Emission properties and structure of heavy metal oxide glasses

Emissions properties of glasses in the PbO-Ga2O3-Bi2O3 system doped with a variety of different rare-earth ions were reviewed with particular attention on the applications towards the amplification of the optical signals in the fiber-optic communication systems and for mid-infrared lasers. Due to the low vibrational phonon energy of the glasses, it was possible to realize the efficient emissions for the O-band and S-band amplification by doping Pr3+, Dy3+ or Tm3+. Amplification at these communication bands has not been possible when conventional oxide glasses were used as host materials. Network structure of the glass was made of mixture of GaO4 tetrahedra and PbO3/PbO4 polyhedra as a backbone. They are connected through bridging oxygens and a portion of these oxygen atoms are connected to three cations instead of two. Pb2+ ions also act as charge compensators as evidenced from the large amount of non-bridging oxygens in the glass network. Bi2O3 form BiO6 octahedra.