Technologies for Future Gravitational-Wave Observatories: Lasers, Optics, Materials, Cryogenics, and Simulations

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's 'Windows on the Universe' Big Idea. Beginning in September 2015, the two Advanced LIGO observatories, in conjunction with Virgo, have carried out observational campaigns for gravitational waves, with more than 10 inspirals of compact objects reported from observing runs O1 and O2. The just-ended O3 run detected more than 50 additional signals, most of which appear likely to be inspirals of black holes and/or neutron stars. One report of a novel source has been published, with other very interesting announcements expected. Improvements in sensitivity and performance are continuing, and Florida's research aims at contributing to these improvements as well as to designs of third-generation gravitational-wave detectors. This work will develop national and international scientific infrastructure through the direct participation of the University of Florida LIGO group in research and operations at the LIGO Observatories. The research will go beyond gravitational-wave science. High-power optical isolators developed in this project have commercial applications to the laser and optics industries. A single-frequency 2.1 μm laser, tunable over GHz of frequency, can affect many areas of precision science. The Florida group also gives students and postdoctoral scientists the opportunity to develop scientific skills from a diverse set of disciplines spanning lasers and optics, electronics and feedback control systems, vacuum and cryogenics, and large-scale detector commissioning and operation. In addition, the group places high value on the education of undergraduate students and each year has involved undergraduates in research.

Advanced LIGO was designed for a 10x sensitivity improvement and much better low-frequency response than initial LIGO. With the introduction of squeezing and the A+ upgrade, the sensitivity will be increased further. These gains require improved performance in all aspects of the detector, including the Input Optics, a responsibility of the Florida LIGO group for many years. Work will address high-power optical isolation, RF modulation, adaptive elements for mode matching, shadow sensors for sensing and control of suspended mirrors and platforms, and improved simulations of the input optics and power/signal recycling cavities. It also addresses basic research needed for next generation detectors to increase the science reach of the observatories. This longer-ranged research includes studies of impurities in silicon, a nearly ideal material for the test masses of cryogenic detectors, cryogenic shadow sensors, and the development of a single-frequency non-planar ring oscillator laser operating at 2.1 μm wavelength.

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.