Martin expression about the quantum defect of single-valence atoms is extended to many-valence atoms by identifying the weakest bound electron (WBE) under the weakest bound electron potential model (WBEPM) theory. Six Rydberg series energy levels of 2p6np
Two silica host magnesium(Mg)-aluminum(Al)-germanium(Ge) co-doped erbium-doped fibers (EDFs) have been fabricated, which have different Mg concentrations. The concentration of all the compositions in the preform is measured through electronics probe micro