Determination of weak optical pulses in amplitude and phase by measurement of the transient polarization state

Unlike in established methods, the phase of an optical pulse is calculated from a single time transient in combination with a single spectrum of its polarization state: For dynamically changing elliptical polarizations the vectorial nature of the electromagnetic radiation results in two independent constraints that uniquely determine the chirp and the spectral phase. The practical feasibility of the method is demonstrated, a phase of a four-wave-mixing signal from a semiconductor single quantum well with a pulse energy of only 0.5 fJ is determined, and the accuracy of the setup is analyzed by a numerical simulation. (C) 1999 Optical Society of America.