Red, green, and blue laser action in solid colloidal quantum dot films

We report on wavelength-variable lasing from optical gain media composed of colloidal quantum-dots (CQD) thin films across the visible spectrum. Exploiting single exciton gain enables amplified spontaneous emission (ASE) and vertical cavity lasing at very low optical pump thresholds. The average number of exciton per CQD at the ASE threshold is <;N>;~ 0.8, which significantly reduces losses from enhanced nonradiative multiexciton Auger recombination in nanometer sized semiconductor particle, enabling quasi-continuous-wave CQD laser performance in densely packed nanocomposites.