Nonlinear and nonlocal effects on dispersion properties of coupled surface plasmon polaritons in linear/wire-medium/nonlinear dielectric structures

We analytically investigate the nonlinear and nonlocal effects on dispersion properties of coupled surface plasmon polariton (SPP) modes at the interfaces of the linear/wire-medium/nonlinear dielectric with a Kerr nonlinearity. By employing a first integral method, we obtain the dispersion relation of coupled nonlinear SPP modes in the nonlinear waveguide system. Numerical results show that there exist two branches of SPP modes in the asymmetric multilayer structure, and both the nonlinearity and the nonlocality have a great impact on dispersion properties. We demonstrate that the focusing and defocusing nonlinearity can lead the SPP frequency to shift downward and upward, respectively, and there is no cutoff frequency for the nonlinear SPP mode when spatial nonlocality is taken into account, evidently different from those in the absence of spatial nonlocality. In addition, the nonlocality of optical response can also induce the SPP frequency to have a blueshift, but the nonlocal effect would be weakened with the nonlinearity enhanced. These interesting nonlinear SPP properties in metamaterial waveguides have potential applications in optoelectronic devices.