The ultrafast Kerr effect in anisotropic and dispersive media

The ultrafast optical Kerr effect (OKE) is widely used to investigate the structural dynamics and interactions of liquids, solutions, solids by observing their intrinsic nonlinear temporal responses through nearly collinear four-wave mixing. Non-degenerate mixing schemes allow for background free detection can provide information on interplay between a material’s internal degrees freedom. Here, we show source in OKE signal that not reflective freedom but arises from group index momentum mismatch. It observed two-color experiments condensed media with sizable spectral dispersion, common property near an resonance. In particular, birefringence crystalline able entirely change character via off-diagonal tensor elements susceptibility. We develop detailed description phase-mismatched how extract quantitative spectrally resolved time-resolved one two dimensions.