Laser beam shaping and stabilization for single-mode laser material processing based on Multi-Plane Light Conversion

Authors: Clément Jacquard¹, Olivier Pinel¹, Pu Jian¹, Jean-François Morizur¹, Guillaume Labroille^1
1Cailabs (France)

Abstract

Laser beam parameters vary over time: tilt, shift, defocusing or modal imperfections can negatively impact the applications. It can drastically degrade the performance of a beam shaping setup (DOE, SLM, etc.), especially with pulsed laser processing.

We present a novel approach for beam shaping coupled with passive modal filtering that compensates for the imperfections and temporal variations of the laser beam parameters. The non-ideal, misaligned beam is projected on an adapted transverse mode basis. The unwanted energy is routed onto higher order modes and dumped or used as a feedback signal, while the energy in the fundamental Gaussian mode is shaped into the spatial mode of interest (e.g. flat-top, Bessel beam, etc.). This approach is implemented with Multi-Plane Light Conversion technique, whose high flexibility and shaping performance enable efficient, versatile and robust shaping for applications where beam pointing accuracy and beam quality are crucial, such as micro-processing and ultrafast laser processing.