DISPERSIVE BISTABILITY IN HOMOGENEOUSLY BROADENED SYSTEMS

We derive from the Maxwell-Bloch equations for a ring cavity a general state equation which describes optical bistability both in the absorptive and in the dispersive case, and both for homogeneously and inhomogeneously broadened systems. In the case of homogeneously broadened systems we derive and discuss analytically the bistability conditions. It turns out that, when the bistability parameter C is smaller than four, also dispersive bistability is not available. In general, for homogeneously broadened systems dispersive optical bistability does not show definite advantages with respect to the absorptive one. The behaviour of the hysteresis cycle as a function of the various parameters in play is discussed. The limits of validity of the cubic approximation are also pointed out. © 1979 Società Italiana di Fisica.