Wide-band optical fiber coupler and its manufacturing method.

摘要

Two optical fibers (11, 12) are reduced in diameter over a predetermined length to form reduced-diameter portions (13) whose center portions have different diameters. The first and the second optical fibers are intersected at a small angle to each other substantially centrally of their reduced-diameter portions and then are fused together at the intersecting portions and the fused portions of the first and second optical fibers are heated and stretched to provide an optical coupler having a desired coupling ratio.