Determination of energy transfer and upconversion constants for Yb~(3+)/Er~(3+) codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb~(3+)/Er~(3+) codoped phosphate glass.Based on the measured curves of output power versus incident power,the laser and spectroscopic parameters of the glass are fitted and analyzed.We focus on the resonant energy transfer constant k from Yb~(3+) to Er~(3+) as well as the cooperation upconversion coefficient C_(up) from ~4I_(13/2) of Er~(3+).The fitted k and C_(up) can give almost the same results for different thicknesses of gl...