Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 3: Quantum dots: Microcavities and photonic crystals

HL 3.7: Talk

Monday, February 25, 2008, 12:45–13:00, ER 270

Efficient single photon generation using single quantum dots in two-dimensional photonic crystals — •Arne Laucht, Michael Kaniber, Andre Neumann, Max Bichler, and Jonathan J. Finley — Walter Schottky Institut, TU-München, Am Coulombwall 3, D-85748 Garching

We present comparative investigations of single photon generation from self-assembled quantum dots (QDs) emitting into (i) a two-dimensional photonic bandgap (PBG) or (ii) a homogeneous photonic environment. The sample investigated consisted of a single layer of In_0.50Ga_0.50As QDs embedded within a 180nm thick GaAs membrane. Specific regions of this air-GaAs-air waveguide were patterned using electron-beam lithography and reactive ion etching to form photonic crystal (PC) nanostructures with a PBG enclosing the QD emission. By probing QDs within, or next to, the PC nanostructures we examine the influence of the PBG on the single photon emission rate and external quantum efficiency. Optical measurements were performed using low temperature confocal microscopy. We observe strong photon anti-bunching with a low multi photon probability both for dots in the unpatterned membrane and the PC of less than 10%. Remarkably, the 2D PBG is shown to enhance the relative photon extraction efficiency by a factor of ∼16×. From measurements under pulsed excitation we estimate the absolute external quantum efficiency of 26±3% for dots in the PC to be much larger than the one for dots in the unpatterned GaAs of 1.6±0.2%. Hence, we conclude that a 2D PBG may provide a simple route towards highly efficient QD based single photon sources.