Collaborative Research: LSC Center for Coatings Research

合作研究：LSC 涂料研究中心

• 批准号: 2011723
• 负责人: Stefan Ballmer
• 金额: $ 54.18万
• 依托单位: Syracuse University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011723&HistoricalAwards=false
• 关键词: Collaborative; Research; LSC; Center; Coatings

The detections of gravitational waves from coalescing black holes in 2015 launched the field of gravitational wave astronomy. The NSF-funded “A+” upgrade to Advanced LIGO is designed to achieve an order of magnitude increase in detection rate for black hole coalescences, and enable detection of fainter objects like binary neutron stars, greatly increasing their value for multi-messenger astronomy. The A+ upgrade and all 3rd generation detector designs depend on the development of mirrors with low coating thermal noise. The coating thermal noise is reduced, primarily, by lowering the mechanical (elastic) loss of the mirror materials. The core research focus of the LIGO Scientific Collaboration (LSC) Center for Coatings Research (CCR) is the development of mirror coatings with low mechanical and optical losses for use in A+ and 3rd generation detectors. The research mission of the CCR includes: understanding and reducing mechanical loss in amorphous metal-oxides, the most widely-used materials in mirror coatings; and developing and testing crystalline (AlGaAs) coatings, which have demonstrated low losses for small mirrors. On a longer time-scale, the CCR is developing mirrors compatible with the proposed 3G detectors’ cryogenic operation. The residual noise visible in the time-domain gravitational waveforms of black hole mergers first recorded by Advanced LIGO is mostly due to quantum noise of the light and thermal noise due to the mirror coatings. Since that first discovery much progress has been made in reducing quantum noise and the coupling from seismic, scatter and jitter noise, leaving coating thermal noise as the dominant barrier limiting gravitational-wave astronomy in the most sensitive observation band. Reducing this noise source for future generations of detectors requires reducing the mechanical dissipation in the mirror coatings on the test masses, and forms the main goal of the CCR. The CCR combines groups working on computational modeling, coating deposition, and characterization of atomic structure and macroscopic material properties. These components are often performed by four diverse communities that work in relative isolation from each other. The strength of the CCR and its promise of accelerating discoveries arises from close integration of these communities focused on a unified research goal. In its first two years of operation, research in the CCR has identified different structural motifs associated with room-temperature vs cryogenic mechanical losses, which led to synthesis of germania (GeO2) films giving rise to the lowest-loss amorphous oxide film other than silica. Going forward, this structural guide will serve as a paradigm informing the development of high-refractive index amorphous coatings with lower elastic loss. In addition, thermo-optically-optimized AlGaAs crystalline coatings have demonstrated a coating thermal noise well below the requirements for A+, and the CCR has generated a development schedule to scale up these coatings to LIGO mirror sizes and will continue investigations into these materials. Other research paths include: exploring deposition techniques to produce “ultrastable glasses” using amorphous metal-oxides; and stabilizing amorphous coatings against crystallization in order to allow elastic loss reduction via high temperature annealing either with nano-layering or with different doping materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

2015年对聚结黑洞的引力波的探测开启了引力波天文学领域。由 NSF 资助的高级 LIGO 的“A+”升级旨在将黑洞聚结的检测率提高一个数量级，并能够检测双中子星等较暗的物体，从而大大提高其在多信使天文学中的价值。 A+ 升级和所有第三代探测器设计都依赖于低涂层热噪声反射镜的开发。涂层热噪声的降低主要是通过降低镜面材料的机械（弹性）损耗来实现的。 LIGO 科学合作组织 (LSC) 涂层研究中心 (CCR) 的核心研究重点是开发用于 A+ 和第三代探测器的低机械和光学损耗镜面涂层。 CCR 的研究任务包括：了解和减少非晶态金属氧化物的机械损耗，非晶态金属氧化物是镜面涂层中使用最广泛的材料；开发和测试晶体 (AlGaAs) 涂层，该涂层已证明小镜子的损耗较低。从长远来看，CCR 正在开发与拟议的 3G 探测器低温操作兼容的镜子。 Advanced LIGO 首先记录的黑洞合并时域引力波形中可见的残余噪声主要是由于镜面涂层引起的光量子噪声和热噪声。自从第一个发现以来，在减少量子噪声以及地震、散射和抖动噪声的耦合方面已经取得了很大进展，使得涂层热噪声成为限制引力波天文学在最敏感观测波段的主要障碍。为下一代探测器减少这种噪声源需要减少测试质量上镜面涂层的机械耗散，这也是 CCR 的主要目标。 CCR 结合了致力于计算建模、涂层沉积以及原子结构和宏观材料特性表征的小组。这些组件通常由四个不同的社区执行，这些社区彼此相对隔离。 CCR 的力量及其加速发现的承诺源于这些社区的紧密结合，这些社区专注于统一的研究目标。在运行的头两年中，CCR 的研究已经确定了与室温和低温机械损失相关的不同结构图案，从而合成了氧化锗 (GeO2) 薄膜，从而形成了除二氧化硅之外损失最低的非晶氧化物薄膜。展望未来，该结构指南将作为开发具有较低弹性损失的高折射率非晶涂层的范例。此外，热光优化的 AlGaAs 晶体涂层已证明涂层热噪声远低于 A+ 的要求，CCR 已制定了开发计划，将这些涂层扩大到 LIGO 反射镜尺寸，并将继续研究这些材料。其他研究路径包括：探索使用非晶金属氧化物生产“超稳定玻璃”的沉积技术；稳定非晶涂层以防止结晶，以便通过纳米分层或不同掺杂材料的高温退火减少弹性损失。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。