Unbalanced third-order correlations for full characterization of femtosecond pulses

Phase and intensity from correlation and spectrum only (PICASO) is a simple and accurate method for fully characterizing femtosecond pulses. We extend this technique to make use of third-order intensity correlations. Unbalanc ing the interferometer makes the retrieval algorithm sensitive to the direc tion of time and improves the retrieval of certain pulse shapes. We investi gate the sensitivity of the retrieval to direction of time as a function of the degree of imbalance in the correlator. (C) 2000 Optical Society of Ame rica.