Scattering Methodology for Gravitational Wave Detectors*

The Laser Interferometer Gravitational-Wave Observatory (LIGO) uses laser interferometry to detect gravitational-waves (GW) produced by astrophysical events such as black hole mergers and binary neutron star systems. This technique requires state-of-the-art optical coatings that produce very little noise from both optical and mechanical losses. Our research focuses on characterizing the optical losses of new coating material, and in some cases on using light scattering as a diagnostic tool of their structure. Specifically, this presentation will focus on our work with two materials, Ti-doped GeO2 (amorphous), and AlGaAs (crystalline). In the former case, we use light scattering to study the crystallization process as a function of doping concentration. In the latter, we combine our scattering measurements with absorption and other coating-characterization measurements to understand defects in the crystalline structure.