Long-term reliability of single-mode fibers when exposed to high-power laser light

The reliability of a pure silica-core single-mode fiber (SCF) and a germanium-doped fiber [dispersion-shifted fiber (DSF)] with long-term exposure to continuous-wave (CW) high-power laser light is reported. It was found that the optical loss in the 0.6-1.6-μm region and the Raman spectra of SCF and DSF remained unchanged after 1900 h of exposure to an 8-W CW laser light and 2000 h of exposure to an 8.5-W CW laser light at 1.48-μm, respectively. The nonbridging oxygen hole center (NBOHC) concentration generated in SCF by 1900 h of exposure is estimated to be below the detection limit of 2×10¹² cm^-3. SCF and DSF can be expected to exhibit long-term (> 20 years) reliability when exposed to several watts of laser power in the S, C, and L bands in terms of optical degradation due to defect formation via multiphoton absorption.