  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.
