Creation and Detection of Optical Spin in a Coupled Emitter–Plasmon System

We investigate the system of a linearly polarized dipole emitter coupled to the plasmonic modes of a gold nanorod (GNR). We show numerically that asymmetrical placement of the emitter relative to the GNR axes gives rise to a net optical spin for the field inside the rod, despite the apparent achirality of the system. We experimentally demonstrate this effect using electron beam excitation to create an effective point dipole emitter and coupling luminescence evanescently to a nanofiber probe which supports spin-momentum locked light. This converts the net spin of the field into a net directionality of propagation in the fiber modes, allowing detection in the far field.