Exploiting hidden singularity on the surface of the Poincaré sphere

Abstract The classical Pancharatnam-Berry phase, a variant of the geometric phase, arises purely from the modulation of the polarization state of a light beam. Due to its dependence on polarization changes, it cannot be effectively utilized for wavefront shaping in systems that require maintaining a...

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Bibliographic Details
Main Authors: Jinxing Li, Aloke Jana, Yueyi Yuan, Kuang Zhang, Shah Nawaz Burokur, Patrice Genevet
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-60956-2
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Summary:Abstract The classical Pancharatnam-Berry phase, a variant of the geometric phase, arises purely from the modulation of the polarization state of a light beam. Due to its dependence on polarization changes, it cannot be effectively utilized for wavefront shaping in systems that require maintaining a constant (co-polarized) polarization state. Here, we present a novel topologically protected phase modulation mechanism capable of achieving anti-symmetric full 2π phase shifts with near-unity efficiency for two orthogonal co-polarized channels. Compatible with -but distinct from- the dynamic phase, this approach exploits phase circulation around a hidden singularity on the surface of the Poincaré sphere. We validate this concept in the microwave regime through the implementation of multi-layer chiral metasurfaces. This new phase modulation mechanism expands the design toolbox of flat optics for light modulation beyond conventional techniques.
ISSN:2041-1723