Abstract

Although there have been laboratory tests of the repeatability of backscattering attenuation measurements⁽¹⁾, there has yet been no careful assessment of the sensitivity of the backscattering technique to launching conditions. It has been shown^(2-3) that a mode-filtering technique can be used to eliminate power fluctuations due to slowly varying fiber parameters. The resulting power decay function then represents a measure of the actual fiber loss. However, graded index multimode fibers can also exhibit rapid parameter variations and differential scattering and absorption effects which cause excess loss. The present work applies some simple modelling of the differential mode attenuation process to interpret the results of back scattering and cut-back measurements of the variation of attenuation of telecommunication grade fibers with launching conditions.