Collaborative Research: LSC Center for Coatings Research

合作研究：LSC 涂料研究中心

• 批准号: 2011688
• 负责人: Steven Penn
• 金额: $ 10.75万
• 依托单位: Hobart and William Smith Colleges
• 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 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011688&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年探测到的聚合黑洞引力波开启了引力波天文学领域。由美国国家科学基金会资助的升级到高级LIGO的A+旨在实现黑洞聚合的探测率提高数量级，并能够探测到像双星中子星这样的较暗物体，大大提高它们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镀膜热噪声反射镜的开发。涂层热噪声主要是通过降低镜面材料的机械(弹性)损耗来降低的。LIGO科学合作(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的镜面涂层。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；以及开发和测试晶态(AlGaAs)涂层，该涂层已显示出小镜面的低损耗。在更长的时间尺度上，CCR正在开发与拟议中的3G探测器的低温操作兼容的反射镜。在Advanced LIGO首次记录的黑洞合并的时间域引力波形中可见的剩余噪声主要是由于光的量子噪声和镜面涂层引起的热噪声。自从第一次发现以来，在减少量子噪声以及地震噪声、散射噪声和抖动噪声的耦合方面取得了很大进展，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。为未来几代探测器减少这种噪声源需要减少测试质量块上的镜面涂层中的机械损耗，这也是CCR的主要目标。CCR结合了从事计算建模、涂层沉积以及原子结构和宏观材料属性表征的小组。这些组件通常由四个不同的社区执行，它们彼此相对独立地工作。CCR的优势及其加速发现的前景源于这些社区的紧密整合，这些社区专注于一个统一的研究目标。在运行的头两年，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主题，这导致了Germania(GeO2)薄膜的合成，从而产生了除二氧化硅之外损耗最低的非晶态氧化物薄膜。展望未来，这一结构指南将成为开发具有较低弹性损耗的高折射率非晶涂层的范例。此外，热光优化的AlGaAs晶体涂层显示出的涂层热噪声远低于A+的要求，CCR已经制定了将这些涂层扩大到LIGO镜面尺寸的开发计划，并将继续对这些材料进行研究。其他研究途径包括：探索沉积技术以使用非晶态金属氧化物生产“超稳定玻璃”；以及稳定非晶态涂层以防止晶化，以便通过使用纳米层或不同掺杂材料的高温退火来降低弹性损耗。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Study on electro-optic noise in crystalline coatings toward future gravitational wave detectors

针对未来引力波探测器的晶体涂层中的电光噪声研究

• DOI: 10.1103/physrevd.107.022003
• 发表时间: 2023
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Tanioka, Satoshi;Vander-Hyde, Daniel;Cole, Garrett D.;Penn, Steven D.;Ballmer, Stefan W.
• 通讯作者: Ballmer, Stefan W.

Substrate-transferred GaAs/AlGaAs crystalline coatings for gravitational-wave detectors

• DOI: 10.1063/5.0140663
• 发表时间: 2023-03-13
• 期刊: APPLIED PHYSICS LETTERS
• 影响因子: 4
• 作者: Cole, G. D.;Ballmer, S. W.;Yu, J.
• 通讯作者: Yu, J.