Coupling optical waveguides by tapers

Abstract

The coupling of single-mode optical waveguides through the use of expanding and contracting tapers is examined theoretically. In particular, the problems of angular and transverse misalignments of an input and output taper are investigated along with the effects of the taper itself. A tradeoff is found to exist, that is, widening the guide by means of a taper leads to less critical coupling tolerances for transverse displacements, but tighter tolerances for angular misalignment. Similar considerations apply to large core single-mode fibers.