Optical bistability and Fano-like resonance transmission in a ring cavity-coupled Michelson interferometer

This paper presents theoretical investigations on a new ring cavity-coupled scheme of a Michelson interferometer with a linear loop mirror, which has the attraction of low loss and high stability due to the closed geometry. The optical transmission response is modeled using a scattering matrix approach and analytical expressions are derived. This single ring cavity-coupled system exhibits optical Fano resonance features and significantly enhances the switching sensitivity to the cavity detuning required for a large ON/OFF contrast ratio. The evolution of Fano-like interference and the effect of ring cavity confinement on the Fano-like resonance are studied numerically. Furthermore, optical bistability and multi-bistability are demonstrated by introducing Kerr nonlinearity inside the ring cavity. The shape and polarity of hysteresis loops are easily controllable by adjusting the phase compensation of the direct channel, while the switching thresholds are affected remarkably by the linear phase shift of the ring cavity. The simple structure of the single cavity-coupled interferometer will be important for practical applications in optical sensors, all-optical switches and logic function elements.