A filtering procedure for systematic removal of pump-perturbed polarization artifacts

In time-dependent optical spectra, fast dynamics of narrow transitions give rise to artifacts consisting of spectral oscillations. In contrast with spectrally-integrated experiments, the interpretation of spectrally-resolved pump-probe experiments is thus far from straightforward in regimes where such coherent effects dominate, i.e., when the timescales of pump-induced processes are shorter than the medium dephasing times. Analyzing the two-dimensional Fourier transform of the time-dependent spectrum, we identify the components responsible for these artifacts and we introduce a simple Fourier-filtering procedure for their systematic removal. This technique is theoretically demonstrated on the time-dependent spectrum of a transition undergoing a frequency shift. The technique is also shown to have the additional benefit of efficient noise filtering of time-dependent spectra.