Using Quantum Dots As On-Demand Probes for Imaging Plasmonic Nanostructures

Plasmonic nanostructures confine light on the nanoscale, enabling ultra-compact optical devices that exhibit strong light–matter interactions. Quantum dots are ideal for probing plasmonic devices because of their nanoscopic size and desirable emission properties. However, probing with single quantum dots has remained challenging because their small size makes them difficult to manipulate. Researchers from the A. James Clark School of Engineering at the University of Maryland have demonstrated the use of quantum dots as on-demand probes for imaging plasmonic nanostructures, as well as for realizing spontaneous emission control at the single emitter level with nanoscale spatial accuracy. A single quantum dot is positioned with microfluidic flow control to probe the local density of optical states of a silver nanowire, achieving 12-nm imaging accuracy. This video is an actual measurement of a single quantum dot (asterisk denotes the position of the dot) as it is manipulated by microfluidic flow control in the region around the midpoint of a silver nanowire (axis denoted with the dashed line). The scale bar corresponds to 500 nm.