Direct Kerr frequency comb atomic spectroscopy and stabilization


Liron Stern, Jordan R. Stone, Songbai Kang, Daniel C. Cole, Myoung-Gyun Suh, Connor Fredrick, Zachary Newman, Kerry Vahala, John Kitching, Scott A. Diddams, and Scott B. Papp. 2020. “Direct Kerr frequency comb atomic spectroscopy and stabilization.” Science Advances, 6, 9, Pp. eaax6230.


\textlessp\textgreaterMicroresonator-based soliton frequency combs, microcombs, have recently emerged to offer low-noise, photonic-chip sources for applications, spanning from timekeeping to optical-frequency synthesis and ranging. Broad optical bandwidth, brightness, coherence, and frequency stability have made frequency combs important to directly probe atoms and molecules, especially in trace gas detection, multiphoton light-atom interactions, and spectroscopy in the extreme ultraviolet. Here, we explore direct microcomb atomic spectroscopy, using a cascaded, two-photon 1529-nm atomic transition in a rubidium micromachined cell. Fine and simultaneous repetition rate and carrier-envelope offset frequency control of the soliton enables direct sub-Doppler and hyperfine spectroscopy. Moreover, the entire set of microcomb modes are stabilized to this atomic transition, yielding absolute optical-frequency fluctuations at the kilohertz level over a few seconds and \textless1-MHz day-to-day accuracy. Our work demonstrates direct atomic spectroscopy with Kerr microcombs and provides an atomic-stabilized microcomb laser source, operating across the telecom band for sensing, dimensional metrology, and communication.\textless/p\textgreater