Nanophotonic hybridization of narrow atomic cesium resonances and photonic stop gaps of opaline nanostructures

TL;DR

This paper investigates a hybrid system combining narrow atomic cesium resonances with the photonic stop gaps of opaline nanostructures, revealing tunable resonance shapes and potential applications in photonics.

Contribution

It demonstrates the integration of cesium vapor into opaline photonic crystals and models the resulting optical resonance modifications due to temperature-induced shifts.

Findings

Resonance lineshape changes from dispersive to inverted dispersion at different stop gap edges.

Reflectivity peaks shift >20% with temperature due to silica reduction.

Transfer-matrix model accurately describes the hybrid system's optical behavior.

Abstract

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 opal's 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=8E5) 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 memory.