SESAMs for high-power femtosecond modelocking: power scaling of an Yb:LuScO₃ thin disk laser to 23 W and 235 fs.

We report on power scaling of a modelocked thin disk laser based on the broadband mixed sesquioxide material Yb:LuScO₃. One of the key elements to achieve this result was an improved SESAM design with reduced two-photon-absorption (TPA) and high damage threshold. In a first experiment, using a standard antiresonant SESAM with no topcoating, we could demonstrate record short pulse durations of 195 fs at a moderate average power of 9.5 W. Furthermore, we were able to power scale our thin disk laser while keeping the pulses short reaching 23 W at a pulse duration of 235 fs. This was made possible by designing a new SESAM with multiple quantum wells (QW) and a suitable dielectric topcoating. We will present SESAM optimization guidelines for short pulse generation from high-power modelocked oscillators.