PROPAGATION EFFECTS IN NONLINEAR STRIP OPTICAL WAVE-GUIDES

A strip waveguide with a nonlinear substrate is investigated numerical ly. Both stationary wave propagation and Gaussian beam excitation were simulated. The Crank-Nicolson finite-difference scheme, combined with the transparent boundary condition, which employs no adjustable param eters, was used in the three dimensional calculations. The numerics su pport the statement that the stationary three dimensional nonlinear gu ided waves are stable on propagation for propagation constants corresp onding to the ascending branches of the nonlinear dispersion curves. W e found that in certain conditions, unstable nonlinear guided waves de cay by emitting a spatial solitary wave into the nonlinear self-focusi ng substrate. Similar effects occur in the case of end firing of Gauss ian beams in the nonlinear strip waveguide.