Highly efficient single-photon emission from single quantum dots within a two-dimensional photonic band-gap

We report highly efficient single-photon generation from InGaAs self-assembled quantum dots emitting within a two-dimensional photonic band-gap. A strongly suppressed multiphoton probability is obtained for single quantum dots in bulk GaAs and those emitting into the photonic band-gap. In the latter case, photoluminescence saturation spectroscopy is employed to measure a $\sim 16$ times enhancement of the average photon extraction efficiency, when compared to quantum dots in bulk GaAs. For quantum dots in the photonic crystal, we measure directly the external quantum efficiencies up to 25%, much higher than for dots on the same sample without a tailored photonic environment. The results show that efficient quantum dot single-photon sources can be realized, without the need for complex nanopositioning techniques.