Rate equation model analysis on the infrared and upconversion emission of Er/Yb co-doped borate-silicate glass

Er/Yb co-doped borate-silicate glasses with various Yb concentrations were fabricated by high-temperature solid-reaction method. The photoluminescence spectra around 1.55 mu m and the visible upconversion spectra were measured. The radiative lifetime of Er-I-4(13/2), compared with the measured one, was obtained by Judd-Ofelt theory based on the absorption spectra. A rate equation model for Er/Yb co-doped system has been established based on the data obtained from the measurements, including the absorption and emission cross section, and decay rate of Er-I-4(13/2) level, etc. Ground-state absorption, excited-state absorption, together with the energy transfer among Er3+ ions and Er3+/Yb3+ ions were considered in the model. The results from the simulation were compared with the experimental ones. Through the model, a much better comprehension on the Er/Yb doped system was expressed.