Rare earth doped oxide, chalcogenide and fluoride glasses as potential laser materials

Radiative and nonradiative transitions between electronic levels of Nd(3+), Er(3+), Ho(3+) and Tm(3+) in oxide glasses, or Nd(3+) in chalcogenide glasses, and of Er(3+) and Ho(3+) in fluoride glasses are treated. It is shown that the nonradiative relaxation of the rare earths in the different glasses depends for the most part on the phonon energies of the glass-forming materials and to a lesser extent on the coupling constant between the excited electronic levels and vibrational frequency of the glass-forming materials. Examples are cited of high-quantum efficiencies of emitting levels in chalcogenide and fluoride glasses as a result of low-phonon energies in these glasses.