Fiber optic directional coupler.

摘要

A fiber optic directional coupler (10) comprises a pair of bases (16), with respective longitudinal, arcuate grooves (13) formed therein on confronting faces (14) thereof, for mounting a pair of optical fibers (12) in close proximity. A portion of the cladding is removed from each of the fibers (12) to form planar facing surfaces (18) which permits the spacing between the fiber cores to be within a predetermined critical zone (34) so that guided modes of the fibers (12) interact, through their evanescent fields, to cause light to be transferred by evanescent field coupling between the fibers (12). The coupler (10) is "tuned" to a desired coupling efficiency by offsetting the planar facing surfaces (18) to increase the spacing between the fiber cores. A method of manufacture of the coupler includes procedures which permit the coupler halves to be made symmetrical. The method also permits couplers (10) having given coupling characteristics to be reproduced.