Instability in injected-laser and optical-bistable systems

An analytical function is derived which can serve as a criterion of the instability boundary of both optical-bistable (OB) systems and laser systems with an injected coherent signal (LIS). By means of the criterion, we analyze, in various asymptotic limits, the instability regions of OB and LIS in the parameter space. In both good- and bad-cavity conditions of LIS a full hysteresis loop between coexisting stable states is observed for the first time.