We study a hybrid system consisting of a narrowband atomic optical resonance and the long-range periodic order of an opaline photonic nanostructure. To this end, we have infiltrated atomic cesium vapor in a thin silica opal photonic crystal. With increasing temperature, the frequencies of the opals reflectivity peaks shift down by >20% due to chemical reduction of the silica. Simultaneously, the photonic bands and gaps shift relative to the fixed near-infrared cesium D1 transitions. As a result the narrow atomic resonances with high finesse (f/df = 880.000) dramatically change shape from a usual dispersive shape at the blue edge of a stop gap, to an inverted dispersion lineshape at the red edge of a stop gap. The lineshape, amplitude, and off-resonance reflectivity are well modeled with a transfer-matrix model that includes the dispersion and absorption of Cs hyperfine transitions and the chemically-reduced opal. An ensemble of atoms in a photonic crystal is an intriguing hybrid system that features narrow defect-like resonances with a strong dispersion, with potential applications in slow light, sensing and optical memories.

http://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.045123

P. J. Harding, P. W. H. Pinkse, A. P. Mosk, and W. L. Vos

2015

01/2015

Phys. Rev. B

91

045123: 1-7

10.1103/PhysRevB.91.045123

alkali atoms, nanophotonics, opal, photonic crystal, vapor