Programmable unitary spatial modes manipulation

TL;DR

This paper introduces a programmable mode converter capable of performing any spatial unitary transform of light fields, surpassing conventional optical systems, with experimental validation demonstrating high efficiency for mode transformations.

Contribution

The paper presents a novel, fully programmable unitary mode converter based on deformable mirrors and free space propagation, enabling arbitrary spatial mode transformations.

Findings

Theoretically capable of perfect any transform with unlimited resources.

Experimental implementation achieves over 80% efficiency for initial modes.

Demonstrates versatility beyond traditional optical systems.

Abstract

Free space propagation and conventional optical systems such as lenses and mirrors all perform spatial unitary transforms. However, the subset of transforms available through these conventional systems is limited in scope. We present here a unitary programmable mode converter (UPMC) capable of performing any spatial unitary transform of the light field. It is based on a succession of reflections on programmable deformable mirrors and free space propagation. We first show theoretically that a UPMC without limitations on resources can perform perfectly any transform. We then build an experimental implementation of the UPMC and show that, even when limited to three reflections on an array of 12 pixels, the UPMC is capable of performing single mode tranforms with an efficiency greater than 80% for the first 4 modes of the TEM basis.