Efficient spatial redistribution of quantum dot spontaneous emission from two-dimensional photonic crystals

The authors investigate the modification of the spontaneous emission dynamics and the external quantum efficiency for self-assembled InGaAs quantum dots coupled to extended and localized photonic states in GaAs two-dimensional photonic crystals. The photonic band gap is shown to give rise to a five to ten times enhancement of the external quantum efficiency, while the spontaneous emission rate is simultaneously reduced by a comparable factor. The findings are quantitatively explained by a modal redistribution of spontaneous emission due to the modified local density of photonic states. The results suggest that quantum dots embedded within photonic crystals are suitable for practical single photon sources with high external efficiency.