Cathodoluminescence of defects in optical fibres and optical fibre preforms

Cathodoluminescence (CL) in the scanning electron microscope has been applied to the analysis of germanosilicate preforms and optical fibres prepared by the MCVD process. While generally sensitive to the distribution of dopants, CL is an even more sensitive indicator of defects in these materials (such as those attributed to GeE' centres) introduced during fabrication. Some preforms manufactured under different conditions were analysed by CL to assess the influence of fabrication technique on the introduction of defects. Results indicate that CL could be useful for routine analysis of optical fibre preforms and for assessing the development of process control for optical fibre manufacture.