Self-similar mode of laser pulse propagation in a medium containing nanorods

摘要

We investigate a self-similar mode of femtosecond laser pulse propagation in a medium containing nanorods, taking into account the dependence of light energy absorption from the aspect ratio of nanorods. Using the density matrix formalism, we derive equations for both two-photon absorption and multiphoton absorption of laser radiation by the medium containing nanorods. Using computer simulation we show that the appropriate nonlinear initial frequency chirp is crucial for the self-similar mode of laser pulse propagation. The distance, along which the laser pulse shape preserves its self-similarity, depends on interaction parameters. Pulse slow down may accompany this laser pulse propagation mode. We discuss its physical mechanism and show that the pulse center shifting becomes smaller if the number of photons involved into the process of absorption grows.