We measure optical bistability in a micron-size silicon ring resonator based on the free-carrier dispersion effect in silicon. Optical transfer function of the resonator shows hysteresis loop with less than 10 mW input optical power.
We demonstrate low-power thermo-optic-based optical bistability in a free-standing silicon ring resonator. A bistable optical response is achieved at reduced pump powers by thermally isolating the ring resonator from its supporting substrate with an air gap. The conversion efficiency from optical power to temperature change in the silicon core is enhanced. The optical transfer function of the resulting free-standing resonator exhibits a hysteresis loop for 80 microW input optical power. Similar nonthermally isolated resonators at the same detuning do not exhibit a bistable mode for input powers less than 2 mW.