Radiation sensitivity of passive components of fibre optic data transfer and sensor systems

Test results of residual passive components of fibre optic systems (apart from optical fibres), such as connectors, couplers, wavelength division multiplexers (WDMs), and optical glues are presented. Most of the components were only irradiated at a 60Co gamma ray source with a dose of about 0.2 Gy/s up to a final dose of 100 (integrated optic devices) or 10E4 Gy (fibre optic components). Direct connectors can contribute < about 0.3 dB to the total loss (10E4 Gy), compared with 0.3 to 0.6 dB for lens connectors. The measured coupler inherent losses were between about 0.01 dB (fused coupler, high OH multimode stepindex fibres, lambda=865 nm) and about 50 dB (coupler made of GRIN lenses, lambda=865 nm). Fused WDMs showed negligible loss increase at the high power outputs and an increase of output power of up to several dB at the isolating output, as well as shifts of the isolating and throughput regions between about 5 and 14 nm (10E4 Gy). Optical glues of 0.02 to 0.04 mm thickness showe d noticeable loss increase only for wavelenghts < about 500 nm (10E4 and 10E5 Gy).