OH absorption in GeO2-doped fused silica fibres

The OH-ion absorption of SiO2/GeO2-core step-index multimode fibres in the 1.2?1.6 ?m region has been studied in relation to changing GeO2 concentrations. It was found that the OH absorption band at ? 1.4 ?m in SiO2/GeO2-core fibres had two components with maxima at 1.39 ?m and 1.42 ?m related to the first overtone of the fundamental OH vibration in SiO2 and GeO2, respectively.