Determining atomic structure of TiO₂-doped GeO₂ coatings

The United States currently operates two ground-based interferometric gravitational wave detectors: LIGO Hanford, WA, and LIGO Livingston, LA. In 2015, these detectors made history by achieving the first direct detection of gravitational waves, heralding a new era in gravitational wave astronomy. Future detectors are being planned that will extend the reach of gravitational wave observations even farther into the universe. These detectors will require significantly higher sensitivity than the current LIGO detectors. To meet this need, in addition to advancements in other detector technologies, the optical coatings used must meet exceptionally stringent requirements. These coatings must exhibit extremely low optical absorption, scattering, and thermal noise to ensure the detectors' high sensitivity. In this talk, I will present the atomic structure of one promising coating material TiO₂-doped GeO₂. I will discuss the atomic structure of these coatings obtained using x-ray scattering measurements and inverse modeling and highlight key features that may influence its perfomance as an optical coating for future gravitational wave detectors.