Tuning optical properties in PbSe quantum dot-doped borosilicate glass fiber by modulation of network topology

Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by traditional melt-quenching followed by thermal treatment. By introducing a metal fluoride (NaF) network modifier that reduces the number of bridge oxygen bonds, the mobility of Pb2+ and Se2-ions is enhanced during thermal treatment, thereby promoting the precipitation of PbSe QDs. With increasing the thermal treatment temperature or NaF concentration, the ab-sorption peak and emission peak undergo a red shift, which is accompanied by an increase and then decrease of the photoluminescence (PL) intensity, and a gradual increase of the PL lifetime. This evolution in spectral properties is associated with the growth in number and size of PbSe QDs. Furthermore, PbSe QD-doped glass fibers were prepared by a direct drawing method, and the addition of 4 mol % NaF results in an enhancement by 13.5 times in the PL intensity as compared with the fiber fabricated from the glass melt without NaF. Our method could be used to regulate the ultra-wideband near infrared PL of QD-doped glasses, which could find potential applications in ultra-wideband fiber amplifiers.