This book aims to study the propagation and transmission characteristics of a variety of all optical couplers to achieve an efficient all optical coupling, steering, multi-frequency generation and logic gates by aptly modeled coupler geometries. The odyssey of the study begins with a brief introduction to the fundamentals of the nonlinear optics, nonlinear effects, photopolymer fibers, PCF and the analytical tools necessary to explore the system dynamics. Two kinds of nonlinear couplers are considered for the study, namely photopolymer- and photonic crystal fiber- (PCF) coupler. And a special...