Nature of doping into pure silica glass by plasma torch CVD

Optical properties of Nd and Ce ion activated silica glasses and their codoping effects of Al, P and F have been investigated on the samples prepared by O₂/Ar plasma torch CVD. At a low doping level of 1×10¹⁹/cm³, most doped Nd ions begin to cluster. This results from the high enthalpy state of their coordination in which they are isolatedly dispersed in the matrix. Codoping of Al and P effectively dissolves the clustering and probably causes the coordination consisting of codopant oxisides (solvation shell), while that of F does not change the absorption and fluorescence properties of Ce doped glass due to Si-F covalent bonding formation. Preparation dependent defect like peroxy linkage in SiO₂ glass is suggested to have influence upon doping state of Ce doped at the same level with the defect density, on the basis of EPR centers induced by XeCl excimer laser irradiation. Possible application of solvation shell model for coordination control around active ions in SiO₂ glass is discussed.