Carrier-induced optical bistability in the silicon micro-ring resonators under continuous wave pumping

The results of a study of the nonlinear frequency response of a silicon micro-ring resonator (MRR) manufactured using silicon-on-insulator technology are presented. Appearance of optical bistability caused by the frequency shift of the MRR resonant spectrum under continuous wave pumping is experimentally demonstrated. The experimental results are explained in the framework of an original theory, which accounts for the linear loss, Kerr nonlinearity, two-photon absorption, free-carrier-induced absorption and dispersion, and the thermo-optic effect. It is shown that the bistability of the frequency response originates from competition between frequency shifts of opposite signs that appear due to the presence of the thermo-optic and free-carrier effects, with the latter one being dominant.