Hydrogen effects in installed cables and under accelerated conditions

Attenuation increases have been measured on installed cables containing high-phosphorus doped fibres, mainly at wavelengths above 1300 nm, the operating wavelength. The hydrogen concentration was determined in some of these cables, making possible a correlation with fibre-in-hydrogen tests. An accelerated aging test was carried out in which two types of cable, each containing three types of fibre, were held at 90¿¿C. Using data from the field measurements and from the aging test, it was confirmed that the fibre-in-hydrogen test results can be extrapolated to the low hydrogen pressures present in cables. The upper limit for degradation of single-mode fibre after a long period in cable was calculated, and shown to be negligible.