The effect of optical fiber endface surface roughness on light coupling

This paper presents a quantitative measurement of the effect of surface roughness of optical fiber end-faces on light coupling efficiency. Fibers tested included cleaved fibers and fibers with ground endfaces of varying degrees of surface roughness. The endfaces were ground on a specially built nano-grinding machine. The assessment was based on the Gaussian distribution of the intensity of light collected from both the cleaved and the ground endfaces of the fibers. Measurements of the total amount of light at the output end were also made. Results showed that light-coupling efficiency has improved dramatically with the improvement of surface finish. Surface roughness measurements were carried out using atomic force microscopy (AFM).