Electronic and optical properties of Ge-doped silica optical fiber

Electronic and optical properties of Germanium-doped (Ge-doped) silica optical fiber are investigated by employing first-principle methods. The substitution of a Ge atom with a Silicon (Si) atom or an Oxygen (O) atom in different "Si-O-Si" membered rings is analyzed. Compared with the experimental data observed at around 5 eV, our calculated results reveal that the characteristic absorption peak at 5.12 eV may be caused by Si-Ge-Si defect in 5-membered ring (5MR). Our study of Ge-doped approach in different ring structures will be useful in the application of Ge-doped optical fiber sensing.