Modulation of the optical properties of transition metal doped PbSe quantum dots in silicate glasses

Optical properties of lead chalcogenide quantum dots (QDs) can be controlled by tuning its bandgaps. We prepared silicate glasses using the melt-quenching method and heat-treated 510 degrees C-540 degrees C for 10 h to precipitate transition metal ions into PbSe QDs. Transition metals oxide such as TiO, MnO & NiO were used in our experiment due to relative ease of incorporation of Ti2+, Mn(2+,)or Ni(2+)ions in PbSe crystal structure lattice compared to rare-earth ions. Emission spectra of PbSe QDs were tuned in a wide wavelength range through changing concentration of transition metals oxide in glasses. For instance, photoluminescence bands of Pb1-xTixSe QDs QDs moved from 1890 nm to 1625 nm with increasing TiO from 0.0 to 0.5 mol% at heat treatment 530 degrees C for 10 h. Absorption bands of QDs also shifted to shorter wavelength sides as concentration of TiO or MnO increased under constant thermal treatment conditions mainly due to the change in the bandgap of QDs. However, absorption & PL peaks moved to longer wavelength sides (red-shifted) with increasing the duration of thermal annealing while keeping the amount of transition metal oxides constant mainly due to enlargement of the QDs sizes with thermal treatment. Tunable optical properties of QDs make them a promising candidate for various photoelectric devices, for example, fiber-optics amplifiers in optical communication and fiber lasers.