High-Q integrated lithium tantalate microring resonators for on-chip comb generation

Lithium tantalate on insulator (LTOI), taking advantage of high cost-effectiveness, ultra-low optical loss, and prominent electro-optic (EO) coefficient, shows great potential as an integrated waveguide-based optical platform for commercialization. Further research on monolithic nonlinear source generators with tunable features is crucial in its early stages. Here, we fabricate low-loss microring resonators (intrinsic Q value above 4 × 10 6 ) via universal subtractive manufacturing. Both Kerr and EO combs are realized based on X-cut LTOI high-Q resonators. Specifically, we elucidate the complicated synergy caused by a photorefractive (PR) effect and thermo-optic modulation, observing the soliton step using the facile laser scanning technique. Furthermore, the preliminary experimental result of the static EO comb is also exploited in a 20 GHz free spectral range (FSR) LTOI microring resonator, verifying the versatility of this unique photonic platform for on-chip microcomb generation.