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.