Surface Plasmon Enhanced Optical Bistability and Optical Switching

A surface plasmon is a collective oscillation involving the coupled motion of the electrons in a metal and the associated electromagnetic field in small structures and at interfaces. In small structures (of order a wavelength and smaller), the oscillations are localized, whereas at a planar interface separating a metal and a dielectric a propagating mode exists that decays exponentially on both sides of the interface. Plasmons can be excited by fast electrons or, in the right geometry, an incoming electromagnetic wave. Here, optical excitation is considered. An optically bistable system can have two different but stable outputs for the same input signal over some range. By changing the input beyond some threshold, the output of an optically bistable system can be switched between the two stable states, a feature that can be used to switch the output between two channels.