Abstract

Previously reported observations of optical bistability in a GaAs/GaAlAs waveguide cavity included whole-sample thermally induced absorptive and refractive bistability [1] and localised (μs) thermally induced absorptive bistability [2]. Other groups have observed refractive bistability due to an optoelectronic mechanism in MQW GaAs/GaAlAs waveguides [3,4]. In this paper we report the observation of bistability due to thermally induced changes in leaky modes within a GaAs/GaAlAs waveguide and discuss the optimisation of optoelectronic nonlinearities in semiconductor guides of this type. A leaky planar waveguide consists of a low index layer bounded by two higher index layers. These exhibit radiative losses, where for the nth order mode the attenuation coefficient is proportional to (n+1)² [5]. In this investigation the waveguides used were short enough to allow good transmission of the lower order modes.

© 1989 Optical Society of America