Macro-Bending Influence on Radiation Induced Attenuation Measurement in Optical Fibres

Abstract

Abstract-Influence of the bending radius on the measurement of radiation induced attenuation in glass optical fibres is discussed in this paper. Radiation induced attenuation measured in two single-mode fibre types shows discrepancies when coiled around a low bending radius spool: the observed attenuation is lower than expected. A series of dedicated tests reveals that this invalid measurement is related to the displacement of the mode field towards the cladding when the fibre is bent with a low radius, and to the different radiation resistances of the core and cladding glasses. For irradiation tests of optical fibres, the spool radius should therefore be carefully chosen.

Characterization of Radiation-Resistant Multimode Optical Fibers for Large-Scale Procurement

“…Two optical fibres of 60 m long were irradiated at the same time, each fibre being coiled around an Aluminium spool of defined radius and placed around a 60 Co source of known radioactivity. The spool diameter was kept above 110 mm to avoid macro-bending influence during the irradiation [18]. The distance of the sample from the source determines the dose rate at which the fibre is exposed to.…”