Classical realization of a strongly driven two-level system

Abstract
A classical two-level system has been realized by coupling two propagation or two polarization modes of an optical ring resonator. This system can be driven by periodic modulation of either the coupling or the bare mode frequencies, at sufficient strength to violate the rotating-wave approximation (RWA) on resonance. Landau-Zener transitions, Rabi oscillation with non-RWA signature, and Autler-Townes doublets have been observed.