Observation of Fano-Type Interference in a Coupled Cavity-Atom System

We present the experimental observation of the Fano-type interference in a coupled cavity-atom system by confining the laser-cooled ^85Rb atoms in an optical cavity. The asymmetric Fano profile is obtained through quantum interference in a three-level atomic system coherently coupled to a single mode cavity field. The observed Fano profile can be explained by the interference between the intra-cavity dark state and the polariton state of the coupled cavity–atom system. The possible applications of our observations include all-optical switching, optical sensing and narrow band optical filters.