can be seen.

[0049] ​​The above-described embodiment is a metasurface using a whole-plate control feed line design. On this basis, by designing the feed line of the electromagnetic metasurface in a unit control form, by applying an independent bias voltage to each basic functional unit, the local dispersion characteristics can be further regulated, thereby enabling more flexible near-field electromagnetic wave regulation and manipulation related functions and device design, such as programmable topological plasmonic waveguide.

[0050] Figure 10 is a schematic diagram of the principle of the programmable topological plasmonic waveguide realized by the electromagnetic metasurface of the embodiment of the present application using a unit control feed line design. Among them, the basic functional units in the green area work in a transmission state, which can support the effective transmission of magnetic plasmonic polaritons; the basic functional units in the orange area work in a cutoff state, at which time the cutoff frequency of the basic functional units in the first mode of the first Brillouin zone is below the working frequency, and the propagation of magnetic plasmonic polaritons will be inhibited and cannot be effectively transmitted. As shown in the transmission path, magnetic plasmonic polaritons can be effectively transmitted in the transmission area, and strong reflection (indicated by the black dashed arrow) will occur at the boundary between the transmission area and the cutoff area, and continue to be transmitted in the transmission area in the form of multiple reflections. By independently regulating the bias voltage loaded on each basic functional unit, the transmission state / cutoff state of the basic functional unit can be switched, the effective transmission channel can be constructed as needed, the propagation of magnetic plasmonic polaritons can be flexibly manipulated, and the rapid switching of the transmission path can be supported. Figure 10

[0051] The programmable topological plasmonic waveguide in the embodiment is composed of basic functional units shown in Figure 11 The basic functional unit includes a vertically placed open resonant ring and a horizontally placed bottom plate feed line, and the open resonant ring includes a first metal patch layer from front to back, a dielectric layer, and a second metal patch layer. The bottom plate feed line includes a feed line first metal patch layer from top to bottom, a feed line dielectric layer, and a feed line second metal patch layer. The configuration of the open resonant ring in the embodiment is the same as the configuration of the basic functional unit described in the above embodiment. Figure 2 ​The basic functional units of the metasurface have similar open-ring resonant structures, differing only in their geometric dimensions. In this embodiment, the basic functional units of the metasurface using a unit-controlled feeder design have an annular metal structure removed from the left side of the first metal patch layer of the base plate feeder. This annular structure can be either a square or circular ring. The inner and outer metal patches formed after removing the annular metal structure from the first metal patch layer of the base plate feeder are connected to the left and right metal patches of the second metal patch layer of the open-ring resonant ring, respectively. The inner metal patch of the first metal patch layer of the base plate feeder is connected to the metal pattern (feeder) of the second metal patch layer through metallized vias and isolated by patch resistors. The outer metal patch of the first metal patch layer of the base plate feeder is grounded, and the feeder of each basic functional unit in the second metal patch layer is connected to the positive terminal of a DC voltage source to provide a bias voltage.

[0052] Figure 11 The basic functional unit of the programmable topological polariton waveguide shown has a period of p. x =15.5mm, p y =9mm, the metal layers of both the split-ring resonator and the base plate feed are made of 0.018mm thick copper foil. The dielectric layer of the split-ring resonator is 2mm thick with a dielectric constant of 2.2, and the dielectric layer of the base plate feed is 1mm thick with a dielectric constant of 3.0. The structural parameters of the first metal patch layer of the split-ring resonator are: inner ring width 9mm, outer ring width 14mm, line width 0.4mm, and metal ring opening gap width 0.2mm. The second metal patch layer of the split-ring resonator has a rectangular feed width a = 0.6mm and b = 2mm. The first metal patch layer of the base plate feed has an etched square ring with an inner side width l. a =2mm, outer width is l b =2.6mm; the diameter of the metallized via is 0.3mm.

[0053] Using CST Microwave Studio Figure 11 The dispersion characteristics of the basic functional unit were simulated and calculated. Figure 12 (a) Dispersion curves of the magnetic polaritons propagating along the y-direction for the basic functional unit under different applied capacitance values ​​are presented. When the capacitance is 0.2 pF, the magnetic polaritons achieve a collimated dispersion topology at 2.76 GHz, and the corresponding dispersion topology at the observation frequency of 3.25 GHz is a hyperbola, as shown in Figure 1. Figure 12 The hyperbola in inset (a) shows that as the capacitance increases, the frequency gradually decreases. When the capacitance increases to 1.3 pF, the magnetic polaritons achieve a collimated dispersive topology at 2.44 GHz. At this point, the observation frequency of 3.25 GHz is higher than the cutoff frequency of the first mode in the first Brillouin zone (2.9 GHz), and the magnetic polariton dispersive propagation is suppressed. The dispersive topology of the second mode in the first Brillouin zone is elliptical, as shown in the figure. Figure 12(a) the inset ellipse. From Figure 12 The simulation results of the super surface near field magnetic field distribution given in (b) can be seen that at a frequency of 3.25GHz, the magnetic plasmon can achieve effective transmission (defined as a transmission mode) when the loading capacitance is 0.2pF (the dispersion topology is a hyperbola); while the magnetic field intensity is significantly reduced and the transmission is inhibited (defined as a cutoff mode) when the loading capacitance is 1.3pF (the dispersion topology is a hyperbola). With the wave front characteristics of the magnetic plasmon in the transmission / cutoff mode, a Figure 10 A programmable topology plasmonic waveguide.

[0054] The designed programmable topology plasmonic waveguide is simulated and calculated by using CST Microwave Studio. Figure 13 、 Figure 14 and Figure 15 The programmable topology plasmonic waveguide is given in (a) and (b) respectively, which realizes the transmission paths of "L" shape, "S" shape and "Ω" shape. It can be seen that the magnetic plasmon is effectively bound in the designed transmission channel, and effective transmission can be achieved for forward, lateral, backward and turning transmission paths. The programmable topology plasmonic waveguide in this embodiment is processed and tested, Figure 16 The front pattern (a), the back pattern (b) and the photo of the test environment (c) of the sample bottom plate feed line are given in (a), (b) and (c) respectively. The bias voltage corresponding to the loading capacitance of 0.2pF and 1.3pF is 11V and 0V respectively in the experimental test. Figure 17 The magnetic field distribution test results corresponding to the "L" shape, "S" shape and "Ω" shape transmission paths at a frequency of 3.58GHz are given. It can be seen that the geometric characteristics of the transmission channel of the magnetic plasmon in the test results are obvious, which is consistent with the simulation results. The deviation of the simulation and test frequency is mainly caused by the external feed line in the actual test, and the error in the sample processing and assembly process.

[0055] The above is only the preferred embodiment of the present application, the same structure can be scaled down or up by the structure size, and the working frequency band of the reconfigurable super surface for dynamically controlling the electromagnetic plasmon topology characteristics can be designed flexibly by using electrically adjustable devices working at higher frequencies, which can be extended to millimeter wave band and terahertz band.

[0056] Obviously, for those skilled in the art, after understanding the content and principles of the present application, various modifications and changes in form and details can be made without departing from the principles and structures of the present application. Any simple equivalent changes and modifications made according to the claims and description of the present application shall still belong to the scope covered by the present application.

Claims

1. An active electromagnetic metasurface implementing a programmable topological polaritonic waveguide, characterized in that, The basic functional unit loaded with a varactor is periodically extended in a two-dimensional plane; the basic functional unit includes a vertically placed open resonant ring and a horizontally placed bottom plate feed line; the open resonant ring includes a first metal patch layer from front to back, a dielectric layer and a second metal patch layer, the first and second metal patch layers are connected by a metalized via, the first metal patch layer has magnetic anisotropy, and the varactor is connected across the two metal patch areas on both sides of the opening above the inner ring of the first metal patch layer; the bottom plate feed line includes a feed line first metal patch layer from top to bottom, a feed line dielectric layer and a feed line second metal patch layer, and the bottom plate feed line includes two different design methods of whole plate control and unit control. When the bottom plate feed line adopts the design method of whole plate control, the first and second metal patch layers of the bottom plate feed line are longitudinally continuous and laterally have a certain interval, and the metal strips on both sides are connected with rectangular metal patches; the metal strips of the first and second metal patch layers are alternately connected laterally by metalized vias on the rectangular metal patches; the metal strips of the first and second metal patch layers of the bottom plate feed line are connected with the positive and negative poles of a direct current voltage source, respectively. When the bottom plate feed line adopts the design method of unit control, the left side area of the first metal patch layer of the bottom plate feed line is dug out in a ring shape, and the ring is a square ring or a circular ring; the metal patches inside and outside the ring formed after the ring-shaped metal structure of the first metal patch layer of the bottom plate feed line is dug out are connected with the left and right metal patches of the second metal patch layer of the open resonant ring, respectively; the metal patch inside the ring of the first metal patch layer of the bottom plate feed line is connected with the independent feed line of the second metal patch layer through a metalized via, and is isolated by a patch resistance; the metal patch outside the ring of the first metal patch layer of the bottom plate feed line is grounded, and the second metal patch layer is connected with the positive pole of a direct current voltage source to provide a bias voltage.

2. The active electromagnetic metasurface implementing programmable topological polaritonic waveguide of claim 1, wherein, The first metal patch layer of the open resonant ring is a center-symmetric two-double-open metal ring geometric pattern; the metal wires at both ends of the opening of the double-open metal ring geometric pattern are straight lines, triangles or arrows.

3. The active electromagnetic metasurface implementing programmable topological polaritonic waveguide of claim 1, wherein, The number of metal ring structures of the first metal patch layer of the open resonant ring is one, two or more; the ring is a square ring or a circular ring, and the inner line width of the square ring / circular ring is greater than the diameter of the metalized via.

4. The active electromagnetic metasurface implementing programmable topological polaritonic waveguide of claim 1, wherein, The varactor is connected across the two metal patch areas on both sides of the opening above the inner ring of the first metal patch layer of the open resonant ring, and is connected with the second metal patch layer of the open resonant ring through a metalized via, and the second metal patch layer of the open resonant ring is connected with the first metal patch layer of the bottom plate feed line; the second metal patch layer of the open resonant ring and the first metal patch layer of the bottom plate feed line are isolated by a patch resistance.

5. The active electromagnetic metasurface implementing programmable topological plasmonic waveguide of claim 1, wherein, When the bottom plate feed line adopts the design method of whole plate control, the electromagnetic super surface supports the generation and propagation of hyperbolic magnetic polariton, and the reconfigurable topology transmission of magnetic polariton is realized by applying different bias voltages, and the dispersion topology of the magnetic polariton dynamically switches between an ellipse, a straight line and a hyperbola.

6. The active electromagnetic metasurface implementing programmable topological polaritonic waveguide of claim 1, wherein, When the bottom plate feed line adopts a unit control design, bias voltage is independently applied to the basic function unit V C1 , so that the dispersion topology of the basic function unit in the set area or on the path is a hyperbola, supporting effective transmission of magnetic polariton; by applying bias voltage to other basic function units outside the set area or path V C2 , the dispersion topology thereof is an ellipse, and transmission of magnetic polariton is inhibited.

7. The active electromagnetic metasurface implementing programmable topological plasmonic waveguide of claim 6, wherein, The design of programmable topology polariton waveguide is realized, the magnetic polariton transmission path supports free and flexible design, the same bias voltage is applied to the basic functional unit within the magnetic polariton effective transmission area or path V C1 The same bias voltage is applied to the basic functional unit outside the magnetic polariton effective transmission area or path V C2 Wherein V C1 > V C2 The magnetic polariton effective transmission path is "L" shape, "S" shape, "Ω" shape and the like containing right-angle turns.

8. The active electromagnetic metasurface implementing programmable topological plasmonic waveguide of claim 6, wherein, The excitation source of the magnetic plasmon is a dipole antenna, which is placed around or in any unit of the active electromagnetic super surface as needed; the number of the excitation source is one, two or more; the effective transmission area or path of the magnetic plasmon is one, two or more; and the working frequency of the magnetic plasmon effectively transmitted in the set area or path can be adjusted by changing the bias voltage applied to the basic functional unit.

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