SPM and XPM nonlinear effects in plasmonic directional couplers, considering the ponderomotive metal nonlinearity

In this paper, a two-dimensional nonlinear plasmonic directional coupler (2D-NPDC), with 90° waveguide bends, has been numerically analyzed by the finite-difference time-domain (FDTD) method, considering the nonlinear response of metal due to the ponderomotive force. It has been shown that the required switching power of the 2D-NPDC is 0.05% of that when only the dielectric is nonlinear and the nonlinearity of metal is neglected. Also, the cross-phase modulation (XPM) nonlinear effect has been investigated, which the power for switching is decreased significantly compared to the one with the self-phase modulation (SPM) effect.