Optical bistability due to increasing absorption.

A novel type of optical bistability is proposed and demonstrated. It is shown theoretically that optical bistability will exist in a material whose optical absorption is more than linearly proportional to the degree to which the material is excited. No cavity or external feedback is required. This bistability and associated differential gain are demonstrated experimentally using a thermal nonlinearity in a GaAs/GaAlAs multiple quantum well semiconductor. Theory and experiment show good agreement.