Nanostructured glass-crystal materials with lead sulfide for passive Q switching of IR lasers

New results are obtained from an investigation of the formation processes of nanostructured material accompanying the heat treatment of silicate glasses containing lead sulfide dissolved during synthesis. Important morphological features of the material have been detected-close-to-monodisperse distribution of PbS nanocrystals (NCs) over size and partial spatial ordering of the NCs. The heat-treatment regimes developed for the initial glasses make it possible to obtain high-quality samples that demonstrate narrow absorption lines of the PbS NCs for the 2-2.5-mu m spectral region. The fundamental physical limitation of the subsequent broadening (lambda>2.5 mu m) of the working range of passive Q switches using such materials is the impossibility of implementing the regime of strong size quantization of electron-hole pairs when the radius of the NCs is comparable with the Bohr radii of electrons and holes. (C) 2006 Optical Society of America.