Cooperative upconversion in erbium-implanted sodalime silicate glass optical waveguides

Soda-lime silicate glass has been locally doped with 0.2-at.% erbium by 3.0- and 5.0-MeV ion implantation. Single-mode fiber-compatible optical waveguides were then fabricated by use of Na⁺ <-> K⁺ ion exchange. Characteristic photoluminescence (PL) of Er³⁺ centered at 1.54 µm is observed on excitation at 1.48 µm. For low pump intensity the PL decay is nearly single exponential with a lifetime of 7.2 ms. At high intensity it becomes nonexponential as a result of cooperative upconversion, an interaction between excited Er ions. Self-consistent modeling of the PL intensity and decay data yields an upconversion coefficient of 3.2±0.8×10^-24m³/s. The effect of upconversion on optical gain is shown and discussed. An extrapolation of measured optical gain shows that 1 dB/cm of net gain is possible in the present Er-implanted soda-lime glass.