Optical loss stability of a fiber cable under lateral force and optimum design of the coated fiber structure.
Optical loss increase characteristics under lateral force were investigated to determine the load limit for coated fiber. Plastic deformation of the coating was analyzed, and the loss increase was found to occur in the large deformation region beyond a limit theoretically determined using structural dimensions (diameter and thickness) and the material constant of the coating. The optimum coating structure for preventing loss increase has been designed by introducing the result of the lateral deformation limit as well as fiber stress induced by the lateral force and fiber strain at low temperature. The nylon outer and silicone layer diameters are 0.9 and 0.4 mm, respectively.
Transmission loss of coated single-mode fiber at low temperatures.
Coated single-mode fibers with various coating thicknesses were manufactured, and loss increases due to cooling were measured. It was found that the excess loss increases steeply in the small V-value region at low temperatures. A simple model for fiber bends in the coating was introduced, and the increases in loss were related to the strain resulting from use of the model. It would appear that the axial compressive strain has a serious influence on the loss increases. A suitable silicone buffer layer for preventing loss increases has been determined. The selected silicone layer diameter is 0.45 mm for a 0.9-mm nylon outer layer diam.
Nylon-jacketed optical fibre with silicone buffer layer
We have developed an optical fibre having a silicone buffer layer which is stable against various environmental attacks. The transmission loss of the fibre after cabling was only 2.3 dB/km at 0.85 ?m.