Fiber-optic link components for maintenance tasks in thermonuclear fusion environments

Abstract

Up to now, fiber optics and several photonic components have been considered for space and nuclear power plant applications, mainly at relatively low dose rates and total doses. In this paper, we present our recent results of particularly high dose gamma irradiation tests performed with different fiber-optic components intended for applications in enhanced radiation environments such as ITER (International Thermonuclear Experimental Reactor), We present a radiation induced loss at 1310 nm as low as 30 dB/km, measured at a cumulated dose of 3 MGy for a pure-silica core single mode fiber. On-line measurements with commercially available vertical-cavity surface-emitting lasers (VCSELs) emitting at 850 nm confirmed their excellent radiation hardness. Furthermore, we demonstrated that an initial power loss of about 6 dB is caused by an early degradation of a focusing lens in these connectorized components. A combined effect of dose rate, cumulated dose and temperature on the degradation of our devices under test (DUT) is evidenced.