Analysis of the dynamics of frequency upconversion in Er3+/Yb3+ co-doped KY(WO4)2 crystal

The absorption spectrum, upconversion spectrum and the fluorescence decay curve of Er
³⁺
/Yb
³⁺
co-doped KY(WO
4
)
2
crystal were measured. The radiative transition rates were calculated by Judd-Ofelt theory. A model for the dynamics of frequency upconversion process in Er
³⁺
/Yb
³⁺
co-doped KY(WO
4
)
2
crystal was proposed. The Yb-to-Er energy transfer rate and the upconversion coefficients were estimated by numerically solving the rate equations and fitting simulated curve to the experimental data.