Interlaboratory comparison of radiation-induced attenuation in optical fibers. Part II. Steady-state exposures

We report herein the results of a series of round-robin experiments performed under strict procedures to determine the measurement veracity by which eventual standards may be established for measuring the effects of steady-state ionizing radiation on optical fibers. The responses of step index multimode, graded index multimode, and single-mode optical fibers exposed to ionizing radiations were measured by eight laboratories of the NATO Panel IV Research Study Group 12, Nuclear Effects Task Group, during the period of 1987-1989. The studies revealed that fiber wrap diameter, radiation dose rates, and launched power levels significantly influenced the measured radiation-induced attenuation in silica core multimode and single-mode fibers, while variations in these parameters did not affect the responses of Ge-doped silica core multimode fibers as severely. Mode scrambling and mode stripping were found not to be influential factors for increasing the measurement accuracies in either graded or step index fibers. Significant improvement in measurement accuracies from earlier studies was noted by reduction of the measurement deviation among the laboratories from greater than 25% to less than 7% of the peak induced attenuation. Discussion is focused on other important test parameters including: radiation dose, dose rates, accuracy of dosimetry, photobleaching, and instrumentation.