Multiplicative noise-induced probability distributions in three-level atomic optical bistability

Effects of multiplicative noise on optical bistability in a three-level atomic medium in a ring cavity are investigated experimentally and theoretically. Steady-state intensity distributions as well as switching and dwell times have been measured as functions of noise strength. System response to an external periodic signal is also explored. It is found that the probability for the system to stay in the upper state increases with increasing noise strength. When a small periodic signal is added to the input field, the probability for the upper state has a maximum as a function of multiplicative noise strength. A simple theoretical model based on nonlinear atomic susceptibility is presented to interpret the experimental observations.