CW and modelocked operation of an Yb:(Sc,Y,Lu)2O3 thin-disk laser

The authors present the first thin-disk laser based on the new sesquioxide material Yb:(Sc,Y,Lu)₂O₃ (Yb:ScYLO). The emission cross section exhibits a peak at 1037 nm and an emission bandwidth of 18.5 nm FWHM, making this material an interesting candidate for short-pulse generation. For the initial cw multimode laser experiments we used a 200 μm thick 3 at.%-doped Yb:ScYLO disk as an active mirror in a simple linear resonator consisting only of an output coupler with a radius of curvature of 100 mm and a highly reflective disk at a distance of 7 cm. The authors pumped the disk at the zero-phonon line using a Volume Bragg Grating stabilized fiber-coupled laser diode emitting at 976 nm with an emission bandwidth of 0.6 nm. The pump module supports 24 absorption passes through the disk. With a 1,9-mm pump spot diameter on the disk and an outcoupling rate of 2.1%, the authors obtained an output power of 50 W for 90.4 W of pump power. This corresponds to an optical-to optical efficiency of 55% and a slope efficiency of 72%.