Feasibility of near-unstable cavities for future gravitational wave detectors

Haoyu Wang1;2, Miguel Dovale-Alvarez1, Christopher Collins1, Daniel David Brown1, Mengyao Wang1, Conor M. Mow-Lowry1, Sen Han2, And Andreas Freise1
2018 Zenodo  
Near-unstable cavities have been proposed as an enabling technology for future gravitational wave detectors, as their compact structure and large beam spots can reduce the coating thermal noise of the interferometer. We present a tabletop experiment investigating the behaviour of an optical cavity as it is parametrically pushed to geometrical instability. We report on the observed degeneracies of the cavity's eigenmodes as the cavity becomes unstable and the resonance conditions become
more » ... ons become hyper-sensitive to mirror surface imperfections. A simple model of the cavity and precise measurements of the resonant frequencies allow us to characterize the stability of the cavity and give an estimate of the mirror astigmatism. The signi cance of these results for gravitational wave detectors is discussed, and avenues for further research are suggested.
doi:10.5281/zenodo.2563784 fatcat:bffo3dmrhjgtlb5suxshcn5ffm