近日，美国普渡大学Kaiyi Wu团队研究了集成光学原子钟用游标微梳。相关论文发表在2025年2月19日出版的《自然—光子学》杂志上。
克尔微梳作为可大规模制造、紧凑的频率梳替代品引起了人们的极大兴趣。这可以部署许多以前仅限于实验室的依赖频率梳的应用程序。特别吸引人的是微梳在紧凑型光学原子钟中执行光学频率分割的前景。不幸的是，由于倍频程频率梳生成通常需要大约太赫兹的重复率，因此很难满足这些系统中微梳的自参考要求。此外，在频谱上设计一个微梳状系统，使频率梳模式与具有足够信噪比的原子钟跃迁相一致，是一项挑战。
研究组采用游标双微梳方案，将871 nm的稳定超窄线宽连续波激光器的光学频率分割为~235MHz的输出频率。该方案能够将超高频（~100 GHz）载波包络偏频向下偏移到可检测的频率，并同时将频率梳线放置在接近871纳米激光器的位置——调整后，如果频率加倍，其将接近171Yb+的时钟跃迁。该双梳系统有可能与集成离子阱结合，用于未来的芯片级光学原子钟。
附：英文原文
Title: Vernier microcombs for integrated optical atomic clocks
Author: Wu, Kaiyi, OMalley, Nathan P., Fatema, Saleha, Wang, Cong, Girardi, Marcello, Alshaykh, Mohammed S., Ye, Zhichao, Leaird, Daniel E., Qi, Minghao, Torres-Company, Victor, Weiner, Andrew M.
Issue&Volume: 2025-02-19
Abstract: Kerr microcombs have drawn substantial interest as mass-manufacturable, compact alternatives to bulk frequency combs. This could enable the deployment of many comb-reliant applications previously confined to laboratories. Particularly enticing is the prospect of microcombs performing optical frequency division in compact optical atomic clocks. Unfortunately, it is difficult to meet the self-referencing requirement of microcombs in these systems owing to the approximately terahertz repetition rates typically required for octave-spanning comb generation. In addition, it is challenging to spectrally engineer a microcomb system to align a comb mode with an atomic clock transition with a sufficient signal-to-noise ratio. Here we adopt a Vernier dual-microcomb scheme for optical frequency division of a stabilized ultranarrow-linewidth continuous-wave laser at 871nm to an ~235MHz output frequency. This scheme enables shifting an ultrahigh-frequency (~100GHz) carrier-envelope offset beat down to frequencies where detection is possible and simultaneously placing a comb line close to the 871nm laser—tuned so that, if frequency doubled, it would fall close to the clock transition in 171Yb+. Our dual-comb system can potentially combine with an integrated ion trap towards future chip-scale optical atomic clocks.
DOI: 10.1038/s41566-025-01617-0
Source: https://www.nature.com/articles/s41566-025-01617-0