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Disputation Xingwen Zhang

26.01.2021 | 12:00
Der Titel der Dissertation lautet:
Supercontinuum Generation by Ghost Pulse
Abstract: Supercontinuum generation represents a versatile and unique source of coherent radiation and has become one of the hottest topics in optical and photonic sciences. According to the self-phase modulation which governs the spectral broadening process in bulk media, the newly generated supercontinuum always features positive chirp inherently which destructs its ultrashort temporal dynamics and generally needs additional chirp compensation.
This dissertation provides a novel method of negatively chirped supercontinuum generation by ghost pulse. The ghost pulse can be described as a short laser pulse (as normally defined), but with negative intensity in a quasi-constant intensity field. To generate the ghost pulse we use the following procedure. A part of the short fundamental pulse radiation is directed into a 4f-line pulse shaping system to produce a picosecond long carrier pulse, which cannot generate supercontinuum itself due to its low peak power. Then the long carrier pulse is combined with the short fundamental pulse in a type I BBO crystal to realize sum frequency generation (SFG) process. Due to strong energy depletion of the long pulse in the range of overlapping with the short one we create the intensity hole and, as result, our ghost pulse. The created ghost pulse is used for negatively chirped supercontinuum generation. We also experimentally observed the ghost pulse creation and the negatively chirped supercontinuum generation using a home-built XFROG setup. Our approach could be a promising new method for the investigation of supercontinuum generation.

Zeit & Ort

26.01.2021 | 12:00