Twin core nonlinear couplers with saturable nonlinearity

In addition to a low power switching characteristic, the nonlinear coupler composed of one self focussing core and one self defocussing core is found to be more tolerable to nonlinear saturation than that composed of two self focussing cores. This leads to the possibility of achieving low power all optical switching over a broad range of power which is not possible using conventional nonlinear couplers composed of two self focussing cores.