Transmission Properties of Optical Fibers*†

Abstract

Equations which describe the flux transmitted and the angular distribution of the emergent light from straight cylindrical fibers of circular cross section have been derived and numerically evaluated. Loss of light due to imperfect reflections, bulk absorption, and Fresnel reflections, are included in the formulation. All skew rays in the fiber have been considered in these calculations.Measurements of the attenuation and angular distribution of the emitted light from plastic scintillating fibers have been made. From the theoretical equations it has been deduced that these fibers are characterized by an internal reflectivity of 0.993±0.002 and an absorption coefficient of 0.015±0.003 cm−1.Measurements of the light transmitted by single-clad glass fibers indicate that these fibers are characterized by an internal reflectivity of 0.9993±0.0002 and an absorption coefficient of the order of 10−4 cm−1. Some experimental data on glass fiber bundles also are included.