Fringe-free spectral phase interferometry for direct electric-field reconstruction

A novel spectral phase interferometry reconstruction for ultrashort optical pulse measurement with high accuracy is presented to overcome the shortcomes of conventional SPIDER. The measured pulse and its two chirped and delayed replicas are mixed synchronously to generate a fringe-free interference pattern. By introducing a suitable small delay into the interference pattern the spectral phase of the measured pulse is retrieved directly and uniquely without using Fourier transformation. This technique is capable of characterizing pulses with long duration or/and complex phase structure.