Development of coating materials and jointing techniques for future gravitational wave detectors

该项目将集中于引力波探测器新型光学涂层材料的开发和表征。光学反射镜涂层是这些探测器的核心部件，涂层中的内耗引起的热噪声是对所能实现的引力波的天体物理源的灵敏度的关键限制。除了具有低的热噪声外，这些涂层还必须具有超低的光吸收，以防止镜面的加热和热变形。该项目将研究新的涂层材料和新型涂层设计，旨在开发所需的涂层解决方案，使计划中的探测器，如爱因斯坦望远镜和宇宙探测器，能够满足其灵敏度目标。特别是所谓的“多材料涂层”将被研究。这些是使用几种材料的新型涂层设计，其中每种材料在涂层堆叠中的位置被优化，以确保可以实现整个涂层的最期望的性能。学生将使用各种技术来测量涂层材料在室温和低温下的内耗。将使用光热共路干涉法来研究涂层的光吸收，并将使用广泛的其他化学、光学和结构表征技术，例如拉曼光谱、椭偏测量、光学应力测量。涂层材料和设计将与斯特拉斯克莱德大学的同事合作开发，这项工作将嵌入全球合作努力中，以解决未来引力波探测器的涂层热噪声问题。许多用于研究涂层的技术也适用于研究将材料连接在一起以构建用于引力波探测器的悬浮镜的新方法。因此，计划将其中一些研究扩展到开发涉及薄金属涂层的连接方法，该方法适合与拟议用于未来探测器的晶体材料一起使用，键的内耗是一个关键参数。

This project will focus on the development and characterisation of novel optical coating materials for gravitational wave detectors. Optical mirror coatings are core components of these detectors, and thermal noise arising from the internal friction in the coatings is a critical limit to the sensitivity to astrophysical sources of gravitational waves that can be achieved. In addition to having low thermal noise, these coatings must have ultra-low optical absorption, to prevent heating and thermal distortion of the mirror. This project will investigate new coating materials and new types of coating design, aiming to develop the required coating solutions to allow planned detectors like the Einstein Telescope and Cosmic Explorer to meet their sensitivity goals. In particular, so-called 'multimaterial coatings' will be investigated. These are novel coating designs using several materials in which the position of each material in the coating stack is optimised to ensure the most desirable properties of the entire coating can be achieved. The student will use a variety of techniques for measuring the internal friction of coating materials at room temperature and at cryogenic temperatures. Photo-thermal common-path interferometry will be used to study the optical absorption of the coatings and a wide-range of other chemical, optical and structural characterisation techniques will be used e.g. Raman spectroscopy, ellipsometry, optical stress measurements. Coating materials and designs will be developed in collaboration with colleagues at the University of Strathclyde, and the work is embedded in the world-wide collaborative effort to solve the coating thermal noise problem for future gravitational wave detectors. Many of the techniques used to study coatings are also applicable to study novel methods of jointing materials together to construct the suspended mirrors used in gravitational wave detectors. It is therefore planned to extend some of these studies to developing jointing methods involving thin metallic coatings suitable for use with the crystalline materials proposed for use in future detectors, with the internal friction of the bonds being a crucial parameter.