Low-Noise 2-W Average Power, 112-fs Kerr-Lens Mode-Locked Ho:CALGO Laser at 2.1 $\mu\mathrm{m}$

High average power, ultrafast laser sources at 2.1
$\mu\mathrm{m}$
have great potential for numerous applications, for example, spectroscopy, nonlinear conversion to the mid-IR, THz, XUV, and for material processing. Particularly attractive are laser systems directly emitting at this wavelength, with no complex parametric nonlinear conversion stages. In this regard, Ho-doped materials are especially attractive because of their excellent thermal properties, simple quasi-three-level energy scheme, enabling high average powers. For applications requiring high repetition rates, high-power mode-locked oscillators are ideally suited. However, so far, short pulses were difficult to achieve with Ho-doped materials due to typically narrow-band emission spectra. In our recent work, we showed that Ho:CALGO is a promising new material to overcome this difficulty, with the demonstration of a SESAM mode-locked laser with 8.7 W of average power and 369 fs of pulse duration [1], the pulse duration is limited by the small modulation depth of the SESAM. In the current work, we report a Kerr-lens mode-locked Ho: CALGO solid-state laser achieving 112 fs at high average power of 2 W, corresponding to a peak power of 173 kW. Additionally, we also studied the noise properties of this laser, indicating very low-noise operation.