All-optical switching in novel waveguide X-junctions with localized nonlinearity

We propose novel all-optical functional devices using waveguide X-junctions with localized third order optical nonlinearity, where one branch is made from a Kerr-like nonlinear material and the rest are made from linear ones. All-optical switching operations can be obtained because of bistable like nonlinear dispersion characteristics in linear and nonlinear coupled guided -wave systems. The performances of the devices are analyzed by the Beam Pro pagation Method (BPM) modified for nonlinear waveguides combined with the n onlinear normal mode analysis. The methods to construct the waveguides with localized nonlinearity are also discussed by utilizing the technologies fo r the selective control of a band-gap energy of semiconductor Multi Quantum Well (MQW) structures and the performances of the designed devices are pre sented.