Broadband nonlinear optical response of lead telluride quantum dots for all-solid-state pulse lasers from visible to mid-infrared

Lead telluride (PbTe), an emerging member of the group IV-VI monochalcogenides, exhibits superior properties such as higher density of states, obvious band anisotropy, and high carrier mobility. Moreover, the stronger nonlinear optical response of quantum dots (QDs) makes this type of low-dimensional material highly competitive for broadband pulse laser applications. In this work, high-quality PbTe QDs are fabricated using a liquid phase exfoliation (LPE) method. Utilizing PbTe QDs as what we believe to be a novel saturable absorber (SA), the broadband nonlinear optical responses spanning from visible to mid-infrared wavelengths are systematically investigated. Experimentally, broadband solid-state passively Q-switched lasers are successfully implemented based on PbTe QDs SA at 0.64, 1.06, 1.9, and 2.7 µm, respectively. Notably, this is believed to be the first time that PbTe QDs have been employed as SA in broadband solid-state pulse lasers. These findings indicate that PbTe QDs exhibit significant potential as saturable absorbing materials and can serve as effective optical modulators in broadband laser applications.