Fujieda Miho, Kumagai Motohiro, Nagano Shigeo, Yamaguchi Atsushi, Hachisu Hidekazu, Ido Tetsuya
National Institute of Information and Communications Technology, 4-2-1, Nukui-kitamachi, Koganei, Tokyo, 184-8795 Japan.
Opt Express. 2011 Aug 15;19(17):16498-507. doi: 10.1364/OE.19.016498.
We developed an all-optical link system for making remote comparisons of two distant ultra-stable optical clocks. An optical carrier transfer system based on a fiber interferometer was employed to compensate the phase noise accumulated during the propagation through a fiber link. Transfer stabilities of 2 × 10(-15) at 1 second and 4 × 10(-18) at 1000 seconds were achieved in a 90-km link. An active polarization control system was additionally introduced to maintain the transmitted light in an adequate polarization, and consequently, a stable and reliable comparison was accomplished. The instabilities of the all-optical link system, including those of the erbium doped fiber amplifiers (EDFAs) which are free from phase-noise compensation, were below 2 × 10(-15) at 1 second and 7 × 10(-17) at 1000 seconds. The system was available for the direct comparison of two distant (87)Sr lattice clocks via an urban fiber link of 60 km. This technique will be essential for the measuring the reproducibility of optical frequency standards.
我们开发了一种全光链路系统，用于对两个远距离的超稳定光钟进行远程比较。采用了基于光纤干涉仪的光载波传输系统，以补偿在通过光纤链路传播过程中积累的相位噪声。在90公里的链路中，实现了1秒时2×10^(-15)和1000秒时4×10^(-18)的传输稳定性。另外引入了一个有源偏振控制系统，以保持传输光处于适当的偏振态，从而完成了稳定可靠的比较。全光链路系统的不稳定性，包括未进行相位噪声补偿的掺铒光纤放大器（EDFA）的不稳定性，在1秒时低于2×10^(-15)，在1000秒时低于7×10^(-17)。该系统可通过60公里的城市光纤链路直接比较两个远距离的（87）Sr晶格钟。这项技术对于测量光频标准的可重复性至关重要。
