论文标题
$ 10^{ - 7} $ for Ultra Stable激光器的剩余幅度调制
Residual amplitude modulation at the $10^{-7}$ level for ultra-stable lasers
论文作者
论文摘要
通过磅 - 二孔（PDH）技术，激光器在超稳定的光腔上的稳定是一种广泛使用的方法。 PDH方法依赖于激光的相位调节，该激光通常由电气调节器（EOM）执行。当接近$ 10^{ - 16} $级别时，该技术需要对EOM生成的残留幅度调制（RAM）进行主动控制，以使激光器的频率稳定性降低到超稳腔的热噪声限制。在本文中，我们报告了基于自由空间EOM的主动RAM还原系统的开发，该系统用于在低温硅腔上对激光进行PDH稳定。通过使用稳定EOM直流电场，晶体温度和激光功率的数字伺服器获得$ 1.4 \ times 10^{ - 7} $的RAM稳定性。考虑到$ 2.5 \ times 10^5 $的超稳定腔，此RAM级别将导致分数频率不稳定性，远低于$ 5 \ times 10^{ - 19} $，远低于数量$ 10^{ - 17} $的最先进的热噪声限制。
The stabilization of lasers on ultra-stable optical cavities by the Pound-Drever-Hall (PDH) technique is a widely used method. The PDH method relies on the phase-modulation of the laser, which is usually performed by an electro-optic modulator (EOM). When approaching the $10^{-16}$ level, this technology requires an active control of the residual amplitude modulation (RAM) generated by the EOM in order to bring the frequency stability of the laser down to the thermal noise limit of the ultra-stable cavity. In this article, we report on the development of an active system of RAM reduction based on a free space EOM, which is used to perform PDH-stabilization of a laser on a cryogenic silicon cavity. A RAM stability of $1.4 \times 10^{-7}$ is obtained by employing a digital servo that stabilizes the EOM DC electric field, the crystal temperature and the laser power. Considering an ultra-stable cavity with a finesse of $2.5\times 10^5$, this RAM level would contribute to the fractional frequency instability at the level of about $5\times 10^{-19}$, well below the state of the art thermal noise limit of a few $ 10^{-17}$.
