Abstract

Directional couplers are the most widely used passive devices in modern optical fibre transmission systems. However, the dispersion effects in a directional coupler have not been thoroughly investigated. Recent work [1] indicates that the common understanding, i.e., the disperison in a coupler is governed by the group-velocity dispersion, is not correct. In this paper, it is argued with the coupled-mode theory that pulse distortion in a coupler is caused mainly by the frequency dependence of the coupling coefficient.

© 1996 IEEE