Clustering in erbium-doped silica glass fibers analyzed using 980 nm excited-state absorption

Abstract
A nonsaturable component to the 980 nm excited state absorption (ESA) is found in Er3+‐doped silica glass fibers. This anomalous behavior of the ESA provides a way of quantitatively characterizing the degree of clustering in these glasses. It is found that the degree of clustering is greater for higher Er3+ concentrations, and is significantly reduced with the addition of aluminum to the glass. With this method it is also found to be possible to distinguish between true clustering and the occurrence of closely spaced Er3+ pairs in a random distribution.