Schioppo M, Kronjäger J, Silva A, Ilieva R, Paterson J W, Baynham C F A, Bowden W, Hill I R, Hobson R, Vianello A, Dovale-Álvarez M, Williams R A, Marra G, Margolis H S, Amy-Klein A, Lopez O, Cantin E, Álvarez-Martínez H, Le Targat R, Pottie P E, Quintin N, Legero T, Häfner S, Sterr U, Schwarz R, Dörscher S, Lisdat C, Koke S, Kuhl A, Waterholter T, Benkler E, Grosche G
National Physical Laboratory (NPL), Teddington, TW11 0LW, UK.
Laboratoire de Physique des Lasers (LPL), Université Paris 13, CNRS, Villetaneuse, France.
Nat Commun. 2022 Jan 11;13(1):212. doi: 10.1038/s41467-021-27884-3.
Ultrastable lasers are essential tools in optical frequency metrology enabling unprecedented measurement precision that impacts on fields such as atomic timekeeping, tests of fundamental physics, and geodesy. To characterise an ultrastable laser it needs to be compared with a laser of similar performance, but a suitable system may not be available locally. Here, we report a comparison of two geographically separated lasers, over the longest ever reported metrological optical fibre link network, measuring 2220 km in length, at a state-of-the-art fractional-frequency instability of 7 × 10 for averaging times between 30 s and 200 s. The measurements also allow the short-term instability of the complete optical fibre link network to be directly observed without using a loop-back fibre. Based on the characterisation of the noise in the lasers and optical fibre link network over different timescales, we investigate the potential for disseminating ultrastable light to improve the performance of remote optical clocks.
超稳激光器是光频计量中的关键工具，能够实现前所未有的测量精度，对诸如原子计时、基础物理测试和大地测量等领域产生影响。为了表征一台超稳激光器，需要将其与性能相似的激光器进行比较，但本地可能没有合适的系统。在此，我们报告了在有史以来最长的计量光纤链路网络（长度为2220公里）上，对两台地理位置分离的激光器进行的比较，平均时间在30秒至200秒之间时，其分数频率不稳定性达到了7×10 。这些测量还使得无需使用回环光纤就能直接观测到整个光纤链路网络的短期不稳定性。基于对激光器和光纤链路网络在不同时间尺度上噪声的表征，我们研究了传播超稳光以提高远程光钟性能的潜力。
