Liquid crystal spatial-mode converters for the orbital angular momentum of light

TL;DR

This paper introduces a tunable liquid crystal device capable of converting and superposing orbital angular momentum modes of light, functioning similarly to a wave plate for polarization, with potential applications in quantum optics.

Contribution

The work presents a novel liquid crystal device that manipulates orbital angular momentum modes, enabling mode conversion and superposition with tunability and specific state simulation.

Findings

Device effectively converts OAM eigenmodes

Simulates a C0/2 phase retarder in OAM space

Generates desired modes from Gaussian input

Abstract

We present a tunable liquid crystal device that converts pure orbital angular momentum eigenmodes of a light beam into equal-weight superpositions of opposite-handed eigenmodes and vice versa. For specific input states, the device may thus simulate the behavior of a {\pi}/2 phase retarder in a given two-dimensional orbital angular momentum subspace, analogous to a quarter-wave plate for optical polarization. A variant of the same device generates the same final modes starting from a Gaussian input.