Effect of Ga 2O 3 on the spectroscopic properties of erbium-doped boro-bismuth glasses

Abstract

The spectroscopic properties and thermal stability of Er 3+-doped Bi 2O 3–B 2O 3–Ga 2O 3 glasses are investigated experimentally. The effect of Ga 2O 3 content on absorption spectra, the Judd-Ofelt parameters Ω t ( t = 2, 4, 6), fluorescence spectra and the lifetimes of Er 3+: 4I 13/2 level are also investigated, and the stimulated emission cross-section is calculated from McCumber theory. With the increasing of Ga 2O 3 content in the glass composition, the Ω t ( t = 2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) and the 4I 13/2 lifetimes of Er 3+ first increase, reach its maximum at Ga 2O 3 = 8 mol.%, and then decrease. The results show that Er 3+-doped 50Bi 2O 3–42B 2O 3–8Ga 2O 3 glass has the broadest FWHM (81 nm) and large stimulated emission cross-section (1.03 × 10 −20 cm 2) in these glass samples. Compared with other glass hosts, the gain bandwidth properties of Er 3+-doped Bi 2O 3–B 2O 3–Ga 2O 3 glass is better than tellurite, silicate, phosphate and germante glasses. In addition, the lifetime of 4I 13/2 level of Er 3+ in bismuth-based glass, compared with those in other glasses, is relative low due to the high-phonon energy of the B–O bond, the large refractive index of the host and the existence of OH − in the glass. At the same time, the glass thermal stability is improved in which the substitution of Ga 2O 3 for B 2O 3 strengthens the network structure. The suitability of bismuth-based glass as a host for a Er 3+-doped broadband amplifier and its advantages over other glass hosts are also discussed.