Dispersive-wave-agile optical frequency division

TL;DR

This paper demonstrates a highly stable microwave signal source using optical frequency division with a microcomb and a dispersive wave, achieving record-low phase noise and compact system design.

Contribution

It introduces a dispersive wave-agile approach in 2-point optical frequency division, enhancing microcomb-based microwave sources with improved stability and integration.

Findings

Record-low phase noise microwave signal achieved

Utilization of a dispersive wave for spectral endpoint

Compact all-solid-state optical cavity used as reference

Abstract

The remarkable frequency stability of resonant systems in the optical domain (optical cavities and atomic transitions) can be harnessed at frequency scales accessible by electronics using optical frequency division. This capability is revolutionizing technologies spanning time keeping to high-performance electrical signal sources. A version of the technique called 2-point optical frequency division (2P-OFD) is proving advantageous for application to high-performance signal sources. In 2P-OFD, an optical cavity anchors two spectral endpoints defined by lines of a frequency comb. The comb need not be self-referenced, which greatly simplifies the system architecture and reduces power requirements. Here, a 2P-OFD microwave signal source is demonstrated with record-low phase noise using a microcomb. Key to this advance is a spectral endpoint defined by a frequency agile single-mode dispersive wave that is emitted by the microcomb soliton. Moreover, the system frequency reference is a compact all-solid-state optical cavity with a record Q-factor. The results advance integrable microcomb-based signal sources into the performance realm of much larger microwave sources.