Detector Technology for Gravitational-Wave Astrophysics

The National Science Foundation’s ground-breaking Advanced LIGO gravitational-wave observatories continue to explore the dark universe and have now measured the collision of over 250 black hole pairs. This award supports gravitational-wave detector technology research to improve the observational reach of the Advanced LIGO observatories. Their sensing is improved by controlling thermal distortion effects when operating at high laser power, and by lowering the thermal noise in their test mass mirror coatings. Specifically, this award explores technology to integrate solid-state laser cooling in optical mirror coatings to create radiation-balanced mirrors exhibiting no thermal deformations. It also supports investigating the suitability of much lower thermal noise crystalline optical mirror coatings. Both technologies can find much wider use in precision sensing and high-power laser applications, with examples including their use in laser fusion and defense. This award supports (i) investigating solid-state laser cooling to control thermal lensing in gravitational wave interferometers, to optimize ion-beam-sputtered materials for use in laser-cooled optical coatings. (ii) Characterizing the performance of low-noise crystalline coatings under high-power optical conditions found in gravitational-wave detectors. (iii) Preparing the LIGO Hanford detector for its O5 observation run, installing hardware to preheat optics so thermal transients during lock acquisition can be avoided. And (iv) designing test mass actuators to be used in the suspensions of the next-generation observatory Cosmic Explorer. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.