Population dynamics of Yb3+, Er3+ co-doped phosphate glass

Excitation dynamics in Er3+–Yb3+ co-doped phosphate glasses were examined as a function of both erbium and ytterbium concentration by monitoring fluorescence on the 1.5 μm I13/24→I15/24 transition of Er3+ following pulsed laser excitation of the system at 977 nm under room temperature. For the range of donor (Yb3+) and acceptor (Er3+) concentration considered, both nonexponential and exponential relaxation dynamics were observed. Nonexponential acceptor fluorescence is characteristic of noninteracting donor (Yb3+) regime, while the exponential response is consistent with interacting donors. For the latter case, the linear acceptor dependence for the Yb3+–Er3+ transfer rate K implies energy super migration among donor ions.