A plasmonic dimple lens for nanoscale focusing of light.

Focusing electromagnetic energy to subwavelength dimensions has become an increasingly active field of research for a variety of applications such as heat-assisted magnetic recording, nanolithography, and nanoscale optical characterization of biological cells and single molecules using the near-field scanning optical microscopy technique. Double-sided surface plasmons in a metal-insulator-metal (MIM) geometry can have very small wavelengths for dielectric of thickness of less than 10 nm. A tapered dielectric structure sandwiched between metal can be used to efficiently couple electromagnetic energy from free space photons to the plasmonic wavelengths at the nanoscale. In this paper, we present the fabrication and characterization of a novel MIM plasmonic lens structure.