Wide-angle all-optical filtering via defective distributed Bragg reflectors.

In this paper, we propose a distributed Bragg reflector (DBR) involving active atoms doped in the defect layer to manipulate the transmission and group velocity of a weak probe field. We exploit three-level rubidium atoms in a Ladder configuration, which provides the possibility of controlling the spontaneously generated coherence (SGC) arising from the radiation decay. We show evidence of excellent control of the optical properties of the proposed DBR by engineering the quantum interference and relative phase between the applied fields. We indicate that the SGC in doped atoms leads to the phase dependency of the defective DBR optical response. Furthermore, our results show that the accurate selection of Rabi-frequency for the coherent laser field and the rate for the incoherent pumping field leads to the conversion of the probe field absorption to amplification (gain). The results may find applications in all-optical filters in wide-angle applied photonics, simple optical communication systems, and active DBR in laser cavity technology in visible and near-IR range.