Design considerations for vertical delta k directional coupler

Theoretical results relevant to the design of a vertical Delta kappa switch are presented. The principle of a Delta kappa switch is the modulation of the coupling length by the application of an even electrooptic perturbation on the coupling region. Power switching requires that Delta kappa L= pi /2. The initial state can be tuned electrically. The coupling length and the change with the index perturbation depend on many factors, such as the thickness and the refractive index of the coupling layer. Based on an analytic solution of the eigenmodes and eigenindices of the symmetric structure, the author clarifies many of these dependencies and obtains the relationship between the switching length required for power crossover and the available index change. The merits of the Delta kappa switch are discussed, and its efficiency is compared with that of the conventional Delta beta switch.<
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