Optical bistability in metal gap waveguide nanocavities

Metal-dielectric nanocavities constructed by filling a piece of nonlinear optical material into metal gap waveguides are introduced for realizing optical bistability in nanodomain. Finite-difference time-domain simulation reveal that such a structure can realize optical bistable effect with much weaker operating light power in a nanoscale nonlinear medium. We attribute it to the enhancement of local field intensity and nanoscale confinement of surface plasmon polaritons. Our results verify a feasible way for constructing nanoscale optical logical gates, switches, and all-optical transistors etc. for high density integration of optical circuits.