Influence of dispersion stretching of ultrashort UV laser pulse on the critical power of self-focusing

TL;DR

This study experimentally investigates how dispersion-induced stretching of ultrashort UV laser pulses affects their critical power for self-focusing in air, revealing a near-linear decrease in critical power with increased pulse duration.

Contribution

It provides the first experimental measurement of the critical power variation for UV pulses stretched by dispersion, highlighting differences from IR laser filament behavior.

Findings

Critical power decreases almost linearly with pulse duration increase.

Maximum plasma distribution remains at the geometrical focus for UV pulses.

Pulse stretching influences self-focusing dynamics distinctly from IR lasers.

Abstract

The critical power of self-focusing in the air for ultrashort UV laser pulses stretched due to dispersion from 90 up to 730 fs was experimentally measured. It was shown that the pulse duration enhancement due to its propagation in condensed media within above mentioned time-range leads to almost linear decrease of self-focusing critical power. It was also observed that when the pulse peak power exceeds the critical one, the maximum of linear plasma distribution along the UV laser filament does not shifted in the direction opposite to the laser pulse propagation as in the case of IR laser filament, but remains at the geometrical focus.