Spin-to-orbital angular momentum conversion in dielectric metasurfaces

TL;DR

This paper presents high-efficiency dielectric metasurfaces capable of converting spin to orbital angular momentum in visible light, enabling advanced vortex beam generation with applications in microscopy and beam shaping.

Contribution

It introduces a novel dielectric metasurface design for spin-to-orbital angular momentum conversion, surpassing previous liquid crystal q-plates in efficiency and versatility.

Findings

Generated vortex beams with high and fractional topological charge

Achieved simultaneous collinear beams with different orbital angular momentum

Demonstrated potential for improved microscopy and vector beam shaping

Abstract

Spin-to-orbital-angular-momentum conversion has attracted considerable interest as a tool to create exotic light beams, leading to the emergence of novel devices that implement this function. These converters exploit the geometrical phase to create helical beams of handedness determined by the chirality of the incident light. This property is finding important applications in quantum optics thanks to the demonstration of liquid crystal spin-to-orbital angular momentum converters (SOC) known as q-plates. Here we demonstrate high-efficiency SOCs in the visible based on dielectric metasurfaces that generate vortex beams with high and even fractional topological charge and show for the first time the simultaneous generation of collinear helical beams with different and arbitrary orbital angular momentum. We foresee that this versatile method of creating vortex beams, which circumvents the limitations of q-plates, will significant impact microscopy and vector beam shaping.