Two-dimensional coupled-mode theory for modeling leaky-mode arrays

The use of a two-dimensional coupled-mode theory for modeling buried-ridge-waveguide index-guided arrays in general and leaky-mode arrays in particular is described. This formalism provides a framework for understanding the complicated modal structure of leaky-mode arrays by expressing their modes as linear combinations of the two dimensional modes of the buried-ridge waveguides and the active-region confinement structure. As a result, the inherently large parameter space of these devices may be collapsed dramatically so that the device behavior is describable in terms of only the propagation constant mismatch between the buried-ridge modes and the activeregion modes and their coupling coefficient.