We present a detailed frequency noise analysis of a feedforward scheme used to faithfully transfer the spectral properties of an individual line of an optical frequency comb spectrum to a single-mode laser and in this way indirectly amplify it, which is applicable to any arbitrary comb mode spacing. In contrast to previously reported implementation of the feedforward method for a similar purpose, we present a more thorough noise study, including the measurement of the additive noise of the setup. The reported experimental investigation was performed using two low-noise ultrafast mode-locked lasers with different repetition rates (~ 1 GHz and 250 MHz) and show a faithful transfer of the comb mode frequency noise to the auxiliary laser with a sub-radian additive phase noise integrated from 1 Hz to 1 MHz. We discuss the present limitations of the method that is able to transfer optical comb lines with sub-Hz linewidth and propose simple improvements.

中文翻译：

---

使用前馈方案实现光学梳状线光谱纯度的低噪声传输

我们对前馈方案进行了详细的频率噪声分析，该方案用于忠实地将光学频率梳谱的单个谱线的光谱特性传输到单模激光器，并以这种方式间接放大它，适用于任何任意梳理模式间距。与之前报道的类似目的的前馈方法的实现方法相比，我们提出了更全面的噪声研究，包括测量设​​备附加噪声。所报告的实验研究是使用两个具有不同重复率（〜1 GHz和250 MHz）的低噪声超快锁模激光器进行的，显示了将梳模频率噪声忠实地转移至具有亚弧度相的辅助激光器噪声从1 Hz到1 MHz积分。