High power, electronically-controlled, source of user-defined vortex and vector light beams based on a few-mode fibre amplifier

TL;DR

This paper demonstrates a high-power, tunable laser source capable of generating user-defined vortex and vector light beams using a few-mode fibre amplifier and a spatial light modulator, overcoming previous power and tunability limitations.

Contribution

It introduces a computer-controlled SLM to adaptively generate various structured light modes in a high-power fibre amplifier, enabling scalable and tunable vortex and vector beams.

Findings

Generated >10 W average power beams with >11 kW peak power.

Able to produce any supported spatial mode, including OAM and vector modes.

Mitigated modal distortion within the fibre amplifier.

Abstract

Orbital angular momentum (OAM) based structured light beams provide an additional degree of freedom for practical applications ranging from optical communication to laser-based material processing. Many techniques exist for generating such beams within laser sources and these primarily rely upon the use of specially designed optical components that limit laser power scaling and ready tunability of the topological charge and polarization of the output OAM beams. Here we show that some of these limitations can be overcome by employing a computer controlled reflective phase-only spatial light modulator (SLM) to adaptively tailor the input (and subsequent output) beam wavefront and polarization in a few-mode fibre amplifier. In this way modal-coupling induced beam distortion within the fibre amplifier can be mitigated and we are able to generate at will any desired supported spatial mode guided in the fibre, including conventional LP modes, scalar OAM modes and cylindrical vector modes, at average powers >10 W and with a peak power of >11 kW. Our results pave the way to the realization of practical high-power structured laser sources with tunable chirality and polarization.