Sagnac interferometry in a slow-light medium.

Abstract

We use a Sagnac interferometer to measure the dispersive and absorptive properties of room temperature Rubidium vapor on the D2 line at 780.2 nm. We apply a pump beam such that the resulting system exhibits electromagnetically induced transparency. Using a "biased alignment" technique we demonstrate a direct and robust method of measuring the rapid variation in the refractive index. Such a "slow-light" Sagnac interferometer is ideally suited to precision measurement applications such as magnetometry and inertial sensing.