Nanoscale plasmonic circulator

Abstract

Here, we propose a conceptual approach for design of an ultracompact nanoscale passive optical circulator based on the excitation of plasmonic resonances. We study a three-port Y-junction with a deep subwavelength plasmonic nanorod structure integrated into its core. We show theoretically that such a structure immersed in the magneto-optical media may function as magnetically tunable scatterer tilting and rotating its near-field distribution and corresponding radiation. We demonstrate, using numerical simulations, that such a rotation of the near-field radiation yields a break in the symmetry of the coupling between the junction arms and the structure in such a way that the signal launched from any of the three ports is mostly transmitted into the next port in the circular order, while the other port is essentially isolated, thus providing the functionality of an optical circulator with subwavelength dimensions.