A novel algorithm for the ultrashort laser pulse characterization method ofinterferometric frequency-resolved optical gating (iFROG) is presented. Basedon a genetic method, namely differential evolution, the algorithm can exploitall available information of an iFROG measurement to retrieve the complexelectric field of a pulse. The retrieval is subjected to a series of numericaltests to prove robustness of the algorithm against experimental artifacts andnoise. These tests show that the integrated error-correction mechanisms of theiFROG method can be successfully used to remove the effect from timing errorsand spectrally varying efficiency in the detection. Moreover, the accuracy andnoise resilience of the new algorithm are shown to outperform retrieval basedon the generalized projections algorithm, which is widely used as the standardmethod in FROG retrieval. The differential evolution algorithm is furthervalidated with experimental data, measured with unamplified three-cycle pulsesfrom a mode-locked Ti:sapphire laser. Additionally introducing group delaydispersion in the beam path, the retrieval results show excellent agreementwith independent measurements with a commercial pulse measurement device basedon spectral phase interferometry for direct electric-field retrieval. Furtherexperimental tests with strongly attenuated pulses indicate resilience ofdifferential evolution based retrieval against massive measurement noise.
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