Phase-locked arrays of antiguides: model content and discrimination

Three classes of array modes of closely spaced antiguides are analyzed: coupled fundamental (element) modes, coupled first-order (element) modes, and modes adjacent to coupled fundamental modes. The behavior of coupled fundamental modes as a function of lateral index step is analyzed and explained from a ray-optics point of view. It is found that at resonance, for both coupled fundamental and first-order modes, the array-mode propagation constant is virtually identical to the propagation constant of the mode of a single, unperturbed antiguide. Several types of mode discrimination mechanisms are discussed. For devices with 3-μm-wide antiguide cores and 1-μm interelement spacing, intermodal discrimination values of 15-20 cm^-1 can be achieved. Excellent agreement is found between experimental data and theoretical predictions based on the effective-index method