Effects of Inhomogeneous Broadening on Resonance Fluorescence and the Growth of Laser Instabilities

Abstract

A recent multimode quantum theory¹ of light interactions shows how spontaneous emission influences the build-up of sidemodes in active and passive cavities containing a homogeneously-broadened medium of two-level strong-signal resonance fluorescence⁴ in appropriate limits, showing how this important phenomenon is explained in the context of Lamb theory. Contrary to what one might expect, the theory predicts a two-peaked spontaneous-emission spectrum for the onset of laser and optical-bistability sidemodes. The elimination of the central peak is due to a quantum three-wave mixing process. The laser sidemode instabilities are of great interest partly because they have led to all-optical chaos.⁵ The chaos experiments that have been performed involve inhomogeneously-broadened media. The present paper includes this broadening in the quantum treatment. This work also predicts the spectrum of resonance fluorescence in inhomogeneously-broadened stationary media, which has not to our knowledge been published. We have obtained analytic expressions for a Lorentzian inhomogeneous broadening function, allowing us to study the transition from homogeneous broadening to the inhomogeneous-broadening limit.