Influences of Yb3+ ion concentration on the spectroscopic properties of silica glass

We investigated optical spectroscopic properties of silica glass doped with ytterbium (Yb³⁺) ions to assess their lasing performance in diode-laser pumped systems. The Yb-doped silica glass preforms were fabricated by solution doping technique using the MCVD process. The stimulated emission cross-section and laser performance parameters were determined from the measured absorption spectra using the method of reciprocity. Fluorescence decay characteristics were observed to be deviated from exponential behavior as the Yb³⁺ ions doping level increases and there exists a lifetime quenching behavior related to the cluster effect of Yb³⁺ ions into silica glass. Nevertheless, lasing parameters indicated that clustering of Yb³⁺ ions does not significantly affect the spectral properties relevant to the predicted lasing performance when concentration is low, but becomes predominant at higher concentration.