64-fs Pulses from a Kerr-Lens Modelocked Yb:LuO thin-disk laser

Summary form only given. Ultrafast thin-disk laser (TDL) oscillators generated up to 275 W in pulses with several hundred femtosecond duration [1]. However, the combination of high average output power with short pulse duration is challenging: the power levels of ultrafast TDL oscillators operating in sub-100-fs pulses are currently limited to the sub-10 W regime. In the last years Kerr-Lens Modelocking (KLM) has been established as a successful alternative to SESAM-modelocking of TDLs. The KLM technique has shown to be advantageous for achieving shorter pulse durations at high power levels [2]. So far, nearly all KLM TDLs use Yb:YAG, which is the best developed gain material for the thin-disk configuration but limited in its emission bandwidth. For achieving shorter pulse durations, it is highly attractive to study KLM TDLs based on gain materials with broader emission bandwidth. Yb:LuO exhibits a more than twice broader emission bandwidth than Yb:YAG [3]. Using SESAM-modelocking, Yb:LuO TDLs achieved 141 W in 740-fs pulses [4] and 7 W in 142 fs [5]. Recently, the first Yb:LuO KLM TDL has been demonstrated, generating 165-fs pulses with an output power of 5.9 W [6]. However, the full emission bandwidth of Yb:LuO was so far never exploited in a TDLHere we present a study on the optimization of the pulse duration of a KLM Yb:LuO TDL, resulting in more than twice shorter pulse duration than previously demonstrated from this gain material in the thin-disk configuration. In more than 200 configurations of one general laser cavity, we studied the influence of key parameters such as Kerr-nonlinearity, dispersion, degree of output coupling, and KLM aperture size. Our results show a trade-off between minimum pulse duration and average output power: at the shortest pulse duration of 64 fs, the output power is only 0.7 W, while it increases to 5.5 W for 83-fs pulses and 11.3 W for 131-fs pulses.