Kerr-Lens Mode-Locked 2-μm Thin-Disk Lasers

Thin-disk technology uniquely enables the simultaneous scaling of both average and peak powers, while maintaining an excellent beam profile. It has been widely adopted in the 1-μm region, not only for continuous wave lasers but also for pulsed oscillators and amplifiers. However, the development of 2-μm thin-disk lasers is still at a very early stage, with passive mode locking having been demonstrated only recently. Here, we describe in detail a new femtosecond Ho:YAG thin-disk oscillator and recent power-scaling experiments that resulted in an average power of up to 25 W-the highest average power of any mode-locked oscillator in the 2-μm region. The future directions toward even higher average and peak power thin-disk oscillators are also discussed.