Application of Grating waveguide structures in high-power thin-disk lasers: requirements and challenges

Grating Waveguide Structures (GWS) capitalise on the combination of sub-wavelength gratings (periodic microstructures) integrated with planar waveguides. This combination results, by means of an appropriate design of the overall GWS, in interferences phenomena that modulate the efficiency of the diffracted or reflected beams over grating-only based devices commercially available today. For instance the -1st order diffraction efficiency of a GWS can reach close to 100% in theory and was experimentally demonstrated to be 99.7%. Such efficiency gains are enabling for new applications in the laser field like pulse compression, spectral stabilization and wavelength multiplexing, as well as polarization shaping (generation of beams with radial and azimuthal polarization). In the present contribution we will report on the requirements and challenges on the GWS for their efficient implementation in high-power laser system. After a short introduction of their operating principle and design, we will present in details the recent achievements using GWS for polarization and wavelength selection (including second harmonic generation) in high-power Yb:YAG thin-disk lasers.