Attenuation and Scattering of Light in Optical Fibers-Effects of Nuclear Radiation (Modulation and Display of Laser Radiation)

This study consists of measurements of effects of nuclear radiation on attenuation and pulse dispersion and light scattering in optical fibers. The radiation induced attenuation in a number of optical fibers was evaluated. Several different types of fibers were exposed to steady state nuclear radiation and the resulting decrease in transmitted power was monitored as a function of wavelength and radiation dose. The wavelengths examined were in the visible and near IR regions that are of specific interest for optical fiber communications. The fibers showed a decrease in transmitted power at all wavelengths examined. The radiation sensitivity in glass core fibers was observed to show dependence on factors such as impurity content and the index modifying dopants in the fiber. Experimental measurements of neutron radiation induced pulse dispersion changes, and attenuation changes in a 100 micron core step index fiber were made. In the course of irradiation pulse dispersion in the fiber was observed to decrease while the attenuation increased. Results indicate greater decreases in the transmission of higher order modes. This reflects the fact that the radiation response of a fiber is determined by the respective refractive indices and absorption coefficients of both the core and cladding of the fiber. Results are presented along with a discussion of mechanisms by which dispersion changes can occur in irradiated fibers.