Abstract

It is well-known that the presence of a thin film on the surface of a wave guiding medium opens up a gap in the spectrum of allowed surface or waveguide modes when the frequency of the film dipole-active excitations falls within the frequency range of the existence of these modes. The splitting is quite analogous to the longitudinal-transverse splitting in bulk crystal optics. However, in the waveguide case under consideration here the gap width Δ depends on the film thickness d, $\Delta \sim \sqrt{\text{d}}/\text{λ}$ [1](λ being the vacuum wavelength of the mode, d≪λ). This splitting was observed for various systems by many investigators (for a review of the experimental results see, e.g. [2,3]). These experiments have stimulated us to study also nonlinear optical phenomena inherent to this frequency region. We found that the presence of the dipole-active film enhances the surface (and guided) wave nonlinearity. In addition, we studied multistability of nonlinear guided waves in an interferometer formed by a thin film of a finite length.

© 1989 Optical Society of America