Ionization of noble gases with pulses directly from a laser oscillator

Opt Lett. 2006 Jul 1;31(13):2072-4. doi: 10.1364/ol.31.002072.

Abstract

A Ti:sapphire oscillator with an extended cavity generates pulses with 0.5 microJ energy at a repetition rate of 6 MHz and pulse durations of 50 fs. Tight focusing creates peak intensities exceeding 10(14) W/cm2, which is sufficient for ionizing helium, a nonlinear process where at least 17 photons are absorbed simultaneously.