Abstract

We report a variety of dynamical phenomena observed in a family of optically bistable devices based on the so-called thermally induced optical bistability with localized absorption (BOITAL).¹ The devices are low-finesse high-contrast Fabry-Perot cavities wiht a partially absorbing film as input mirror and a multilayer of transparent thermooptic materials as cavity spacer. Nonlinear dynamical features are associated wth a nonlinear feedback loop involving: (i) heat propagation from the localized absorbing source through the cavity spacer, (ii) temperature effects on the round-trip phase shift of the cavity by thickness expansion and refractive index variations, and (iii) light interference effects where absorption takes place. Nonlinearity arises from the interferometric function describing the cavity response as a function of the round-trip phase shift. Dynamical complexity may be achieved when the spacer of the BOITAL cavity consists of a multilayer structure of alternatively opposite thermooptic materials because the contributions of the various layers to the phase shift are competitive and time delayed.

© 1994 IEEE