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 μJ/cm². While perfect linear recombination is observed across four orders of magnitude, an additional radiative recombination mechanism emerges at an excitation density of 1 μ J/cm² per pulse at 390 nm excitation and increases the external quantum efficiency. The time constant of this process is ~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.