A broadband and efficient terahertz polarization-selective flexible metasurface device

Abstract

The present invention discloses a broadband and efficient terahertz polarization-selective flexible metasurface device, wherein the unit structure of the metasurface device consists of a three-layer metal structure and two layers of flexible polyimide dielectric layers; the device has high linear polarization conversion efficiency in a broadband range of 0.6 to 1.0 THz; the device can be used to realize broadband and efficient beam deflection and vortex waves; and provides ideas for realizing broadband applications in the fields of information encryption, terahertz wireless communication, and spectroscopy.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz metamaterials and electromagnetic functional devices, and specifically relates to a broadband and efficient terahertz polarization-selective flexible metasurface device. Background Art

[0002] In recent years, terahertz technology has developed rapidly and has shown good prospects in many basic research and engineering application fields. For example, due to the abundant spectrum resources, terahertz communication has a higher data capacity than existing microwave communication, and polarization and orbital angular momentum (OAM) multiplexing can further increase the information capacity. However, traditional terahertz devices are usually limited by large size and low efficiency, especially when the available space is limited, such as ultra-compact imaging systems. Metasurfaces are two-dimensional metamaterials composed of ultrathin subwavelength structures. By cleverly designing the resonant mode of the structure and the change of its spatial distribution, the output electromagnetic field of the metasurface can be arbitrarily manipulated to realize various functional devices such as planar lenses, beam deflectors, holographic imaging, and vortex wave generators.

[0003] High efficiency and wide bandwidth are important indicators for measuring the performance of terahertz transmission devices. Single-layer metal metasurface devices with the advantages of ultra-thinness, flexibility and easy processing can effectively control terahertz electromagnetic waves and realize many interesting functions and phenomena. However, since the single-layer metal structure only has electrical resonance, its maximum cross-polarization efficiency is limited to 25%. In addition, some terahertz all-dielectric metasurfaces have also attracted attention due to their low ohmic losses, but they are still limited by shortcomings such as narrow bandwidth and difficulty in conformality. At present, in the terahertz frequency band, flexible devices that can achieve broadband high efficiency and polarization selection performance are relatively rare, and those that can effectively characterize their application performance are even rarer. Summary of the invention

[0004] Purpose of the invention: In order to solve the problems of narrow transmission bandwidth and low efficiency of existing devices in the terahertz frequency band, the present invention proposes a broadband and efficient terahertz polarization-selective flexible metasurface device and application. By effectively designing the metal structure pattern and making full use of the electromagnetic response between the multi-layer metal structures, broadband and high polarization efficiency can be achieved at terahertz frequencies, and it can be applied to beam deflection and asymmetric transmission of vortex waves.

[0005] Technical solution: A broadband and efficient terahertz polarization selective flexible metasurface device, which includes, from the top layer to the bottom layer: a top metal structure, a first flexible polyimide dielectric layer, an intermediate metal structure, a second flexible polyimide dielectric layer and a bottom metal structure;

[0006] The top metal structure includes rectangular grating stripes on one side, rectangular grating stripes in the middle, and rectangular grating stripes on the other side; the rectangular grating stripes on one side, the rectangular grating stripes in the middle, and the rectangular grating stripes on the other side all extend along the y-axis direction; the length of the rectangular grating stripes on one side, the length of the rectangular grating stripes in the middle, and the length of the rectangular grating stripes on the other side are all the same, and are the same as the period length of the metasurface device, and the three are parallel to each other; the rectangular grating stripes on one side and the rectangular grating stripes on the other side are symmetrical about the rectangular grating stripes in the middle; the width of the rectangular grating stripes on one side is the same as the width of the rectangular grating stripes on the other side;

[0007] The intermediate layer metal structure includes a first C-shaped opening ring, a second C-shaped opening ring and a solid circle; the opening angles of the first C-shaped opening ring and the second C-shaped opening ring are the same, and the opening positions of the two are opposite; the first C-shaped opening ring intersects with the second C-shaped opening ring; the solid circle is located inside the second C-shaped opening ring; the opening midpoint, the center of the opening ring and the center of the solid circle are located on a straight line;

[0008] The bottom metal structure is the same as the top metal structure, and the top metal structure is rotated 90 degrees to obtain the bottom metal structure.

[0009] Furthermore, the first flexible polyimide dielectric layer and the second flexible polyimide dielectric layer have the same thickness.

[0010] Furthermore, the first flexible polyimide dielectric layer and the second flexible polyimide dielectric layer are both made of a flexible polyimide material having a dielectric constant of 3.5 and a loss tangent of 0.0027.

[0011] Furthermore, the angle between the straight line and the horizontal line is 45°.

[0012] A method for preparing a broadband and efficient terahertz polarization-selective flexible metasurface device of the present invention comprises the following steps:

[0013] Step 1: Spin-coat a polyimide liquid on a silicon substrate, and after high-temperature curing by baking, obtain a first polyimide film as a support layer;

[0014] Step 2: After photolithography and development, a gold film with a thickness of 200 nm is deposited, and then a bottom metal structure is formed on the first polyimide film through a lift-off process;

[0015] Step 3: Spin-coat polyimide liquid on the bottom metal structure multiple times, and after high-temperature heat curing, obtain a second polyimide film as the second flexible polyimide dielectric layer of the bottom metal structure and the middle metal structure;

[0016] Step 4: After photolithography and development, a gold film with a thickness of 200 nm is deposited, and then an intermediate metal structure is formed on the second flexible polyimide dielectric layer through a lift-off process;

[0017] Step 5: Spin-coat polyimide liquid on the intermediate metal structure for multiple times, and after high-temperature heat curing, obtain a third polyimide film as the first flexible polyimide dielectric layer of the intermediate metal structure and the top metal structure;

[0018] Step 6: After photolithography and development, a gold film with a thickness of 200 nm is deposited, and then a top metal structure is formed on the first flexible polyimide dielectric layer through a lift-off process to form a sample;

[0019] Step 7: After heating the sample in an 80° water bath for 1 hour, use a knife or sharp tweezers to scratch the edge of the polyimide film and peel the polyimide film off the silicon substrate to obtain a broadband and efficient terahertz polarization-selective flexible metasurface device.

[0020] The present invention also discloses a metasurface device for realizing the function of abnormal beam deflection, comprising 8 basic unit structures, wherein the 8 basic unit structures are arranged in sequence according to different phase gradients along the x-axis direction and arranged in a pattern of keeping the phase along the y-axis unchanged; and abnormal transmission of the incident x-polarized beam within a broadband range is realized; and each of the basic unit structures is a broadband and efficient terahertz polarization-selective flexible metasurface device disclosed above.

[0021] The present invention also discloses a metasurface device for generating broadband vortex wave function, comprising 8 basic unit structures. According to the vortex wave phase distribution formula φ=larctan(y / x), the phase distribution of the vortex wave generator metasurface carrying different topological charges l is determined. Based on the phase distribution of the vortex wave generator metasurface, 8 basic unit structures are arranged to realize the regulation of vortex waves within a broadband range. Each of the basic unit structures is a broadband and efficient terahertz polarization-selective flexible metasurface device disclosed above.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention adopts a three-layer metal structure and two flexible polyimide dielectric layers. The multi-layer structure forms a Fabry-Perot resonant cavity, and the reflection and transmission generated thereby can improve the transmission efficiency. In addition, the electromagnetic resonance between the multi-layer metal structures and the multi-mode resonance of the intermediate layer metal structure enable the device to achieve a higher polarization conversion efficiency within a broadband range.

[0024] (2) The present invention can obtain 8 basic units with a phase gradient of 45° by simply adjusting the opening angle of the open ring and rotating the intermediate metal structure, thereby achieving a 360° coverage range of the cross-transmission phase. Compared with other devices, the structure is simple, easy to process, and has the characteristics of wide bandwidth and high efficiency, and can be used to realize multifunctional terahertz wave control. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The schematic diagram is a broadband and efficient terahertz polarization selective flexible metasurface device structure; Figure 1 (a) is the unit structure. Figure 1 (b) is the top metal structure; Figure 1 (c) is the intermediate metal structure; Figure 1 (d) in the figure is the underlying metal structure;

[0026] Figure 2 It is a curve diagram of the simulation and measurement results of the transmission coefficient and polarization conversion coefficient (PCR) of the metasurface unit structure of the present invention; wherein, Figure 2 (a) is the transmission coefficient curve. Figure 2 (b) in the figure is the PCR corresponding to co-polarization and cross-polarization;

[0027] Figure 3 Schematic diagram of 8 basic unit structures of the metasurface of the present invention and the cross transmission coefficient; wherein, Figure 3 (a) is a schematic diagram of the 8-unit structure, and the last four units are rotated 90° counterclockwise relative to the first four units; Figure 3 (b) in the figure shows the amplitude distribution of 8 unit structures; Figure 3 (c) in the figure shows the phase distribution of 8 unit structures;

[0028] Figure 4 The metasurface device of the present invention is applied to abnormal deflection; wherein Figure 4 (a) shows the arrangement of the supersurface unit structure; Figure 4 (b) shows the distribution of deflection angles of electromagnetic waves in the y-polarization direction at different frequencies when an electromagnetic wave in the x-polarization direction is incident on the metasurface device;

[0029] Figure 5 The metasurface device of the present invention is applied to the regulation of vortex waves; wherein, Figure 5 (a) shows the arrangement of the metasurface unit structure with topological charge number l = +1; Figure 5 (b) shows the arrangement of the metasurface unit structure with topological charge number l = +2; Figure 5 (c) shows the electric field distribution of the y-polarized vortex beam when the topological charge number l = +1 is incident and transmitted with an electromagnetic wave in the x-polarization direction; Figure 5(d) in the figure is the electric field distribution of the y-polarized vortex beam generated by the transmission when an electromagnetic wave with x-polarization direction is incident when the topological charge number l=+2. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is now further described in conjunction with the accompanying drawings and embodiments.

[0031] Embodiment 1:

[0032] This embodiment discloses a broadband and efficient terahertz polarization-selective flexible metasurface device, which is mainly composed of a three-layer metal structure and two layers of flexible polyimide dielectric layers. The multilayer structure forms a Fabry-Perot resonant cavity, and the reflection and transmission generated thereby can improve the transmission efficiency; in addition, the electromagnetic resonance between the multilayer metal structures and the multi-mode resonance of the intermediate metal structure enable the device to achieve a high polarization conversion efficiency within a broadband range.

[0033] like Figure 1 As shown, the three-layer metal structure includes a top metal structure 1, a middle metal structure 3 and a bottom metal structure 5; the material of the three-layer metal structure of this embodiment is gold; the two-layer flexible polyimide dielectric layer includes a first flexible polyimide dielectric layer 2 and a second flexible polyimide dielectric layer 4.

[0034] The flexible polyimide dielectric layer of this embodiment is made of a flexible polyimide material with a dielectric constant of 3.5 and a loss tangent of 0.0027. The first flexible polyimide dielectric layer 2 and the second flexible polyimide dielectric layer 4 have the same thickness.

[0035] The top metal structure 1 of this embodiment is a metal grating, and the grating stripes of the metal grating are along the y-axis direction; the grating stripes include three rectangular structures of the same length and parallel to each other, which are recorded as the two side rectangles and the middle rectangle; the two side rectangles have the same width and are symmetrical about the y-axis; the middle rectangle is located at the center of the metal grating. The length of the rectangular structure in the top metal structure 1 is the same as the period length of the broadband and efficient terahertz polarization selective flexible metasurface device.

[0036] The bottom metal structure 5 of this embodiment is exactly the same as the grating structure of the top metal structure 1, but is rotated 90° relative to each other and is responsible for selecting the polarization direction of the incoming / outgoing electromagnetic wave. The length of the rectangular structure in the bottom metal structure 5 is the same as the period length of the broadband and efficient terahertz polarization-selective flexible metasurface device.

[0037] The intermediate layer metal structure 3 of this embodiment is composed of two C-shaped open rings of different sizes and a solid circle. The opening angles of the two C-shaped open rings are the same, but the opening positions are opposite. For the convenience of description, they are recorded as the first C-shaped open ring and the second C-shaped open ring. The first C-shaped open ring and the second C-shaped open ring intersect; the solid circle is located in the second C-shaped open ring; the opening midpoints of the two open rings are on a straight line with the center of the circular ring and the center of the solid circle, and the angle between the straight line and the horizontal direction is 45°. The radius of the first C-shaped open ring, the radius of the second C-shaped open ring, the radius of the solid circle, the opening angle and the width of the C-shaped open ring are optimized and determined by simulation software to achieve the highest polarization conversion efficiency in a wide band.

[0038] Embodiment 2:

[0039] This embodiment discloses a method for preparing a broadband and efficient terahertz polarization-selective flexible metasurface device, which mainly includes the steps of preparing polyimide dielectric layers of different thicknesses, sputtering a metal pattern layer, and peeling off a polyimide film. The specific operations include:

[0040] Step 1: Spin-coat a polyimide liquid on a silicon substrate, and heat-bake and cure it at high temperature to obtain a polyimide film with a thickness of about 3 μm, which serves as a support layer for the underlying metal structure; the high-temperature heat-bake curing conditions in this step are: heating at 80°C, 120°C, 170°C, and 220°C for 30 minutes, and finally heating at 320°C for 2 hours to cure the polyimide film;

[0041] Step 2: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then the underlying metal structure is formed on the support layer by a lift-off process;

[0042] Step 3: Spin-coat polyimide liquid on the bottom metal structure multiple times, and cure it through high-temperature heat baking to obtain a polyimide film with a thickness of about 25 μm, which serves as the second flexible polyimide dielectric layer between the bottom metal structure and the middle metal structure; the high-temperature heat baking curing conditions in this step are: heating at 80°C, 120°C, 170°C, and 220°C for 30 minutes, respectively, and finally heating at 320°C for 2 hours to cure to form a polyimide film.

[0043] Step 4: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then an intermediate metal structure is formed on the dielectric layer by a lift-off process;

[0044] Step 5: Spin-coat polyimide liquid on the middle layer metal structure multiple times, and cure it through high-temperature baking to obtain a polyimide film with a thickness of about 25 μm, which serves as the first flexible polyimide dielectric layer between the middle layer metal structure and the top layer metal structure; the high-temperature baking curing conditions in this step are: heating at 80°C, 120°C, 170°C, and 220°C for 30 minutes, respectively, and finally heating at 320°C for 2 hours to cure to form a polyimide film.

[0045] Step 6: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then a top metal structure is formed on the dielectric layer obtained in step 5 by a lift-off process to obtain a sample;

[0046] Step 7: Heat the sample in an 80° water bath for 1 hour, scratch the edge of the polyimide film with a knife or sharp tweezers, and peel the polyimide film on the silicon substrate from the silicon substrate to obtain a flexible metasurface device.

[0047] Embodiment 3:

[0048] like Figure 1 As shown, the flexible metasurface device of this embodiment is mainly composed of three layers of metal structure and two layers of flexible polyimide dielectric layers; Figure 1 As shown, the three-layer metal structure includes a top metal structure 1, a middle metal structure 3 and a bottom metal structure 5; the material of the three-layer metal structure of this embodiment is gold, and the thickness is 0.2um. The two-layer flexible polyimide dielectric layer includes a first flexible polyimide dielectric layer 2 and a second flexible polyimide dielectric layer 4. The flexible polyimide dielectric layer of this embodiment is prepared from a flexible polyimide material with a dielectric constant of 3.5 and a loss tangent of 0.0027. And the first flexible polyimide dielectric layer 2 and the second flexible polyimide dielectric layer 4 have the same thickness h=25um.

[0049] The top metal structure 1 of this embodiment is a metal grating, and the grating stripes of the metal grating are along the y-axis direction; the grating stripes include three rectangular structures of the same length and parallel to each other, which are recorded as the two side rectangles and the middle rectangle; the two side rectangles have the same width and are symmetrical about the y-axis; the middle rectangle is located at the center of the metal grating. The length of the rectangular structure in the top metal structure 1 is the same as the period length of the broadband and efficient terahertz polarization selective flexible metasurface device. Figure 1 As shown, the structural parameters designed in this embodiment include: period length P = 120μm, width d1 of the middle rectangle of the top metal structure = 25μm, width d2 of the two side rectangles of the top metal structure = 10μm, and spacing g between the middle rectangle and the two side rectangles = 20μm.

[0050] The bottom metal structure 5 of this embodiment is exactly the same as the grating structure of the top metal structure 1, but is rotated 90° relative to each other and is responsible for selecting the polarization direction of the incoming / outgoing electromagnetic wave. The length of the rectangular structure in the bottom metal structure 5 is the same as the period length of the broadband and efficient terahertz polarization-selective flexible metasurface device.

[0051] The intermediate layer metal structure 3 of the present embodiment is composed of two C-shaped opening rings of different sizes and a circle. The opening angles of the two C-shaped opening rings are the same, but the opening positions are opposite. For the convenience of expression, they are recorded as the first C-shaped opening ring and the second C-shaped opening ring. The first C-shaped opening ring and the second C-shaped opening ring intersect. The solid circle is located inside the second C-shaped opening ring. The opening midpoints of the two opening rings are on a straight line with the center of the circular ring and the center of the solid circle, and the angle between the straight line and the horizontal direction is 45°.

[0052] like Figure 1 As shown, the structural parameters designed in this embodiment include: the width of the C-shaped opening ring w = 10μm, the inner radius of the large C-shaped opening ring r1 = 30μm, the inner radius of the small C-shaped opening ring r2 = 8μm, the radius of the circle r3 = 12μm, the opening angle of the C-shaped opening ring a = 135°, and the centers of the large and small opening rings and the solid circle are O1 (12.5, 12.5), O2 (-26.5, -26.5), and O3 (20, 20), respectively.

[0053] In order to characterize the electromagnetic properties of the above-mentioned metasurface unit, the metasurface device of this embodiment is prepared according to the following steps:

[0054] Step 1: Spin-coat a polyimide liquid (JA-101A1, Nantong Jingai Microelectronics) on a silicon (500 μm ± 25 nm) substrate at a rotation speed of 1500 rpm / 15 s and 6000 rpm / 60 s, then heat at 80°C, 120°C, 170°C, and 220°C for 30 min, and finally heat at 320°C for 2 hours to solidify into a polyimide film with a thickness of 3 μm as a support layer for the underlying metal structure;

[0055] Step 2: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then the underlying metal structure is formed on the support layer by a lift-off process;

[0056] Step 3: Continue to spin-coat the polyimide liquid at a speed of 1500 rpm / 15s and 3000 rpm / 60s. After high-temperature baking and curing, a polyimide film with a thickness of about 8.3 μm is obtained. The spin-coating of the polyimide liquid is repeated three times to finally form a polyimide film with a thickness of about 25 μm, which serves as the second flexible polyimide dielectric layer of the bottom layer and the middle layer metal structure.

[0057] Step 4: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then an intermediate metal structure is formed on the second flexible polyimide dielectric layer by a lift-off process;

[0058] Step 5: Continue to spin-coat the polyimide liquid at a speed of 1500 rpm / 15s and 3000 rpm / 60s. After high-temperature baking and curing, a polyimide film with a thickness of about 8.3 μm is obtained. The spin coating of the polyimide liquid is repeated three times to finally form a polyimide film with a thickness of about 25 μm, which serves as the first flexible polyimide dielectric layer of the top layer and the middle layer metal structure.

[0059] Step 6: After photolithography and development, a titanium film with a thickness of 10 nm and a gold film with a thickness of 200 nm are deposited by magnetron sputtering, and then a top metal structure is formed on the first flexible polyimide dielectric layer by a lift-off process to obtain a sample;

[0060] Step 7: Heat the sample in an 80° water bath for 1 hour, scratch the edge of the polyimide film with a knife or sharp tweezers, and peel the polyimide film off the silicon substrate to obtain Figure 1 The flexible metasurface device shown.

[0061] The characteristics of the metasurface device of this embodiment are now described through the transmission coefficient and the deflection conversion efficiency. Figure 2 It can be seen that in the operating frequency range of 0.5~1.0THz, the cross-polarization transmission coefficient t yx Close to 1, the cross-polarization transmission coefficient t xy is always close to zero, while the co-polarization transmission coefficient t xx and the co-polarization transmission coefficient t yy is suppressed to below 0.3. In addition, the polarization conversion efficiency in the x-polarization direction is also close to 100% in the wideband range of 0.5 to 1.0 THz. Therefore, the metasurface device of this embodiment can achieve high deflection conversion efficiency in a wideband range.

[0062] In addition, by changing the opening angle of the C-shaped opening ring of the intermediate metal structure 3 and rotating the intermediate metal structure 3, the phase coverage range of the cross transmission can be adjusted, thereby realizing functions such as abnormal refraction and vortex beam control. Figure 3 As shown in (a), the eight basic unit structures are obtained by changing the opening angle of the C-shaped opening ring and rotating the intermediate structure. The opening angles a corresponding to the first four unit structures are 30°, 95°, 135°, and 166°, respectively. The opening angles of the last four unit structures remain unchanged, but they are rotated 90° counterclockwise relative to the first four unit structures. The cross transmission coefficients of the eight unit structures are shown in Figure 3As shown in (b) and (c), it can be seen that in the range of 0.6 to 1.0 THz, the transmission amplitude remains unchanged, the phase gradient is 45°, and the phase of the 8-unit structure covers a range of 360°.

[0063] Embodiment 4:

[0064] This embodiment proposes a metasurface device for realizing the abnormal beam deflection function, which mainly includes: 8 basic unit structures; the 8 basic unit structures are arranged in sequence along the x-axis direction with a phase gradient of 45°, and the y-axis phase remains unchanged. The basic unit structure of this embodiment refers to Embodiment 1.

[0065] Figure 4 (a) is the unit structure arrangement, Figure 4 (b) is the cross transmission coefficient t yx From the distribution of beam deflection angles at different frequencies, we can see that in the frequency range of 0.5 to 1.0 THz, the incident x-polarized waves are transmitted as electromagnetic waves in the y-polarized direction at different angles, and the deflection angles satisfy the generalized Snell's refraction law.

[0066] Embodiment 5:

[0067] This embodiment proposes a metasurface device for generating broadband vortex wave function, which mainly includes: 8 basic unit structures; according to the vortex wave phase distribution formula φ=larctan(y / x), the phase distribution of the vortex wave generator metasurface carrying different topological charges l is determined, and the 8 basic unit structures are arranged to achieve the regulation of vortex waves within a broadband range. The basic unit structure of this embodiment refers to Example 1.

[0068] Figure 5 The metasurface device is used to generate broadband vortex waves, wherein: Figure 5 (a) is the arrangement of the metasurface unit structure with topological charge number l = +1; Figure 5 (b) is the arrangement of the supersurface unit structure with topological charge number l = +2; Figure 5 (c) shows the field intensity and phase distribution of the vortex beam in the y-polarization direction generated by the transmission at frequencies f = 0.6 THz, f = 0.8 THz, and f = 1.0 THz when an electromagnetic wave in the x-polarization direction is incident on a metasurface device with a topological charge number of l = +1; Figure 5 (d) in the figure is the field intensity and phase distribution of the vortex beam in the y-polarization direction generated by the transmission at frequencies f=0.6THz, f=0.8THz, and f=1.0THz when the x-polarized electromagnetic wave is incident on the metasurface device with a topological charge number of l=+2.

[0069] The experimental results are in good agreement with the simulation results, indicating that the metasurface device designed in this embodiment can achieve broadband and efficient vortex beam control in the frequency range of 0.6 to 1.0 THz.

[0070] The present invention arranges the supersurface unit structures differently for different electromagnetic functions.

Claims

1. A broadband and efficient terahertz polarization-selective flexible metasurface device, characterized in that: The invention comprises, from the top layer to the bottom layer, a top metal structure (1), a first flexible polyimide dielectric layer (2), an intermediate metal structure (3), a second flexible polyimide dielectric layer (4) and a bottom metal structure (5); The top metal structure (1) comprises rectangular grating stripes on one side, rectangular grating stripes in the middle and rectangular grating stripes on the other side; the rectangular grating stripes on one side, the rectangular grating stripes in the middle and the rectangular grating stripes on the other side are all arranged along y The length of the rectangular grating stripes on one side, the length of the middle rectangular grating stripes and the length of the rectangular grating stripes on the other side are all the same, are the same as the period length of the metasurface device, and are parallel to each other; the rectangular grating stripes on one side and the rectangular grating stripes on the other side are symmetrical about the middle rectangular grating stripes; the width of the rectangular grating stripes on one side is the same as the width of the rectangular grating stripes on the other side; The intermediate layer metal structure (3) comprises a first C-shaped opening ring, a second C-shaped opening ring and a solid circle; the opening angles of the first C-shaped opening ring and the second C-shaped opening ring are the same, and the opening positions of the two are opposite; the first C-shaped opening ring intersects with the second C-shaped opening ring; the solid circle is located inside the second C-shaped opening ring; the opening midpoint, the center of the opening ring and the center of the solid circle are located on a straight line; The bottom metal structure (5) is the same as the top metal structure (1), and the top metal structure (1) is rotated 90 degrees to obtain the bottom metal structure (5); The first flexible polyimide dielectric layer (2) and the second flexible polyimide dielectric layer (4) are both made of a flexible polyimide material having a dielectric constant of 3.5 and a loss tangent of 0.0027.

2. The broadband and efficient terahertz polarization selective flexible metasurface device according to claim 1, characterized in that: The first flexible polyimide dielectric layer (2) and the second flexible polyimide dielectric layer (4) have the same thickness.

3. The broadband and efficient terahertz polarization selective flexible metasurface device according to claim 1, characterized in that: The angle between the straight line and the horizontal line is 45°.

4. A metasurface device for realizing the abnormal beam deflection function, characterized in that: It includes 8 basic unit structures, and the 8 basic unit structures are as follows: x The axial direction is arranged in sequence according to different phase gradients. y The axis phase is kept unchanged to arrange the arrangement rules; to achieve the incident within a broadband range x Abnormal transmission of polarized beams; Each of the basic unit structures is a broadband and efficient terahertz polarization-selective flexible metasurface device according to any one of claims 1 to 3.

5. A metasurface device for generating broadband vortex wave function, characterized in that: It includes 8 basic unit structures, according to the vortex wave phase distribution formula φ = larctan ( y / x ), determine the number of topological charges carried l Based on the phase distribution of the vortex wave generator metasurface, 8 basic unit structures are arranged to achieve the regulation of vortex waves in a broadband range; Each of the basic unit structures is a broadband and efficient terahertz polarization-selective flexible metasurface device according to any one of claims 1 to 3.

Images