Progress and challenges developing a coating for next generation gravitational-wave detectors

The worldwide effort to detect gravitational-waves uses long baseline laser interferometry. The optics in the interferometers use ion-beam deposited multilayer dielectric coatings, for high reflectivity. In addition, the coatings must have very low optical absorption to reduce thermal effects, low mechanical loss and low changes in optical path with temperature to reduce thermal noise. We discuss progress made on developing a suitable coating for the next generation of detectors. © 2007 Optical Society of America.