Spontaneous emission from a driven atom embedded in a photonic crystal

We have studied the spontaneous emission from a three-level atom with an ex ternal-driving field in a photonic crystal. As a result of quantum interfer ence and photon localization, the population in the two upper levels displa ys quasi-oscillatory or oscillatory behavior. This depends on the' initial atomic state and the relative positions of the two upper levels from the fo rbidden gap. The intensity and the phase of the external field can affect s pontaneous emission from the atom. The properties are different from a thre e-level atom either in vacuum or in a photonic crystal without an external driving field.