CEP-Stable Generation of Close to Single-Cycle and Ultrashort UV Pulses at 800 kHz Repetition Rate using a Gas-Filled Hollow-Core PCF

Ultrashort laser pulses at high repetition rates are a fundamental tool in a wide range of applications in strong-field physics and attosecond science, where particular attention has to be given to the stability of the carrier to envelope phase (CEP) of the ultrashort optical waveform [1]. Here we report the generation of close to single-cycle pulses with stable CEP at 800 kHz repetition rate, obtained via soliton-effect self-compression in a gas-filled kagome-type hollow-core photonic crystal fibre (kagome-PCF) [2]. In addition, we have measured for the first time the CEP stability of soliton-emitted dispersive waves (DWs) lying in the ultraviolet spectral region.