A Double End-Mirror Sloshing cavity for optical dilution of thermal noise in mechanical resonators

The sensitivity of gravitational wave detectors at high frequencies is currently limited by quantum shot noise. It has been shown theoretically that white light signal recycling using optomechanical negative dispersion filter cavities can increase the gain-bandwidth product of gravitational wave detectors that is usually limited by conventional signal recycling. This sensitivity enhancement is most pronounced at high frequencies above 500 Hz. This technology could be implemented in current facilities or future detectors, but requires thermal noise dilution of the mechanical resonator. Here we provide a theoretical analysis of a double end-mirror sloshing (DEMS) cavity to achieve strong thermal noise dilution with low radiation pressure noise and suppression of optical anti-damping. We demonstrate experimentally that the DEMS cavity can be tuned to a regime that is expected to support these favorable conditions.