Spatial Nonlinearity in Anisotropic Metamaterial Plasmonic Slot Waveguides

Abstract

We study the main nonlinear solutions of plasmonic slot waveguides made from an anisotropic metamaterial core with a positive Kerr-type nonlinearity surrounded by two semi-infinite metal regions. First, we demonstrate that for a highly anisotropic diagonal elliptical core, the bifurcation threshold of the asymmetric mode is reduced from the GW/m level for the isotropic case to 50 MW/m level indicating a strong enhancement of the spatial nonlinear effects. In addition, the slope of the dispersion curve for the asymmetric mode remains positive, at least near the bifurcation, suggesting a stable mode. Second, we show that for the hyperbolic case, there is no physically meaningful asymmetric mode, and that the sign of the effective nonlinearity can become negative.