International audienceAbstract—The radiation responses of two erbium doped fibers are studied in harsh pulsed X-ray and gamma ray environments. Their transient and continuous responses were measured in the near-infrared spectral range. The online transmission measurements of Radiation-Induced Attenuation (RIA) show no detectable change in the 1450–1600 nm erbium-ions-absorption domain, whereas the background losses from the silica-based host matrix are strongly increased by the creation of point defects. For both harsh environments, the rare-earth doped samples exhibit higher RIA levels compared than standard passive optical fibers. From all our measurements, we proposed that the main contribution to the induced losses is due to the radiati...