Development of High Power Continuous Wave Lasers, Components, and Optical Contamination Diagnostics for Future Ground-based Gravitational Wave Detectors

这一研究奖将使对高级激光干涉仪引力波天文台(高级LIGO)重要的研究得以继续。首先，镜面质量对先进LIGO的性能至关重要。正在开发一种方法，使用一种称为表面二次谐波产生(SSHG)的非线性光学技术来监测先进LIGO运行期间的镜面污染。将对多层介质涂层产生SSHG的理论研究和SSHG的实验研究，特别是对用于先进LIGO的超抛光反射镜的污染控制进行研究。其次，高功率激光光束的光学隔离对于高级LIGO非常重要，这项研究解决了能够处理更高激光功率的光学(法拉第)隔离器的开发问题。将开展的活动包括表征大口径法拉第隔离器的热去极化、隔离率和热透镜。先进的LIGO法拉第隔离器的设计和真空测试。先进的法拉第隔离器将打开一个新的天文窗口--通过发射引力波探测宇宙中一些最大的灾难性事件的能力，这是阿尔伯特·爱因斯坦近100年前提出的一种机制，但尚未被直接观察到。这些调查将有助于高级LIGO在长时间范围内的运行，并有可能在其投入运行后改善其性能。它们还将影响许多使用高功率激光的应用。最后，这项研究还将促进国际合作。

This research award will enable the continuation of investigations important to the Advanced Laser Interferometer Gravitational-wave Observatory (Advanced LIGO). First, the quality of the mirror surfaces is crucial to the performance of Advanced LIGO. A method is under development to monitor mirror surface contaminants during the operation of Advanced LIGO using a nonlinear optical technique known as surface second harmonic generation (SSHG). Theoretical investigation of SSHG generation from multi-layer dielectric coatings and experimental investigation of SSHG, specifically investigations of controlled contamination on superpolished mirrors used in Advanced LIGO, will be conducted. Second, optical isolation of high power laser beams is important for Advanced LIGO, and this research addresses issues with the development of optical (Faraday) isolators capable of handling higher laser powers. Activities to be undertaken are characterization of thermal depolarization, isolation ratio, and thermal lensing for a large aperture Faraday isolator design and testing of Advanced LIGO Faraday isolators in vacuum.

Advanced LIGO will open a new astronomical window --- the ability to probe some of the most cataclysmic events in universe through the emission of gravitational waves, a mechanism proposed by Albert Einstein almost 100 years ago, but yet to be directly observed. These investigations will both aid in the operation of Advanced LIGO over long time scales and potentially improve its performance once it is in operation. They will also impact many applications which use high power lasers. Finally, this research will also foster international collaborations.