Optical solitons in nonlinear directional couplers by sine-cosine function method and Bernoulli's equation approach

This paper obtains soliton solutions to optical couplers by two methods. These are sine-cosine function method and Bernoulli's equation approach. There are four laws that are touched upon in this paper. These are Kerr law, power law, parabolic law and dual-power law. The first integration scheme is applicable to Kerr and power laws only where bright soliton solutions are retrievable. The second tool is applicable to parabolic and dual-power laws only that leads to dark and singular solitons for these two nonlinear media.