Mode structure and lateral confinement in strip-loaded optical waveguides: Effects of asymmetric cladding

Strip-loaded waveguides formed from three dielectric layers are used in integrated optics to confine and channel light in two dimensions. The numerical analysis reported shows that modal characteristics of such systems can be strongly affected by any differences between the refractive indexes of the upper and lower cladding. Asymmetries that tend to shift intensity toward the upper cladding generally act to tighten lateral confinement, introduce additional lateral modes, and displace the modes up into the strip. These effects are explained by noting the interplay of vertical and lateral confinement in a strip-loaded waveguide, and by analogy to one-dimensional slab waveguides.<
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