Non-reciprocal paper folding type metasurface structure with two independently adjustable surfaces

Abstract

The non-reciprocal paper folding type metasurface structure with the two independently adjustable faces comprises a plurality of monomers, the monomers are arranged periodically, each monomer comprises a foldable dielectric plate and an artificial microstructure unit etched on the dielectric plate, the artificial microstructure unit is of an open annular structure, and the artificial microstructure units are arranged in the annular structure. The annular structure is one of a metal layer, a graphene layer, a carbon fiber layer, an ITO layer and a resistive film, and the opening is deviated to one side of the center line of the annular structure. The deformation of the non-reciprocal origami type metasurface structure in the third dimension destroys the mirror symmetry of the structure in the plane, so that strong bianisotropy is generated, and the space-time and space-space characteristics of the effective dielectric constant and the equivalent magnetic conductivity are destroyed. And meanwhile, continuous geometric deformation of the paper folding electromagnetic surface can realize continuous regulation and control on bianisotropy, so that the transmissivity / reflectivity / absorptivity of the metasurface is linearly regulated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metamaterials, and more particularly to a two-sided independently adjustable non-reciprocal origami super surface structure. BACKGROUND

[0002] With the progress of radar detection technology and the diversification of detection means, the stealth performance of long-distance communication systems faces greater challenges. Conventional super surfaces can absorb electromagnetic waves in a wide bandwidth, thereby avoiding detection, but at this time the friendly signal cannot be normally transmitted. How to control the super surface structure unit to make the long-distance communication system avoid enemy detection while the friendly communication system can work normally is a major issue in the field of weapon equipment stealth design and manufacturing. At present, frequency selective super surfaces are mainly designed based on equivalent circuit method, supplemented by spectral domain method and classification theory. Due to the additional consideration of polarization characteristics, polarization loss, cross-polarization suppression and consistency of frequency selection under different polarizations need to be considered in performance indicators. In terms of structure, electromagnetic resonance type surface structures are mainly used, and in general design, highly symmetrical structures are often used to ensure polarization consistency. However, in order to realize the selection characteristics under different polarizations, the super surface structure needs to have a certain asymmetry. Moreover, unlike active frequency selective super surfaces, passive frequency selective super surfaces usually need to rely on the characteristics of the incident electromagnetic wave to realize the switching of polarization function.

[0003] Due to the involvement of multiple polarizations, the design of reconfigurable active frequency selective super surfaces is relatively more than that of passive frequency selective surfaces, among which the combination of resonant structures loaded with varactor diodes, PIN diodes, micro-electromechanical systems and other elements is commonly used.

[0004] Existing active super surface design mainly relies on changing the position of active devices loaded and the RLC values of active device equivalent circuits and other parameters to affect the transmission and reflection characteristics of electromagnetic waves, thereby realizing the regulation of electromagnetic wave polarization, amplitude, phase and other characteristics. The design and debugging are relatively complex, and active super surfaces are usually reciprocal, which cannot guarantee that the friendly communication system can work normally while avoiding enemy detection.

[0005] In order to realize non-reciprocal transmission, one is to load magnetic materials based on ferrite, which can break the time reversal symmetry of magnetic field intensity by using the Faraday rotation effect of magnetic materials; two is to use nonlinear materials with asymmetric changes in electromagnetic parameters in the direction of electromagnetic wave propagation to realize non-reciprocal transmission under high-power electromagnetic wave incidence, such as energy selective surface; three is to introduce nonlinear source modulation super surface active devices through time-space modulation technology to change the spectral characteristics of electromagnetic waves, thereby breaking the time reversal symmetry; four is to introduce transistors with one-way transmission characteristics, which can realize non-reciprocal transmission of electromagnetic waves by simulating the Faraday rotation effect.

[0006] Current non-reciprocal devices are almost exclusively based on ferromagnetic (dielectric) compounds such as Yttrium Iron Garnet (YIG) and materials composed of iron oxide and other elements (Al, Co, Mn, Ni). The non-reciprocity of ferrites is caused by electron spin precession at microwaves and electron cyclotron orbits in optics, both of which are caused by the static magnetic field bias provided by permanent magnets or resistive / superconducting coils.

[0007] Ferrite-based non-reciprocal devices have the advantages of small insertion loss, strong non-reciprocity and excellent tunability. However, due to the incompatibility of ferrite lattice, ferrite-based systems tend to be large in size, heavy in weight, expensive and incompatible with semiconductor materials in integrated circuit technology.

[0008] These problems have recently led to an in-depth exploration of non-magnetic non-reciprocity, and from past research it has been found that non-reciprocal systems are based on time reversal symmetry breaking, external bias in linear cases, and self-bias and structural asymmetry in nonlinear cases. One important feature of nonlinear non-reciprocal systems is that "time reversal symmetry breaking is caused by spatial asymmetry and nonlinear self-bias (nonlinearity triggered by the wave itself)". SUMMARY

[0009] The present application provides a two-sided independently adjustable non-reciprocal origami super surface structure to solve the problems of existing non-reciprocal super surface technology, such as dependence on ferrite material, complex structure, difficulty in integration, and inflexible control.

[0010] According to one aspect of the present application, a two-sided independently adjustable non-reciprocal origami super surface structure is provided, comprising a plurality of monomers, the monomers being periodically arranged, the monomers comprising a foldable dielectric plate and an artificial microstructure unit etched on the dielectric plate, the artificial microstructure unit being a ring structure with an opening, and the ring structure being one of a metal layer, a graphene layer, a carbon fiber layer, an ITO layer, and a resistive film, the opening being offset to one side of the center line of the ring structure.

[0011] Preferably, on the basis of the above scheme, the dielectric plate is a similar material with low dielectric loss and high resistivity.

[0012] Preferably, on the basis of the above scheme, the dielectric plate is one of FR-4 / PDMS / PI / PET / ITO.

[0013] Preferably, on the basis of the above scheme, the monomers are m*n, and m or n is not less than 10.

[0014] Preferably, on the basis of the above scheme, the opening width of the ring structure is 0.05mm.

[0015] Preferably, on the basis of the above scheme, the medium plate is folded to form a folding angle, and the folding angle is greater than 0° and less than 180°.

[0016] The two-surface independently adjustable non-reciprocal fold paper type metasurface structure has the advantages that radio wave signals can be more efficiently processed, noise and echo interference can be prevented, and the time reversal symmetry does not need to be broken by an external magnetic field bias, and in addition, the transmittance / reflection / absorptance of the metasurface can be linearly adjusted by changing the angle of the medium plate included angle.

[0017] The two-surface independently adjustable non-reciprocal fold paper type metasurface structure provided by the application breaks the mirror symmetry of the structure in the plane by deforming in the third dimension, thereby generating strong biaxial anisotropy and breaking the space-time parity characteristics of the equivalent permittivity and equivalent permeability. At the same time, since the electromagnetic wave is obliquely incident, the magnetic field will increase a component along the Z direction, which makes it produce an effect similar to the spin magnetic phenomenon when obliquely incident, thereby causing the appearance of non-reciprocity. In addition, the continuous geometric deformation of the fold paper electromagnetic surface can realize continuous regulation of biaxial anisotropy, thereby linearly adjusting the transmittance / reflection / absorptance of the metasurface. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor. In the drawings: Figure 1 is a front view of the first state of the metasurface structure unit of the application; Figure 2 is a side view of the first state of the metasurface structure unit of the application; Figure 3 is a front view of the first state of the metasurface structure unit of the application; Figure 4 is a front view of the second state of the metasurface structure unit of the application; Figure 5 is a side view of the second state of the metasurface structure unit of the application; Figure 6 is a front view of the second state of the metasurface structure unit of the application; Figure 7 is a front view of the third state of the metasurface structure unit of the application; Figure 8is a third state side view of the metasurface structure unit of the present application; Figure 9 is a third state forward incidence schematic diagram of the metasurface structure unit of the present application; Figure 10 is a third state TE polarization transmittance schematic diagram of the present application at forward incidence; Figure 11 is a third state TE polarization transmittance schematic diagram of the present application at reverse incidence; Figure 12 is a third state TM polarization transmittance schematic diagram of the present application at forward incidence; Figure 13 is a third state TM polarization transmittance schematic diagram of the present application at reverse incidence.

[0019] BRIEF DESCRIPTION OF DRAWINGS 100, monomer; 101, dielectric plate; 102, artificial microstructure unit. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application will be further described in conjunction with the drawings and examples. The following examples are used to illustrate the present application but are not used to limit the scope of the present application.

[0021] It should be understood that the term "comprising" as used in the specification and the appended claims indicates the presence of the described features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0022] For the purpose of simplicity, only the parts related to the present application are shown in the drawings, which do not represent the actual structure of the product. In addition, in order to make the drawing simple and easy to understand, in some drawings, only one of the components with the same structure or function is schematically shown, or only one of them is marked. In this text, "one" not only means "only one", but also means "more than one" situation.

[0023] It should be further understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0024] In the embodiments shown in the drawings, the indications of directions such as up, down, left, right, front and back are not absolute but relative to explain the structure and movement of various components of the present application. When these components are in the position shown in the drawings, these descriptions are appropriate. If the position of these components changes, the indications of these directions also change accordingly.

[0025] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0027] Please refer to Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a non-reciprocal origami-type metasurface structure with two independently adjustable sides, comprising a plurality of monomers 100 arranged in a periodic continuous manner.

[0028] Among them, the 100 monomers are arranged continuously in an m×n array, where m and n are both not less than 10, so as to ensure that the metasurface has uniform electromagnetic properties on a macroscopic scale.

[0029] Each unit 100 of the present invention includes a foldable dielectric substrate 101 and an artificial microstructure unit 102 etched on the dielectric substrate 101.

[0030] The dielectric substrate 101 preferably uses a flexible material with low dielectric loss and high resistivity, such as FR-4, PDMS, PI, PET or ITO, to achieve good folding performance and electromagnetic response characteristics.

[0031] The artificial microstructure unit 102 is an open-ended ring structure 103. The opening width of the ring structure is preferably 0.05 mm, and the opening is located on one side of the ring structure's centerline, forming an asymmetric structure. When the structure folds, it breaks the symmetry in three-dimensional space, ensuring that the off-diagonal elements in the equivalent dielectric constant or permeability tensor of the metamaterial structure are not all zero. This ultimately achieves the non-reciprocal properties of bipolarized transmittance / reflectance / absorption on both sides of the structure. This ring structure can be composed of conductive materials such as metal layers, graphene layers, carbon fiber layers, ITO layers, or resistive films, and is used to excite electromagnetic resonance within a specific frequency band.

[0032] The working principle of this invention is as follows: When electromagnetic waves are incident from different directions, due to the asymmetry of the foldable dielectric plate 101 in three-dimensional space, the metasurface exhibits different electromagnetic responses to electromagnetic waves incident from the two opposite directions. Specifically, by folding the dielectric plate 101 and changing the folding angle θ (e.g., ... Figure 2As shown, the spatial arrangement and orientation of the artificial microstructure unit 102 can be continuously controlled, thereby changing its equivalent electromagnetic parameters. This change in three-dimensional configuration disrupts the mirror symmetry of the structure, introduces strong bi-anisotropy, and thus breaks the time reversal symmetry, achieving non-reciprocal transport.

[0033] To verify and illustrate the technical solution of the present invention, the following will describe in detail the reciprocal origami-type metasurface structure with 100 monomers arranged in a 3*3 array.

[0034] Among them, such as Figure 1 As shown, the dielectric substrate 101 is in a planar state. Figure 2 This is a side view of a metasurface structure unit. Figure 3 This is a schematic diagram of a 3x3 metasurface array incident from the forward direction. Figure 4 This is a front view of the folded medium plate 101 when its included angle is changed to 135° and 90°. Figure 5 This is a side view of the folded medium plate 101 when its included angle is changed to 135° and 90°. Figure 6 A schematic diagram of the forward incident radiation when the included angle of the folded medium plate 101 is changed to 135° and 90°; Figure 7 This is a front view of the folded medium plate 101 when its included angle is changed to 90°. Figure 8 This is a side view of the folded medium plate 101 when its included angle is changed to 90°. Figure 9 A schematic diagram of the forward incident light when the included angle of the folded medium plate 101 is changed to 90°.

[0035] Furthermore, regarding Figure 1 , Figure 4 and Figure 7 Three metasurface structures with different folding angles were subjected to TE and TM polarization tests with forward and reverse incident detectors. The test results are as follows: Figures 10-13 As shown.

[0036] To describe the transmission matrix (also known as the Jones matrix) of a linearly polarized electromagnetic wave, let's assume A, B, C, and D represent the transmission matrix. (Txx, Txy, Tyx and Tyy), This represents all polarization components obtained during the propagation of linearly polarized electromagnetic waves. This indicates forward transmission (+Z direction). This represents the transmission matrix for electromagnetic waves propagating in the negative direction (-Z direction). Considering only reciprocal media, i.e., without magnetic materials, we have:

[0037] Assuming the plane wave is coherent, it can be calculated using the generalized Jones matrix. In general... One part originates from the transmission of the incident wave's x-polarized component, and the other part originates from the conversion of the incident wave's y-polarized component, which can be expressed as: .

[0038] When a linearly polarized electromagnetic wave propagates from one direction to another, the energy Tx of the incident X-direction polarized wave at the time of exit can be composed of the X-direction polarized wave energy Txx and the Y-direction polarized wave energy Txy. Similarly, the energy Ty of the incident Y-direction polarized wave at the time of exit can be composed of the X-direction polarized wave energy Tyx and the Y-direction polarized wave energy Tyy.

[0039] Asymmetric propagation of electromagnetic waves is usually expressed using parameters. This indicates that it describes the difference in transmission transmittance between forward and backward transmission, and can be expressed as:

[0040] in, This represents the transmittance of the x-polarized wave during forward transmission. This represents the transmittance of the y-polarized wave during forward transmission. This represents the transmittance of the x-polarized wave during negative transmission. This represents the transmittance of the y-polarized wave during negative transmission.

[0041] From the above analysis, it can be seen that the asymmetric transmission parameter of linearly polarized electromagnetic waves represents the difference in transmission transmittance between the propagation directions x and y, i.e.

[0042] Therefore, the asymmetric transmission of x-polarized waves and y-polarized waves are opposite. We can selectively analyze x-polarized electromagnetic waves. For ideal electromagnetic wave asymmetric transmission, the transmission efficiency in one direction is 1 and the transmission efficiency in the other direction is 0. This requires that the two diagonal elements (A and D) and one off-diagonal element (B or C) in the T matrix be 0, and the last remaining element (B or C) be 1.

[0043] Please see Figure 1 and combined Figure 2 - Figure 9 As shown, the asymmetric transparent origami-type metasurface structure with two independently adjustable sides consists of a foldable dielectric plate and an open resonant ring etched on the dielectric plate.

[0044] from Figures 10~Figures 13 It can be seen that electromagnetic waves of different polarizations have different transmittances along the Z+ and Z- directions. Electromagnetic waves of the same polarization also have different transmittances when incident on metasurfaces of different states. The reason for these differences in transmittance can be attributed to... Figures 4~9It can be seen that the microstructure units of the metasurface are different along the X, Y, and Z directions, and the structure along these three directions is asymmetrical. Therefore, the structures on the front and back sides of the metasurface are different when electromagnetic waves of different polarizations are incident on it, resulting in different transmittance / reflectance / absorption.

[0045] Depend on Figures 10~Figures 13 It can be seen that when electromagnetic waves are incident on the metamaterial structure along the Z+ direction, the transmission rate of TE polarization increases as the angle between the dielectric plates decreases at a frequency of 8.2 GHz, and the absorption rate of TM polarization increases as the angle between the dielectric plates decreases at a frequency of 8.2 GHz. However, when electromagnetic waves are incident along the Z- direction, the absorption rate of TE polarization increases as the angle between the dielectric plates decreases at a frequency of 8.2 GHz, and the transmission rate of TM polarization increases as the angle between the dielectric plates decreases at a frequency of 8.2 GHz.

[0046] Due to the different structural angles, the magnitudes of the magnetic field components with different polarizations also change, resulting in different electromagnetic response characteristics of the metasurface, achieving a linear tuning effect. Moreover, the magnetic field components also generate gyromagnetism on the structural surface, disrupting the symmetry of the structure's equivalent permeability, thus leading to asymmetric transmission / absorption phenomena under different polarizations and different incident directions.

[0047] The variation pattern of the low resonant frequency can be explained as follows. First, according to the coupled Lorentz oscillation model, during the plasma element hybridization process, the resonant frequency of the open ring shifts towards the transmission peak, i.e., towards higher frequencies. Simultaneously, the decrease in physical displacement widens the bandwidth, causing a redshift in the resonant frequency. Therefore, there is a competing relationship between the reduction in physical displacement and the influence of plasma element hybridization. Specifically, as the folding angle decreases, the physical spacing decreases, causing a redshift in the open ring resonant frequency. Conversely, as the metasurface bandwidth widens, a blueshift occurs, resulting in a relatively stable resonant frequency response.

[0048] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention provides a non-reciprocal origami-type metasurface structure with independent and adjustable transmissivity / reflectivity / absorbivity on both sides. It achieves non-reciprocal characteristics on the basis of linear adjustment of transmissivity / reflectivity / absorbivity, and realizes unidirectional transmission / reflection / absorption of electromagnetic waves. Moreover, compared with traditional non-reciprocal metasurface structures, which cannot independently adjust the transmission rate on both sides, its bipolar transmission rate on both sides is independently adjustable.

[0049] (2) This invention provides a non-reciprocal origami-type metasurface structure with two independently adjustable sides. By changing the angle between the dielectric plates, the transmittance of the metasurface is gradually changed. Compared with the traditional method of using the Faraday rotation effect of magnetic materials, the transmittance / reflectance / absorption rate of the metasurface can be linearly adjusted.

[0050] (3) The present invention provides a non-reciprocal origami metasurface structure with two independently adjustable sides. Compared with the conventional method of using an external magnetic field to break the time reversal symmetry, the method of changing the included angle of the dielectric plate does not require an external magnetic field, making the overall structure simpler, lighter, and easier to integrate and apply.

[0051] (4) The present invention provides a non-reciprocal origami-type metasurface structure that is independently adjustable on both sides. Compared with active frequency selective surfaces, it has a simple structure, does not require complex power supply networks, active devices and control circuits, reduces production costs and process difficulty, and reduces the complexity of design and debugging. Moreover, since there are no active devices, it has higher reliability, longer service life, simpler maintenance, and more stable performance. It is not affected by the power supply, has stronger environmental adaptability, and can maintain stable electromagnetic characteristics under different environmental conditions.

[0052] Finally, the method described in this application is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A non-reciprocal origami-type metasurface structure with two independently adjustable sides, characterized in that, It includes multiple monomers arranged periodically. Each monomer includes a foldable dielectric substrate and an artificial microstructure unit etched on the dielectric substrate. The artificial microstructure unit is a ring structure with an opening, and the ring structure is one of a metal layer, a graphene layer, a carbon fiber layer, an ITO layer, or a resistive film. The opening is biased towards one side of the center line of the ring structure.

2. The non-reciprocal origami-type metasurface structure with two independently adjustable sides as described in claim 1, characterized in that, The dielectric substrate is a material with low dielectric loss and high resistivity.

3. The non-reciprocal origami-type metasurface structure with two independently adjustable sides as described in claim 1, characterized in that, The dielectric substrate is one of FR-4 / PDMS / PI / PET / ITO.

4. The non-reciprocal origami-type metasurface structure with two independently adjustable sides as described in claim 1, characterized in that, The number of monomers is m*n, and neither m nor n is less than 10.

5. The non-reciprocal origami-type metasurface structure with two independently adjustable sides as described in claim 1, characterized in that, The opening width of the annular structure is 0.05 mm.

6. The non-reciprocal origami-type metasurface structure with two independently adjustable sides as described in claim 1, characterized in that, The medium plate is folded to form a folded angle, which is greater than 0° and less than 180°.

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