Terahertz chiral metasurface structure
By designing the terahertz chiral metasurface structure, the problem of traditional materials insufficient terahertz wave amplitude and polarization regulation capabilities is solved, and the multifunctional regulation and broadband response of terahertz waves are realized.
Patent Information
- Application Number
- CN202510619875.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-08-05
AI Technical Summary
In the prior art, traditional natural materials have limited amplitude and polarization regulation capabilities for terahertz waves, which are difficult to meet the needs of broadband wireless communications, biosensing and security inspections.
A terahertz chiral metasurface structure is designed, including a terahertz chiral metasurface unit composed of a top pattern layer, an intermediate dielectric layer and a base material layer. The top pattern layer contains a non-enclosed chiral structure of arcuate strips and linear strips to achieve circular dichroic effect and selective transmission of circular polarized waves.
It realizes multifunctional regulation of terahertz waves, including circular dichroism in the reflection channel and circular polarization wave selection transmittance in the transmission channel, and has broadband response capabilities.
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Figure CN120432884A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present disclosure belong to the technical field of terahertz multifunctional devices, and specifically relate to a terahertz chiral metasurface structure. Background Art
[0002] Electromagnetic metamaterials (metamaterials), also known as metamaterials, new artificial electromagnetic media, or exotic media, are artificial composite materials constructed from periodically or aperiodically arranged subwavelength unit structures. By precisely designing the geometric parameters and spatial arrangement of their unit structures, electromagnetic metamaterials can achieve unusual electromagnetic properties that are difficult or impossible to achieve with traditional materials in nature, such as negative dielectric constant, negative magnetic permeability, negative refractive index, and arbitrary non-uniform distributions of medium parameters. These properties can trigger a series of novel physical phenomena, providing new possibilities for electromagnetic wave manipulation. However, three-dimensional electromagnetic metamaterials are significantly limited in practical applications due to inherent drawbacks such as bulk, difficulty in integration, and high losses. To overcome these limitations, artificial electromagnetic metasurfaces (metasurfaces), a two-dimensional form of electromagnetic metamaterials, have emerged. Artificial electromagnetic metasurfaces, also known as new artificial electromagnetic surfaces or electromagnetic metasurfaces, can be considered the two-dimensional equivalent of three-dimensional electromagnetic metamaterials at ultra-thin thicknesses. Their structure consists of subwavelength artificial unit structures arranged in a specific pattern on a flat or curved surface, with their longitudinal dimensions much smaller than the operating wavelength. Compared with three-dimensional electromagnetic metamaterials, artificial electromagnetic metasurfaces have significant advantages in weight, volume, manufacturing cost and energy loss, while also having higher design flexibility and system integration capabilities.
[0003] Due to their low photon energy, strong penetration, and wide frequency bandwidth, terahertz waves hold great promise for applications in broadband wireless communications, biosensing, security inspections, and spectral imaging. These applications, such as terahertz communications, imaging, and sensing, require the ability to manipulate the amplitude and polarization of terahertz waves. However, traditional natural materials have limited ability to control these effects due to size constraints. Therefore, a metasurface structure capable of achieving terahertz wave manipulation is urgently needed. Summary of the Invention
[0004] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a terahertz chiral metasurface structure.
[0005] The present disclosure provides a terahertz chiral metasurface structure, comprising a plurality of periodically arranged terahertz chiral metasurface units, wherein the terahertz chiral metasurface units comprise a top pattern layer, an intermediate dielectric layer, and a base material layer sequentially arranged from top to bottom;
[0006] The top pattern layer includes a pair of chiral structures arranged opposite to each other, the chiral structures including arcuate bars and straight bars, the straight bars being formed by extending from one end of the arcuate bars toward the other end of the arcuate bars, and the two arcuate bars of a pair of chiral structures are concave in the direction toward each other.
[0007] In some embodiments of the present disclosure, the two linear bars of a pair of the chiral structures are parallel and spaced apart along an extension direction perpendicular to the linear bars.
[0008] In some embodiments of the present disclosure, a pair of the chiral structures are arranged in circular symmetry with respect to any one of the arc-shaped strips.
[0009] In some embodiments of the present disclosure, the thickness of the top pattern layer is 0.3 μm, the outer diameter of the arc strip is 9 μm, the inner diameter of the arc strip is 8 μm, the width of the straight strip is 1 μm, and the minimum length of the straight strip is 8 μm.
[0010] In some embodiments of the present disclosure, the top pattern layer is made of gold or graphene.
[0011] In some embodiments of the present disclosure, the intermediate dielectric layer is made of polyimide, has a thickness of 7 μm, a dielectric constant of 3.5, and a dielectric loss angle of 0.0027.
[0012] In some embodiments of the present disclosure, the base material layer includes a plurality of grid bars, and the plurality of grid bars are spaced apart and evenly arranged.
[0013] In some embodiments of the present disclosure, an extension direction of the grid bars is perpendicular to an extension direction of the linear bars.
[0014] In some embodiments of the present disclosure, the distance between two adjacent grid bars is 10 / 3 μm, and the width of the grid bar is 10 / 3 μm.
[0015] In some embodiments of the present disclosure, the base material layer is made of gold, the thickness of the base material layer is 0.3 μm, and the electrical conductivity of the base material layer is 4.561×10 7 S / m.
[0016] The terahertz chiral metasurface structure of the embodiment of the present disclosure includes a plurality of periodically arranged terahertz chiral metasurface units, the terahertz chiral metasurface units include a top pattern layer, an intermediate dielectric layer and a base material layer, the top pattern layer includes a pair of relatively arranged chiral structures, the chiral structure includes an arcuate bar and a straight bar, the straight bar is connected to one end of the arcuate bar, the straight bar extends from one end of the arcuate bar toward the other end of the arcuate bar, and the straight bar is non-contacting with the other end of the arcuate bar, that is, the chiral structure formed by the arcuate bar and the straight bar is a non-closed structure. The two arcuate bars of a pair of chiral structures are concave in the direction toward each other. The terahertz chiral metasurface structure disclosed in the present disclosure can achieve a circular dichroism effect in the reflection channel and a selective transmittance effect of circularly polarized waves in the transmission channel, that is, it can achieve the regulation, multi-functional integration and broadband response of terahertz nuclear magnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 Schematic diagram of the overall structure of the terahertz chiral metasurface structure according to an embodiment of the present disclosure;
[0018] Figure 2 for Figure 1 Top view of the terahertz chiral metasurface structure shown;
[0019] Figure 3 for Figure 1 A schematic structural diagram of the base material layer shown;
[0020] Figure 4 This is the reflection coefficient curve of the terahertz chiral metasurface structure under different circularly polarized wave incidences;
[0021] Figure 5 This is the transmission coefficient curve of the terahertz chiral metasurface structure under different circularly polarized wave incidences;
[0022] Figure 6 This is the reflectivity curve of the terahertz chiral metasurface structure under different circularly polarized wave incidences;
[0023] Figure 7 This is the transmittance curve of the terahertz chiral metasurface structure under different circularly polarized wave incidences;
[0024] Figure 8 This is a comparison diagram of the circular dichroism of the terahertz chiral metasurface structure and the mirror structure of the terahertz chiral metasurface structure on the reflection channel.
[0025] The reference numerals in the accompanying drawings represent the following:
[0026] 100. Terahertz chiral metasurface unit;
[0027] 10. Top pattern layer; 11. Chiral structure; 111. Arc strip; 112. Straight strip;
[0028] 20. Intermediate dielectric layer;
[0029] 30. Base material layer; 31. Grid bars;
[0030] h1, thickness of the base material layer; h2, thickness of the intermediate dielectric layer; h3, thickness of the top pattern layer; l1, width of the straight strip; l2, minimum length of the straight strip; l3, width of the grid strip; l4, spacing between two adjacent grid strips; r1, outer ring radius of the arc strip; r2, inner ring radius of the arc strip; P, period of the terahertz chiral metasurface unit. DETAILED DESCRIPTION
[0031] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.
[0032] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.
[0033] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.
[0034] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside," "outside," "inside," "outside," "below," "beneath," "above," and the like. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, an element described as "below" or "below" another element or feature would then be oriented as "above" or "above" another element or feature. Thus, the example term "below" can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.
[0035] like Figures 1 to 3 As shown, the present disclosure provides a terahertz chiral metasurface structure, including a plurality of periodically arranged terahertz chiral metasurface units 100, the terahertz chiral metasurface unit 100 including a top pattern layer 10, an intermediate dielectric layer 20 and a base material layer 30 arranged in sequence from top to bottom; the top pattern layer 10 includes a pair of relatively arranged chiral structures 11, the chiral structure 11 includes an arcuate bar 111 and a straight bar 112, the straight bar 112 is formed by extending from one end of the arcuate bar 111 toward the other end of the arcuate bar 111, and the two arcuate bars 111 of the pair of chiral structures 11 are concave toward each other.
[0036] The terahertz chiral metasurface structure of the disclosed embodiment includes a plurality of periodically arranged terahertz chiral metasurface units 100. The terahertz chiral metasurface units 100 include a top pattern layer 10, an intermediate dielectric layer 20, and a base material layer 30. The top pattern layer 10 includes a pair of oppositely disposed chiral structures 11. The chiral structures 11 include an arcuate bar 111 and a linear bar 112. The linear bar 112 is connected to one end of the arcuate bar 111. The linear bar 112 extends from one end of the arcuate bar 111 toward the other end of the arcuate bar 111. The linear bar 112 does not contact the other end of the arcuate bar 111, that is, the chiral structure 11 formed by the arcuate bar 111 and the linear bar 112 is a non-enclosed structure. The two arcuate bars 111 of the pair of chiral structures 11 are concave toward each other. The terahertz chiral metasurface structure disclosed herein can achieve a circular dichroism effect in the reflection channel and a selective transmittance effect of circularly polarized waves in the transmission channel, that is, it can realize the regulation, multifunctional integration and broadband response of terahertz nuclear magnetic waves.
[0037] In some embodiments of the present disclosure, a pair of chiral structures 11 are arranged symmetrically about the circle of any arcuate strip 111. Specifically, the centers of the two arcuate strips 111 of a pair of chiral structures 11 coincide, and the two arcuate strips 111 are arranged symmetrically about the center of the circle. The two linear strips 112 of a pair of chiral structures 11 are arranged symmetrically about the center of the arcuate strip 111.
[0038] Specifically, the two linear strips 112 of a pair of chiral structures 11 are parallel and spaced apart in a direction perpendicular to the extension direction of the linear strips 112. That is, along the width direction of the linear strips 112, the two linear strips 112 are spaced apart, that is, there is a gap between the two linear strips 112, that is, the two linear strips 112 are non-contacting.
[0039] like Figure 1 and Figure 2 As shown, in some embodiments of the present disclosure, the thickness h3 of the top pattern layer 10 is 0.3 μm, the outer radius r1 of the curved strip 111 is 9 μm, and the inner radius r2 of the curved strip 111 is 8 μm. The width l1 of the straight strip 112 is 1 μm, and the minimum length l2 of the straight strip 112 is 8 μm. Specifically, the minimum length l2 of the straight strip 112 refers to the length of the side of the straight strip 112 facing away from the other straight strip 112.
[0040] Specifically, in this embodiment, along the length direction of the straight bar 112, the straight bar 112 has a first end and a second end that are relatively arranged, and the first end of the straight bar 112 is connected to one end of the curved bar 111. The first end of the straight bar 112 is adapted to the structure of one end of the curved bar 111, that is, the first end of the straight bar 112 is the curved bar 111 structure, and the second end of the straight bar 112 is located on the concave side of the curved bar 111, and the second end of the linear metal bar is a rectangular structure.
[0041] In some embodiments of the present disclosure, the top pattern layer 10 is made of gold or graphene. This gold or graphene top pattern layer 10 can enhance the controllability of the terahertz chiral metasurface structure. Specifically, the top pattern layer 10 is fabricated using laser direct write etching or other photolithography techniques.
[0042] In some embodiments of the present disclosure, the material of the intermediate dielectric layer 20 is polyimide, the dielectric constant of the intermediate dielectric layer 20 is 3.5, and the dielectric loss factor of the intermediate dielectric layer 20 is 0.0027.
[0043] Furthermore, the thickness h2 of the intermediate dielectric layer 20 is 7 μm. The cross-section of the intermediate dielectric layer 20 is square, perpendicular to the thickness direction of the intermediate dielectric layer 20, and the side length of the square is 20 μm. The side length of the intermediate dielectric layer 20 is the period of the terahertz chiral metasurface structure, that is, the period of the terahertz chiral metasurface structure is 20 μm.
[0044] like Figure 3 As shown, in some embodiments of the present disclosure, the base material layer 30 includes a plurality of grid bars 31, and the plurality of grid bars 31 are spaced and evenly arranged. Specifically, the plurality of grid bars 31 are arranged in parallel, and along the width direction of the grid bars 31, the plurality of grid bars 31 are spaced and evenly arranged.
[0045] In some embodiments of the present disclosure, the extension direction of the grid bars 31 is perpendicular to the extension direction of the linear bars 112 , that is, the length direction of the grid bars 31 is perpendicular to the length direction of the linear bars 112 .
[0046] In some embodiments of the present disclosure, the width l3 of the grid bars 31 is 10 / 3 μm, and the spacing l4 between two adjacent grid bars 31 is 10 / 3 μm, that is, the spacing l4 between two adjacent grid bars 31 is the same as the width l3 of any grid bar 31 .
[0047] In some embodiments of the present disclosure, the thickness h1 of the base material layer 30 is 0.3 μm, that is, the thickness of the grid bars 31 is 0.3 μm. Specifically, the base material layer 30 is formed by preparing a plurality of spaced and evenly distributed grid bars 31 by reactive ion etching.
[0048] Specifically, the base material layer 30 is made of gold, and the electrical conductivity of the base material layer 30 is 4.561×10 7 S / m.
[0049] The terahertz chiral metasurface structure in the embodiments of the present disclosure reflects its performance through parameters such as reflectivity, transmittance, reflection coefficient, and transmission coefficient.
[0050] When left-handed circularly polarized (LCP) wave is incident, the reflectivity formula of the terahertz chiral metasurface structure is:
[0051] R L =|R RL | 2 +|R LL | 2 ;
[0052] Among them, R L is the absorption rate when left-hand circularly polarized wave (LCP) is incident, R RL R represents the cross-polarization reflection coefficient when left-hand circularly polarized wave (LCP) is incident. LLIt represents the co-polarization reflection coefficient when a left-hand circularly polarized wave (LCP) is incident.
[0053] When right-handed circularly polarized (RCP) wave is incident, the reflectivity formula of the terahertz chiral metasurface structure is:
[0054] R R =|R LR | 2 +|R RR | 2 ;
[0055] Among them, R R is the absorption rate when right-hand circularly polarized wave (RCP) is incident, R LR R represents the cross-polarization reflection coefficient when right-hand circularly polarized wave (RCP) is incident. RR It represents the co-polarization reflection coefficient when a right-hand circularly polarized wave (RCP) is incident.
[0056] When left-handed circularly polarized (LCP) wave is incident, the transmittance formula of the terahertz chiral metasurface structure is:
[0057] T L =|T RL | 2 +|T LL | 2 ;
[0058] Among them, T L is the transmittance when left-hand circularly polarized wave (LCP) is incident, T RL represents the cross-polarization transmission coefficient when left-hand circularly polarized wave (LCP) is incident, T LL It represents the co-polarization transmission coefficient when left-hand circularly polarized wave (LCP) is incident.
[0059] When right-handed circularly polarized (RCP) wave is incident, the transmittance formula of the terahertz chiral metasurface structure is:
[0060] T R =|T LR | 2 +|T RR | 2
[0061] Among them, T R is the transmittance when right-hand circularly polarized wave (RCP) is incident, T LR represents the cross-polarization transmission coefficient when right-handed circularly polarized wave (RCP) is incident, T RR It represents the co-polarization transmission coefficient when right-hand circularly polarized wave (RCP) is incident.
[0062] The circular dichroism (CD) formula of the terahertz chiral metasurface structure in the reflection channel is:
[0063] CD=|R LL | 2 -|R RR | 2 ;
[0064] Among them, R LL R represents the co-polarization reflection coefficient when left-hand circularly polarized wave (LCP) is incident. RR It represents the co-polarization reflection coefficient when a right-hand circularly polarized wave (RCP) is incident.
[0065] like Figures 4 to 8 As shown, the reflectivity, transmittance, etc. of the above embodiment are simulated and calculated using SCT simulation software to obtain corresponding curves.
[0066] Figure 4 The figure shows the reflection coefficient curve of the terahertz chiral metasurface structure under different circularly polarized wave incidences, where the horizontal axis is the frequency (THz) and the vertical axis is the reflection coefficient. Figure 4 It can be seen that when different circularly polarized waves are incident on the terahertz chiral metasurface structure, the reflection response of the terahertz chiral metasurface structure is different. Specifically, in the frequency range of 3.47-4.72THz, R LL Exceeding 0.8, at a frequency of 4.1 THz, R LL Reached 0.93, at this time, R RL 、R LR and R RR Therefore, in the reflection channel, the terahertz chiral metasurface structure can reflect the co-planned left-handed circularly polarized wave.
[0067] Figure 5 The transmission coefficient curve of the terahertz chiral metasurface structure under different circularly polarized wave incidence is shown, where the horizontal axis is the frequency (THz) and the vertical axis is the transmission coefficient. Figure 5 It can be seen that when different circularly polarized waves are incident on the terahertz chiral metasurface structure, the transmission response of the terahertz chiral metasurface structure is different. Specifically, when the RCP wave is incident, the frequency is at 4.1 THz, T LR and T RR Close to 0.7; when LCP wave is incident, T LL 、T RL Therefore, in the transmission channel, the terahertz chiral metasurface structure can only transmit right-handed circularly polarized waves.
[0068] Figure 6 The reflectivity curve of the terahertz chiral metasurface structure under different circularly polarized wave incidence is shown, where the horizontal axis is the frequency (THz) and the vertical axis is the reflectivity. Figure 6It can be seen that when different circularly polarized waves are incident on the terahertz chiral metasurface structure, the reflection response of the terahertz chiral metasurface structure is different. In the reflection channel, the terahertz chiral metasurface structure has a good reflection effect on LCP waves.
[0069] Figure 7 The transmittance curves of a terahertz chiral metasurface structure under different incident circularly polarized waves are shown, with frequency (THz) on the horizontal axis and transmittance on the vertical axis. When different circularly polarized waves are incident on the terahertz chiral metasurface structure, the transmission response of the terahertz chiral metasurface structure varies. In the transmission channel, the terahertz chiral metasurface structure has a good transmission effect on RCP waves and can suppress the transmission of LCP waves.
[0070] Figure 8 The circular dichroism comparison diagram of the terahertz chiral metasurface structure on the reflection channel and the mirror structure of the terahertz chiral metasurface structure is shown. Figure 8 It can be seen that in the reflection channel, the circular dichroism effects of the chiral structure 11 and the mirror image structure of the chiral structure 11 are opposite.
[0071] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.
Claims
1. A terahertz chiral metasurface structure, characterized in that: The invention comprises a plurality of periodically arranged terahertz chiral metasurface units, wherein the terahertz chiral metasurface units comprise a top pattern layer, an intermediate dielectric layer and a base material layer arranged in sequence from top to bottom; The top pattern layer includes a pair of chiral structures arranged opposite to each other, the chiral structures including arcuate bars and straight bars, the straight bars being formed by extending from one end of the arcuate bars toward the other end of the arcuate bars, and the two arcuate bars of a pair of chiral structures are concave in the direction toward each other.
2. The terahertz chiral metasurface structure according to claim 1, characterized in that: The two linear strips of a pair of the chiral structures are parallel and spaced apart along an extending direction perpendicular to the linear strips.
3. The terahertz chiral metasurface structure according to claim 1, characterized in that: A pair of the chiral structures are arranged in circular symmetry with respect to any one of the arc-shaped strips.
4. The terahertz chiral metasurface structure according to claim 1, characterized in that: The thickness of the top pattern layer is 0.3 μm, the outer ring radius of the arc strip is 9 μm, the inner ring radius of the arc strip is 8 μm, the width of the straight strip is 1 μm, and the minimum length of the straight strip is 8 μm.
5. The terahertz chiral metasurface structure according to claim 1, characterized in that: The material of the top pattern layer is gold or graphene.
6. The terahertz chiral metasurface structure according to claim 1, characterized in that: The material of the intermediate dielectric layer is polyimide, the thickness of the intermediate dielectric layer is 7 μm, the dielectric constant of the intermediate dielectric layer is 3.5, and the dielectric loss angle of the intermediate dielectric layer is 0.0027.
7. The terahertz chiral metasurface structure according to claim 1, characterized in that: The base material layer includes a plurality of grid bars, and the plurality of grid bars are spaced and evenly arranged.
8. The terahertz chiral metasurface structure according to claim 7, characterized in that: The extending direction of the grid bars is perpendicular to the extending direction of the straight bars.
9. The terahertz chiral metasurface structure according to claim 7, characterized in that: The distance between two adjacent grid bars is 10 / 3 μm, and the width of the grid bar is 10 / 3 μm.
10. The terahertz chiral metasurface structure according to claim 1, characterized in that: The base material layer is made of gold, the thickness of the base material layer is 0.3 μm, and the electrical conductivity of the base material layer is 4.561×10 7 S / m.