Formation and selective micron-regional control of PbS quantum dots in glasses using femtosecond laser pulsation

The direct and effective synthesis of PbS quantum dots (QDs) in a solid-state matrix is of great importance in the production and application of PbS QDs photonic devices. The present article describes the direct precipitation of PbS QDs in an inorganic glass matrix by the irradiation of a femtosecond (fs) laser. It has been demonstrated that the formation of the QDs is strongly influenced by the thermal effect of the fs laser. The effect of the irradiation parameters and of Ag clusters on the precipitation of QDs has been investigated, in addition to the spatial distribution of the QDs in the irradiated area, and a mechanism is suggested. The confocal Raman spectra indicate that after irradiation the concentration of the QDs is the highest at the center. On the other hand, heat treatment of the irradiated sample has also been carried out to adjust the size, distribution and photoluminescence of QDs within the glass matrix. The electron probe microanalyzer (EPMA) has provided direct evidence for the large change in refractive index and for the ring-shaped structure formed on irradiation. Based on selective local control of the PbS QDs, a waveguide demonstration has been conducted to illustrate the feasibility of directly writing a PbS QDs waveguide with an fs laser in a glass matrix.