Gamma radiation effects on Long Period Gratings and transmitted power in different optical fibers: towards dosimetry applications

In this work, we present a comparative study of the effects of gamma irradiation on standard and radiation hardened optical fibers. The analysis is focused on: i) resonant wavelengths shifts of the attenuation bands in Long Period Gratings (LPGs) written by Electric Arc Discharge technique in these fibers; and ii) the radiation induced optical power losses. Different responses were observed during the irradiation, depending on the fiber type: the standard fiber exhibits significant changes in terms of resonant shift and optical transmission loss, while the radiation resistant fiber, with doped core, exhibits trivial power losses but still significant LPG resonant wavelength shift. Moreover, the pure silica core fiber is completely insensitive to radiation in terms of both investigated effects. By combining the results with numerical modeling, the LPG proved to be a valuable tool to evaluate the radiation effects on the studied optical fibers. Additionally, the possibility of developing an all-fiber, temperature compensated, gamma dosimeter is envisaged.