Reconfigurable chiral metasurface based on origami flexible structure and chiral modulation method and manufacturing process thereof

Abstract

The application provides a reconfigurable chiral metasurface based on a paper folding flexible structure, a chiral control method and a manufacturing process.The reconfigurable chiral metasurface based on the paper folding flexible structure comprises a flexible medium substrate and a plurality of chiral excitation units arranged on the flexible medium substrate.A plurality of crease units and cutting line units are arranged on the flexible medium substrate, so that the plurality of chiral excitation units are folded in different directions and form a three-dimensional structure that is mutually inclined and dislocated.The chiral control method of the reconfigurable chiral metasurface based on the paper folding flexible structure is to control the folding angle of the flexible medium substrate to realize chiral control of the metasurface.The manufacturing process of the reconfigurable chiral metasurface based on the paper folding flexible structure is to electroplate and wet-etch a metal pattern on the substrate.The application realizes continuous adjustment of the folding angle and continuous change from weak chirality to strong chirality, and the gradual change of the chiral response intensity can be finely adjusted, and has high polarization control ability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metasurfaces, in particular to a reconfigurable chiral metasurface based on origami flexible structure and a chiral control method and manufacturing process thereof. BACKGROUND

[0002] Chirality refers to a geometric property that a structure cannot coincide with itself after mirror reflection. In nature, chirality widely exists in molecular structures (such as DNA helix, amino acid) and macroscopic structures. Chiral structures also have important significance in optical, electromagnetic and other physical systems. Electromagnetic chiral structures will produce different responses to left-handed and right-handed circularly polarized waves, such as transmission rate or phase difference, thereby realizing selective regulation of circular polarization.

[0003] In recent years, the research on artificial chiral metasurfaces has attracted widespread attention. The design inspiration of chiral metasurfaces is derived from chiral structures at the molecular scale. By introducing mirror symmetry breaking in geometric configuration at the macroscopic scale, the physical properties of molecular chirality are simulated to realize the regulation of polarized waves at the macroscopic scale. In recent years, inspired by traditional Japanese art origami and paper cutting structure, the flexible deformable design based metasurface provides a new path for dynamic chiral function regulation. By applying mechanical stress to the flexible substrate structure, controllable configuration transformation from two-dimensional planar structure to three-dimensional asymmetric structure can be realized, thereby dynamically changing the chiral response. Although this direction shows great potential, most of the related researches are still in the stage of principle verification, and there is still a lack of systematic structure design method, engineering implementation path and chiral dynamic control strategy. In the existing scheme, the polarization regulation of the flexible deformable design based metasurface mainly depends on discrete state change, and cannot realize the fine regulation of angle continuous adjustable and chiral response strength gradual change, which lacks high degree of freedom. SUMMARY

[0004] The present application aims to provide a reconfigurable chiral metasurface based on origami flexible structure and a chiral control method and manufacturing process thereof, in order to solve the problem that the polarization regulation of the flexible deformable design based metasurface mainly depends on discrete state change, and cannot realize the fine regulation of angle continuous adjustable and chiral response strength gradual change, which lacks high degree of freedom.

[0005] To this end, the technical scheme adopted by the present application is as follows: a reconfigurable chiral metasurface based on origami flexible structure, comprising a flexible medium substrate and a plurality of chiral excitation units arranged in an array on the flexible medium substrate, a plurality of crease units and cutting line units are arranged on the flexible medium substrate, the crease unit comprises two side creases arranged in parallel and a center crease, the two side creases are respectively located on both sides of the chiral excitation unit, and the center crease passes through the center of the chiral excitation unit, so that a plurality of chiral excitation units are folded in different directions and form three-dimensional structures that are tilted and misaligned with each other.

[0006] As a preferred solution of the above-mentioned scheme, the chiral excitation unit comprises a first metal conductor rectangular ring and a second metal conductor rectangular ring, the second metal conductor rectangular ring is located in the first metal conductor rectangular ring and is arranged concentrically, and the first metal conductor rectangular ring and the second metal conductor rectangular ring are respectively provided with a first opening and a second opening in a staggered manner, so that the first metal conductor rectangular ring and the second metal conductor rectangular ring are staggered after the flexible dielectric substrate is folded, and the symmetry is broken, and the folding angle θ of the flexible dielectric substrate is the dihedral angle between the folding surface of the flexible dielectric substrate and the xy plane.

[0007] Further preferably, the cutting line unit comprises a first cutting line, a second cutting line and a third cutting line in a U shape, the first cutting line is arranged outside the bottom end of the first metal conductor rectangular ring, the second cutting line is arranged in the first metal conductor rectangular ring and above the second metal conductor rectangular ring, the third cutting line is arranged in the first metal conductor rectangular ring and below the second metal conductor rectangular ring, and the width of the second cutting line is greater than the width of the third cutting line.

[0008] Further preferably, the thickness of the flexible dielectric substrate is 0.1 mm, and the thickness of the first metal conductor rectangular ring and the second metal conductor rectangular ring is 0.035 mm.

[0009] Further preferably, the length of the left conductor segment of the first metal conductor rectangular ring, the length of the right upper conductor segment g1 and the width of the right lower conductor segment t1 are 12 mm, 3 mm and 0.5 mm respectively, and the width of the second opening of the second metal conductor rectangular ring, the length of the left conductor segment d, the length of the top conductor segment b and the length of the right conductor segment c are 1 mm, 6 mm, 4 mm and 8 mm respectively.

[0010] Further preferably, the material of the flexible dielectric substrate is polyimide film, and the material of the first metal conductor rectangular ring and the second metal conductor rectangular ring is copper. The dielectric constant of polyimide film is stable and flexible, which is conducive to accurately controlling the folding behavior and improving the stability of the device.

[0011] Further preferably, the calculation formula of the chiral evaluation index CD is as follows:

[0012]

[0013] In the formula, CD is the chiral evaluation index, T is the total transmission amount of the left-handed circularly polarized wave incidence, T is the total transmission amount of the right-handed circularly polarized wave incidence, is the co-polarization transmission coefficient when the left-handed circularly polarized wave is incident, is the cross-polarization transmission coefficient when the left-handed circularly polarized wave is incident, co-polarization transmission coefficient for right-hand circularly polarized wave incidence, cross-polarization transmission coefficient for right-hand circularly polarized wave incidence.

[0014] The chiral control method of the reconfigurable chiral metasurface based on the origami flexible structure comprises the following steps:

[0015] S1, the position of the achiral excitation unit on the flexible medium substrate is set as a planar connection area;

[0016] S2, a plurality of hardened foam strips are attached on the back of the planar connection area to provide flexible support and deformation limitation;

[0017] S3, a plurality of slidable bases are arranged in the length direction in the bottom groove, and a sliding groove is opened on the base, and the plurality of hardened foam strips are respectively inserted into the plurality of sliding grooves, so as to form the connection of the hardened foam strips and the base;

[0018] S4, by moving the base, the relative movement between the hardened foam strips is driven, so as to realize the folding of the flexible medium substrate through the creases, and the plurality of chiral excitation units are folded in different directions and form a three-dimensional structure inclined and dislocated to each other;

[0019] S5, the folding angle of the flexible medium substrate is adjusted, and the chirality of the metasurface is also changed, so as to realize the chiral control of the metasurface.

[0020] The manufacturing process of the reconfigurable chiral metasurface based on the origami flexible structure comprises the following steps:

[0021] S1, a flexible medium substrate with a thickness of 0.1 mm and a dielectric constant of εr = 3.5 is used as a substrate, a copper layer with a thickness of 35 microns is deposited on one side of the flexible medium substrate through electroplating to form a uniform conductive surface for subsequent pattern processing;

[0022] S2, the chiral excitation unit is defined by a printed circuit board process and is formed on the copper layer by wet etching;

[0023] S3, a plurality of crease units and cutting line units are manufactured by femtosecond laser micromachining technology, so as to realize high-precision cutting without thermal damage.

[0024] The beneficial effects of the present application are:

[0025] 1. A flexible medium substrate is provided with a plurality of crease and cutting line units by laser cutting, and combined with mechanical folding operation, a plurality of chiral excitation units can be folded in different directions and form a three-dimensional structure with mutual inclination and dislocation, breaking the z-axis symmetry and exciting significant chiral response, the chiral response can reach 0.9, and the folding angle is continuously adjustable and continuously changes from weak chirality to strong chirality, the gradual change of chiral response intensity can be finely adjusted, and the polarization control ability has high degree of freedom.

[0026] 2. The metasurface of the present application has the characteristics of thin structure and light weight, and has high efficiency and flexibility, combined with structural design freedom, response enhancement capability and processing feasibility, and has potential application value in polarization control, chiral recognition and sensing fields.

[0027] 3. The metasurface structure of the present application is simple, and the process is mature, which has engineering realizability suitable for microwave and terahertz wave bands, is suitable for laser cutting and batch flexible manufacturing process, and has good practical popularization potential. This flexible paper-based control mechanism does not need to introduce electric field, temperature, phase change material or MEMS device, the structure is simple, the energy consumption is extremely low, and the complexity and production cost of the metasurface are greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of the planar and folded state of the reconfigurable chiral metasurface based on the flexible structure of the present application.

[0029] Figure 2 is the transmission characteristic and chiral response diagram of the reconfigurable chiral metasurface based on the flexible structure of the present application at different folding angles.

[0030] Figure 3 is an experimental verification diagram of the reconfigurable chiral metasurface based on the flexible structure of the present application. DETAILED DESCRIPTION

[0031] The present application will be further described below in combination with the drawings and examples.

[0032] As shown in Figures 1-3 , the reconfigurable chiral metasurface based on the flexible structure of the present application includes a flexible medium substrate and a plurality of chiral excitation units arranged in an array on the flexible medium substrate, the flexible medium substrate is provided with a plurality of crease units and cutting line units, the crease unit includes two side creases and a center crease arranged in parallel, the two side creases are respectively located on both sides of the chiral excitation unit, and the center crease passes through the center of the chiral excitation unit, so that a plurality of chiral excitation units can be folded in different directions and form a three-dimensional structure with mutual inclination and dislocation.

[0033] The laser precision cutting technology can be used to form preset creases and cutting lines on the flexible medium substrate, and then mechanical deformation is applied at the creases, so that the originally coplanar chiral excitation units are folded in different directions to form a three-dimensional structure with mutual tilting and dislocation. The change in the spatial configuration breaks the mirror symmetry of the structure in the z-axis direction, significantly introduces chiral geometric features, and thus causes the transmission response of left-handed and right-handed circularly polarized waves to be asymmetric, thereby exhibiting obvious chiral electromagnetic response.

[0034] The chiral excitation unit includes a first metal conductor rectangular ring and a second metal conductor rectangular ring, the second metal conductor rectangular ring is located in the first metal conductor rectangular ring and is arranged concentrically, and the first metal conductor rectangular ring and the second metal conductor rectangular ring are respectively arranged with a first opening and a second opening in a dislocation manner, so that the first metal conductor rectangular ring and the second metal conductor rectangular ring are arranged in a dislocation manner after the flexible medium substrate is folded, and stronger symmetry breaking is caused. The folding angle θ of the flexible medium substrate is the dihedral angle between the folding surface of the flexible medium substrate and the xy plane.

[0035] The first metal conductor rectangular ring and the second metal conductor rectangular ring are both open resonant rings, which can effectively enhance the resonant coupling and the multi-pole excitation strength. By selecting the distance, opening direction and relative twist angle of the two open resonant rings, the two open resonant rings can form a non-coplanar and strongly coupled three-dimensional configuration after being folded, thereby exciting stronger intrinsic chiral response. The open resonant ring unit composed of the two open resonant rings has a highly localized resonant mode, and its electromagnetic response is mainly concentrated near the metal ring structure, and has a lower dependence on external deformation. Therefore, during the folding process, the resonant frequency does not shift significantly, which is beneficial to maintaining stable and controllable response characteristics under different folding angles. In the unfolded state, the first metal conductor rectangular ring and the second metal conductor rectangular ring are in the same plane, and the super surface structure is mirror symmetric with respect to the xy and xz planes, so the super surface does not have intrinsic chirality. After the flexible medium substrate is folded, the originally coplanar first metal conductor rectangular ring and the second metal conductor rectangular ring become interlaced, which greatly breaks the mirror symmetry of the super surface in the z-axis direction, thereby inducing strong intrinsic chirality.

[0036] In addition to the double-open ring structure composed of the first metal conductor rectangular ring and the second metal conductor rectangular ring, other structure units capable of producing asymmetric electromagnetic response can also be used, such as asymmetric cross-shaped, Z-shaped, L-shaped, Ω-shaped coplanar structures, and double-layer offset resonant units such as upper and lower offset rectangular rings or non-coaxial spiral structures. These structures can achieve three-dimensional mirror symmetry breaking after being folded or twisted, thereby producing adjustable intrinsic chiral response, which is equivalent to the design principle of the present application.

[0037] The cutting line unit includes a first cutting line, a second cutting line, and a third cutting line in a U-shape. The first cutting line is located outside the bottom end of the first metal conductor rectangular ring. The second cutting line is located inside the first metal conductor rectangular ring and above the second metal conductor rectangular ring. The third cutting line is located inside the first metal conductor rectangular ring and below the second metal conductor rectangular ring. The width of the second cutting line is greater than the width of the third cutting line.

[0038] By using creases, a first cutting line, a second cutting line, and a third cutting line, a three-dimensional structure can be achieved where the first and second metal conductor rectangular rings form a mutually tilted and misaligned shape when the flexible dielectric substrate is folded.

[0039] like Figure 1 As shown in (b), the geometric parameters of the metasurface are defined as follows: width W = 25 mm, length L = 18 mm, the length a of the left conductor segment of the first metal conductor rectangular ring, the length g1 of the upper right conductor segment, and the width t1 of the lower right conductor segment are 12 mm, 3 mm, and 0.5 mm, respectively; the second opening width g2 of the second metal conductor rectangular ring, the length d of the left conductor segment, the length b of the top conductor segment, and the length c of the right conductor segment are 1 mm, 6 mm, 4 mm, and 8 mm, respectively; the thickness of the flexible dielectric substrate is 0.1 mm; and the thickness of both the first and second metal conductor rectangular rings is 0.035 mm.

[0040] The flexible dielectric substrate is made of polyimide film, and the first and second metal conductor rectangular rings are made of copper.

[0041] The flexible dielectric substrate can also be made of materials such as polyethylene terephthalate, polytetrafluoroethylene, and thermoplastic polyurethane, possessing good mechanical flexibility and dielectric properties. The first and second metal conductor rectangular rings can also be made of printable conductors such as silver paste, ITO film, and carbon nanotube ink. The metasurface of this invention can be fabricated using flexible circuit board technology, and the fabrication process can also employ low-cost and scalable processes such as inkjet printing, laser etching, and molding transfer. The copper layer thickness of the first and second metal conductor rectangular rings can be between 18 and 140 μm to balance structural strength and processing flexibility.

[0042] Figure 1 (a) is a schematic diagram of a metasurface, which describes the specific deformation process (i.e., folding process) of the metasurface. The deformation process is reversible.

[0043] When the folding angle is 0, the metasurface can simultaneously transmit both left-handed and right-handed circularly polarized light beams. As the folding angle gradually increases, the metasurface exhibits a gradually enhanced chiral response. When the folding angle is further increased, the metasurface can completely transmit a specified circularly polarized wave, with maximum efficiency in transmitting left-handed circularly polarized light and preventing the passage of right-handed circularly polarized light.

[0044] Figure 1 (c) is a folding state diagram of the metasurface, a mechanical deformation state achieved through laser precision cutting and folding. This process introduces geometric perturbations in the normal direction on the metasurface, thereby breaking the symmetry.

[0045] Figure 2 (a)-(d) demonstrate the circular polarization transmission of the metasurface at different folding angles. Among them, t ij (i, j = L, R, L is LCP, and R is RCP) represents the transmission coefficient under circular polarization. In the case of no folding, the calculated co-polarization transmission spectrum t RR and t LL are almost the same. As the folding angle increases, such as to 10-20°, the difference between t LL and t RR gradually increases. When the folding angle is 45°, t LL is close to 1 and t RR is close to 0, realizing high-efficiency circularly polarized selective transmission. In order to better understand the chiral performance of the metasurface, the chiral evaluation index (also known as circular dichroism) CD can be used.

[0046] The calculation formula of the chiral evaluation index CD is as follows:

[0047]

[0048] In the formula, CD is the chiral evaluation index, is the total transmission amount under left-handed circularly polarized wave incidence, is the total transmission amount under right-handed circularly polarized wave incidence, is the co-polarization transmission coefficient under left-handed circularly polarized wave incidence, is the cross-polarization transmission coefficient under left-handed circularly polarized wave incidence, is the co-polarization transmission coefficient under right-handed circularly polarized wave incidence, is the cross-polarization transmission coefficient under right-handed circularly polarized wave incidence.

[0049] Figure 2 (e) plots the CD spectrum of the metasurface at 0, 15, 20, 30, and 45 degrees. When the folding angle is 45°, a large CD value (CD = 0.90) of the metasurface at the resonance frequency of 10.1 GHz can be observed. Figure 2(f) It is shown that the chiral response is significantly enhanced with the increase of the folding angle. Meanwhile, the increase of the folding angle leads to the change of the relative position between the two split-ring resonators, which changes the effective path and coupling mode of the resonant mode, and the equivalent resonant length is changed, resulting in the frequency blue shift of the resonant mode.

[0050] To further investigate the mechanism of the chiral enhancement induced by the folding structure, Figure 2 (g) The surface current distributions of the metasurface under the excitation of left- and right-circularly polarized waves at different folding angles are shown. When θ = 0°, the structure is in a planar configuration, and the current distributions under the excitation of left- and right-circularly polarized waves are relatively symmetric, showing very low chiral response. With the increase of the folding angle to 20° and 45°, the structure gradually forms a three-dimensional configuration, and the difference between the current distributions under the excitation of left- and right-circularly polarized waves gradually increases, forming asymmetric current channels. This phenomenon is consistent with the change of the chiral response. Figure 2 (b-d) The separation of t RR and t LL components in the transmission spectrum corresponds.

[0051] In fact, the difference in the excitation of multipole in the double-split ring resonator under the excitation of left- and right-circularly polarized waves (especially the asymmetry in the intensity of electric dipole and ring dipole response) is the main source of strong intrinsic chirality. In summary, the difference in the current distribution induced by the structural reconstruction directly leads to the enhancement of the chiral response, and produces significant circular polarization selectivity at high folding angles.

[0052] To quantitatively evaluate the tuning ability of the metasurface to electromagnetic waves, Figure 3 (a) The schematic diagram of the experimental system for measuring the transmission characteristics of the metasurface is shown. The experimental system consists of a pair of linearly polarized horn antennas for transmitting and receiving electromagnetic waves, respectively, and is connected to a vector network analyzer for signal measurement and transmission coefficient extraction. The measured metasurface sample is placed between the two antennas, and the response measurement under different configurations is realized by adjusting the geometric folding angle. In order to obtain the transmission coefficient of circularly polarized wave, the transmission coefficients of four linear co-polarization and cross-polarization are measured respectively, and the conversion between linear polarization and circular polarization is realized through the complex transmission Jones matrix.

[0053] Antenna configuration: A pair of aligned linearly polarized horn antennas are placed axially on both sides of the metasurface sample in the experimental system, with the center aligned to ensure that the signal is perpendicular to the surface of the sample. The distance between the antennas is usually set to λ / 2 to λ (the wavelength of the metasurface), which ensures that the wave front is approximately planar and avoids near-field coupling interference.

[0054] Microwave measurement and analysis device: the microwave measurement system adopts a pair of linearly polarized horn antennas and a vector network analyzer. The horn antennas are used as the transmitting end and the receiving end, respectively, and work in the microwave frequency band, which can efficiently generate and receive linearly polarized electromagnetic waves. The vector network analyzer is used to excite the signal source and measure the transmission and reflection coefficients. By extracting the complex transmission coefficient, the transmission behavior under linear polarization can be further calculated, and the transmission coefficient under circular polarization can be obtained through linear-circular polarization conversion, realizing the quantitative evaluation of the chiral response of the metasurface. The sampling step of the vector network analyzer is set to 10 MHz, and the number of sampling points is increased to finely capture the electromagnetic wave response. The scanning frequency range covers 8-12 GHz.

[0055] Multi-angle incidence measurement: under the condition of normal incidence of circularly polarized electromagnetic waves, the chiral response changes of θ = 0°, 15°, 20°, 30°, and 45° are measured to evaluate the multi-scene adaptability and stability of the reconfigurable metasurface under different application scenarios.

[0056] Figure 3 (b) is a photograph of a prepared metasurface sample and its folded state, and the insert shows an enlarged detail of the chiral excitation unit structure. Figure 3 (c)-(g) are respectively the measured circularly polarized transmission coefficient spectra at folding angles of 0°, 15°, 25°, 30°, and 45°. Figure 3 (h) is the calculated circular dichroism (CD) spectrum according to Figure 3 (c)-(g) are respectively the measured circularly polarized transmission coefficient spectra at folding angles of 0°, 15°, 25°, 30°, and 45°.

[0057] The chiral control method of the reconfigurable chiral metasurface based on the origami flexible structure comprises the following steps:

[0058] S1, set the position of the achiral excitation unit on the flexible medium substrate as a planar connection area.

[0059] S2, attach a plurality of hardened foam strips on the back of the planar connection area to provide flexible support and deformation limitation.

[0060] S3, a plurality of slidable bases are arranged in the length direction in the bottom groove, and a sliding groove is formed on the base, and the plurality of hardened foam strips are respectively inserted into the plurality of sliding grooves, thereby forming the connection between the hardened foam strips and the base.

[0061] S4, by moving the base, the relative movement between the hardened foam strips is driven, so that the flexible medium substrate is folded through the creases, and a plurality of chiral excitation units are folded in different directions and form a three-dimensional structure with mutual inclination and dislocation.

[0062] S5, adjusting the folding angle of the flexible dielectric substrate, the chirality of the metasurface will also change, thereby realizing chirality control of the metasurface.

[0063] By continuously controlling and adjusting the folding angle through the above method, the chirality of the metasurface can be dynamically controlled from 0 to 1. In addition to the base and sliding groove used in the present application for angle control, the following low-cost mechanical control methods can also be used:

[0064] 1. Screw knob type adjusting mechanism: a micro knob or nut is arranged at the edge of the metasurface, and the folding angle is controlled by rotating the connecting rod system, which has the advantages of simple structure, good repeatability and low cost.

[0065] 2. Lockable folding structure: an adjustable folding page with angle scale is used, and the folding state of multiple stable angles can be controlled by sliding and buckling positioning, which is suitable for rapid assembly and batch testing.

[0066] 3. Elastic limit pull rope structure: a fixed length of thin rope or adjustable elastic wire is connected to the unit to control the stretching length, which can realize folding angle adjustment without complex support system, and is suitable for portable device design.

[0067] 4. Paper-based / plastic crease preformed structure: laser cutting / thermal forming is used to preform creases on the flexible substrate to realize programmable folding structure similar to paper folding effect, which is suitable for one-time or ultra-low cost application scenarios.

[0068] 5. Sliding groove + baffle combination positioning: standard T-shaped sliding groove is combined with movable baffles for angle positioning, which can be manually adjusted and is convenient for mechanical integration, and is suitable for laboratory and industrial environment.

[0069] The manufacturing process of the reconfigurable chirality metasurface based on the paper folding flexible structure includes the following steps:

[0070] S1, a flexible dielectric substrate with a thickness of 0.1 mm and a dielectric constant of εr = 3.5 is used as the substrate, and a copper layer with a thickness of 35 microns is deposited on one side of the flexible dielectric substrate by electroplating to form a uniform conductive surface for subsequent pattern processing;

[0071] S2, the chirality excitation unit is defined by printed circuit board technology, and is formed on the copper layer by wet etching;

[0072] S3, a plurality of the crease units and the cutting line units are made by femtosecond laser micromachining technology, thereby realizing high-precision cutting without thermal damage.

[0073] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and application of the present application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present application, which is defined by the following claims and their equivalents.

Claims

1. A reconfigurable chiral metasurface based on origami flexible structure, comprising a flexible dielectric substrate and a plurality of chiral excitation units forming an array on the flexible dielectric substrate, characterized in that: The flexible medium substrate is provided with a plurality of crease units and cutting line units, the crease unit comprises two side creases and a center crease arranged in parallel, the two side creases are respectively located on both sides of the chiral excitation unit, and the center crease passes through the center of the chiral excitation unit, so that the plurality of chiral excitation units are folded in different directions and form a three-dimensional structure with mutual inclination and dislocation.

2. The origami-based flexible structure reconfigurable chiral metasurface of claim 1, wherein: The chiral excitation unit comprises a first metal conductor rectangular ring and a second metal conductor rectangular ring, the second metal conductor rectangular ring is located in the first metal conductor rectangular ring and is arranged concentrically, and the first metal conductor rectangular ring and the second metal conductor rectangular ring are respectively provided with a first opening and a second opening in dislocation, so that the first metal conductor rectangular ring and the second metal conductor rectangular ring are arranged in dislocation after the flexible medium substrate is folded, and symmetry is broken, and the folding angle θ of the flexible medium substrate is the dihedral angle of the folding surface of the flexible medium substrate and the xy plane.

3. The origami-based flexible structure reconfigurable chiral metasurface of claim 2, wherein: The cutting line unit comprises a first cutting line, a second cutting line and a third cutting line in the shape of U, the first cutting line is arranged outside the bottom end of the first metal conductor rectangular ring, the second cutting line is arranged in the first metal conductor rectangular ring and above the second metal conductor rectangular ring, and the third cutting line is arranged in the first metal conductor rectangular ring and below the second metal conductor rectangular ring, and the width of the second cutting line is greater than that of the third cutting line.

4. The origami-based flexible structure reconfigurable chiral metasurface of claim 2, wherein: The thickness of the flexible medium substrate is 0.1 mm, and the thickness of the first metal conductor rectangular ring and the second metal conductor rectangular ring is 0.035 mm.

5. The origami-based flexible structure reconfigurable chiral metasurface of claim 2, wherein: The length a of the left conductor segment, the length g1 of the right upper conductor segment and the width t1 of the right lower conductor segment of the first metal conductor rectangular ring are 12 mm, 3 mm and 0.5 mm respectively, and the width g2 of the second opening, the length d of the left conductor segment, the length b of the top conductor segment and the length c of the right conductor segment of the second metal conductor rectangular ring are 1 mm, 6 mm, 4 mm and 8 mm respectively.

6. The origami-based flexible structure reconfigurable chiral metasurface of claim 4, wherein: The material of the flexible medium substrate is polyimide film, and the material of the first metal conductor rectangular ring and the second metal conductor rectangular ring is copper.

7. The origami-based flexible structure reconfigurable chiral metasurface of claim 6, wherein: The calculation formula of the chiral evaluation index CD is as follows: ， wherein CD is a chiral evaluation index, Ttot is the total transmission for left-handed circularly polarized wave incidence, Ttot is the total transmission for right-handed circularly polarized wave incidence, Tco is the co-polarized transmission coefficient for left-handed circularly polarized wave incidence, Tcx is the cross-polarized transmission coefficient for left-handed circularly polarized wave incidence, Tco is the co-polarized transmission coefficient for right-handed circularly polarized wave incidence, Tcx is the cross-polarized transmission coefficient for right-handed circularly polarized wave incidence. 8.A method for chiral modulation of a reconfigurable chiral metasurface based on origami flexible structure, characterized in that, The reconfigurable chiral metasurface based on the origami flexible structure is used, and the steps include the following: S1, the position of the achiral excitation unit on the flexible medium substrate is set as a planar connection area; S2, a plurality of hardened foam strips are attached on the back of the planar connection area to provide flexible support and deformation limitation; S3, a plurality of movable bases are arranged in the length direction in the bottom groove, and a sliding groove is formed on the base, and the plurality of hardened foam strips are respectively inserted into the plurality of sliding grooves, so as to form the connection between the hardened foam strips and the base; S4, by moving the base, the relative movement between the hardened foam strips is driven, so that the flexible medium substrate is folded by the crease, and the plurality of chiral excitation units are folded in different directions and form a three-dimensional structure with mutual inclination and dislocation. S5, adjusting the folding angle of the flexible dielectric substrate, the chirality of the metasurface will also change, thereby realizing the chirality regulation of the metasurface.

9. A fabrication process of reconfigurable chiral metasurfaces based on origami flexible structures, characterized in that, The reconfigurable chirality metasurface based on the origami flexible structure according to any one of claims 6-7 comprises the following steps: S1, a flexible dielectric substrate with a thickness of 0.1 mm and a dielectric constant of εr = 3.5 is used as a substrate, and a copper layer with a thickness of 35 microns is deposited on one side of the flexible dielectric substrate by electroplating to form a uniform conductive surface for subsequent pattern processing; S2, the chirality excitation unit is defined by a printed circuit board process, and is formed on the copper layer by wet etching; S3, a plurality of the crease units and the cutting line units are made by femtosecond laser micromachining technology, thereby realizing high-precision cutting without thermal damage.

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