Investigation of saturation and excitation behavior of 1.5 μm emission from Er3+ ions in SiO2 sensitized with Si nanocrystals

Using time-resolved photoluminescence spectroscopy we investigated the 1.5 μm emission from Er3+ ions embedded in SiO2 matrix sensitized with Si nanocrystals. Temporal characteristics are analyzed as the function of excitation powers and temperatures. We confirm the predominance of two excitation channels - a fast one, with nanosecond dynamics, and a slow one, taking place on the microsecond time scale. Upon increasing excitation power, the fast mechanism saturates and further increase of total photoluminescence intensity is facilitated by the slow energy transfer process. Consequences of this finding on the microscopic modeling of the excitation process are discussed