Interferometric technique for measuring broadband ultrashort pulses at the sampling limit

We present a new technique for measuring ultrashort optical pulses using spectral phase interferometry for direct electric- field reconstruction (SPIDER) which is suitable for very large bandwidth pulses. It does not require the generation of a replica of the pulse to be measured and encodes the spectral phase information in a spatial interference pattern. A major advantage of this method is that the spectral sampling saturates the Whittaker-Shannon bound. Moreover, the technique allows for the characterization of some types of space-time coupling. An experimental demonstration of the technique is presented.