Stimulated emission from PbS-quantum dots in glass matrix

The luminescence behavior of PbS-quantum dots in glass matrix (PbS:Glass) is investigated. Steady-state and time-resolved photoluminescence are applied in a wide range of excitation densities up to pulse energies exceeding 50 mu J/cm(2). While perfect linear recombination is observed across four orders of magnitude, an additional radiative recombination mechanism emerges at an excitation density of 1 mu J/cm(2) per pulse at 390 nm excitation and increases the external quantum efficiency. The time constant of this process is similar to 20-40 ps. It is ascribed to stimulated emission. No hint to any non-linear non-radiative processes such as Auger recombination is observed. Thermal effects, however, still set limits. This is encouraging news for PbS: Glass as potential laser material.