Manipulation of the spontaneous emission dynamics of quantum dots in two-dimensional photonic crystals

Abstract

We demonstrate the ability to control the spontaneous emission dynamics of self-assembled quantum dots via the local density of optical modes in two-dimensional (2D) photonic crystals. We show that an incomplete 2D photonic band gap is sufficient to significantly lengthen the spontaneous emission lifetime $(>2\ifmmode\times\else\texttimes\fi{})$ over a wide bandwidth $(\ensuremath{\Delta}\ensuremath{\lambda}\ensuremath{\geqslant}40\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$. For dots that are both spectrally and spatially coupled to strongly localized $[{V}_{\mathit{\text{modes}}}\ensuremath{\sim}1.5{(\ensuremath{\lambda}∕n)}^{3}]$, high $Q\ensuremath{\sim}2700$ optical modes, we have directly measured a strong Purcell-enhanced shortening of the emission lifetime $\ensuremath{\geqslant}5.6\ifmmode\times\else\texttimes\fi{}$, limited only by our temporal resolution. Analysis of the spectral dependence of the recombination dynamics shows a maximum lifetime shortening of $19\ifmmode\pm\else\textpm\fi{}4$. From the directly measured enhancement and suppression we show that the single-mode coupling efficiency for quantum dots in such structures is at least $\ensuremath{\beta}=92%$ and is estimated to be as large as $\ensuremath{\sim}97%$.