Beware of warped surfaces: near-unstable cavities for future gravitational wave detectors

Wang, Haoyu (2017). Beware of warped surfaces: near-unstable cavities for future gravitational wave detectors. University of Birmingham. Ph.D.

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Abstract

The present thesis focuses on the behaviour of a particular type of Near-Unstable Cavities (NUCs), and their application to the sensitivity enhancement of current and future gravitational wave detectors. Advanced detectors use high power laser beams. A small fraction of the light energy is absorbed by the cavity mirrors and converted into heat. The operation of near-unstable cavities requires high-precision thermal control of the cavity mirrors, and thus a thermal model of the cavity mirror and its surroundings was built and is presented in this thesis. The model aids the development of mitigation strategies of thermal effects on detector sensitivity. Nearunstable cavities have been proposed as an enabling technology for future gravitational wave detectors, as their compact structure and large beam spot can reduce the thermal noise floor of the interferometer. Throughout my Ph.D., I designed and built an experiment to investigate the technical hurdles associated with near-unstable cavities. A near-unstable table-top cavity was built and accurate control achieved through length and alignment control systems. This experiment provides an insight into how far cavity parameters can be pushed towards geometrical instability. The work I carried out will aid the design of future ground-based gravitational wave detectors.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):