Dynamic control of plasmonic beams.

We experimentally demonstrate dynamic, electrically controlled shaping of plasmonic beams, propagating at the boundary between a metal and a dielectric, by using the thermo-optic effect. The concept is based on selectively heating a specific region in which the plasmonic beam passes by injecting electrical current to an isolated metal layer. This leads to transverse modulation of the wavefront through the thermal dispersion of the dielectric layer above this metal region. We demonstrate two active plasmonic devices: a plasmonic mode converter between the fundamental and first-order Hermite-Gauss modes and a tunable plasmonic lens with a dynamically varying focal length.