Gravitational waves, first predicted by Einstein in 1916, eluded detection for nearly a century. These faint ripples in the fabric of spacetime, with typical strain amplitudes at the Earth on the order of |h| ∼ 10−22, carry secrets of the universe untold by electromagnetic radiation. Following decades of research and development, a network of terrestrial interferometric detectors succeeded in measuring the passing of a gravitational wave (GW150914) for the first time in 2015. Individual detectors within this network are currently said to be operating in a “second-generation” configuration; over the next decade, planned upgrades will take these detectors beyond this into a new generation. This thesis concerns the characterization and reduction of noise in one of these second-generation detectors, Advanced LIGO, as well as efforts underway to improve its sensitivity in the coming years.
The first part of this thesis is a detailed overview of gravitational waves, the history of gravitational wave detection, and a reasonably thorough description of the Advanced LIGO detector. Particular attention is paid to a pedagogical motivation of the optical configuration of Advanced LIGO with reference to its forebears. This part ends with an overview of the sources of noise limiting the sensitivity of Advanced LIGO, and an exposition of plans to reduce their influence in the future.
The second part describes the development of a laser gyroscope for use in tilt sensing in Advanced LIGO, starting with a motivation of the work based on limitations in the area of seismic noise sensing and cancellation.
The third part recounts the design, fabrication, testing, installation and commissioning of an important component of the Advanced LIGO detector: the output mode cleaner (OMC).
The fourth part outlines a proposed scheme for reduction of quantum noise in gravitational wave detectors and other experiments. In particular, this scheme allows for the operation of a so-called “optical spring” cavity in such a way as to be largely immune from the deleterious effects of quantum radiation pressure noise.
The fifth and final part describes progress towards a direct measurement of thermal noise in thin silicon ribbons, which is pertinent to the design of suspensions in future cryogenic gravitational wave detectors.
This thesis has the internal LIGO document number P1900035.</p
