Phase-retrieval of femtosecond pulses utilizing omega /2 omega quantum interference control of electrical currents

We propose and implement a versatile scheme to analyze the phase structure of femtosecond pulses. It relies on second harmonic generation in combination with phase-sensitive sub( chi ) super((3))-current injection driven by two time-delayed portions of the emerging omega /2 omega pulse pair. Most strikingly, the group velocity dispersions of both the omega and 2 omega components can be unambiguously determined from a simple Fourier transformation of the resulting current interferogram. We test the concept for 45 fs pulses at 1.45 mu m and directly compare it to second harmonic frequency resolved optical gating. By choosing appropriate frequency doublers and semiconductor detectors, the scheme is applicable to many wavelength regimes and to pulses as short as a few optical cycles.