Laser Pump Noise Effects on the Stability of Optical Clockworks

激光泵浦噪声对光学时钟稳定性的影响[j]。布莱恩·科尔纳，加州大学戴维斯分校智力优点：最近发明的f-2f自参考模型锁定激光时钟装置预示着精确时间和频率计量的新时代。尽管取得了惊人的进步，但关于这些时钟的基本性能限制，仍然存在未解之谜。本项目将研究激光时钟性能的一个重要组成部分；泵浦源中噪声引起的激光幅值和相位波动。要研究的耦合机制包括：1)通过能级居群的复磁化率的扰动，2)增益介质长度（热），3)折射率（直接热），4)热诱导应力引起的折射率，5)光子数，6)非线性指数（克尔效应）。当泵浦含有随机噪声时，这些机制结合在一起会降低激光器的性能。通过在泵浦光束上诱导小信号调制，将测量这些效应的大小并与理论进行比较。然后，它们将用于预测模型锁定激光时钟的最终性能，并为更好的时钟设计提供指导。最后，f-2f干涉仪控制回路将安装在两个独立的激光器上，将闭环性能与理论预测进行比较。更广泛的影响：精确的时间和频率标准构成了航海、商业、电信和许多科学技术分支的基础。时钟精度的提高将影响人类生活的方方面面。随着我们以更高的精度探索原子和分子，检验“自然常数”是否真的是恒定的，以及改进我们的宇宙学理论，它对推动基础科学的前沿将具有特别重要的意义。这项工作的结果将被纳入加州大学戴维斯分校光学科学与工程项目的课堂讲座，也将吸引该项目以外的学生的注意，他们自然对技术的基本限制以及它们如何推动基础科学着迷。

Laser Pump Noise Effects on the Stability of Optical Clockworks0622235Dr. Brian Kolner, UC DavisIntellectual Merit: The recent invention of f-2f self-referencing modelocked laser clockworks has heralded a new era in precision time and frequency metrology. In spite of phenomenal advances, there are still unanswered questions about the fundamental performance limits which might be expected from these clocks. This project will investigate an important component of laser clock performance; that of laser amplitude and phase fluctuations induced by noise in the pump source. The coupling mechanisms to be studied include perturbations to the: 1) complex susceptibility through the energy level populations, 2) length of the gain medium (thermal), 3) index of refraction (direct thermal), 4) index due to thermally-induced stress, 5) photon number, and 6) nonlinear index (Kerr-effect). These mechanisms combine to degrade the performance of the laser when the pump contains random noise. By inducing small-signal modulations on the pump beam, the magnitude of these effects will be measured and compared with theory. They will then be used to predict the ultimate performance of modelocked laser clocks and provide guidance toward better clock designs. Finally, f-2f interferometer control loops will be installed on two separate lasers to compare the closed-loop performance against predictions from theory. Broader Impacts: Precision time and frequency standards form the very foundation of navigation, commerce, telecommunications and many branches of science and technology. Improved clock precision will affect all aspects of human life. It will be especially significant in pushing the frontiers of fundamental science as we explore atoms and molecules with ever-higher precision, test whether or not the ``constants of nature'' are truly constant and improve our theories of cosmology. The results of this work will be incorporated into classroom lectures in the Optical Science and Engineering program at UC Davis and will also attract the attention of students outside of the program who are naturally fascinated by the fundamental limits of technology and how they advance basic science.