227-fs pulses from a mode-locked Yb:LuScO3 thin disk laser

The highest average output power and pulse energy from mode-locked laser oscillators are currently achieved using semiconductor saturable absorber mirror (SESAM) mode-locked thin disk lasers (TDL). The new mixed sesquioxide Yb:LuScO₃ provides a nearly doubled gain bandwidth compared to Yb:Lu₂O₃ of more than 20 nm and supports the generation of significantly shorter pulses. Here we present the results of our experiments on SESAM mode-locking of this material in the TDL setup. In a 66.5-MHz cavity the Yb(3%):LuScO₃ thin disk of 250 mum thickness was used as a folding mirror. A fiber coupled diode with an emission bandwidth of 3 nm at the center wavelength of 976 nm was used as a pump source in a TDL head with 24 passes of the pump light through the gain medium. The cavity contained two dispersive mirrors introducing a total of ~2200 fs² of negative group delay dispersion (GDD) per cavity roundtrip. A 5-mm thick fused silica plate was inserted at Brewster´s angle and is accountable for the self-phase modulation required in soliton mode-locked lasers.