Reflection broadband polarization conversion and phase precise control unit structure metasurface

Abstract

The invention discloses a reflection broadband polarization conversion and phase precise control unit structure metasurface which comprises a plurality of unit structures, and each unit structure is square. Each unit structure comprises a top metal pattern layer, a dielectric layer and a bottom metal reflecting layer from top to bottom. Wherein the top metal pattern layer comprises two metal resonance rings, the internal metal resonance ring is in a complete circular ring shape, the external metal resonance ring is formed by slotting the complete metal circular ring, the external metal resonance ring is provided with two slots, and the two slots are orthogonal to each other. According to the reflection broadband polarization conversion and phase precision control unit structure metasurface, the reflection type broadband cross polarization conversion and circular polarization phase adjustable metasurface which is simple in structure is provided, larger frequency band coverage of incident electromagnetic waves can be achieved, the higher bandwidth and precision are achieved, two degrees of freedom can be effectively managed, and the structure is simple. And the manufacturing complexity is simplified, and the potential application field is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic metasurfaces, and in particular to a metasurface with a reflective broadband polarization conversion and phase precision control unit structure. Background Art

[0002] Terahertz waves (THz) have attracted widespread attention due to their excellent operability and penetration ability. As an artificially designed two-dimensional structure, metasurfaces have significant advantages over traditional multilayer metal structures in electromagnetic wave manipulation, especially in the THz band. Polarization and phase are basic properties of electromagnetic waves and play a key role in electromagnetic wave regulation. Polarization describes the oscillation direction of the electric field vector of an electromagnetic wave. Precise control of polarization is crucial to optimizing antenna design and improving imaging resolution. Phase describes the oscillation state of an electromagnetic wave at a specific point. The wavefront can be adjusted through phase control, which is used to correct wavefront distortion and accurately guide light beams in adaptive optics and holographic wavefront shaping. Therefore, extending bandwidth in the THz band and flexibly controlling the polarization and phase of the incident wave are one of the current hot topics in metasurface research.

[0003] Currently, electromagnetic metasurfaces in the terahertz band have made significant progress, but due to the complexity of the current working environment, many multifunctional devices rely on multilayer structures and phase change materials, which increases their complexity and manufacturing challenges. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is the existing problems of narrow bandwidth, single function, complex structure, etc. The present invention provides a reflective broadband polarization conversion and phase precision control unit structure metasurface, provides a simple structure reflective broadband cross-polarization conversion and circular polarization phase adjustable metasurface, can achieve a wider frequency band coverage of the incident electromagnetic wave, has higher bandwidth and accuracy, can effectively manage two degrees of freedom, and simplifies the manufacturing complexity, and expands the potential application field.

[0005] To achieve the above-mentioned object, the present invention provides a reflective broadband polarization conversion and phase precision control unit structure metasurface, comprising a plurality of unit structures, each of which is square; the unit structures are respectively a top metal pattern layer, a dielectric layer and a bottom metal reflective layer from top to bottom; wherein,

[0006] The top metal pattern layer includes two metal resonant rings, wherein the inner metal resonant ring is a complete circular ring, and the outer metal resonant ring is a complete metal circular ring with grooves, and is set to have two grooves, and the two grooves are orthogonal to each other.

[0007] Furthermore, the two metal resonant rings in the top metal pattern layer and the bottom metal reflective layer are covered by copper sheets.

[0008] Furthermore, the dielectric layer is configured to use polytetrafluoroethylene material, with a dielectric constant of 2.33, a loss tangent of 0.0012, and a thickness of the dielectric layer of h=28 μm.

[0009] Furthermore, the unit size of the unit structure is l=100 μm.

[0010] Furthermore, the inner radius r4 = 5 μm and the outer radius r3 = 10 μm of the inner metal resonance ring of the top metal pattern layer, the inner radius r2 = 20 μm and the outer radius r1 = 45 μm of the outer metal resonance ring; the opening angle of the two slots of the outer metal resonance ring is β = 60°, and the angle between the center lines of the two slots is β1 = 90°.

[0011] Furthermore, the dielectric layer and the bottom metal reflective layer are configured to be square in shape, and the side lengths of the dielectric layer and the bottom metal reflective layer are the same as the unit size of the unit structure.

[0012] Furthermore, by selecting α in a counterclockwise direction for the two metal resonant rings of the top metal pattern layer, a uniform change in the phase of the reflected wave is achieved, and the corresponding phase change is 2α.

[0013] Furthermore, the conductivity is 5.96*10 7 S / m, wherein the copper sheet thickness of the top metal pattern layer is d1 = 0.1 μm, and the copper sheet thickness of the bottom metal reflective layer is d2 = 1 μm.

[0014] Furthermore, the bandwidth of the metasurface is set to 0.7044 to 2.0859 Thz, and its relative bandwidth is 99%.

[0015] Furthermore, by controlling the incident polarization angle, the incident angle is emitted at an angle symmetrical about the y=x axis, and the modulation accuracy of the polarization angle can be achieved within 1°; when linear polarization is incident, the incident angle is symmetrical about the y=x axis.

[0016] Technical Effects

[0017] A reflective broadband polarization conversion and phase precision control unit structure metasurface of the present invention separates the top metal pattern layer and the bottom metal reflection layer by an intermediate dielectric layer, and a resonant structure is formed by a slotted ring and an unslotted ring in the top metal pattern layer. The bottom metal reflection layer is used for the reflection of the incident wave, and finally forms a metasurface with a high reflection coefficient and high bandwidth with a three-layer structure. The metasurface can effectively convert the incident x-polarized wave and y-polarized wave in the range of 0.7044 to 2.0859 Thz. In this frequency band, the reflection coefficient of the metasurface of the present invention is higher than 0.7, and the relative bandwidth is 99%. For linear polarization incidence, the metasurface can modulate the angle of the incident different polarization angles about the y=x axis, and the modulation accuracy can reach 1°. At the same time, it has the function of converting the incident left-handed circularly polarized wave and right-handed circularly polarized wave in this bandwidth range; and by rotating the angle of the top pattern layer, it can perform full phase control between 0 and 2π, and the array is arranged according to the reflection phase of the metasurface at 1.3 Thz, and 2-bit encoding and 4-bit encoding are successfully realized. At the same time, the arrangement of the focusing array using the phase of the same frequency point not only achieves focusing at 1.3 Thz, but also has the focusing effect at 0.75 Thz and 1.8 Thz using the same array, which also shows that the metasurface can not only have uniform phase changes but also has broadband characteristics. The metasurface proposed by the present invention integrates the above functions on a unit structure metasurface at the same time.

[0018] At the same time, the present invention has the advantages of simple structure, small size, high broadband, high polarization conversion rate, and easy preparation. It also provides a new idea for polarization and phase manipulation in the terahertz band, and can be applied to ultra-wideband anomalous refraction, focusing, orbital angular momentum, imaging, holography, communication, etc., and has broad application prospects.

[0019] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a top view and a right view of a reflective broadband polarization conversion and phase precision control unit structure metasurface of a preferred embodiment of the present invention;

[0021] Figure 2 It is a reflection coefficient diagram of a reflective broadband polarization conversion and phase precision control unit structure metasurface when the incident light is linearly polarized in a preferred embodiment of the present invention;

[0022] Figure 3 It is a reflection phase diagram of a reflective broadband polarization conversion and phase precision control unit structure metasurface when the incident light is linearly polarized in a preferred embodiment of the present invention;

[0023] Figure 4 (a) is a schematic diagram of the operation of the x and y components of a reflective broadband polarization conversion and phase precision control unit structure metasurface when the linear polarization incident passes through two orthogonal slots in a preferred embodiment of the present invention;

[0024] Figure 4 (b) is a schematic diagram of a preferred embodiment of the present invention, in which an arbitrary linear polarization incident on a reflective broadband polarization conversion and phase precision control unit structure metasurface is decomposed into x and y components and synthesized after orthogonal slotting;

[0025] Figure 5 A reflective broadband polarization conversion and phase precision control unit structure metasurface of a preferred embodiment of the present invention emits a conversion spectrum diagram about the y=x axis when the polarization angles of the linear polarization are 15°, 30°, 60°, and 75° respectively;

[0026] Figure 6 It is a diagram showing the relationship between the rotation angle α and the conversion angle θ of a reflective broadband polarization conversion and phase precision control unit structure metasurface maintained under the condition of x-polarization incidence in a preferred embodiment of the present invention;

[0027] Figure 7 It is a reflection coefficient diagram of a reflective broadband polarization conversion and phase precision control unit structure metasurface when the incident light is circularly polarized and the top metal pattern layer is rotated in a preferred embodiment of the present invention;

[0028] Figure 8 It is a reflection phase diagram of a reflective broadband polarization conversion and phase precision control unit structure metasurface when the incident light is circularly polarized and the top metal pattern layer is rotated in a preferred embodiment of the present invention;

[0029] Fig. 9 (a) is a focusing array structure diagram of a reflective broadband polarization conversion and phase precision control unit structure metasurface arranged according to the circular polarization reflection phase at 1.3 Thz in a preferred embodiment of the present invention;

[0030] Fig. 9 (b) is a simulation effect diagram of a focusing array arranged according to a 1.3 Thz phase when the incident wave of a reflective broadband polarization conversion and phase precision control unit structure metasurface of a preferred embodiment of the present invention is 1.3 Thz;

[0031] Fig. 9 (c) is a simulation effect diagram of a focusing array arranged according to a 1.3 Thz phase when the incident wave of a reflective broadband polarization conversion and phase precision control unit structure metasurface of a preferred embodiment of the present invention is 0.75 Thz;

[0032] Fig. 9 (d) is a simulation effect diagram of a focusing array arranged according to a 1.3 Thz phase when the incident wave of a reflective broadband polarization conversion and phase precision control unit structure metasurface of a preferred embodiment of the present invention is 1.8 Thz;

[0033] Fig.10 It is a schematic diagram of the array structure and far-field effect of a reflective broadband polarization conversion and phase precision control unit structure metasurface when implementing 2-bit encoding in a preferred embodiment of the present invention;

[0034] Fig.11 It is a schematic diagram of the array structure and far-field effect of a reflective broadband polarization conversion and phase precision control unit structure metasurface when implementing 4-bit encoding in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] In the following description, specific details such as specific internal procedures and techniques are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0037] like Figure 1 As shown, the present invention provides a reflective broadband polarization conversion and phase precision control unit structure metasurface, and the metasurface structure is a three-layer structure. The metasurface includes a plurality of unit structures, each of which is square; the unit structures are respectively a top metal pattern layer 1, a dielectric layer 2, and a bottom metal reflective layer 3 from top to bottom; wherein,

[0038] The top metal pattern layer includes two metal resonant rings, wherein the inner metal resonant ring 5 is a complete circular ring, and the outer metal resonant ring 4 is a complete metal circular ring with slots, and is arranged as two slots, the two slots are orthogonal to each other, and the interaction of these two orthogonal slots gives the metasurface the ability to convert the polarization of any incident wave.

[0039] Among them, the inner radius of the inner metal resonant ring of the top metal pattern layer is r4 = 5μm, the outer radius is r3 = 10μm, the inner radius of the outer metal resonant ring is r2 = 20μm, and the outer radius is r1 = 45μm; the opening angle of the two slots of the outer metal resonant ring is β = 60°, and the angle between the center lines of the two slots is β1 = 90°, that is, the two slots are orthogonal to each other. The two metal resonant rings in the top metal pattern layer and the bottom metal reflective layer are covered by copper sheets with a conductivity of 5.96*10 7 S / m, wherein the copper sheet thickness of the top metal pattern layer is d1 = 0.1 μm, and the copper sheet thickness of the bottom metal reflective layer is d2 = 1 μm.

[0040] In this embodiment, the dielectric layer is configured to use polytetrafluoroethylene (Rogers RT5870) material, with a dielectric constant of 2.33, a loss tangent of 0.0012, and a thickness of h = 28 μm. Due to the transparency and low loss of polytetrafluoroethylene material in the terahertz band, the medium is used to separate the top metal pattern layer and the bottom metal reflective layer.

[0041] In addition, the unit size of the unit structure is l=100 μm. The dielectric layer and the bottom metal reflective layer are set to be square in shape, and the side length of the dielectric layer and the bottom metal reflective layer is the same as the unit size of the unit structure.

[0042] Furthermore, by selecting α counterclockwise for the two metal resonant rings of the top metal pattern layer, a uniform change in the phase of the reflected wave is achieved, and the corresponding phase change is 2α. Under different rotation angles α, the reflection phase of the metasurface changes uniformly, and the corresponding phase change is 2α. The array is arranged according to the characteristics of the reflection phase for focusing and 2-bit encoding and 4-bit encoding applications.

[0043] In order to verify the performance of a reflective broadband polarization conversion and phase precision cell structure metasurface of an embodiment of the present invention, this embodiment uses the finite integral time domain (FDTD) method to model and analyze the parameters of the metasurface in CST Microwave Studio software. During the simulation process, in order to simulate the infinite element structure, the structure is arranged in a unit cell manner in the x-axis and y-axis directions to form a periodic arrangement structure, and Floquet port excitation is set in the z-direction to simulate the propagation of electromagnetic waves.

[0044] An embodiment of the present invention is a simple-structured reflective broadband polarization conversion and phase precision control unit structural metasurface. By grooving the external metal resonant ring in the top metal pattern layer, openings are performed along the x-axis and y-axis respectively in this example. Simulation experiments show that these two orthogonal openings can perform polarization conversion on the incident electromagnetic waves.

[0045] The simulation results were obtained by using the simulation software CST Microwave Studio and the finite integral time domain (FDTD) method. yx and r xy is the cross-polarization component of the x-polarized wave and the y-polarized wave, using r xx , r yy is the co-polarization component of the x-polarized wave and the y-polarized wave. Figure 2 and Figure 3 As shown in the figure, the results show that when x- and y-polarized waves are incident on the metasurface, the reflection coefficient r xy (r yx ) and r xx (r yy ) have the same amplitude and phase, so r xy =r yx And r yy =r xx In the frequency range of 0.7044–2.0859 THz, |r xy |(|r yx |) exceeds 0.7, and the relative bandwidth is 99.02%. In the frequency range of 0.7466–2.0571THz, this value exceeds 0.9, and the relative bandwidth is 93.48%. f The calculation formula is:

[0046]

[0047] Among them, f h and f l They refer to the upper and lower frequency limits of the bandwidth respectively.

[0048] At 1.158THz, |r xy |(|r yx |) is about 0.9869; and |r xx |(|r yy |) is only about 0.0018. These results show that the metasurface has broadband characteristics and high conversion efficiency.

[0049] Specifically, if Figure 4 As shown in (a), when the electric field of the incident linear polarization wave is decomposed into two orthogonal components along the x-axis and the y-axis, the reflected wave is transformed through the orthogonal slots in the structure, so that the x-direction component is rotated 90° clockwise and the y-direction component is rotated 90° counterclockwise. Due to this orthogonal transformation, the x-component of the incident wave is transformed into the y-component of the reflected wave, and the y-component of the incident wave is transformed into the x-component of the reflected wave, resulting in a symmetrical relationship between the reflected wave and the incident wave. More importantly, there is an inverse relationship between the polarization angles of the incident and reflected waves, that is, Figure 4 As shown in (b), the polarization axis direction of the reflected wave is symmetrical with the direction of the incident wave about the y=x axis. When the incident wave is linearly polarized, the polarization direction of the reflected wave will also change symmetrically along the y=x axis. In addition, in some cases, such as when the polarization angle is π / 4 or 3π / 4, the cross-polarization component of the reflected wave disappears and only the co-polarization component exists, which further strengthens the symmetry between the incident and reflected waves. Therefore, this design of the structure achieves the symmetry of the incident and reflected waves on the y=x axis.

[0050] In order to verify the emission conditions for different incident polarization angles, this embodiment uses linear polarized waves with polarization angles of γ = 15°, 30°, 60° and 75°. According to the design principle, the polarization angles should be converted to 75°, 60°, 30° and 15° respectively. The spectrum obtained after calculation is as follows: Figure 5 As shown. In linear polarization, the rotation angle is the same as the polarization angle. In order to more intuitively demonstrate the ability of the metasurface to control polarization, in this embodiment, the 1.1580THz frequency point with the highest conversion efficiency in the working frequency band is selected to show the polarization state of the incident wave and the reflected wave. During the verification process, this embodiment keeps the incident wave as x-polarized. Figure 6 As shown, the metasurface is rotated at angles of α = 0°, 15°, 30°, 44.5°, 45°, 45.5°, 60° and 75° in sequence, and then the properties of the reflected waves are observed. Figure 6 The polarization states of the incident and reflected waves are shown, indicating that the transformation angles θ correspond to -90°, -60°, -30°, -1°, 0°, 1°, 30°, and 60°, respectively. The calculated results are highly consistent with the theoretical analysis. When α = 44.5° and 45.5°, the reflected field can still undergo precise polarization transformation, and the polarization angle rotates accurately by 1°.

[0051] At the same time, when circularly polarized waves are incident, r lr and r rl is the cross-polarization component of the right-handed circular polarization wave and the left-handed circular polarization wave, using r rr , r ll It is the co-polarization component of right-hand circularly polarized wave and left-hand circularly polarized wave.

[0052] Figure 7 is the reflection amplitude of the metasurface when circular polarization is incident at different rotation angles α. When the rotation degree α=0, the amplitude of the circular polarization incident wave of the present invention is the same as that of the linear polarization incident wave, and the reflection coefficient r rl (r lr ) and r rr (rll ) have the same amplitude. In the frequency range of 0.7044–2.0859THz, |r rl |(|r lr |) exceeds 0.7, and the relative bandwidth is 99.02%. In the frequency range of 0.7466–2.0571THz, this value exceeds 0.9, and the relative bandwidth is 93.48%. The two metal resonant rings on the top metal pattern layer are rotated counterclockwise by α, and it is found that as the rotation angle changes, the amplitude of the reflected circular polarization does not change much, but the reflected phase changes uniformly, and the amplitude of the change is about 2α. The specific reflection phase is as follows Figure 8 As shown, Figure 8 (a) and (b) are the phase spectra of the reflected phase when right-hand circular polarization (RCP) and left-hand circular polarization (LCP) are incident, respectively. Figure 8 (c) and (d) show the phase spectra of the relationship between the rotation angle α and the frequency, respectively.

[0053] like Fig. 9 (a) shows a schematic diagram of an array structure using the reflection phase at 1.3 Thz for array arrangement according to the change in the reflected circular polarization phase. A focusing array structure diagram of a 24*24 unit structure is arranged at 1.3 Thz using CST software. The calculation formula for the phase of the unit structure arranged at each position is:

[0054]

[0055] It refers to the position in the arranged unit structure, λ represents the wavelength of the incident electromagnetic wave, (x, y) represents the relative position of the unit structure, and l represents the focal length.

[0056] The phase of the unit structure at each position is arranged by calculation of this formula. The boundaries of the array are all set to open boundaries to indicate that the array is in an open space, such as Fig. 9 As shown in (b), this figure shows the focusing effect of the array when circularly polarized incident light is incident at 1.3 Thz. From the figure, it can be seen that at the 1.3 Thz frequency point, the array successfully achieves the focusing function, and its focal length is 2051 μm.

[0057] At the same time, in order to verify the broadband characteristics of the metasurface, the metasurface amplitude does not change much within the bandwidth, and the phase change within the bandwidth is relatively uniform. At the 0.75 Thz and 1.8 Thz frequency points within its bandwidth, the array arranged according to the phase distribution at the 1.3 Thz frequency point (i.e. Fig. 9 (a)), the focusing effect was observed, such as Fig. 9As shown in (c), the metasurface achieves focusing function when circularly polarized incident light is incident at a frequency of 0.75 Thz, and its focal length is 1188 μm. Fig. 9 As shown in (d), the focusing function is also achieved when circular polarization is incident at a frequency of 1.8 Thz, and the focal length is 3094 μm. It can be concluded that the invention has the characteristics of high broadband, high cross-polarization reflection efficiency, and uniform circular polarization phase change, and the excellent characteristics of the invention are proved by this embodiment.

[0058] At the same time, according to the phase characteristics of circular polarization incidence, a 2-bit coding array with a 24*24 unit structure is designed at the 1.3Thz frequency point. The selected phase is two units with an actual reflection phase difference of π. The actual reflection phase of coding unit "0" is 0°, and the corresponding α angle is 70°; the actual reflection phase of coding unit "1" is 180°, and the corresponding α angle is 159°. Each 3-column unit is regarded as a subarray and is designated as "0" or "1". There are open boundaries around the array, and the total period is 2400μm. The core of this function is to be able to use a discrete method of digital coding sequence to achieve highly controllable electromagnetic waves and achieve more precise regulation, such as Fig.10 As shown, the invented metasurface can achieve the far-field effect of 2-bit coding through the encoding operation of its reflection phase, verifying the controllability of the metasurface over the incident electromagnetic waves.

[0059] At the same time, the present invention also designs a 4-bit coding array composed of a 24*24 unit structure at the 1.3 Thz frequency point. Two units with an actual reflection phase difference of π are also selected. The specific rotation angles of the coding units "0" and "1" are the same as those of the 2-bit coding. Each 3*3 unit is used as a subarray to form a new "0" and "1" unit structure. There are open boundaries around the array, and the total period is 2400μm. Fig.11 As shown, the far field of the invented metasurface successfully achieved the effect of 4-bit encoding.

[0060] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A reflective broadband polarization conversion and phase precision control unit structure metasurface, characterized in that: It includes several unit structures, each of which is square; the unit structures are respectively a top metal pattern layer, a dielectric layer and a bottom metal reflection layer from top to bottom; wherein, The top metal pattern layer includes two metal resonant rings, wherein the inner metal resonant ring is a complete circular ring, and the outer metal resonant ring is a complete metal circular ring with grooves, and is set to have two grooves, and the two grooves are orthogonal to each other.

2. A reflective broadband polarization conversion and phase precision control unit structure metasurface as claimed in claim 1, characterized in that: The two metal resonant rings in the top metal pattern layer and the bottom metal reflective layer are both covered by a copper sheet.

3. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: The dielectric layer is configured to be made of polytetrafluoroethylene material, with a dielectric constant of 2.33, a loss tangent of 0.0012, and a thickness of the dielectric layer of h=28 μm.

4. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: The cell size of the cell structure is l=100 μm.

5. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: The inner radius r4 of the inner metal resonance ring of the top metal pattern layer is 5 μm, the outer radius r3 is 10 μm, the inner radius r2 of the outer metal resonance ring is 20 μm, and the outer radius r1 is 45 μm; the opening angle of the two slots of the outer metal resonance ring is β=60°, and the angle between the center lines of the two slots is β1=90°.

6. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 4, characterized in that: The dielectric layer and the bottom metal reflective layer are arranged in a square shape, and the side lengths of the dielectric layer and the bottom metal reflective layer are the same as the unit size of the unit structure.

7. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: By selecting α in a counterclockwise direction for the two metal resonant rings of the top metal pattern layer, a uniform change in the phase of the reflected wave is achieved, and the corresponding change phase is 2α.

8. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 2, characterized in that: The conductivity is 5.96*10 7 S / m, wherein the copper sheet thickness of the top metal pattern layer is d1=0.1 μm, and the copper sheet thickness of the bottom metal reflective layer is d2=1 μm.

9. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: The bandwidth of the metasurface is set to 0.7044 to 2.0859 Thz, and its relative bandwidth is 99%.

10. The reflective broadband polarization conversion and phase precision control unit structure metasurface according to claim 1, characterized in that: By controlling the incident polarization angle, the incident angle is emitted at an angle symmetrical about the y=x axis, and the modulation accuracy of the polarization angle can be achieved within 1°; when linear polarization is incident, the incident angle is symmetrical about the y=x axis.

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