Er3+ ions doped bismuthate glasses sensitized by Yb3+ ions for highly efficient 2.7 μm laser applications

Abstract

In present study, we investigated the emissions from visible to mid-infrared and energy transfer processes in Er3+/Yb3+ co-doped germanate–gallate–bismuthate (BGG) glasses. Larger absorption cross-section of Yb3+ ions (7.5×10−21cm2) and enhanced up-conversion, near-infrared and mid-infrared emissions indicate that the introduced sensitized Yb3+ ions can efficiently absorb and transfer pumping energy (980nm) to activate the Er3+ ions. The intensity of 2.7μm emission in Er3+/Yb3+ co-doped samples is about 3 times higher than that of Er3+ singly doped sample. But, the intensity of 2.7μm emission decreases with excessive Yb3+ ions. The optimized ratio of Er3+ and Yb3+ ions for 2.7μm emission is 1.0:0.2 in this BGG glasses. Large emission cross-section σe (−13×10−21cm2 and −9.57×10−21cm2 for 2.7μm and 1.5μm emissions, respectively) is obtained in Er3+/Yb3+ co-doped BGG glasses. According to absorption and emission spectra, energy transfer processes between Yb3+ and Er3+ ions were proposed and main reason for increased up-conversion is the strong excited state absorption (ESA) from excited Er3+ ions at 4I11/2 and 4I13/2 levels. Therefore, high pumping efficiency, intense emissions, large emission cross-section of 2.7μm and 1.5μm emissions and efficient energy transfer processes in this Er3+/Yb3+ co-doped BGG glasses hints its potential applications in laser materials, especially in 2.7μm wavelength.