Critical slowing down with bistable higher harmonics

Switching response in an optical bistable model of two-level atoms in a ring cavity is investigated outside the rotating wave approximation (RWA) in the high- and low-Q cavity cases. Analytical and numerical investigations of the non-autonomous model Bloch equations, up to first Fourier harmonics, show that the switching time in response to linear perturbation of the incident field at the critical points of the bistable curves is significantly affected by the atomic and cavity detuning parameters. The faster oscillatory behavior outside the RWA reflects itself in the additional ultra-low output (first harmonic) field component, which has reversed bistable feature in both the high-Q and low-Q cases. Irregular oscillations with increased atomic detuning are showed only in the lower bistable branch of the first harmonic field. Irregularity of the oscillations is due to the interference of the oscillations of the higher frequency terms with the atomic dispersive polarization in the high-Q case, and the Rabi oscillations in the low-Q case.