Upconversion fluorescence property of Er3+/Yb3+-codoped novel bismuth–germanium glass

Infrared-to-visible upconversion fluorescence property of Er3+/Yb3+-codoped novel bismuth–germanium glass under 975 nm LD excitation has been studied. Intense green and red emissions centered at 525, 546 and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were observed at room temperature. The quadratic dependence of the 525, 546 and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs. The structure of the bismuth–germanium glass has been investigated by peak-deconvolution of FT-Raman spectrum, and the structural information was obtained from the peak wavenumbers. This novel bismuth–germanium glass with low maximum phonon energy (∼750 cm−1) can be used as potential host material for upconversion lasers.