Directional optical absorption and scattering in conical plasmonic nanostructures

Opt Lett. 2019 May 1;44(9):2212-2215. doi: 10.1364/OL.44.002212.

Abstract

Asymmetric plasmonic nanostructures can be exploited to realize directional optical absorption or scattering for oppositely propagating optical waves. Here we theoretically investigate the roles of asymmetry and interaction of nanoparticles in directional optical responses. It is shown that adding optical interaction to a single truncated nanocone by dividing it into interacting nanodisks without changing geometrical asymmetry causes significant enhancement of directionality. We achieve an increase of about six times in directional optical absorption by using four nanodisks arranged in conical form. This effect is obtained due to the constructive interference of the excited modes of each nanodisk.