<title>Gamma-ray vulnerability of light-emitting diodes, injection-laser diodes, and pin photodiodes for 1.3-um-wavelength fiber optics</title>

Abstract

With the increasing use of optical data links it becomes essential to test for radiation vulnerability not only the transmission support -fiber and cable -but also fiber-end electro-optical components that could be exposed to hostile environment. Numerous silica-based fibers were currently tested over the world. Present paper gives a comparison of radiation resistance between two gradient index multimode fibers with and without phosphor in core. From that result a technological change in standard 1.3 m wavelength light-emitting diodes (LED), injection-laser diodes (LD) and p-i-n photodiodes (PD) was made. Results of tests under steady-state medium dose-rate Co° exposure show a significant enhancement of improved components optical performance. Especially LED and PD present a small degradation of optical caracteristics for 50 kGy (for a dose-rate of about a few 10 Gy h1). Multicomponent laser-diode modules (LDM) were extensively tested up to about 20 kGy. Two degradation processes clearly appear : a wrong decrease of stimulated light emission after 3-4 kGy and a bad operation of thermoelectric element cooler beyond about 10 kGy. Hardened optical data links are now able to withstand successfully some nuclear environments.

Optical Fibres in Nuclear Radiation Environments

“…All of these elements are also sensitive to ionising radiation and they have also been subjected to radiation experiments [8,10,37]. Though it is very important to know their behaviour in radiation fields, the effects of radiation on these components may be considered as less important than on the fibre itself since where possible, sources and detectors should be isolated from radiation.…”