Independent Control of Copolarized Amplitude and Phase Responses via Anisotropic Metasurfaces

Abstract

A class of anisotropic, transmissive electromagnetic metasurfaces is presented, which enable independent and simultaneous control of copolarized phase and amplitude responses to two linear, orthogonal polarizations. By varying the geometrical parameters, the transmission response of the proposed structure can yield a full phase coverage, accompanied by broadly adjustable amplitude and negligible cross‐polarized components. The full amplitude‐phase control together with the novel anisotropic character allows efficient implementation of complicated field manipulations. As representative application examples, which cannot be realized via conventional (phase‐only) metasurfaces, it is presented here: (1) the radiation of multiple equal‐power vortex beams (along arbitrarily predesigned directions, with designable orbital angular momentum modes under different polarizations), and (2) the realization of polarization‐reconfigurable multifocal metalenses. Full‐wave numerical simulations and experimental results demonstrate good agreement and confirm the versatility and effectiveness of the proposed approach to design advanced field‐manipulation systems.

Frequency‐Multiplexed Complex‐Amplitude Meta‐Devices Based on Bispectral 2‐Bit Coding Meta‐Atoms

“…More recently, a few complex-amplitude meta-holograms have been reported. [38][39][40][41][42][43][44][45] Nevertheless, most of existing meta-holograms only access one or two of the several basic dimensions (e.g., amplitude, phase, frequency, and polarization) of EM manipulations.…”

Recent advances and perspectives on space-time coding digital metasurfaces

“…As previously mentioned, although the reflection coefficient is defined for a linear time-invariant system, equation 9is approximately valid in the adiabatic limit f 0 ≪ f c [38,39]. From equation (9), it is possible, in principle, to attain arbitrary harmonic distributions by judiciously designing the temporal modulation for the reflection coefficient G (t), which opens up interesting pathways in the spectral shaping of EM waves. Figure 5b illustrates a practical implementation of a coding element, featuring two rectangular patches linked by a varactor diode acting as a tunable element, controlled via a biasing voltage [32].…”

“…This is an extremely fascinating concept, with a wealth of interesting implications and ramifications, which has found a broad variety of applications. At microwave frequencies, particularly worth of mention are those to dynamical beam/polarization manipulations [5,6], reprogrammable holograms [7] and imaging [8], independent control of co-polarized amplitude and phase responses [9], scattering-signature reduction [10,11], and direct transmission of digital messages [12]. Applications to terahertz frequencies have also been actively pursued [13], as well as transmission-type [14], transmission-reflection-integrated [15], and acoustic [16] scenarios.…”

Programmable Controls to Scattering Properties of a Radiation Array

“…The programmable and real‐time manipulations of EM waves by the programmable metasurface have been demonstrated in space and time domains, [ 35–40 ] leading to many novel applications such as holographic imaging, diffuse scattering, vortex beams in the visible spectral and microwave regions, conversions between propagation waves and surface waves, anomalous reflection and transmission, information processing, harmonic beam steering in space and frequency domains, and new architectures of wireless communication systems. [ 41–57 ] More recently, a thin self‐feeding Janus metasurface and digital‐coding‐feeding metasurface have been proposed for manipulating incident waves and emitting radiations simultaneously, which exhibit multiple functions including polarization conversion, scattering manipulation, EM wave radiation, and beam scanning. [ 58,59 ] However, the scattering properties cannot be programmable controlled.…”