Near-Perfect Sorting of Orbital Angular Momentum and Angular Position States of Light

TL;DR

This paper introduces a new optical method combining log-polar transform and holographic beam-splitting to efficiently sort photons in orbital angular momentum and angular position states, enhancing mode discrimination and mutual information.

Contribution

The paper presents a novel optical sorting technique that improves mode discrimination and reduces cross-talk for OAM and ANG photon states, with both simulation and preliminary experimental results.

Findings

Mutual information of 2.43 bits/photon for OAM modes

Mutual information of 2.29 bits/photon for ANG modes

Enhanced mode discrimination compared to previous methods

Abstract

We present a novel method for efficient sorting of photons prepared in states of orbital angular momentum (OAM) and angular position (ANG). A log-polar optical transform is used in combination with a holographic beam-splitting method to achieve better mode discrimination and reduced cross-talk than reported previously. Simulating this method for 7 modes, we have calculated an improved mutual information of 2.43 bits/photon and 2.29 bits/photon for OAM and ANG modes respectively. In addition, we present preliminary results from an experimental implementation of this technique. This method is expected to have important applications for high-dimensional quantum key distribution systems.