Abstract

Recently,¹ we reported on the measurement of the coherence properties of 1.06-µm fiber-grating compressed 4-ps duration laser pulses using photorefractive beam coupling in GaAs:Cr. We utilized the conventional pulse width measurement geometry of noncollinear background-free second harmonic generation (SHG). With an SHG crystal the intensity autocorrelation is measured (pulse duration). A photorefractive crystal will result in the measurement of the electric field correlation or coherence function (coherence time). The coherence function is obtained by detecting the fraction of modulated pump beam scattered by the photorefractive index grating into the probe beam as a function of probe delay. Only for the case of a transform limited pulse would the width of the coherence function equal that of the intensity autocorrelation function. This coherence function is equivalent to measuring the pulse spectrum and Fourier transforming it to the time domain. Thus a picosecond optical pulse can be fully characterized by the simple exchange of a photorefractive and SHG crystal.

© 1989 Optical Society of America