Focal field analysis of highly multi-mode fiber beams based on modal decomposition

TL;DR

This paper introduces a numerical modal decomposition method to analyze the complex optical fields of laser beams after passing through highly multi-mode fibers, enabling detailed wave-optical modeling and free-space propagation analysis.

Contribution

It presents a novel modal decomposition algorithm based on measured intensity profiles and spectral coherence, improving accuracy in modeling highly multi-mode fiber beams.

Findings

Effective modal decomposition into LP modes achieved

Enhanced accuracy through various modeling strategies

Facilitates wave-optical simulation and free-space propagation analysis

Abstract

In this work, a numerical modal decomposition approach is applied to model the optical field of laser light after propagating through a highly multi-mode fiber. The algorithm for the decomposition is based on the reconstruction of measured intensity profiles along the laser beam caustic with consideration of intermodal degrees of coherence derived from spectral analysis. To enhance the accuracy of the model, different approaches and strategies are applied and discussed. The presented decomposition into a set of LP modes enables both the wave-optical simulation of radiation transport by highly multi-mode fibers and, additionally, the analysis of free-space propagation with arbitrarily modified complex amplitude distributions.