Enhancement of 1.5 μm fluorescence signal from Er3+ due to Yb3+ in yttrium silicate powders pumped at 975 and 808 nm

The effect of the presence of ytterbium (Yb3+) on the near-infrared (NIR) emission profile of erbium (Er3+), more specifically the I-4(13/2) -> I-4(15/2) radiative transition around 1.5 mu m, in yttrium silicate crystalline ceramic powders prepared by combustion synthesis was investigated under different NIR laser excitation wavelengths (lambda = 808 and 975 nm). Enhancement of fluorescence around 1.5 mu m due to the presence of Yb3+ was observed, which has potential use in medicine (NIR-III biological window) and optical communications (C-band transmission window). Two different excitation channels involving energy transfer between Er3+ and Yb3+ were studied: one involving the sensitization of Er3+ by Yb3+ (for lambda = 975 nm laser light excitation) and the other involving direct excitation of Er3+ with Yb3+ acting as an energy reservoir (for lambda = 808 nm laser light excitation). The energy transfer mechanisms of both processes are discussed in the text.