Thanks to their 3D-confined nanostructures, quantum dots (QDs) have properties that are far superior to the corresponding materials in bulk form, such as high quantum efficiency, size-dependent tunable emission and high sensitivity. We have demonstrated sub-diffraction limit QD waveguides, nanogap QD photodetectors with high sensitivity and spatial resolution, plasmonic-enhanced QD photodetectors with color selectivity and Si QDs with high 
photoluminescence quantum yield. We have also demonstrated photostimulation of cells and neurons through QDs with extremely low optical intensities.
