Photo-Induced Effect in Heavy Metal Oxide Glasses

Photo-induced phenomena in binary (PbO-Ga2O3) and ternary (PbO-Bi2O3-Ga2O3) heavy metal oxide glasses were investigated. A red shift up to similar to 0.05 eV in the absorption edge of 75PbO-25Ga(2)O(3) glass (mol%) was observed by illuminating the subbandgap light for 30 min. This shift was completely erased by the heat treatment near the glass transition temperature. Refractive index of the glass at 600 nm also increased similar to 0.011 by the illumination. It is believed that the presence of lone-pair electrons associated with Pb-polyhedra is essential to realize a reversible photo-induced effect in these oxide glasses.