Optical gain and stimulated emission in nanocrystal quantum dots

The development of optical gain in chemically synthesized semiconductor nan oparticles (nanocrystal quantum dots) has been intensely studied as the fir st step toward nanocrystal quantum dot Lasers, We examined the competing dy namical processes involved in optical amplification and Lasing in nanocryst al quantum dots and found that, despite a highly efficient intrinsic nonrad iative Auger recombination, Large optical gain can be developed at the wave length of the emitting transition for close-packed solids of these dots. Na rrowband stimulated emission with a pronounced gain threshold at wavelength s tunable with the size of the nanocrystal was observed, as expected from q uantum confinement effects. These results unambiguously demonstrate the fea sibility of nanocrystal quantum dot lasers.