Phase Coherent Link of an Atomic Clock to a Self-Referenced Microresonator Frequency Comb

TL;DR

This paper demonstrates phase-coherent linking of an atomic clock to a silicon chip microresonator frequency comb, enabling self-referencing and phase stabilization at high repetition rate for the first time.

Contribution

It introduces a method to achieve f-2f self-referencing and phase stabilization of a microcomb directly linked to an atomic clock, advancing integrated frequency comb technology.

Findings

Achieved the highest repetition rate octave-span microcomb.

Demonstrated low-noise microcomb properties compatible with atomic clock stability.

Realized phase-coherent linking of a microcomb to an atomic clock.

Abstract

The counting and control of optical cycles of light has become common with modelocked laser frequency combs. But even with advances in laser technology, modelocked laser combs remain bulk-component devices that are hand-assembled. In contrast, a frequency comb based on the Kerr-nonlinearity in a dielectric microresonator will enable frequency comb functionality in a micro-fabricated and chip-integrated package suitable for use in a wide-range of environments. Such an advance will significantly impact fields ranging from spectroscopy and trace gas sensing, to astronomy, communications, atomic time keeping and photonic data processing. Yet in spite of the remarkable progress shown over the past years, microresonator frequency combs ("microcombs") have still been without the key function of direct f-2f self-referencing and phase-coherent frequency control that will be critical for enabling their full potential. Here we realize these missing elements using a low-noise 16.4 GHz silicon chip microcomb that is coherently broadened from its initial 1550 nm wavelength and subsequently f-2f self-referenced and phase-stabilized to an atomic clock. With this advance, we not only realize the highest repetition rate octave-span frequency comb ever achieved, but we highlight the low-noise microcomb properties that support highest atomic clock limited frequency stability.