Optimizing the time resolution of supercontinuum spectral interferometry

Single-shot supercontinuum spectral interferometry is a powerful technique for measuring transient refractive index changes. In principle, its time resolution is limited only by the available probe bandwidth. However, this assumes that the phase extraction has sufficient spectral resolution and that the probe spectral phase is exactly known. Using an analytical model for the spectral phase and amplitude modulation of a chirped probe pulse by a weak transient phase perturbation, we show how the probe chirp and spectral resolution determine the achievable time resolution. A simple, practical technique for precise in situ measurement of the probe spectral phase is described in detail, and the sensitivity of the extracted temporal phase profile to uncertainty in the probe spectral phase is demonstrated in numerical simulations.