High-Q TeO2–Si Hybrid Microring Resonators

We present the design and experimental measurement of tellurium oxide-clad silicon microring resonators with internal Q factors of up to 1.5 × 106, corresponding to a propagation loss of 0.42 dB/cm at wavelengths around 1550 nm. This compares to a propagation loss of 3.4 dB/cm for unclad waveguides and 0.97 dB/cm for waveguides clad with SiO2. We compared our experimental results with the Payne–Lacey model describing propagation dominated by sidewall scattering. We conclude that the relative increase in the refractive index of TeO2 reduces scattering sufficiently to account for the low propagation loss. These results, in combination with the promising optical properties of TeO2, provide a further step towards realizing compact, monolithic, and low-loss passive, nonlinear, and rare-earth-doped active integrated photonic devices on a silicon photonic platform.