Abstract

The current state of knowledge of finite amplitude nonlinear surface-guided waves will be reviewed together with a limited indication of their potential for application in modern optical signal processing. Both TE and TM waves in planar guides and novel types of LP waves in optical fibres will be analysed but attention will be restricted to isotropic materials. These nonlinear waveguides have field distributions that are substantially altered as the light intensity increases. This means that the usual coupled-mode theory is inapplicable since the really interesting effects will occur near to the light-line. The nonlinearity arises from the symmetry-reduced third-order term in the electric polarisation or in some phenomenological fashion designed to fit experiment. This means that all processes occur at the same frequency and the standard boundary conditions apply. Self-focussing waves occur for which some kind of hysteretic switching schemes can be devised. It is emphasised, however, that this behaviour must not be taken as a definition of optical bistablity. Many types of waveguiding structures will be presented. These will be discussed physically in terms of the electric field distributions and the variation of the total power flow down the guide with the effective refractive index of the surface-guided wave. The differences between TE and TM waveguide structures and the role of saturation effects will be critically assessed as will the status of recent results concerning the prediction of optical bistablity in plane wave reflection-based devices. These will be contrasted with some recent results on the behaviour of laser beams in layered structures.

© 1985 Optical Society of America