Distribution of timing and frequency signals in a fast-changing world requires unprecedented levels of stability for characterization. Transfer of frequency references over long distance without introducing any additional instability is of urgent concern for optical clock development. Choice of optical transmitter is critical to achieving accurate and stable RF clocks for end users. In this paper, we report the stability performance of the distributed feedback (DFB) laser and the Raman pump for transmitted clock signals. The DFB laser and the Raman pump were modulated with 2, 4, and 6 GHz RF clock signals from a signal generator and transmitted over 24.69 km SMF-Reach fiber. At 10 kHz offset frequency, we measured lowest phase noise of ${-}{121.22}\;{\rm{dBc/Hz}}$ and highest spectra power of ${-}{5.38}\;{\rm{dBm}}$ at 2 GHz for the DFB laser. Transfer stabilities of ${1.366} \times {10}^{- 12}$ and ${1.626} \times {10}^{- 12}$ for 2 and 4 GHz, respectively, at 1000 s averaging time were achieved. This technique does not require additional amplifiers for long-distance frequency distribution, making it simple and economical, and hence satisfying the requirements for next-generation optical fiber networks.

中文翻译：

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频率稳定性表征：DFB激光器和拉曼泵浦在24.69 km光纤上的分布式时钟信号上的性能

在瞬息万变的世界中，定时和频率信号的分配需要前所未有的稳定性来表征。在不引入任何其他不稳定性的情况下，长距离传输频率参考是光时钟开发的迫切关注点。选择光发射器对于为最终用户实现准确，稳定的RF时钟至关重要。在本文中，我们报告了分布式反馈（DFB）激光器和拉曼泵浦对于传输时钟信号的稳定性能。用来自信号发生器的2 GHz，4 GHz和6 GHz RF时钟信号调制DFB激光器和拉曼泵浦，并通过24.69 km SMF-Reach光纤传输。在10 kHz偏移频率下，我们测得的最低相位噪声为$ {-} {121.22} \; {\ rm {dBc / Hz}} $，而最高的频谱功率为对于DFB激光器，在2 GHz时为$ {-} {5.38} \; {\ rm {dBm}} $。在平均时间为1000 s的情况下，对于2 GHz和4 GHz，分别达到了$ {1.366} \ times {10} ^ {-12} $和$ {1.626} \ times {10} ^ {-12} $的传输稳定性。该技术不需要用于长距离频率分布的附加放大器，使其简单而经济，因此可以满足下一代光纤网络的要求。