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HL: Halbleiterphysik
HL 18: Symposium Quantum optics in semiconductors II
HL 18.4: Fachvortrag
Tuesday, March 28, 2006, 16:30–16:45, HSZ 01
Imaging the Local Density of Photonic States in Photonic Crystal Nanocavities — •Michael Kaniber, Felix Hofbauer, Simon Grimminger, Max Bichler, Gerhard Abstreiter, and Jonathan J. Finley — Walter Schottky Institut, Am Coulombwall 3, 85748 Garching
We present investigations of the coupling of InGaAs quantum dots
(QDs) to both extended and strongly localised optical modes in 2D
photonic crystal (PC) nanostructures. The samples consist of a
180nm thick GaAs membrane into which a PC is formed by etching a
triangular lattice of air holes. By measuring the local QD
spontaneous emission rate (Rspon) we "image" the photonic DOS
at frequencies throughout the photonic bandgap (PBG) and close to
localised modes at single missing hole defects (Q∼10000,
Vmode<0.5(λ/n)3). For QDs emitting into the PBG but
detuned from the cavity mode, we observe a strong suppression of
Rspon compared to its value in a homogenous photonic
environment (R0/Rspon=30±6) due to the reduced photon
DOS. In contrast, for QDs coupled to the cavity modes we measure
1/Rspon∼ 50ps, corresponding to a large Purcell enhancement
(Rcavity/R0=18x).
Single dot measurements reveal clear photon anti-bunching when the
emission frequency is detuned from the cavity mode and enhanced
photon extraction efficiency (∼30%) due to the PBG which
suppresses in-plane emission. Most surprisingly, anti-bunching is
not observed for QDs coupled to the cavity modes
possibly due to the onset of low threshold lasing.
Supported financially via Sonderforschungsbereich-631