We characterize the instability of an rf clock signal caused by free-space transmission of a frequency comb (FC) under typical laboratory conditions. The phase-noise spectra show the involvement of multiple random processes. For a 10 m transmission, the rms timing jitter integrated over 1-10~(5) Hz is 95 fs, and the root Allan variance over 1 s is 4 X 10~(-13). The measured Allan variance has a (tau)~(-1) behavior and an excellent agreement with the phase noise measurement. These results indicate the feasibility of FC-based free-space rf clock distribution over short distances.
展开▼
机译：我们表征了在典型的实验室条件下，由于频率梳（FC）的自由空间传输而导致的射频时钟信号的不稳定性。相位噪声谱表明涉及多个随机过程。对于10 m的传输，在1-10〜（5）Hz上积分的rms定时抖动为95 fs，在1 s上的根艾伦方差为4 X 10〜（-13）。测得的艾伦方差具有（τ）〜（-1）行为，并且与相位噪声测量具有极好的一致性。这些结果表明在短距离上基于FC的自由空间射频时钟分配的可行性。
展开▼
