Effects of nonlinearity in asymmetric adiabatic three-waveguide directional couplers

We study the effects of optical nonlinearity in asymmetric adiabatic three-waveguide directional couplers, that consist of both linear and nonlinear waveguides. We consider several combinations of linear and nonlinear waveguides and show that the different combinations have different switching characteristics. We also find that in the structure where the central waveguide is nonlinear and the two outer waveguides are linear the nonlinearity does not play a role.