Enhancing high frequency sensitivity of gravitational wave detectors with a Sagnac interferometer

Sensitivity of gravitational-wave detectors is limited in the high-frequency band by quantum shot noise and eventually optical loss signal recycling cavity. This limit main obstacle on way to detect gravitational waves from binary neutron star mergers current future generation detectors, as it does not depend either arm length, or injected squeezing level. In this paper, we come up with sloshing Sagnac interferometer topology, which can be obtained Michelson optically connecting end mirrors into an additional transforms a triply-coupled cavity system capable beating loss-induced signal-recycled interferometer. With advanced LIGO+ comparable parameters, sloshing-Sagnac scheme achieve 7 times better sensitivity at 2.5\,kHz 4 ratio for typical waveform post merge. Being evolution interferometer, possibly used topology upgrade detectors.