Width of OB Switching Time Distribution

In the OB experiments the commutation between the lower and upper branches of the bistability cycle (or viceversa) occurs within a time dependent on the relaxation rates of the cavity and of the absorbing medium. For an OB operation near the hysteresis region,the critical slowing- down phenomenon takes place and the commutation occurs with a time very long compared to the relaxation rates of the system. If a control parameter is modified by a step-function, the monitored output power of the bistable system reaches a new equibrium state after a delay time τD. A complete description of the transient regime is obtained only through a statistical analysis, where the intrinsic fluctuations and the external noise are included. Such a statistical analysis of the delay time in an optical bistability experiment has been recently presented for sodium atoms in an optical cavit