Er³⁺ doped boro-tellurite glasses for 1.5 μm broadband amplification

B₂O₃ has been introduced in Er³⁺-doped tellurite glasses in order to increase their phonon energy and the multiphonon relaxation rate of the Er³⁺:⁴I_11/2→ ⁴I_13/2 transition, which will allow efficient 980 nm pumping. The inclusion of additional glass components such as GeO₂ and Al₂O₃ has been shown to enhance the thermal stability of the boro-tellurite glasses. No crystallization peak (T_c) was observed in glass samples containing GeO₂ and Al₂O ₃. The suitability of these boro-tellurite glasses as host for broadband erbium-doped fiber amplifiers and their advantages over the other tellurite glasses are discussed.