Thermal analysis and optical properties indicate that Tm3+ and Dy3+ co-dope
d oxyfluoride tellurite glasses can be excellent candidates for fiber ampli
fiers at 1.47 mu m region. Substitution of GeO2 and In2O3 in tellurite glas
ses increased the glass stability without decreasing the lifetime of the up
per Tm3+:H-3(4) level, and the fluoride substitution increased lifetime of
excited energy levels of Tm3+ ion. Dy3+ co-doping in the Tm3+-doped oxyfluo
:appride tellurite glasses enhanced the depopulation of the Tm3+:F-3(4) lev
el through an energy transfer Tm3+:F-3(4) --> Dy3+:(6)(H)over dot(11/2). We
report the measurements of crystallization, glass transition temperatures,
and optical properties of Tm3+, Dy3+ co-doped oxyfluoride tellurite glasse
s. (C) 2000 Elsevier Science B.V. All rights reserved.