Stabilizing a frequency comb to an ultra-stable optical frequency reference requires a multitude of optoelectronic peripherals that have to operate under strict ambient control. Meanwhile, the frequency comb-to-comb stabilization aims to synchronize a slave comb to a well-established master comb with a substantial saving in required equipment and efforts. Here, we report an utmost case of frequency comb-to-comb stabilization made through a 1.3 km free-space optical (FSO) link by coherent transfer of two separate comb lines along with a feedback suppression control of atmospheric phase noise. The FSO link offers a transfer stability of 1.7 × 10^–15 at 0.1 s averaging, while transporting the master comb’s stability of 1.2 × 10^–15 at 1.0 s over the entire spectrum of the slave comb. Our remote comb-to-comb stabilization is intended to expedite diverse long-distance ground-to-ground or ground-to-satellite applications; as demonstrated here for broadband molecular spectroscopy over a 6 THz bandwidth as well as ultra-stable microwaves generation with phase noise of -80 dBc Hz^–1 at 1 Hz.

将频率梳稳定到超稳定的光学频率参考需要大量光电外围设备，这些外围设备必须在严格的环境控制下运行。同时，频率梳到梳的稳定旨在使从梳与成熟的主梳同步，从而大大节省所需的设备和工作量。在这里，我们报告了通过 1.3 km 自由空间光学 (FSO) 链路通过两条单独的梳状线的相干传输以及大气相位噪声的反馈抑制控制实现的频率梳到梳稳定的极端情况。FSO 链路在 0.1 s 的平均速度下提供 1.7 × 10 ^–15的传输稳定性，同时传输主梳的 1.2 × 10 ^{–15的稳定性}在从梳的整个频谱上以 1.0 秒的速度。我们的远程梳对梳稳定旨在加快各种长距离地对地或地对卫星应用；如此处所示，用于 6 THz 带宽上的宽带分子光谱以及在 1 Hz 时相位噪声为 -80 dBc Hz ^–1的超稳定微波生成。