Complementary metal-oxide-semiconductor compatible athermal silicon nitride/titanium dioxide hybrid micro-ring resonators

Micro-ring resonators have been widely utilized in silicon photonics. However they often exhibit a high sensitivity to ambient temperature fluctuations. In this letter, we have demonstrated a complementary metal-oxide-semiconductor compatible athermal micro-ring resonator made from titanium dioxide (TiO₂) and silicon nitride (SiN_x). We have exploited the negative thermo-optic coefficient of TiO₂ to counterbalance the positive coefficient of SiN_x. By a precise control over the TiO₂ layer thickness, an athermal condition remarkably consistent with the simulation can be achieved. Therefore, a SiN _x-TiO₂ hybrid micro-ring resonator with a temperature dependent wavelength shift of 0.073 pm/ °C has been realized.