Numerical studies in twin core directional couplers using asymmetric nonlinear refractive index profiles

Nonlinear directional couplers including an increasing self-phase modulation profile are examined. In this case, the asymmetry is associated with one channel having an unitary steady value while the other will have a different nonlinear refractive index profile. Looking at the transmission characteristics of the device, one observes that it is possible to decrease greatly the critical power or to present regions of multistability depending on which channel the power is pumped. It is concluded that the asymmetry can lead the coupler to operate in a multivalued function of the critical power for certain values of nonlinear parameters.