Photonic versus random lasing in opal single crystals

We demonstrate a photopumped photonic crystal laser based on synthetic opal single crystal infiltrated with various laser dye solutions. The optical feedback in these lasers is provided via Bragg scattering of light from crystallographic planes in the opal. Localization of the laser modes within the stop band is assigned to defect states caused by crystal structure faults. We distinguish this photonic lasing mechanism from another regime of stimulated emission associated with random lasing what could be also observed in dye-infiltrated opals, but at higher excitation intensities.