NEW PHOSPHO-TELLURITE GLASSES FOR ULTRA-BROADBAND FIBER RAMAN AMPLIFIERS

摘要

Phospho-tellurite glasses containing heavy metal oxides and alkaline earth oxides have been fabricated. The presence of BaO and SrO in the glasses remarkably increased their thermal stabilities. These glasses have thermal stabilities as high as 224°C, which make them suitable for various fiber devices applications. The corrected relative Raman intensities (I{sub}(corr)) and scattering cross sections (σ{sub}(corr)) of various peaks for all the glasses are compared with respect to silica. These glasses show superior relative Raman cross sections than silica and conventional tellurite glasses, the most widely studied for fiber devices applications (TeO{sub}2-ZnO-Li{sub}2O-Bi{sub}2O{sub}3, TZLB). The gain bandwidth is also an important parameter apart from the Raman gain coefficient in selecting a material for Raman amplifiers. The bandwidth broadening effect can be estimated based on σ{sub}(corr)/I{sub}(corr) as σ{sub}(corr) is proportional to the Raman scattering intensity and broadness of the spectrum. For simplicity the broadness of the bandwidth of the present glasses are also judged by the normalized bandwidth with respect to silica (i.e. bandwidth of sample/bandwidth of silica). It is 1.55 for one of the representative phospho-tellurite glasses and 0.75 for TZLB. The presence of heavy metal oxides and alkaline earth oxides makes the Raman bands due to TeO{sub}2 and P{sub}2O{sub}5 continuous and one such glass has continuous Raman bandwidths exceeding 700 cm{sup}(-1). Thus, these glasses could be potential candidates for ultra-broadband fiber Raman amplifiers.