Sensing and control scheme for the inteferometer configuration with an L-shaped resonator

Abstract

Abstract The detection of high-frequency gravitational waves (GWs) around kHz is critical to understand the physics of binary neutron star mergers. A new interferometer design has been proposed in (Zhang et al 2023 Phys. Rev. X 13 021019), featuring an L-shaped optical resonator as the arm cavity, which resonantly enhances kHz GW signals. This new configuration has the potential to achieve better high-frequency sensitivity than the dual-recycled Fabry–Perot Michelson. In this paper, we propose a sensing and control scheme for this configuration. Despite having the same number of length degrees of freedom as the dual-recycled Fabry–Perot Michelson, the new configuration requires one less degree of freedom to be controlled owing to the system’s insensitive to the fluctuation of L − − l − . We have also shown that introducing the Schnupp asymmetry is ineffective for controlling the signal-recycling cavity length. Therefore, we propose adding control fields from the dark port to control this auxiliary degree of freedom.