TRACING THE PHASE-DISTORTION OF A SINGLE ULTRASHORT LIGHT-PULSE FROM ANGULARLY RESOLVED 2ND-HARMONIC AUTOCORRELATION

We implement for the first time the frequency tracer based on the seco nd-harmonic autocorrelator able to measure pulse duration and instanta neous frequency of a single ultrashort light pulse. This tracer is use d to characterize femtosecond pulses from a Ti:sapphire CPA system. Th e data on chirp and pulse duration are in good agreement with the esti mations of dispersion at the system output. We show by computer simula tion that the second-harmonic autocorrelator is able to trace quadrati c (linear chirp), fourth and other even orders of phase distortions. C omputed images directly reproduce the phase distortions and no mathema tical algorithm is required for phase retrieval. (C) 1998 Elsevier Sci ence B.V. All rights reserved.