On precursor propagation in linear dielectrics

This paper presents a generalized definition for precursors, which are transients that appear when ultra-short pulses propagate through a dielectric. It also investigates under what assumptions pulses can propagate through an absorbing medium experiencing less than exponential decay with distance. Finally, it uses the fast-Fourier transform for simulating ultrafast optical pulse propagation in pure water to exemplify some of the precursor properties. We also use a temporal group-velocity description, valid in regions with absorption, to predict where and when precursors will appear. All simulations and predictions are performed using measured dielectric data rather than model dielectrics.