Transparency Near a Photonic Band Edge

We study the absorption and dispersion properties of a ${\bf \Lambda}$-type atom which decays spontaneously near the edge of a photonic band gap (PBG). Using an isotropic PBG model, we show that the atom can become transparent to a probe laser field, even when other dissipative channels are present. This transparency originates from the square root singularity of the density of modes of the PBG material at threshold.