Spin‐to‐Orbital Angular Momentum Conversion with Quasi‐Continuous Spatial Phase Response

Abstract

Vortex beams carrying orbital angular momentum have captivated great interest in the past few decades due to the inspiring application potential in both optical and microwave fields. More recently, assisted by Pancharatnam–Berry (PB) phase‐based meta‐atom, achieving spin–orbit‐converter becomes an encouraging topic. Commonly, however, spin–orbital‐converters are based on discontinuous phase distribution, which inevitably deteriorates their overall performance. To overcome this difficulty, here a paradigm of spin–orbital‐converter made of spirally arranged metastrip that can produce quasi‐continuously rotated phase profile with high‐efficiency is simulated and experimentally demonstrated in microwave regime. Using dispersion engineering, a meta‐atom capable of exciting spoof surface plasmon polaritons mode is designed to achieve PB phases. The metastrip consisting of a series of identical meta‐atoms is arranged along a proposed Archimedean spiral to obtain the rotated phase distribution of 4π. Near‐field performances reveal that the vortex electric distribution with topological charges of l = ± 2 can be generated. Significantly, this effort provides a strategy of achieving spin‐to‐orbital angular momentum conversion with phase continuity that may find applications in the fields of holography and communication systems.

Six‐Mode Orbital Angular Momentum Generator Enabled by Helicity‐Assisted Full‐Space Metasurface with Flexible Manipulation of Phase, Polarization, and Spatial Information

“…[4,5] Especially when numerous simulations and experiments demonstrate that OAM can be successfully applied in radio frequencies, the OAM technology shows great application potential in wireless communications. [6,7] Furthermore, a series of OAM generators are proposed to improve OAM performances, such as working bandwidth, [8][9][10] conversion efficiency, [11] and so on. [12][13][14] However, generating multiple OAM modes by the single OAM generator has always been a long-held knotty issue, which limits its communication capability.…”

Tailoring the Excited and Cutoff States of Spoof Surface Plasmon Polaritons for Full-Space Quadruple Functionalities

“…Recently, metamaterial technology has provided a new route for this academic issue. Metamaterials, consisting of periodically arranged meta-atoms in the deep subwavelength scale, reveal the formidable capability of tailoring electromagnetic waves. − With the assistance of metamaterials, various unprecedented phenomena and devices can be achieved, including anomalous reflection/refraction, , vortex light generation, − invisible cloak, perfect absorbers, polarizers, , etc. Especially, research on the integration of multiple functionalities resorts to this promising artificial material.…”

Tailoring Circular Dichroism for Simultaneous Control of Amplitude and Phase via Ohmic Dissipation Metasurface

“…[ 18–24 ] Because of the tremendous in‐plane design flexibility, metasurfaces are widely applied to realize diverse electromagnetic properties of effective media, such as isotropy, anisotropy, and chirality. Accordingly, plenty of meta‐devices are boosted, including isotropic perfect absorbers, [ 25 ] polarized‐dependent multifunctional reflectors/lens, [ 26,27 ] anisotropic spin‐to‐orbital converters, [ 28 ] and so on. Particularly, the researches of chiral metasurfaces have covered an astoundingly large portfolio of designs and spanned the frequencies from visible to gigahertz (GHz).…”