Ultrashort self-induced transparency plasmon solitons.

We study the interband self-induced transmission of surface plasmon polaritons in a gold film surrounded by an external Kerr medium. We model the optical propagation by using a version of the generalized nonlinear Schrödinger equation for the field envelope coupled to Bloch equations for valence electrons of gold, predicting self-induced transparency of ultrashort plasmon solitons with a pulse duration below 10 fs. We demonstrate that the Kerr nonlinearity from the surrounding dielectric can be used to compensate for the group velocity dispersion, and that the impact of dephasing and decay processes can be effectively reduced by the self-induced transmission mechanism.