Increasing the efficiency of the intra-cavity generation of ultra-short radially polarized pulses in thin-disk resonators with grating waveguide structures

In this paper, we report on the investigation of two different approaches based on grating waveguide structures (GWS) to generate radially polarized ultra-short pulses in thin-disk laser resonators. In previously reported mode-locked thin-disk oscillators emitting radially polarized pulses, a partly reflective GWS was employed as an outcoupling element for polarization shaping. This partly reflective GWS introduced significant losses for the outcoupled radiation, resulting in a reduced optical efficiency. The aim of the investigations presented here is to explore the possibility of improving the optical efficiency by using a highly reflective GWS in different resonator configurations, which circumvents the loss port present for the partly reflective GWS. The investigations show that using a highly reflective GWS as a folding mirror of the resonator enables a significant improvement of the optical efficiency compared to the previously reported configurations. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This paper investigates two different approaches based on grating waveguide structures to generate radially polarized ultra-short pulses in thin-disk laser resonators. By using a highly reflective GWS instead of a partly reflective GWS, significant improvement in optical efficiency can be achieved.