The need for ultra-short (sub-ps) pulsed laser systems with high power and high energy has advanced the mode-locked
Ytterbium-doped thin-disk technology in the last decade. Therefore several research groups have made efforts to explore
new laser crystals e.g. Yb:SSO, Yb:CAlGO or Yb:Lu<sub>2</sub>O<sub>3</sub> for the generation of sub-500 fs pulses in thin-disk oscillators.
Another promising and known candidate for ultra-short pulsed lasers is Yb:CaF<sub>2</sub>, which has been so far only used in bulk
laser architecture. In this work, we present the first demonstration of a mode-locked Yb:CaF<sub>2</sub> laser in thin-disk
configuration. The resonator cavity was designed for eight passes through the disk per roundtrip at a repetition rate of
35 MHz. A saturable absorber mirror (SESAM) was used to obtain the soliton mode-locking. We achieved close-to
transform-limited pulses with a pulse duration of less than 445 fs and an emission spectral width of 2.6 nm at FWHM
(i.e. time-bandwidth product of 0.323). At the average output power of 6.6 W this corresponds to a peak-power of
430 kW and pulse energy of 190 nJ. To the best of our knowledge, this is the highest average output power and pulse
energy using Yb:CaF<sub>2</sub> as gain material reported to date. Taking into account the dispersion, self-phase modulation, pulse
energy, output coupling ratio and laser gain, the pulse-duration estimated from the soliton-equation and our numerical
calculations of pulse-propagation is in good agreement with the pulse-duration obtained in the experiment. Higher
powers and shorter pulse-durations with this material are the subject of our future investigations.
We present first experimental investigations on Ytterbium-doped Sc<sub>2</sub>SiO<sub>5</sub> as a promising gain medium for thin-disk
lasers. This oxyorthosilicate laser material combines good thermo-mechanical properties and a broad emission
bandwidth suitable for high-power cw and mode-locked laser operation. The demonstrated average output powers of up
to 75 W with a not yet optimized thin-disk crystal confirm the power capability of this new material and preliminary tests
on passive mode-locking indicate the high potential for future ultrafast thin-disk laser oscillators.
We present results from diode-pumped cw and semiconductor saturable absorber mirror (SESAM) mode-locked
resonators containing multiple bulk Yb:KYW crystals. The dual-crystal resonator generated more than 24W of cw-power
at a wavelength of 1042nm in a diffraction limited beam with the maximum power limited by the available pump power.
Two mode-locking regimes were explored. From the soliton mode-locked oscillator we obtained Fourier limited pulses
with a pulsewidth of 450fs at a repetition rate of 79MHz and with an average power of 14.6W. When operating the same
resonator in the positive dispersion regime we achieved an output power of 17W. Using a grating compressor these
pulses could be compressed to a pulse width of 470fs. Both mode-locked lasers were self-starting and operated stably
and in turn key fashion over days and through varying lab conditions. Regarding the power scaling of this type of laser
we anticipate further scalability by once again doubling the number of crystals inside the resonator.