The interpretation of ultrafast pump-probe spectroscopy in solids can be extremely challenging or even misleading if anistropic and dispersive light propagation is overlooked. Here we joined forces with L. Huber et al. from Columbia University to give a comprehensive four-wave mixing model for these phenomena; relevant to all types of time- and polarization-resolved methods, such as OKE, MOKE and Faraday effect. With this general model, the observed features can be used to quantitatively determine the anisotropic refractive index and group index dispersion.

J. Chem. Phys.: L. Huber et al. “The ultrafast Kerr effect in anisotropic and dispersive media” (2021).