Accuracy criterion for ultrashort pulse characterization techniques: application to spectral phase interferometry for direct electric field reconstruction

We propose a procedure for the comparison of two ultrashort optical pulses based on the root-mean-square field error. This procedure supplies a practical criterion that allows one to test the accuracy of pulse characterization techniques. We apply this procedure to spectral phase interferometry for direct electric field reconstruction (SPIDER), a method that uses shearing interferometry in the frequency domain to measure ultrashort light pulses. Two novel reconstruction algorithms are described in detail, one based on the reconstruction of the spectral phase by concatenation, the other by integration. The range of validity of these algorithms and the influence of noise on the accuracy of the reconstruction are studied using the proposed criterion.