Activity: Talk or presentation › Oral presentation
We have introduced hot Cs vapor in a silica opal photonic crystal to observe novel nanophotonic properties. In comparison to dyes and quantum dots, gaseous alkali atoms are better understood and have strong and very narrow resonances ω/dω = 107. As the temperature is increased, we observe shifts of the opals reflectivity peak in excess of 20%, which is attributed to the reduction of the silica to SiOx. This shift tunes the frequency of the photonic bands relative to the near-infrared Cs D1 transition. Simultaneously, the Cs resonances undergo dramatic changes in strength, off-resonance reflectivity, and shape. The results are in good agreement with a transfer-matrix model including the dispersion and absorption of two of the Cs hyperfine transitions.