# Measuring the complex orbital angular momentum spectrum and spatial mode decomposition of structured light beams

## TL;DR

This paper introduces a simple, experimentally validated method for measuring the complex orbital angular momentum spectrum and spatial mode decomposition of structured light beams using digital interference analysis, enabling comprehensive characterization.

## Contribution

The authors present a novel, practical approach for fully characterizing structured light beams' orbital angular momentum and spatial modes through digital interference analysis.

## Key findings

- Successfully measured complex OAM spectrum and spatial modes
- Method reduces measurement complexity and number of measurements
- Validated approach with experimental results

## Abstract

Light beams carrying orbital angular momentum are key resources in modern photonics. In many applications, the ability of measuring the complex spectrum of structured light beams in terms of these fundamental modes is crucial. Here we propose and experimentally validate a simple method that achieves this goal by digital analysis of the interference pattern formed by the light beam and a reference field. Our approach allows one to characterize the beam radial distribution also, hence retrieving the entire information contained in the optical field. Setup simplicity and reduced number of measurements could make this approach practical and convenient for the characterization of structured light fields.