Ji Qing-Xin, Zhang Wei, Savchenkov Anatoliy, Liu Peng, Sun Shuman, Jin Warren, Guo Joel, Peters Jonathan, Wu Lue, Feshali Avi, Paniccia Mario, Ilchenko Vladimir, Bowers John, Matsko Andrey, Vahala Kerry
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA USA.
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA.
Nat Photonics. 2025;19(6):624-629. doi: 10.1038/s41566-025-01667-4. Epub 2025 May 23.
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 two-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 factor. A hybridly packaged version of the system offers excellent longer term stability. The results advance integrable microcomb-based signal sources into the performance realm of much larger microwave sources.
光学领域（光学腔和原子跃迁）中谐振系统显著的频率稳定性，可以通过光学分频在电子学可及的频率尺度上加以利用。这种能力正在彻底改变从计时到高性能电信号源等一系列技术。一种名为两点光学分频（2P-OFD）的技术版本，正被证明在应用于高性能信号源方面具有优势。在2P-OFD中，一个光学腔固定由频率梳的谱线所定义的两个光谱端点。该频率梳无需自参考，这极大地简化了系统架构并降低了功率需求。在此，利用一个微梳展示了一个具有创纪录低相位噪声的2P-OFD微波信号源。这一进展的关键在于由微梳孤子发射的频率捷变单模色散波所定义的一个光谱端点。此外，系统频率参考是一个具有创纪录品质因数的紧凑型全固态光学腔。该系统的混合封装版本具有出色的长期稳定性。这些结果将基于微梳的可集成信号源推进到了更大微波源的性能领域。
