Active control over nanofocusing with nanorod plasmonic antennas.

Active control over light nanofocusing in a nanorod plasmonic antenna coupled to a photonic crystal cavity is proposed and demonstrated by means of full-vectorial 3D simulations. By varying the excitation of the cavity with laser beam spot size allows us to achieve a gradual control over light nanofocusing at the tip of the nanoantenna. The demonstrated control mechanism eliminates the need for nonlinear effects or mechanical reconfiguration and represents a step towards the implementation of reliable tunable subwavelength light sources.