Abstract

In the over 100 years since Wood first observed that gratings can resonantly couple light to guided modes – in this case surface plasmon polaritons (SPPs) on a metal film [1] – this process has been extensively studied, modeled, and is now used in countless plasmonic and photonic devices. At the heart of grating mediated resonant coupling lies the phenomenon of interference: coherent scattering from the periodic structure adds momentum to the incident light, matching it to the higher momentum of the guided mode, leading to the resonant coupling. However, what has been neglected, to date, is that the coupling process itself carries a phase as well as amplitude. Consequently, when two coupling pathways are simultaneously available they can interfere. In effect, exploiting the intrinsic phase of the coupling process adds another degree-of-freedom to the control of resonant coupling.

© 2013 IEEE