Cavity-enhanced polarization control and observation of off-resonant coupling in quantum dot nanocavities

We study the linear polarization of the emission from single quantum dots (QDs) embedded in an “L3” defect nanocavity in a two-dimensional photonic crystal. We found that all the dots we observed emitted very strongly linearly polarized light. In stark contrast to the behaviour observed in QDs emitting into a homogeneous medium, the QD polarization has the same orientation as the spectrally closest photonic mode. Surprisingly, this is true even in the cases where the QDs are detuned by several times the mode linewidth, where the off-resonant Purcell enhancement should be 10
⁻³
times that on resonance.