Infrared-to-visible upconversion flurescence of Er3+/Yb3+-codoped bismuthate glasses

Er3+/Yb3+-codoped bismuthate glasses for developing potential upconversion lasers have been fabricated and characterized. The optimal Yb3+ doping content was investigated in the glasses with different Yb3+–Er3+ concentration ratios and the optimal Yb3+–Er3+ concentration ratio is 5:1. Under 975 nm excitation, 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 under 975 nm excitation.