Antireflection and Wavefront Manipulation with Cascaded Metasurfaces

Yang, Fengyuan; Raeker, Brian O.; Nguyen, Dat T.; Miller, Joseph D.; Xiong, Ze; Grbic, Anthony; Ho, John S.

doi:10.1103/physrevapplied.14.064044

Cited by 32 publications

(19 citation statements)

References 34 publications

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“…In 2011, Yu et al first proposed the generalized Snell's law, including abrupt phase shifts from the metasurface unit cells to realize nearly arbitrary wavefront shaping [24]. Since then, various fascinating wavefront manipulations have been demonstrated, such as reflectionless wide-angle refraction [25,26], sub-diffraction focusing with ultrathin planar lens [27,28], and wave-impedance matching across different material boundaries [29]. Such metasurfaces have only a static function once fabricated, whereas reconfigurable metasurfaces with tunable functions are gaining attention.…”

Section: Terahertz Reconfigurable Intelligent Surfacementioning

confidence: 99%

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

2022

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The forthcoming sixth generation (6G) communication network is envisioned to provide ultra-fast data transmission and ubiquitous wireless connectivity. The terahertz (THz) spectrum, with higher frequency and wider bandwidth, offers great potential for 6G wireless technologies. However, the THz links suffers from high loss and line-of-sight connectivity. To overcome these challenges, a cost-effective method to dynamically optimize the transmission path using reconfigurable intelligent surfaces (RISs) is widely proposed. RIS is constructed by embedding active elements into passive metasurfaces, which is an artificially designed periodic structure. However, the active elements (e.g., PIN diodes) used for 5G RIS are impractical for 6G RIS due to the cutoff frequency limitation and higher loss at THz frequencies. As such, various tuning elements have been explored to fill this THz gap between radio waves and infrared light. The focus of this review is on THz RISs with the potential to assist 6G communication functionalities including pixel-level amplitude modulation and dynamic beam manipulation. By reviewing a wide range of tuning mechanisms, including electronic approaches (complementary metal-oxide-semiconductor (CMOS) transistors, Schottky diodes, high electron mobility transistors (HEMTs), and graphene), optical approaches (photoactive semiconductor materials), phase-change materials (vanadium dioxide, chalcogenides, and liquid crystals), as well as microelectromechanical systems (MEMS), this review summarizes recent developments in THz RISs in support of 6G communication links and discusses future research directions in this field.

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Section: Terahertz Reconfigurable Intelligent Surfacementioning

confidence: 99%

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

2022

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“…In essence a GSTC connects the tangential field discontinuities across a surface to the averaged fields of both sides of the surface through material (surface) proportionality constants. These proportionality constants are sometimes referred to as effective polarization densities as in (14), or surface susceptibilities as in (15), or even surface impedances as in (23). These different nomenclatures lead to different models with their own interpretations.…”

Section: E E E X Y Z E X Y Z H H H X Y Z H X Y Zmentioning

confidence: 99%

“…Another useful application of bianisotropic metasurfaces is seamless impedance matching and antireflection [22], [23]. Consider the work presented in [23].…”

Section: B Impedance Matching and Antireflectionmentioning

confidence: 99%

“…The tensors 𝑌 , 𝑍 ̅ ̅ , 𝜒̅ ̅ , and 𝛾̅ ̅ are collectively known as the constituent surface parameters. Note, (23) can also be expressed as [91] av ee me…”

Section: Sheet Impedance Modelmentioning

confidence: 99%

“…In recent years, extreme, reflectionless polarization control [14]- [21], seamless impedance matching between input and output fields [22], [23], as well as wide angle refraction [24]- [29] have been demonstrated using these sheet boundaries. Scientific works have also revealed that arbitrary field transformations can be achieved with bianisotropic boundaries consisting of complex electric, magnetic, and magneto-electric susceptibilities involving loss and gain.…”

Section: Introductionmentioning

confidence: 99%

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A Rigorous Approach to Designing Reflectarrays

Budhu

Grbic

2019

2019 23rd International Conference on Applied Electromagnetics and Communications (ICECOM)

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In recent years, new functionality and unprecedented wavefront control has been enabled by the introduction of bianisotropic metasurfaces. A bianisotropic metasurface is characterized by an electric response, a magnetic response, and an electro-magnetic/magneto-electric response. In general, these metasurfaces consists of an array of metallic or dielectric particles located within a subwavelength thick host medium, and are approximated and modelled as infinitely-thin, idealized sheet boundaries defined along a surface. An appropriate sheet boundary condition which effectively models the tangential field discontinuity due to the array of magnetoelectric inclusions is the Generalized Sheet Transition Condition or GSTC. Several forms of the GSTC appear in literature. Here, we present each interpretation and show how they are related. Synthesis approaches unique to each form are overviewed. By utilizing the GSTC in metasurface design, new possibilities emerge which are not possible with conventional design techniques incorporating only electric or only magnetic responses. Since the metasurfaces are designed using bianisotropic boundary conditions, they must be realized using particles which contain magnetoelectric responses. This review article discusses the design of metasurfaces using the GSTC, and the bianisotropic particles used to realize GSTC's. Further, it discusses new and recent applications that have emerged due to bianisotropy, and future prospects in metasurface design using bianisotropic boundary conditions. The intent is to provide a comprehensive overview of metasurface design involving bianisotropy and for this review article to serve as a starting point for engineers and scientist that wish to introduce bianisotropy into metasurface design.

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Reconfigurable Wide‐Angle Beam‐Steering Terahertz Metasurfaces Based on Vanadium Dioxide

Yang,

Tan,

Prakash

et al. 2023

Advanced Optical Materials

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The sixth generation (6G) wireless network is envisioned to provide faster and more reliable communication by utilizing electromagnetic waves in the terahertz spectrum. However, terahertz waves suffer from high propagation loss and, hence, wavefront manipulation solutions to focus and redirect terahertz waves are of paramount importance. Reconfigurable intelligent surface (RIS) is one such promising dynamic wavefront engineering solution proposed for 6G networks, but the technological realization of 6G (>100 GHz) RIS is still largely lacking. Here, spatially‐selective vanadium dioxide (VO2) patches incorporating coding metasurfaces for dynamic beam steering of terahertz waves are presented. The reversible and abrupt insulator‐to‐metal phase transition property of VO2 is exploited to achieve a reconfigurable transmission angle for the normal incident terahertz wave. By designing metasurfaces with specific linear phase gradients and designer phase sequencing, electrically switchable beam steering is achieved from co‐polarized 0° (normal transmission) in the OFF state to cross‐polarized 0° (control), 11°, 23°, 36°, and 52° in the ON state at 0.6 THz. Scaling up the proposed concept to achieve individual control of each active element (VO2) within the metasurface will enable a complete 6G RIS solution for full 3D terahertz beam manipulation to support the future THz wireless communication networks.

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Antireflection and Wavefront Manipulation with Cascaded Metasurfaces

Cited by 32 publications

References 34 publications

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

A Rigorous Approach to Designing Reflectarrays

Reconfigurable Wide‐Angle Beam‐Steering Terahertz Metasurfaces Based on Vanadium Dioxide

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