Observation of harmonic beams inside a Kerr lens mode-locked thin-disk ring laser oscillator beyond a repetition rate of 10 MHz

We report the highest intra-cavity pulse energy of 80 mu J inside a Kerr lens mode-locked thin-disk ring laser oscillator at a repetition rate beyond 10 MHz enabling observation of the 2nd and 3rd harmonic beams directly generated by the Kerr medium. By adding a tight focusing setup to the ring cavity, we could observe krypton gas flame at an intra-cavity peak intensity of similar to 28 TW/cm(2) yielding a conversion efficiency of 10(-5) for the 3rd harmonic beam. A further upgrade of the ring oscillator could lead to realizing a table-top source of vacuum ultraviolet pulses for application in photoelectron spectroscopy. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study demonstrates the achievement of the highest intra-cavity pulse energy of 80 µJ in a Kerr lens mode-locked thin-disk ring laser oscillator at a repetition rate exceeding 10 MHz, allowing for direct observation of the 2nd and 3rd harmonic beams. By adding a tight focusing setup to the ring cavity, krypton gas flame could be observed at an intra-cavity peak intensity of approximately 28 TW/cm(2), resulting in a conversion efficiency of 10(-5) for the 3rd harmonic beam. Further improvements in the ring oscillator could lead to the realization of a table-top source of vacuum ultraviolet pulses for applications in photoelectron spectroscopy.