DFG-NSF: Novel Low Loss Coatings – Enabling the Third Generation of Gravitational-Wave Detectors

DFG-NSF：新型低损耗涂层 â 实现第三代引力波探测器

• 批准号: 399440421
• 负责人: Professor Dr. Roman Schnabel, since 9/2019
• 金额: --
• 依托单位: Institut für Laser-Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/399440421?language=en
• 关键词: DFG; NSF; Novel; Low; Loss

100 years ago, Einstein predicted the existence of gravitational waves which are ripples in the curvature of space-time. On 14th September 2015, the (second-generation) detectors of the LIGO project made the first gravitational-wave detection.This was a ground-breaking event for fundamental physics, observing for the first time a binary black hole system merging to form a single black hole, and has opened a new window into the universe allowing us to ‘listen’ to its gravitational signatures, revealing previously hidden objects.A successful outcome of this project would enable sensitivities envisioned for the next generation gravitational-wave detectors and new discoveries in gravitational astronomy, e.g. the detection of new sources, an improvement of the detection rates for population studies of sources, and enable to see fainter and more distant sources.Gravitational waves cause changes of < 1e-19m in the separation of mirrors forming an interferometric detector. This is a displacement so small that the thermal vibration of the mirrors and their coatings, so called Brownian thermal noise, will limit the sensitivity of current and future detectors at the detectors’ most sensitive frequencies, where the detection of many interesting sources is expected such as merging neutron stars and spinning pulsars.In this project we will develop new materials with low thermal noise, which involves understanding the atomic processes in the materials, to enable sensitivity improvements of interferometric gravitational wave detectors.Thermal noise in highly-reflective mirror coatings is directly proportional to the coating thickness, the mechanical loss of the materials and the mirror temperature. To significantly reduce coating thermal noise, future gravitational wave detectors will be cryogenically operated. Cryogenic detectors require low optical absorption in the mirrors to minimize heating from the laser beam, and therefore maintain the cryogenic operation temperature. The aim of this project is the development of highly-reflective multilayer coatings based on studies of coating properties, composition and structure, to meet the challenging requirements on absorption, reflectivity and mechanical loss.While the proposal is mainly targeted at future cryogenic detectors, thermal noise reduction for upgrades of detectors operating at room temperature (such as Advanced LIGO and VIRGO) will also be part of the proposed research.

100年前，爱因斯坦预言了引力波的存在，引力波是时空曲率中的涟漪。2015年9月14日，LIGO项目的（第二代）探测器进行了首次引力波探测。这是基础物理学的一个突破性事件，首次观察到一个双黑洞系统合并成一个黑洞，并打开了一扇通往宇宙的新窗口，让我们能够“倾听”它的引力特征，揭示以前隐藏的物体。这个项目的成功成果将使下一代引力波探测器的灵敏度和引力波天文学的新发现成为可能，例如探测新的引力波源，提高对引力波源群体研究的探测率，并使人们能够看到更微弱和更远的引力波源。引力波在形成干涉探测器的反射镜的分离中引起< 1e-19m的变化。这是一个非常小的位移，以至于镜面及其涂层的热振动，即所谓的布朗热噪声，将限制当前和未来探测器在探测器最敏感频率上的灵敏度，在探测器最敏感频率上，预计会探测到许多有趣的源，如合并中子星和旋转脉冲星。在这个项目中，我们将开发具有低热噪声的新材料，这涉及到了解材料中的原子过程，从而提高干涉引力波探测器的灵敏度。高反射镜面涂层中的热噪声与涂层厚度、材料的机械损耗和镜面温度成正比。为了显著降低涂层热噪声，未来的引力波探测器将采用低温操作。低温探测器要求反射镜的光吸收低，以尽量减少激光束的加热，从而保持低温操作温度。该项目的目标是在研究涂层性能、成分和结构的基础上开发高反射多层涂层，以满足对吸收、反射率和机械损耗的挑战性要求。虽然该提案主要针对未来的低温探测器，但在室温下运行的探测器（如Advanced LIGO和VIRGO）的升级热噪声降低也将是拟议研究的一部分。