Lithium niobate makes ultra-high-Q resonators

Researchers at Harvard University in the US have made the first ultra-high-quality micro-ring and racetrack resonators from lithium niobate. The new devices, which consist of plasma-etched subwavelength waveguides that can propagate light across a metre-length path while losing only about half their optical power, have quality factors of up to 107. They might be used to make ultra-efficient integrated photonics circuits, in quantum photonics and optical communications……..