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.

Figure 1

(Color online) (a) $\mu$-PL spectrum recorded from a QD ensemble. (b) Three-dimensional calculation of the photonic band structure for the GaAs 2D-PC slab with $r∕a=0.335$, lattice constant $a=280\mathrm{nm}$, and thickness $d=180\mathrm{nm}$. The dark blue region denotes the light cone. (c) Calculated 3D photonic density of states for light propagation in the plane of the PC slab (only guided modes in the free space light cone) as a function of the wavelength. The gray region denotes the 2D-PBG.

Figure 2

(Color online) (a) $\mu$-PL spectra of single QDs in bulk GaAs $\left({\mathrm{QD}}_{\mathit{\text{bulk}}}\right)$ and in PC nanostructures (${\mathrm{QD}}_{\mathit{PC}1}$, ${\mathrm{QD}}_{\mathit{PC}2}$) recorded with an excitation power of $10\mathrm{W}{\mathrm{cm}}^{-2}$. (b) Power dependent measurements for all three QDs indicating ground state emission due to the linear behavior. The gray shaded region indicates the saturation regime.

Figure 3

(Color online) (Left panel) Time-resolved PL data for (a) ${\mathrm{QD}}_{\mathit{\text{bulk}}}$, (b) ${\mathrm{QD}}_{\mathit{PC}1}$, and (c) ${\mathrm{QD}}_{\mathit{PC}2}$, respectively. (Right panel) Corresponding photon correlation measurements for (a) ${\mathrm{QD}}_{\mathit{\text{bulk}}}$, (b) ${\mathrm{QD}}_{\mathit{PC}1}$, and (c) ${\mathrm{QD}}_{\mathit{PC}2}$, demonstrating clear signature of photon antibunching.