Hybrid Si-LiNbO₃ microring electro-optically tunable resonators for active photonic devices

Hybrid Si-LiNbO₃ electro-optic tunable ring resonators have been proposed and demonstrated as a path to achieving ultracompact and high-speed electro-optic devices. Free standing single crystal LiNbO₃ microplatelets (~mm long and ~1 μm thick) were obtained from a z-cut LiNbO₃ substrate by ion implantation and thermal treatment. The platelets were transferred and thermally bonded on top of Si resonators that were fabricated in a Si-on-insulator platform by a 0.18 μm standard complementary metal-oxide-semiconductor process. For the hybrid microring resonator, a free spectral range of 16.5 nm, a finesse F of ~1.67 × 10², a Q-factor of ~1.68 × 10⁴, and an effective r coefficient of ~1.7 pm/V were achieved for the TE mode. These values are in good agreement with the calculated results.