RUI: Survey of Magneto-Optical Materials for Faraday Isolators in Future Gravitational-wave Detectors

在上线后的头两年，经过一次重大升级，旨在将其灵敏度提高10倍，双先进LIGO探测器已经从二元黑洞合并和碰撞中子星中进行了多次探测，开启了多信使天文学的新时代。为了观察来自更多种类的引力波源的事件并进一步观察宇宙，需要新一代探测器在更宽的引力波谱范围内具有更高的灵敏度。新一代探测器将采用更高的激光功率，更大的测试质量的低损耗材料冷却到低温，并在更长的激光波长下工作，等等。高激光功率和更长的波长对法拉第隔离器提出了挑战，其性能受到工作波长的强烈影响，需要重新审视当前的设计。这项研究将调查新的磁光材料的法拉第隔离器在未来的引力波探测器，以确定高性能，低吸收的候选人在波长超过一微米。拟议的项目将加强蒙特克莱尔州立大学（MSU）在实验引力领域的研究活动，将培训和指导本科生和硕士生，并将帮助他们发展光学和激光，光谱学，真空系统和低温。密歇根州立大学的小组将进行光谱测量的透射率和法拉第旋转的几类磁，波长大于1微米的光学材料。由于费尔德常数通常在低温下增加，这些测量将在室温和低温下进行，低至5K。本文的工作将对未来引力波探测器的法拉第隔离器的研制和设计产生直接的影响。早期识别合适的材料将允许新的隔离器的及时实施和适当的审查。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

In the first two years after coming online following a major upgrade designed to boost their sensitivity by a factor of ten, the twin Advanced LIGO detectors have made several detections from binary black hole mergers and colliding neutron stars, opening a new era of multi-messenger astronomy with gravitational waves. To observe events from a larger variety of gravitational wave sources and to see further into the universe requires a new-generation of detectors with even higher sensitivity over a broader range of the gravitational wave spectrum. This new generation of detectors will employ higher laser powers, larger test masses of low-loss materials cooled to cryogenic temperatures, and the operation at longer wavelength of the laser, among many others. High laser power and longer wavelength present a challenge for the Faraday isolators whose performance is strongly affected by the operating wavelength, requiring the current designs to be revisited. This study will investigate new magneto-optical materials for Faraday isolators in future gravitational wave detectors, in order to identify high-performance, low-absorption candidates at wavelengths longer than one micrometer. The proposed projects will enhance the research activities in the field of experimental gravitation at Montclair State University (MSU), will train and mentor undergraduate and master's degree students, and will help them develop hands-on skills in areas of optics and lasers, spectroscopy, vacuum systems and cryogenics.The MSU group will perform spectral measurements of transmittance and Faraday rotation on several classes of magneto-optical materials at wavelengths longer than one micrometer. As the Verdet constant typically increases at low temperatures, these measurements will be carried out both at room and at cryogenic temperatures, as low as 5K. The proposed work will have a direct impact on developing and designing Faraday isolators for the future gravitational wave detectors. Early identification of suitable materials will allow for timely implementation and proper review of the new isolators.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.