Abstract
Modified interferometric field autocorrelation (MIFA) can completely retrieve ultrafast pulse and only need simple device such as point detector and do not need iterative algorithm, and we are interested in its robustness against noise contamination. Frequency-resolved optical-gating (FROG) and spectral phase interferometry for direct electric-field reconstruction (SPIDER) has some similar research too. We come up with a new unbalanced power splitting MIFA (UPS-MIFA) to solve traditional MIFA problems such as sign ambiguity and theoretically larger error by retrieving spectral phase by retrieving real part and imaginary part of modified field autocorrelation instead of its real part and absolute value, and has less error at the presence of the same noise.