Development of mirror coatings and test-mass substrates for future gravitational wave detectors

Following the first detection of gravitational waves in 2015, over 40 black hole merger events, two neutron star mergers and two black-hole/neutron start mergers have been detected, providing new astrophysical insight into these bodies. Future, more sensitive, gravitational wave detectors are planned to allow observation of more signals, from a wider variety of sources. One of the critical sensitivity limits to current detectors is thermal noise - vibrations in the detector mirrors due to their temperature. This project aims to develop new mirror materials, with low thermal noise and extremely high optical performance, for application in future detectors operating at room-temperature and at cryogenic temperature. The project will focus particularly on the optical absorption and optical scattering of mirror substrates and the highly reflective coatings applied to them. Low optical absorption is essential to maintain cryogenic mirror temperatures and prevent thermal deformations of the mirrors. Low optical scattering is essential to prevent noise effects from stray light. The main application of this research is future gravitational wave detectors, and upgrades to current detectors. However, this work is also of relevance to the optical coatings industry, where many applications require extreme performance coatings with low absorption and high tolerance to laser-induced damage, and the project has many synergies with the newly established Centre for Extreme Performance Optical Coatings (EPOC) being set up in Glasgow, as part of the National Manufacturing Institute Scotland (NMIS), with significant investment from NMIS, the University of Strathclyde and the University of Glasgow.