In-Situ Observation of Fiber-Fuse Propagation

Ultrahigh-speed photographs of fiber-fuse propagation in single-mode silica fibers revealed a new factor, other than pumping laser power that affects the morphology of damage sites: the length of the running optical discharge. Nine W pumping of 1480 nm light generated a discharge of ~130 um in half-width moving rapidly and leaving discrete voids along the fiber core, whereas 2-W-pumped discharge was ~27 um long, moved slowly and left nearly continuous thin voids. This is because 9-W-pumped discharge takes a longer time to travel its half-width, about 5/3 times longer than that of the 2-W-pumped discharge, which provides longer interaction time for modifying the fiber core.