Remote Nonlinear Switching and Large Nonlinear Effects in Resonant Optical Waveguides

Waveguide configurations are promising candidates for all-optical switching and modulation due to the combination of diffractionless propagation of the fields (large interaction length) and the strong confinement of power. Both peculiarities enhance the effectiveness of the nonlinear processes that produce the needed induced index change. The phenomena on which nonlinear guided wave devices are based can be categorized as weakly and strongly nonlinear. When the nonlinear contribution to the refractive index is much smaller than any variations in the linear refractive index that define the waveguide the guided field profile is assumed to be unchanged and perturbation methods can be used to describe the nonlinear mode coupling. The most studied weak nonlinear device to date has been the nonlinear directional coupler where the intensity of the input signal determines the routing of this signal, thus representing an all-optical switch. In the case of large nonlinearities where the induced refractive index changes are comparable with the index discontinuities the very guiding mechanism is affected. The large induced index changes result in the arising of nonlinear guided waves (NGW) which exhibit power-dependent field profiles and propagation constants and can be unstable in certain domains of the nonlinear dispersion curve. This article is from 'OSA Proceedings of the Topical Meeting on Nonlinear Guided-Wave Phenomena Held in 2-4 September 1991. Cambridge, England United Kingdom. Volume 15', AD-A253 471, p240-243.