Prototype Advanced LIGO Diagnostics and Optical Components: In Situ Measurement and Control of Thermo-optical Effects

Advanced LIGO will use high power lasers to detect gravitational waves from a variety of astrophysical objects in the universe. In order to operate the Advanced LIGO detectors at sufficiently high laser powers, the laser beam must pass through optical components, including simple elements mirrors and lenses as well as more complicated elements such as Faraday isolators and electro-optic modulators. Because nothing is perfectly transmitting, infinitesimal amounts of the laser beam are absorbed and heat the component. This heating reacts back upon the laser beam and changes its properties in a way that is detrimental to the operation of the detector. This research will develop methods to detect these tiny distortions. In addition, optical components will be developed that are immune to the optical distortions that accompany laser beam absorption.

This research will enable gravitational wave detectors to operate with a sensitivity sufficient to potentially detect gravitational waves from many classes of astrophysical sources. The detection of gravitational waves will open an entirely new window on the universe, and allow astrophysicists to look at exotic objects such as black holes in ways that are impossible with any observational technique. This research will also add to the technology base of high power laser systems as well as foster international scientific collaborations.