Development and manufacture of laser mirror coatings for future gravitational wave observatories and other space applications

Future improvements to gravitational wave detector sensitivities are required to truly exploit the new field of gravitational wave astronomy. One of the most challenging areas is reducing thermally driven motion (Brownian thermal noise) associated with the laser mirror coatings used in the interferometric detection system. The University of Strathclyde and the National Manufacturing Institute Scotland (NMIS) have established novel ECR (electron cyclotron resonance) ion beam deposition, in addition to procuring the industry-best RF (radio frequency) ion deposition technology. This project will seek to study both RF and ECR ion beam systems. Of particular interest is studying the use of novel oxide mixtures to enable enhanced optical and mechanical properties of multi-layer mirror coatings for use in ultra-narrow linewidth cavities. Beyond this, based on recent research carried out elsewhere and within the LIGO Scientific Collaboration (LSC) (which includes Strathclyde and other UK groups), the project will investigate novel annealing approaches for removing (by diffusion) the trapped inert gas within these coatings. Trapped gas, which is required in the manufacturing process, is now known to cause increased laser damage susceptibility, in addition to causing gas aggregation during the required high-temperature annealing that can cause blistering and stress-induced damage.