Investigation of broadband mid-infrared emission and quantitative analysis of Dy-Er energy transfer in tellurite glasses under different excitations

Broadband mid-infrared emissions are obtained from Dy3+/Er3+ co-doped tellurite glasses under 808 or 980 nm excitation. The maximum effective emission bandwidths of mid-infrared emission is 92.45 nm in Dy3+/Er3+ co-doped tellurite glass pumped by 808 nm, while it can reach 209.00 nm pumped by 980 nm. The effects of different laser excitations on the energy transfer mechanism between Dy3+ and Er3+ ions have been investigated in tellurite glasses. Under 808 nm excitation, the energy transfer efficiency from Er3+:4I13/2 to Dy3+:6H11/2 level is 73.1% and the energy transfer coefficient from Er3+:4I11/2 to Dy3+:6H5/2 level and from Er3+:4I13/2 to Dy3+:6H11/2 level are 6.89 × 10−38 and 0.01 × 10−38 cm6/s, respectively. Under 980 nm excitation, the energy transfer efficiency from Er3+:4I13/2 to Dy3+:6H11/2 level can reach as high as 80%. Moreover, the maximum emission cross-section of 2500-3100 nm broadband emission when pumped by 808 nm is 1.90 × 1020 cm2 at 2765 nm, while it can reach as high as 4.99 × 1020 cm2 at 2724 nm pumped by 980 nm. Thus, the 980 nm excitation is more efficient for Dy3+/Er3+ co-doped tellurite glass to realize low-threshold and high gain applications at broadband mid-infrared laser.