Net Optical Gain from PbS Quantum Dot-Doped Glasses under Continuous-Wave Pumping

Lead chalcogenide quantum dots (QDs) have been considered promising gain media in the near-infrared region. Precipitation of lead chalcogenide QDs into glasses can significantly improve their stabilities and processabilities using mature fiber-optic technologies and has great potential for application as a broad-band optical amplification in optical telecommunication. However, the net optical gain of lead chalcogenide QD-doped glasses has not been realized upon continuous-wave (CW) pumping, hindering their application as fiber-optic amplifiers. Here, the study reports a heterostructured PbS/NaCl QD-doped glass and realizes a net optical gain in the near-infrared region upon CW pumping. The photoluminescence quantum efficiencies of these QD-doped glasses are boosted to 43-75% with significantly improved photo/thermal stabilities, and the gain threshold is reduced to similar to single exciton level due to the passivation and charge doping of the PbS QDs by the NaCl wrapping. As a result, net optical gain in the conventional band of telecommunication is realized from the 1 mm thick PbS QD-doped glasses under CW pumping. Precipitation of heterostructured PbS/NaCl QDs in glasses leads to passivation of surface defects and improvement in photoluminescence quantum yield. Reduction in gain threshold is achieved and net optical gain is realized upon continuous-wave pumping. image