Optical multistability in a cross-coupled double-ring resonator system

A silicon cross-coupled double-ring resonator system is proposed and fabricated for an optical multistability application, which consists of a racetrack resonator, a cross-coupled microring and a feedback U-shape waveguide. Transfer matrix method and rigorous simulation is used to analyze the static property. The measured device transmission spectrum can be modulated by applying a voltage to the microheater above the feedback waveguide, coinciding well with the theoretical expectation. With increase and decrease the input light power, optical multistability can be observed, which may be explained with consideration of the two-photon absorption and Kerr nonlinear effect. The presented device shows a favorable design freedom and energy consumption, which could be widely applied in optical logic gates and all-optical signal processing. •A silicon cross-coupled double-ring resonator system is demonstrated.•Transmission spectrum can change with an external thermo-optical heater.•The optical multistability is observed at low power input.•This system can be applied in all-optical signal processing.