Appl. Phys. Lett. 103, 171104 (2013)

Colloidal quantum dots (QD) have demonstrated their potential as versatile light-emitting materials for photonic applications. However, detrimental fast multiexcitonic Auger recombination processes, which compete with the onset of optical gain, usually require ultrashort, high-power pulsed optical excitation sources to achieve amplified spontaneous emission in films of QDs. But CdSe/Zn0.5Cd0.5S core/shell QDs demonstrate optical gain at single-exciton pumping conditions, where Auger processes are less effective. Cuong Dang and colleagues now show that densely packed films of these QDs can be deposited on nanostructured surfaces, such as the one-dimensional periodic gratings used in distributed feedback lasers, by means of a simple spin-casting process. Using this approach, they realize optically pumped QD-based lasers, which have low threshold excitation densities that can be easily reached using compact nanosecond-pulsed sources.