Self-induced decay of intense laser pulse into a pair of surface plasmons

Abstract

We show theoretically that an intense femtosecond optical pulse incident normally on a metal surface tends to decay into a pair of counterpropagating surface plasmon polaritons (SPPs). The interference field heats the medium periodically, which causes a periodic permittivity perturbation and, in turn, resonantly amplifies the magnitudes of the SPPs. The instability growth time is 10--50 fs for typical metals at laser fluences of about $\ensuremath{\sim}1\phantom{\rule{0.16em}{0ex}}\mathrm{J}/{\mathrm{cm}}^{2}$, so this mechanism is important for understanding the dynamics of the optical pulse absorption under damaging conditions, and it is promising for the interpretation of laser-induced periodic surface structure formation in single- and few-pulse pumping regimes.