Slow-light interferometry: practical limitations to spectroscopic performance

Abstract

We investigate how the use of slow-light methods can enhance the performance of various types of spectroscopic interferometers under practical conditions. We show that, while in ideal cases the enhancement of the spectral resolution is equal to the magnitude of the group index of the slow-light medium, the ratio between the associated gain or loss and the group index of the slow-light medium actually determines the spectral resolution under more-general conditions. Moreover, the dispersion of this ratio leads to frequency-dependent spectral resolution, which limits the useful working bandwidth of the interferometer. We also evaluate the performance of interferometers using three specific slow-light processes in terms of the achievable spectral resolution and the effective working finesse. We show that the spectral resolution is typically limited by the characteristic linewidth of each slow-light process and that there is no fundamental upper limit for the effective working finesse.