Time-dependent degradation of photonic crystal fiber attenuation around OH absorption wavelengths

We present a study of the time-dependent degradation of attenuation in Photonic Crystal Fibers in the wavelength region from 1350 nm to 1450 nm. Changes in spectral attenuation were monitored over 16 weeks of exposure to a laboratory environment in different solid core PCF's as well as in a hollow-core bandgap fiber. Increasing spectral attenuation was observed at 1364 nm and at 1384 nm, wavelengths corresponding to known OH absorption features in silica. We also observe the appearance of a broad attenuation peak around 1398 nm. The observed degradation is shown to decrease exponentially from the ends of the fiber, and is attributed to ingress of contaminants from the fiber ends. This attribution is supported by measurements on a fiber stored with sealed ends.