Femtosecond autocorrelator based on a swinging birefringent plate

A new scheme of an interferometric scanning autocorrelator for measuring ultrashort light pulse durations in the femtosecond and subpicosecond ranges is considered. The distinguishing features of this scheme are its compact structure and a very simple adjustment. A variable time delay of ultrashort light pulse components is produced by a swinging birefringent plate made of a uniaxial crystal. Analytic expressions are obtained for the width of the scanning range and an optimal orientation of the optical axis of the crystal. The effect of disbalance in the intensities of waves that have propagated different optical paths on the form of the autocorrelation function (ACF) is analysed numerically. An experimental ACF for Ti:sapphire laser pulses of duration ~25 fs is presented.