Modulation instability effects of the conventional Kerr type nonlinearity on the three-core oppositely directed coupler

Abstract

The present design deals with a three-core system in which two channels are made of negative index material and one made of positive index material. The nonlinear Schrodinger equation is modified by adding the Kerr-type nonlinearity and coupling coefficient terms. We derive the dispersion relation for the optical coupler under investigation in the presence of added terms. Using a linear stability analysis, we examine the modulation instability characteristic gain in both the normal and anomalous group-velocity dispersion regimes. We study the system in diversified physical parameter space to unveil many possibilities. The analytical results demonstrate that, in contrast to Shafeeque et al. (2016), some novel instability bands are produced in the normal and anomalous dispersion regimes. We observe the modulational instability (MI) occurring due to Kerr-type nonlinearity. It is also evident that MI can be controlled by varying pump power and nonlinear factors. As a result, we observe new possibilities for producing and managing the MI in three-core oppositely directed couplers with the impact of opposite directionality.