Origin of periodic void formation during fiber fuse.

An optical discharge running through a single-mode silica glass fiber during fiber fuse was observed and the front part of the generated damage was examined. Their pump power dependences were investigated using a 1.48 mum laser light at powers ranging from 1.1 to 9.0 W. Periodic voids were left by an optical discharge that was in a cavity with a tail. The tail appears because the optical discharge is strongly enclosed in core region. Another mode of periodic void formation was found at near the threshold pump power for fiber fuse propagation. The optical discharge in this case also forms a transient tail during the void formation cycle.