Time direction determination of asymmetric ultrashort optical pulses from second-harmonic generation autocorrelation signals

Abstract

A general procedure for determining pulse asymmetry including time direction is described. Fundamental and second-harmonic interferometric autocorrelations are measured before and after passing through a glass block. Pulse form is reconstructed iteratively for each pulse, yet time direction is ambiguous. Time direction for both pulses is then simultaneously determined by phase curvature comparison in the frequency domain, taking the known dispersion of the glass block into account. This results in complete evaluation of ultrashort optical pulses. This method is demonstrated successfully for passively mode-locked dye laser pulses.