Radially polarized high-power lasers

Abstract

In the recent years high-power laser beams with radial polarization have attracted an increasing interest because of their interesting properties in material processing. We present an overview of the current activities and different techniques to generate such beams in CO₂ and solid-state lasers. With a polarising end-mirror which comprises a resonant grating on a dielectric multilayer Bragg-structure we recently demonstrated a 3-kW radially polarised CO₂ laser. Current investigations are also focused especially on the application of this technology to thin-disk lasers. The specific requirements and the whole development from the design and fabrication to the characterization and test are illustrated with the example of a multilayer polarizing grating mirror developed to generate a radially polarised beam in an Yb:YAG thin-disc laser resonator. The potential of this kind of beams are discussed with a number of first application results, which largely confirm the predictions presented by Niziev et al1.