Generation of a radially polarized beam in a polycrystalline ceramic Yb:Lu 2 O 3 thin-disk laser

We report on the generation of a continuous-wave (CW) radially polarized beam with an Yb:Lu 2 O 3 polycrystalline ceramic disk in a thin-disk laser (TDL) oscillator. A circular grating-waveguide mirror (CGWM) with a high polarization discrimination given by a reflectivity difference between the two orthogonal polarization states of 44.6% was used as a polarization-selective cavity end-mirror. An output power of 175 W was achieved with an optical efficiency of 39.6%. A high degree of radial polarization of 96.2% and a beam propagation factor of M 2 hor. = 2.05 and M 2 ver. = 2.32 were measured at the maximum output power.