Two-dimensional waveguide modeling of leaky-mode arrays

We examine the structure and modal gains of the leaky modes of an infinite periodic index-guided array by direct solution of the two-dimensional Helmholtz equation. These findings serve to validate the physical insights suggested by our previous calculations based on the effective-index method and, in particular, confirm the concept of guidewidth tailoring for affecting fundamental-mode operation of these devices at high power levels. Our newer model also provides new insights into the mode-selection mechanism and demonstrates clearly the necessity of a full twodimensional treatment if one is to describe the mode profiles or their relative gains accurately.