Non-linear optical spectroscopy, ultrafast dynamics and quantum transport in disordered media

Abstract

We present for the first time the conceptual links between the non-linear optical responses of a dense medium, as induced by the propagation of an intense, ultrashort femtosecond laser pulse, and the electron mobility, as determined by the scattering and propagation of a quasi-free electron injected into the same medium. The link for the class of non-polar molecular fluids predicts an inverse relationship between the electron mobility and the anisotropic orientational component of the nuclear part of the third-order non-linear suspectibility χ⁽³⁾_ijkl. Non-linear optical experiments are then described for pulse propagation in solid state and liquid systems from which a theory is presented whose numerical solutions are a more pragmatic route to predict pulse phase modulation and pulse shaping than the formalism of the non-linear Schrödinger equation. Four-wave mixing experiments in molecular liquids are then detailed from which the anisotropic orientational χ⁽³⁾_or can be deduced from field-perturbed g(Ω)′ orientational pair distribution functions.