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arXiv · 2301.07408

Toward arbitrary spin-orbit flat optics via structured geometric phase gratings

Chun-Yu Li·Si-Jia Liu·Bing-Shi Yu·Hai-Jun Wu·Carmelo Rosales-Guzmán·Yijie Shen·Peng Chen·Zhi-Han Zhu·Yan-Qing Lu
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Abstract

Reciprocal spin-orbit coupling (SOC) via geometric phase with flat optics provides a promising platform for shaping and controlling paraxial structured light. Current devices, from the pioneering q-plates to the recent J-plates, provide only spin-dependent wavefront modulation without amplitude control. However, achieving control over all the spatial dimensions of paraxial SOC states requires spin-dependent control of corresponding complex amplitude, which remains challenging for flat optics. Here, to address this issue, we present a new type of flat-optics elements termed structured geometric phase gratings that is capable of conjugated complex-amplitude control for orthogonal input circular polarizations. By using a microstructured liquid crystal photoalignment technique, we engineered a series of flat-optics elements and experimentally showed their excellent precision in arbitrary SOC control. This principle unlocks the full-field control of paraxial structured light via flat optics, providing a promising way to develop an information exchange and processing units for general photonic SOC states, as well as extra-/intracavity mode convertors for high-precision laser beam shaping.

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Chun-Yu Li, Si-Jia Liu, Bing-Shi Yu, Hai-Jun Wu, Carmelo Rosales-Guzmán, Yijie Shen, Peng Chen, Zhi-Han Zhu, Yan-Qing Lu. 2023-01-18. Toward arbitrary spin-orbit flat optics via structured geometric phase gratings. https://doi.org/10.1002/lpor.202200800

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