Realization of a scalable Laguerre-Gaussian mode sorter based on a robust radial mode sorter

TL;DR

This paper presents a scalable, efficient, and crosstalk-free scheme for complete Laguerre-Gaussian mode sorting, enabling simultaneous determination of radial and angular momentum indices for advanced optical applications.

Contribution

The authors introduce a novel, robust radial mode sorter integrated with phase shifters and OAM sorters for complete LG mode sorting, advancing beyond previous partial solutions.

Findings

Successfully demonstrated complete LG mode sorting experimentally.

Scheme is efficient, scalable, and crosstalk-free.

Potential applications in quantum communication and superresolution imaging.

Abstract

The transverse structure of light is recognized as a resource that can be used to encode information onto photons and has been shown to be useful to enhance communication capacity as well as resolve point sources in superresolution imaging. The Laguerre-Gaussian (LG) modes form a complete and orthonormal basis set and are described by a radial index p and an orbital angular momentum (OAM) index l. Earlier works have shown how to build a sorter for the radial index p or/and the OAM index l of LG modes, but a scalable and dedicated LG mode sorter which simultaneous determinate p and l is immature. Here we propose and experimentally demonstrate a scheme to accomplish complete LG mode sorting, which consists of a novel, robust radial mode sorter that can be used to couple radial modes to polarizations, an l-dependent phase shifter and an OAM mode sorter. Our scheme is in principle efficient, scalable, and crosstalk-free, and therefore has potential for applications in optical communications, quantum information technology, superresolution imaging, and fiber optics.