Spectral properties of and energy transfer in Bi/Tm co-doped silicate glasses

Abstract

Bi, Tm singly doped and Bi/Tm co-doped glasses with molar compositions of 60SiO2–20Ga2O3–15Na2O–5Al2O3 were prepared by the conventional melt-quenching method. The enhanced emission of the Tm3+:3H4→3F4 transition at 1470 nm, and the quenched emission of the Tm3+:3F4→3H6 transition at 1860 nm were observed for Bi/Tm co-doped silicate glasses under 808 nm excitation. For 980 nm excitation, no Tm-related emission was observed for Tm singly doped glasses, while the emission of the Tm3+:3F4→3H6 transition at 1860 nm was observed for Bi/Tm co-doped glasses. These results indicated that the energy transfer occurred between active Bi ions and Tm3+ in Bi/Tm co-doped silicate glasses, in which the energy corresponding to the Bi-related emission level excited the Tm3+ from 3H6 to the 3H5 level under 980 nm excitation, and from 3F4 to the 3H4 level under 808 nm excitation. The energy-transfer processes were studied on the basis of the Inokuti–Hirayama model, and the energy transfer of the electric dipole–dipole interaction was confirmed to be dominant in Bi/Tm co-doped glasses. The Bi/Tm co-doped silicate glasses may be potential materials for producing broadband optical fiber amplifiers and tunable lasers.