P/Al atomic ratio dependence of local structure around Yb3+ ions and optical properties of Yb-Al-P-doped silica glass

Abstract

The local structure around Yb3+ ions in Yb-Al-P-doped silica glass and its P/Al and P/Yb dependences were elucidated by EXAFS, absorption measurements, and Rayleigh and Raman scattering. It was found that P and Al preferentially form AlPO4 diclusters in the silica glass matrix instead of forming Yb-O-P and Yb-O-Al linkages. In 0 < 1, Yb-O-P linkages do not increase even with increasing P concentration, and the Yb-O coordination number decreases from 7 to 4. In P/Al > 1, the EXAFS spectra become similar to those in Yb-P-doped silica glass, where the Yb-O coordination number is 6-7. This suggests that the local structures of Yb-Al-P-doped and Yb-P-doped silica glass are similar, but the coordination environments are different from each other. In Yb-Al-P-doped silica glass, the symmetry of the ligand field is lower than that in Yb-P-doped silica glass. Furthermore, the Yb-Yb distance is longer due to the formation of AlPO4 diclusters in the glass matrix.