Sub-Wavelength Multi-Channel Imaging Using a Solid Immersion Lens: Spectroscopy of Excitons in Single Quantum Dots

We demonstrate sub-wavelength imaging of excitons confined to single CdTe quantum dots. By combining slit-confocal microscopy with a hemispherical solid immersion lens we simultaneously map the emission of thousands of single quantum dots with a spatial resolution of 400 nm. By analyzing the linear polarization of the quantum dot emissions at B=0T, we find that the distribution of the exchange splitting is centered at zero with a standard deviation of 0.34 meV. Similar experiments performed at B=3T give an average value of the exciton effective g factor of 3.1. This experimental approach provides an effective means to gain statistical information about the quantum dot exciton fine structure in the ensemble.