Measurement of long term, radiation induced losses in fibre optics using optical time domain reflectometry

Fibre optics exposed to ionizing radiation, exhibit enhanced transmission loss. Recovery processes can take place over a wide time scale and, for extended exposures, as in space, will limit the observed loss. Prediction of the survivability of a fibre optic link in such an environment requires knowledge of the form of the recovery over a time comparable with the mission duration. The use of an Optical Time Domain Reflectometer to make the appropriate measurements with the necessary accuracy and sensitivity is discussed, and results are presented for recovery curves, extending to time <1 year, for a number of fibre types