摘要： In this work, the investigation of radiation response for modified cladding multimode optical fibres exposed to UV radiation (N2 Laser) in terms of Radiation-Induced Attenuation (RIA) had been presented. The optical fibres were tapered to 65 and 60 μm then dipped into (5wt % of Germanium to modify the cladding region. By exposing these fibres to different energies of UV irradiation, the transmission spectra were online monitored and recorded every ten seconds to analyze the attenuation changes with the increasing of the radiation dose. The experimental results revealed two points: the first point is that the sensor undergoes the RIA effect which is resulted from the interaction between the radiation and the dopant material, and the second point shows that the sensitivity increases as the diameter of the sensor decrease. From these outcomes, we can conclude that such a sensor can be employed in different dosimetry applications.