LAUSR

Abstract We propose a modification of the second-harmonic generation frequency resolved optical gating method (SHG-FROG) utilizing asymmetric spectral interferometry (aiFrog) for complete unambiguous reconstruction of ultrashort optical pulse intensity and phase. The large amount of information encoded in the aiFrog trace allows a straightforward calculation of the fundamental pulse spectrum and a direct reconstruction of the pulse envelope and phase. A simple and robust iterative algorithm with fast convergence is developed for pulse reconstruction from the aiFrog trace, taking advantage of large data redundancy and noise averaging. Due to the asymmetry of the setup, our method is free from the known challenges of a standard SHG-FROG (direction-of-time ambiguity, almost identical FROG traces for well separated pulses with different phases and for asymmetric well separated pulses). The method is highly sensitive to the weak satellite pulse of the main pulse, which can be used to track pre- or post-pulses even without full processing of the measured aiFrog trace.