A study of environmental effects on the attenuation of chalcogenide optical fibre

The attenuation of a number of chalcogenide glass optical fibres has been studied with regard to their exposure the environment. We demonstrate that gallium lanthanum sulfide (Ga:La:S) based glasses appear to be as resilient if not more so than arsenic sulfide (As₂S₃) glass to the attack of moisture when stored uncoated in ambient conditions for various periods exceeding 1 year. The increase in the characteristic OH^- attenuation peak was ∼3-4 dB/m for all fibres following storage. Given the significant improvements achieved in As₂S₃ glass technology over recent years we believe that Ga:La:S based fibres can also be improved to at least match these levels with the advantage of being non-toxic and having a significantly higher melting temperature. Studies of the time-dependant attenuation of the optical fibres during immersion in water have also been carried out. These results show that the deleterious effect of moisture on these glasses occurs over a short time, ∼24 h, thus having implications on the treatment and storage of fibre preforms prior to optical fibre drawing.