Berlin 2005 – scientific programme
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HL: Halbleiterphysik
HL 62: Photonische Kristalle IV
HL 62.4: Talk
Wednesday, March 9, 2005, 11:30–11:45, TU P164
Giant Purcell Effect for InGaAs self-assembled Quantum Dots in Photonic Crystal Microcavities — •A. Kress, F. Hofbauer, N. Reinelt, M. Kaniber, G. Böhm, and J. J. Finley — Walter Schottky Institut, TU München, 85748 Garching, Germany
We present investigations of the coupling of InGaAs self-assembled quantum dots (QD) to localised optical modes in 2D photonic crystal defect microcavities, where a very strong enhancement of the light-matter interaction in the weak coupling regime was directly measured.
Our samples consist of thin active GaAs membranes into which a layer of QDs are incorporated. The photonic crystal cavities are formed by single missing hole defects in an etched 2D hexagonal lattice of air holes. Finally the membranes are fabricated by removing a sacrificial AlAs layer in a wet etching process.
The investigated cavity modes have Q-factors of >2500 and mode-volumes V<(λ/n)3. Up to a 50x enhancement of the emission intensity is observed for QDs on-resonance with the cavity modes suggesting the presence of significant cavity QED phenomena. Time resolved luminescence measurements reveal a shortening of the spontaneous emission lifetime by a factor ∼20, for single QDs inside our cavities on-resonance with the optical modes compared with QD emission outside any cavity. Furthermore, over a spectral range of >40nm we obtain factor >2 longer excitonic lifetimes for QDs inside these cavities but off-resonance with optical modes.