Martin Duda, in cooperation with his colleagues from the HiLASE Centre, Ondřej Novák, Martin Cimrman, Jaroslav Huynh, Martin Smrž, and Tomáš Mocek, had an article published in the Optics Continuum journal just in the very beginning of 2022. In the article, they covered the topic of Spectral broadening and a prospect for pulse compression of Yb:YAG thin-disk laser pulses by nonlinear SHG in a BBO crystal with time predelay and tilting of the pulse fronts.
Pulse compression by second harmonic generation in a type II nonlinear optical crystal controlled by a time predelay of the faster input pulse is not simple to achieve high-average-power Yb:YAG lasers with wavelength of 1030 nm. The reason is that the borate nonlinear crystals with their excellent thermal properties do not have the optimal ratio of group velocities of the interacting pulses to achieve efficient pulse compression. The authors have changed the effective group velocities by tilting the pulse fronts at a diffraction grating and imaging the tilted 1.7 ps pulses into the 6 and 8.5 mm thick BBO crystals. As a result, the research team has measured significant spectral broadening to 4.5 nm, supporting pulses as short as 100 fs, with an energy conversion efficiency in excess of 20 %. The measured data correspond well with numerical simulations. This research opens a way to extend the range of possible applications of Yb:YAG high-average-power thin-disk lasers into the fs regime.
For more details please read the whole article.