Ion Beam, SEM and EDXRS Analysis on Doped SiO2 Optical Fibres

Abstract

Optical fibres have been demonstrated by this group to show promising thermoluminescence (TL) properties with respect to ionizing radiation for low-energy X-rays, megavoltage photons, - rays, accelerated electrons and accelerated protons, α -particles and fast neutrons. Present research has focused on commercially produced single-mode telecommunication optical fibres manufactured by INOCORP (Canada). These being either in the form of SiO 2 optical fibres doped with Ge or Al at concentrations appropriate for total internal reflection, as required for telecommunication fibres. It is to be noted that dopant concentrations are not included among the data provided in the accompanying product data sheets. Each of these INOCORP fibres has a core diameter of 125.0 ± 0.1 ! m. To achieve this aim using ion beam analysis, PIXE (Proton Induced X-ray Emission) which, while having limited depth resolution, can unambiguously identify elements and analyse for trace elements with detection limits approaching ! g/g. For Al-doped fibres, dopant concentration in the range 0.98 - 2.93 mol % have been estimated, the equivalent range for Ge-doped fibres being 0.53 - 0.71 mol %. Based on SEM (Scanning Electron Microscope) and EDXRS (Energy Dispersive X-ray Spectroscopy) analysis, the Al-doped fibres were evaluated to have dopant concentrations in the range 0.35 – 0.88 mol %, the equivalent range for Ge-doped fibres being 0.15 - 0.19 mol %.