Measured Attenuation and Depolarization of Light Transmitted Along Glass Fibers

The possibility of using glass fibers as dielectric waveguides in optical communication systems is well known. This paper describes the light (A = 6328 A) transmission properties of unclad glass fibers surrounded by index matching oil. Their characteristics are compared with those of similar clad fibers in which the cladding was glass. Two types of optical measurements were made: the attenuation and the state of polarization of the light from a fiber end. Measurements were made on several sizes of fibers (28 pm and 13 jum diameter unclad fibers; 19 / . and 3 ^m core diameter clad / m fibers) .* The index of refraction of the oil medium surrounding unclad fibers was varied to mismatch the bulk glass by 8.94, 3.05, and 1.17 percent. The clad fibers were surrounded by glass whose refractive index was 0.824 percent lower than that of the bulk material.1 * All fibers were manufactured by DeBell and Richardson, Inc. of Hazardville, Connecticut. The bulk material of the core was S S K l glass. Its index of refraction was measured to be 1.614 at 6328 A. 23