$.5-\mu\mathrm{J}$, 328-fs KLM Ho:YAG Thin-Disk Oscillator at $2.1\ \mu\mathrm{m}$

High-power ultrafast laser systems working in
$2-3-\mu\mathrm{m}$
wavelength range continue to draw significant interest in the laser community due to the possibilities they open for nonlinear conversion, material processing, among others. Directly modelocked high-power thin-disk laser (TDL) oscillators are in this regard potentially interesting candidates for applications where MHz repetition rates and high pulse energy are beneficial. Early on, Kerr-Lens Modelocked (KLM) Ho:YAG TDLs demonstrated that they can achieve much higher powers in this wavelength region than other solid-state oscillator technologies, with the first demonstration of 18.4-W, 260-fs pulses at 2090-nm [1]. Recently, we confirmed this potential for power and energy scaling in this wavelength range by developing a SESAM-modelocked
$50-\mathrm{W},2-\mu\mathrm{J}$
system [2], representing, to the best of our knowledge, the highest output power and pulse energy from
$2-\mu\mathrm{m}$
single-oscillator, however, we were limited by the low modulation depth of the SESAM to rather long pulses > 1 ps. Although pulse compression methods can be applied; reaching shorter pulses from the oscillator is still a significantly more elegant and efficient option, in particular when combining with high pulse energies. So far, the highest achieved pulse energy and peak power reported from the
$2-\mu\mathrm{m}$
KLM TDL in this range are
$0.24\ \mu\mathrm{J}$
and 0.8 MW at an output power of 18.4 W [1]. In the current work we report a
$0.5-\mu\mathrm{J},1.3-\text{MW}$
and 328-fs oscillator with an output power of 14 W, representing two-fold improvements in pulse energy and peak power in comparison to previously demonstrated state-of-the-art Ho:YAG KLM results, limited by gain narrowing due to intracavity losses. In the near future, it will be straightforward to reach
$\mu\mathrm{J}$
-levels of pulse energies and several MW of peak power directly from the modelocked
$2-\mu\mathrm{m}$
oscillator.