FAILURE CASE-STUDY FOR LOOSE TUBE JACKETED OPTICAL FIBERS

In fiber optic devices, the 250 to 400-mu m-diameter tight jacketed fi bers are sometimes jacketed additionally by loose tube-type materials. However, the loose tube jacketed fibers fail possibly due to the shri nkage of the loose tubes, if the tubes are not stabilized enough by pr eheat aging, etc. Although such phenomena are empirically known, here when the loose tube shrinks, the inner fiber is found to relax by bein g helically deformed. As a result, commercial fibers could endure at l east 1-1.5% longitudinal shrink without a mechanical break, but exhibi ted excess optical propagation losses due to the bending. (C) 1998 Aca demic Press.