The relevance of dispersion in optical bistability is outlined. The results are compared with those for absorptive bistability, and a connection with experiments is discussed.
The optical bistability of a four-level system with triplet-state absorption typical of organic media is studied. We derive the state equation of optical bistability with triplet-state absorption. Different bistabilities with resonant absorption or dispersion of the triplet state are numerically discussed. The effects of the cooperativity parameter and the atomic- and cavity-detuning parameters on optical bistable behavior are analyzed. It is found that the hysteresis loops decrease with an increase of both the cooperativity parameter and the atomic-detuning parameter of the triplet state and that under some conditions reverse saturable-absorptive media can display bistability.