Abstract

A new theory describing coupled mode propagation in an array of coupled arbitrary optical waveguides is developed. The formulation unambiguously accounts for real and/or imaginary index perturbations and its solutions yield array mode (supermode) patterns and propagation constants. Several examples of coupled TE slab waveguides are evaluated and the results are shown to compare very favorably with exact solutions. The calculated propagation constants and mode patterns differ quantitatively and qualitatively from those derived from the prior theory. In particular, the array mode gains derived according to the new theory agree very well with exact solutions and predict different ordering and splitting than those derived by the prior theory. These results are illustrated by examples of real-refractive-index 10-waveguide arrays with various chirps in waveguide dimensions and locations. Near-field and far-field patterns are shown for the array modes (supermodes) generated by such lasers.

© 1985 Optical Society of America