Low-OH MCVD fibres without a barrier layer using OH → OD-exchanged substrate tubes

The effect of deuteration (OH → OD exchange) of the MCVD substrate tube on the absorption loss in fibres was studied using tubes of moderate and low OH content. The OH absorption at 1.39 μm was reduced from 4 dB/km and 0.9 dB/km to 1 dB/km and 0.7 dB/km, respectively, in fibres made without a barrier layer using deuterated tubes.