A broadband chip-scale optical frequency synthesizer at 2.7 × 10(-16) relative uncertainty

• Published in: Science advances Vol. 2; no. 4; p. e1501489
• Main Authors: Huang, Shu-Wei, Yang, Jinghui, Yu, Mingbin, McGuyer, Bart H, Kwong, Dim-Lee, Zelevinsky, Tanya, Wong, Chee Wei
• Format: Journal Article
• Language: English
• Published: United States 01.04.2016
• Subjects: Astronomy - instrumentation; Equipment Design; Fiber Optic Technology - instrumentation; Spectrum Analysis - instrumentation; Telecommunications - instrumentation; Optical frequency comb; precision spectroscopy; astronomical spectrography; coherent communications; chip-scale
• ISSN: 2375-2548
• DOI: 10.1126/sciadv.1501489

Optical frequency combs-coherent light sources that connect optical frequencies with microwave oscillations-have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb's two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of [Formula: see text]. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10(-16), heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography.