Stress-Loss Correlation and Dispersion Control in Highly GeO2-Doped Fibers

We report a fabrication route to achieve highly GeO
₂
-doped silica fibers with GeO
₂
molar concentration as high as 74% using the conventional modified chemical vapor deposition (MCVD) process. The dependence of background loss on fiber frozen-in stress in these highly doped fibers is investigated. A central dip of refractive index in the core is found to introduce stress variation, and contribute to the background loss. Dispersion control and supercontinuum generation in 2.1-2.8-μm region using the 74-mol% fiber are also presented.