High-Q microresonators on a high-crystallinity homoepitaxial 3C-silicon carbide-on-insulator platform

Cubic silicon carbide (3C-SiC) is attractive for integrated photonics, yet heteroepitaxial films on silicon often limit microresonator quality factors (Q), while amorphous SiC (a-SiC) typically exhibits a nearly vanishing second-order nonlinearity. Here, we develop a homoepitaxial 3C-SiC-on-insulator (3C-SiCOI) platform via hydrophilic bonding and thinning. Using femtosecond laser direct writing combined with chemical mechanical polishing (CMP), we demonstrate suspended microdisk resonators with an intrinsic Q up to 1.2 × 10⁶. To the best of our knowledge, this is the highest value reported for 3C-SiC microresonators. We further observe linear electro-optic tuning in a racetrack micro-ring resonator and estimate an effective electro-optic coefficient (r₄₁) of 0.6 pm/V. These results bridge high optical quality and crystalline functionality, positioning homoepitaxial 3C-SiCOI as a platform for next-generation active SiC integrated photonics.