Pump-Profile Engineering for Spatial- and Spectral-Mode Control in Two-Dimensional Colloidal-Quantum-Dot Spasers

In the initial proposal of the spaser – a source of coherent, intense, and narrow-band surface plasmons – colloidal quantum dots were envisioned as an ideal gain medium for compensation of the significant losses intrinsic to plasmonics. However, many spasers shown to date have required a single material to both serve as a gain medium and define the plasmonic cavity, a design that prevents the use of quantum dots or other colloidal nanomaterials. In addition, these concepts are inherently challenging for integration in a larger plasmonic circuit.