Strongly confined semiconductor quantum dots theoretically offer for broadband and continuous tunability of their emitting wavelength based upon simply varying the particle size. However, prior art consistently has demonstrated a lower particle size limit below which optical gain cannot be achieved, for example 2.3 nm for CdSe in toluene. As such the prior art points to combinations of alternative materials and host media as the route to achieving the goal of broadband emission sources using quantum dots. However, according to the invention optical gain can be achieved in quantum dots below these previous experimental limits by resonantly pumping the quantum dots to a specific excitonic state, i.e. electron position relative to the quantum dot, such that the multiexcitonic interferences are minimized. Using this approach optical gain in CdSe of R=2.1 nm and 1.5 nm has been demonstrated in the yellow/amber region of the visible spectrum.