Feasibility of near-unstable cavities for future gravitational wave detectors

Research output: Contribution to journalArticlepeer-review


  • Haoyu Wang
  • Miguel Dovale-Álvarez
  • Christopher Collins
  • Sen Han

Colleges, School and Institutes

External organisations

  • University of Shanghai for Science and Technology


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 behavior 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 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 significance of these results for gravitational wave detectors is discussed, and avenues for further research are suggested.


Original languageEnglish
Article number022001
JournalPhysical Review D
Issue number2
Publication statusPublished - 12 Jan 2018


  • general physics , particles & fields , atomic, molecular & optical , gravitation, cosmology & astrophysics

ASJC Scopus subject areas