Superfocusing of Low-Dimensional Optical Waves in Tapered Plasmonic Waveguides

Abstract

Plasmonic waveguides are metal optical waveguides that confine and guide low-dimensional optical waves in nano-space beyond the diffraction limit. Recently, many types of subwavelength plasmonic waveguides have been proposed. We classify structures of the waveguides and review superfocusing observed in tapered plasmonic structures. We can apply tapered plasmonic waveguide to nano-optical couplers in order to focus optical energy into nano-space. We study electromagnetic field in wedged metal gap waveguide by numerical simulations. We report selective excitation of superfocusing mode by ATR method in metal gap waveguides that support propagation of coupled mode of surface plasmon polariton.