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Direct kerr-frequency comb atomic spectroscopy



Liron Stern, Jordan R. Stone, Songbai Kang, Daniel C. Cole, Zachary L. Newman, Kerry Vahala


Microresonator-based soliton frequency combs- microcombs -have recently emerged to offer low- noise, photonic-chip sources for optical measurements. Owing to nonlinear-optical physics, microcombs can be built with various materials 1-3 and tuned or stabilized with a consistent framework. A few applications have been characterized that require absolute phase stabilization, including optical-frequency synthesis 4, optical-frequency division, and optical clocks5. Partially stabilized microcombs can also benefit several applications, including ranging 6, dual-comb spectroscopy 7,8, and optical communications 9. The benefits of broad optical bandwidth, brightness, coherence and frequency stabilization have made frequency-comb sources important for studying atoms and molecules, especially in the detection of trace gases 10, multiphoton light-atom interactions 11,12, and for fundamental spectroscopy in the extreme ultraviolet 13. Here , we explore direct microcomb atomic spectroscopy, utilizing a cascaded, two-photon 1529-nm atomic transition of rubidium. Both the microcomb and the atomic vapor are implemented with planar fabrication techniques to support integration. By fine and simultaneous scanning of the repetition rate and carrier-envelope-offset frequency of the soliton microcomb, we obtain direct sub-Doppler and hyperfine spectroscopy of the 42D5/2 manifold. Moreover, the entire set of microcomb modes are stabilized to this atomic transition, yielding absolute optical-frequency fluctuations of the microcomb at the kHz-level over a few seconds and <1 MHz day-to-day accuracy. Our work demonstrates atomic spectroscopy with microcombs and provides a rubidium-stabilized microcomb laser source, operating across the 1550 nm band for sensing, dimensional metrology, and communication.
Nature Photonics


Atomic physics, chip-scale atomic devices, Kerr frequency combs


Stern, L. , Stone, J. , Kang, S. , Cole, D. , Newman, Z. and Vahala, K. (2020), Direct kerr-frequency comb atomic spectroscopy, Nature Photonics (Accessed April 14, 2024)
Created February 27, 2020, Updated July 31, 2020