Nano Lett. 13, 1898–1902 (2013)

Diamond has a number of desirable materials properties that make it a promising candidate for on-chip high-performance photonic devices. In particular, its large Raman-gain, relatively large Kerr nonlinearity, wide bandgap (∼5.5 eV), negligible multiphoton loss mechanisms as well as its excellent thermal properties are of interest for the fabrication of active and passive optical devices that are capable of handling high optical powers. Marko Loncar and colleagues now report the realization of an integrated diamond photonic platform based on a thin single-crystal diamond film on top of a silicon dioxide/silicon substrate. Using this approach, the researchers demonstrated high-quality-factor single-crystal diamond racetrack resonators that operate at near-infrared wavelengths (1,550 nm). Optical characterization of these resonators revealed quality factors as high as ∼250,000 and overall insertion losses as low as 1 dB per facet. Furthermore, in these waveguides scattering-induced mode splitting, as well as signatures of nonlinear effects, such as optical bistability, were observed at an input pump power of ∼100 mW.