Experimental proof of saturation in nonresonant multiple-photon ionization

Abstract
Saturation in nonresonant multiple‐photon ionization is directly proved by a novel two‐pulse technique. Ultrashort laser pulses with a pulse duration of 17.5 ps are used for multiple‐photon ionization. They provide experimental conditions which allow double‐pulse experiments on sub‐ns time‐scales. Data of saturation intensities and cross sections are derived from the experiments.