Parametric oscillatory instability in a Fabry–Perot cavity of the Einstein Telescope with different mirror's materials

Abstract

We discuss the parametric oscillatory instability in a Fabry-Perot cavity of the Einstein Telescope. Unstable combinations of elastic and optical modes for two possible configurations of gravitational wave third-generation detector are deduced. The results are compared with the results for gravitational wave interferometers LIGO and LIGO Voyager.