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 < P/Al < 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.