PHASE-SPACE DESCRIPTION OF NONLINEAR DIRECTIONAL-COUPLERS

A comprehensive analysis of the symmetric nonlinear directional couple r as a function of the excitation conditions is reported. The analysis is based on a coupled-mode technique in normalized (dimensionless) pa rameters, using the linear supermodes of the guiding structure, most o f the results being derived from the Hamiltonian of the resulting nonl inear equations. The exchange of power between the branches in the cou pler is graphically described by means of the trajectories of the moti on in the phase space. The effect of saturation of the nonlinear index has been included.