<title>Characterization of cooperative upconversion and energy transfer of Er3+ and Yb3+/Er3+ doped phosphate glasses</title>

Abstract

Cooperative upconversion and Yb<SUP>3+</SUP>-Er<SUP>3+</SUP> energy transfer in newly developed phosphate glasses were studied in this paper. The cooperative upconversion coefficients of <SUP>4</SUP>I<SUB>13/2</SUB> level for different Er<SUP>3+</SUP> concentrations were deduced from the pump intensity- dependent luminescence decay curves. Yb<SUP>3+</SUP>-Er<SUP>3+</SUP> energy transfer efficiencies for different Yb<SUP>3+</SUP> concentrations codoped with Er<SUP>3+</SUP> (approximately 2 X 10<SUP>20</SUP> ions/cm<SUP>3</SUP>) were estimated from the lifetime measurements of <SUP>2</SUP>F<SUB>5/2</SUB> level of Yb<SUP>3+</SUP> ions. The small cooperative upconversion coefficients and high Yb<SUP>3+</SUP>-Er<SUP>3+</SUP> energy transfer efficiencies indicate these newly developed Er<SUP>3+</SUP> and Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> doped phosphate glasses are excellent for amplifier and laser applications.