Tailoring Circular Dichroism in an Isomeric Manner: Complete Control of Amplitude and Phase for High‐Quality Hologram and Beam Forming

Abstract

Nowadays, the research of metasurfaces has been developed from singledimensional toward multi-dimensional manipulation of electromagnetic (EM) waves, which greatly boosts the practical application of metasurfaces in both microwave and optics regimes. Currently, the demand for new methods to implement effective manipulation of EM waves in multiple dimensions is ever being increased yet it is still a challenging task. Here, a metasurface-based paradigm is proposed for tailoring both amplitude and phase by isomeric manner in a dichroism level, which reveals a flexible capability of manipulating EM waves within all isotropic, anisotropic and chiral characteristics. Circular dichroism (CD) meta-atoms are implemented via loading lumped resistors into planar chiral resonators. The cross-polarization reflection amplitude of the circularly polarized wave is tailored precisely and continuously from 0 to 1 using the diastereomers of CD meta-atoms, while the phase is independently manipulated by the rotamer counterparts based on Pancharatnam-Berry (PB) phase. By controlling both amplitude and phase profiles of the metasurfaces with subwavelength spatial resolution, high-quality complex amplitude hologram and far-field beam forming are demonstrated. Encouragingly, this approach for achieving simultaneous control of amplitude and phase makes a milestone on multi-dimensional metasurfaces which may find applications in integrated planar EM functional systems.

Recent Advances in Tunable Metasurfaces: Materials, Design, and Applications

“…Holographic metasurface uses a concept similar to traditional optical holography to recreate complex optical wavefronts. − However, metasurface holograms exhibit limited bandwidth. Hence, the resolution of metasurface holographic images is not comparable to conventional digital holograms.…”

Smart Metasurface for Active and Passive Cooperative Manipulation of Electromagnetic Waves

“…Simultaneously, metasurfaces, an artificial material for arbitrary passive control of EM waves, have been investigated widely. A series of noticeable functionalities, including polarization conversion, − vortex beams, − holograms, − cloaks, and so on, , have been explored and achieved by meticulous design. Although metasurfaces exhibit excellent capabilities for light field modulation, the functions of a single metasurface are still limited.…”

Dynamically tunable multimodal vortex beam generator based on reflective metasurface

“…17,18 Compared to conventional phased array systems using digital or analog phase shifters, programmable metasurfaces offer tremendous advantages in terms of reduced dynamic beam formation, scanning complexity, and cost. 19 According to the spatial phase distribution of vortex EM waves exp(ilφ), where φ is the spatial azimuthal angle, ℓ is the OAM mode number, which is generally taken as an integer, the metasurface can be used to generate vortex EM waves in optics and RF. [20][21][22] The use of transmissive or reflective metasurfaces to generate individual OAM modes, broadband vortex beams, and reconfiguration of OAM modes by active elements has been explored.…”

“…In contrast, programmable metasurfaces are reconfigurable planar arrays composed of artificially designed electromagnetic scattering units that can efficiently and flexibly modulate parameters such as vortex electromagnetic wave amplitude, phase, and polarization state 17,18 . Compared to conventional phased array systems using digital or analog phase shifters, programmable metasurfaces offer tremendous advantages in terms of reduced dynamic beam formation, scanning complexity, and cost 19 . According to the spatial phase distribution of vortex EM waves exp ( ilφ ), where φ is the spatial azimuthal angle, ℓ is the OAM mode number, which is generally taken as an integer, the metasurface can be used to generate vortex EM waves in optics and RF 20–22 .…”