Broadband generation of perfect Poincaré beams via dielectric spin-multiplexed metasurface

M Liu, P Huo, W Zhu, C Zhang, S Zhang… - Nature …, 2021 - nature.com
M Liu, P Huo, W Zhu, C Zhang, S Zhang, M Song, S Zhang, Q Zhou, L Chen, HJ Lezec
Nature communications, 2021nature.com
The term Poincaré beam, which describes the space-variant polarization of a light beam
carrying spin angular momentum (SAM) and orbital angular momentum (OAM), plays an
important role in various optical applications. Since the radius of a Poincaré beam
conventionally depends on the topological charge number, it is difficult to generate a stable
and high-quality Poincaré beam by two optical vortices with different topological charge
numbers, as the Poincaré beam formed in this way collapses upon propagation. Here …
Abstract
The term Poincaré beam, which describes the space-variant polarization of a light beam carrying spin angular momentum (SAM) and orbital angular momentum (OAM), plays an important role in various optical applications. Since the radius of a Poincaré beam conventionally depends on the topological charge number, it is difficult to generate a stable and high-quality Poincaré beam by two optical vortices with different topological charge numbers, as the Poincaré beam formed in this way collapses upon propagation. Here, based on an all-dielectric metasurface platform, we experimentally demonstrate broadband generation of a generalized perfect Poincaré beam (PPB), whose radius is independent of the topological charge number. By utilizing a phase-only modulation approach, a single-layer spin-multiplexed metasurface is shown to achieve all the states of PPBs on the hybrid-order Poincaré Sphere for visible light. Furthermore, as a proof-of-concept demonstration, a metasurface encoding multidimensional SAM and OAM states in the parallel channels of elliptical and circular PPBs is implemented for optical information encryption. We envision that this work will provide a compact and efficient platform for generation of PPBs for visible light, and may promote their applications in optical communications, information encryption, optical data storage and quantum information sciences.
nature.com
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