Effect of BaF ₂ and Y ₂ O ₃ on the Raman scattering characteristics of fluorotellurite glasses

In this letter, we investigated the Raman scattering characteristics of a series of aTeO ₂ -(90-a)BaF ₂ -10Y ₂ O ₃ (a = 85, 80, 75, 70, 65, 60, 55 mol%), bTeO ₂ -(95-b)BaF ₂ -5Y ₂ O ₃ (b = 90, 85, 80, 75, 70, 65, 60, 55, 50 mol%) and cTeO ₂ -(100-c)BaF ₂ (c = 95, 90, 85, 80, 75, 70, 65, 60 mol%) fluorotellurite glasses. With increasing the concentration of BaF ₂ , the peak Raman gain coefficient at 785 cm ⁻¹ increased while the Raman gain bandwidth (full spectral width at half maximum of the Raman peaks around 785 cm ⁻¹ ) decreased, which was attributed to the increasing proportion of non-bridge oxygen bonds in the fluorotellurite glass systems. The same results were also observed for the case of the increasing of the concentration of Y ₂ O ₃ . In these samples, the 50TeO ₂ -40BaF ₂ -10Y ₂ O ₃ glass has the largest Raman gain coefficient of 29.9 × 10 ⁻¹³ m/W, and the 95TeO ₂ -5BaF ₂ glass has the widest Raman gain bandwidth of 7.35 THz for the pumping laser at 633 nm. Furthermore, the first-order Raman Stokes light peaked at ∼2373 nm was obtained by using fluorotellurite fiber based on the above glasses as Raman gain medium and a 2000nm picoseconds laser as pump light. Our results provide guidance for further improving the performance of Raman fiber lasers or amplifiers based on fluorotellurite fibers.