High-Q Ring Resonators in Low-Loss Monolithic Barium Titanate on Silicon

We investigate loss mechanisms in monolithic photonic structures fabricated from barium titanate grown epitaxially by RF-sputtering on silicon-on-insulator substrates. We characterize barium titanate waveguide loss using three photonic architectures, and demonstrate straight waveguide loss of less than 0.15 dB/cm, well below previously published loss measurements of barium titanate-containing waveguiding structures. Additionally, we demonstrate high-Q barium titanate resonators with quality factors of 𝑄 ∼ 100, 000. The low loss of the barium titanate photonic structures, coupled with barium titanate’s large non-linear optical response offers a path to compact and high efficiency barium titanate photonic devices and structures for high-speed modulation, optical computing, and non-linear applications.