Reflectivity of a nonlinear discontinuity in optical waveguides

The reflective properties of a nonlinear discontinuity in an inhomogeneous dielectric waveguide are analysed. The transmission coefficient is calculated through a semi-analytical technique. The behaviour of the transmission coefficient as a function of the discontinuity length, the refractive indices and the incident wave characteristics is investigated. For practical values of the parameters involved the reflectivity is found to be relatively low, while it is increased as the power and/or the percentage difference between the linear discontinuity index and the index of the surrounding waveguides are increased. In addition, the effects of bistability and multistability (for both self-focusing and self-defocusing discontinuities) are observed and found to be associated with the increase of the aforementioned parameters.