近日，美国西北大学的Zifan Zhou及其研究团队取得一项新进展。经过不懈努力，他们揭示了拉曼激光器与其泵浦激光器在正色散和负色散下的强频率相关和反相关。相关研究成果已于2024年6月14日在国际知名学术期刊《物理评论A》上发表。

该研究团队发现拉曼激光器的频率与拉曼泵浦激光器的频率高度相关或反相关，这取决于拉曼激光器所经历的色散是正的还是负的。对于亚光速激光器，对应于群指数远大于1的正色散，其频率位移与拉曼泵浦激光器的频率位移大致相同。

相比之下，对于一个超光速激光器，对应于一个负色散的群指数接近于零，它的频率在与拉曼泵浦激光器相反的方向上移动，并且具有一个更大的系数，大约等于群指数的倒数。

这些发现将在确定采用这种激光器的传感器的，最大可实现灵敏度方面发挥关键作用，特别是在由于经典波动，而使泵浦激光线宽大大超出肖洛-汤斯线宽的情况下。

附：英文原文

Title: Strong frequency correlation and anticorrelation between a Raman laser and its pump laser for positive and negative dispersions

Author: Zifan Zhou, Ruoxi Zhu, Selim M. Shahriar

Issue&Volume: 2024/06/14

Abstract: We show that the frequency of a Raman laser is highly correlated or anticorrelated with the frequency of the Raman pump laser, depending on whether the dispersion experienced by the Raman laser is positive or negative. For a subluminal laser, corresponding to a positive dispersion with a group index that is much larger than unity, the shift in its frequency is approximately the same as that in the Raman pump laser. In contrast, for a superluminal laser, corresponding to a negative dispersion with a group index that is close to zero, its frequency shifts in the direction opposite to that of the Raman pump lasers and has an amplitude that is larger by a factor approximately equaling the inverse of the group index. These findings would play a critical role in determining the maximum achievable sensitivity of sensors employing such lasers, especially under conditions where the pump laser linewidth is broadened significantly beyond the Schawlow-Townes linewidth due to classical fluctuations.

DOI: 10.1103/PhysRevA.109.063513

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.063513