First-principles study of ultrafast and nonlinear optical properties of graphite thin films

Abstract

We theoretically investigate ultrafast and nonlinear optical properties of graphite thin films based on first-principles time-dependent density functional theory. We first calculate electron dynamics in a unit cell of graphite under a strong pulsed electric field and explore the transient optical properties of graphite. The optical response of graphite shows a sudden change from the conducting to the insulating phase at a certain intensity range of the applied electric field. It also appears to be a saturable absorption (SA) in the energy transfer from the electric field to electrons. We next investigate a light propagation in graphite thin films by solving the coupled dynamics of the electrons and the electromagnetic fields simultaneously. It is observed that the SA manifests in the propagation with small attenuation in the spatial region where the electric field amplitude is about $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}\phantom{\rule{4.pt}{0ex}}\text{to}\phantom{\rule{4.pt}{0ex}}7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}\phantom{\rule{0.16em}{0ex}}\mathrm{V}/\AA{}$.