Transmission Loss of Electromagnetic Wave in Deformed Optical Fibers

Abstract

It has been found that the transmission loss of electromagnetic wave in deformed optical fiber cables, caused by mechanical installation forces and thermal stresses from the environmental temperature variation and the large difference in thermal expansion coefficients between glass fiber and coating material, may seriously influence and eventually destroy the normal operation of communication systems with optical fibers as transmission media. To study this phenomenon, especially the microbending loss in single-mode fibers at low temperature, a theoretical model based on electromagnetic wave mechanics is therefore being introduced in this paper. Formulae of calculating the transmission loss in various types of deformed optical fibers and cables are then derived. Some experiments on the testing of attenuation of electromagnetic power flow in optical fibers at low temperature are also performed. It is shown that the calculated excess losses in single-mode fibers and fiber cable with random bends from the fiber buckling at low temperatures can be in good agreement with the experimental measurements. Discussions on the optimal construction of optical fiber and fiber cables for having low transmission losses caused by the deformation of the fibers are finally given.