Overcoming the Challenges in Power Scaling Ultrafast Thin-Disk Oscillators: Nonlinearity Management and Thermal Effects

Ultrafast high-power laser sources have a crucial role in science and industry. One way to reach performance in the multi-100-W average output power with sub-ps, tens-of-mJ pulses is through thin-disk laser (TDL) oscillators [1]. The oscillator approach to high power, compared to amplifier systems, offers superior beam quality and reduced system complexity but comes at the expense of a challenging nonlinearity management and a high sensitivity to thermal lensing. In particular, the MW-level intracavity peak power leads to a large amount of self-phase modulation (SPM) picked up in the intracavity air. The SPM needs to be compensated with negative group-delay dispersion (GDD) to ensure stable soliton pulse formation. Hence, there is a trade-off in GDD versus pulse energy for TDLs operated in air ("Standard TDLs" in Fig. 1a). Dispersive mirrors can provide the required GDD but, due to their resonant structure, they are more subject to thermal effects and damage compared to standard dielectric mirrors. A workaround is to operate the TDL in vacuum ("Vacuum TDLs" in Fig. 1a).