Frustrated tunnel ionization with few-cycle pulses

Abstract

Frustrated tunnel ionization (FTI) is one of the dominant channels in strong field ionization that results in the excitation of atoms. Recent studies have shown that there is a significant number of FTI events for multi-cycle pulses with the theory predicting that the excitation efficiency increases with pulse duration decreasing into the few-cycle regime. Our work concentrates on experimentally investigating the effect of few-cycle pulses on the FTI excitation process. We use pulses with duration 6 fs centred at 800 nm at intensities up to 0.8 PW crossed with an atomic Ar beam. We find that with few-cycle pulses there is more FTI per tunneling event and that for the same pulse energy more FTI is generated.