Optical Aging of Chalcogenide Microstructured Optical Fibers

The evolution with time of optical transmission of chalcogenide microstructured optical fibers has been studied. Microstructured optical fibers with “grapefruit” geometry (six holes) have been prepared from four glass compositions (Te
₂₀
As
₃₀
Se
₅₀
, As
₃₈
Se
₆₂
, Ge
₁₀
As
₂₂
Se
₆₈
, and As
₄₀
S
₆₀
). Optical aging has been investigated by means of attenuation measurements carried out for each fiber. Fibers were stored in air between measurements. Transmission spectra show absorption bands due to O-H bonds and molecular water. Aging kinetics vary with glass compositions. For As
₄₀
S
₆₀
glass, the O-H absorption band appears 2 h after the drawing step, while for Te
₂₀
As
₃₀
Se
₅₀
glass that band is observed after an aging period as long as 21 months.