IMPROVED ULTRASHORT PULSE-RETRIEVAL ALGORITHM FOR FREQUENCY-RESOLVED OPTICAL GATING

We report on significant improvements in the pulse-retrieval algorithm used to reconstruct the amplitude and the phase of ultrashort optical pulses from the experimental frequency-resolved optical gating trace data in the polarization-gate geometry. These improvements involve the use of an intensity constraint, an overcorrection technique, and a mu ltidimensional minimization scheme. While the previously published, ba sic algorithm converged for most common ultrashort pulses, it failed t o retrieve pulses with significant intensity substructure. The improve d composite algorithm successfully converges for such pulses. It can n ow retrieve essentially all pulses of practical interest. We present e xamples of complex waveforms that were retrieved by the improved algor ithm.