Abstract
Optical bistability (OB) for a homogeneously broadened two-level atomic system in a ring cavity is investigated within and without the rotating wave approximation (RWA) using nonautonomous Maxwell-Bloch equations subject to a time delay. It is shown that the dynamics both within and without the RWA are susceptible to the introduction of time delays in the differential equations. A range of instability scenarios are found as certain parameters are ramped up and down and these can affect the bistable operation of the physical devices. However, the introduction of a time delay can also result in an important positive application; for the first time, as far as the authors are aware, it is shown that a type of butterfly hysteresis can occur in the fundamental component, which is a relatively strong output signal, and may be desired in optical signal processing.