Thermal characteristics of jacketed optical fibers with initial imperfection

Thermal characteristics of optical loss and fiber strain in jacketed single-mode optical fibers with initial fiber axis deformation have been examined theoretically and experimentally. Fiber axis deformation due to temperature change is theoretically analyzed by applying buckling theory for a bar on an elastic foundation. Optical loss increase and fiber strain are measured for two kinds of fibers which have different initial fiber axis deformation. Experimental results approximately coincide with values calculated from the theory. It is clarified from these results that the fiber strain due to temperature change is smaller and loss increase at low temperatures is larger for the fiber with larger initial axis deformation. A design method for jacketed single-mode optical fibers to prevent loss increase at low temperatures is given.