Application of fast-light in gravitational wave detection with interferometers and resonators

In this paper, we study several designs for interferometric gravitational wave detectors, and the potential for enhancing their performance with a fast-light medium. First, we explore the effect of such a medium on designs similar to those already planned for Advanced LIGO. Then we review the zero-area Sagnac interferometer for GW detection, comparing its properties against the more conventional GW detector based on a Michelson interferometer. We next describe a modified version of such a detector where the Sagnac interferometer is replaced by a zero-area Sagnac ring resonator fed by an external laser. We then consider a GW detector based on an active, zero-area Sagnac ring resonator, where a gain medium is present inside the cavity. Finally, we show that if a medium with negative dispersion, which yields the fast-light effect, is also present inside this detector, then its sensitivity to GW strain is enhanced by the inverse of the group index of the dispersive medium. We describe conditions under which this enhancement factor could be as large as 105.