| Abstract [eng] |
Supercontinuum generation can be realized in almost any transparent medium and represents an appealing method for producing coherent broadband radiation. This dissertation aims at identifying the most suitable bulk solid-state materials that provide low supercontinuum generation threshold, efficient spectral broadening and robust long-term performance at high repetition rates with the state-of-the-art high average power ultrafast Yb:KGW lasers. In this work, reliable long-term operation at high pulse repetition rates was achieved in nonlinear materials with bandgaps below 6 eV, exhibiting high nonlinearity and, consequently, low thresholds for supercontinuum generation. First demonstration of stable octave-spanning, low-threshold supercontinuum in bulk KGW crystal pumped by a 76 MHz Yb:KGW oscillator was achieved. It was also shown that, spectral broadening of femtosecond laser pulses in highly nonlinear bulk materials offers a promising alternative to fiber-based approaches, providing an all-solid-state setup for post-compression of low-energy (∼200 nJ) pulses at high repetition rates. Finally, it was revealed that the supercontinuum generation threshold rises for the second and subsequent pulses in a burst, increasing further with intra-burst repetition rate, thus imposing a practical limitation on burst-mode supercontinuum generation in solid-state materials. This work identified new efficient nonlinear bulk materials and revealed practical aspects for optimizing high repetition rate supercontinuum generation schemes, with potential direct applicability to high average power wavelength-tunable light sources, and high-speed spectroscopy and imaging. |
