OPTIMIZATION OF SYMMETRIC ZERO-GAP DIRECTIONAL COUPLERS FOR LARGE SWITCH-ARRAY APPLICATIONS.

Summary form only given. Integrated optic switch arrays require development of compact, efficient, easy to fabricate 2 multiplied by 2 switches. The optimization of such individual switches from which a large array could be formed is described. The authors consider directional coupler switches where the guide spacing is allowed to shrink to zero and find that a symmetric zero-gap coupler with modifications has significant advantages. Such a system should be treated as one structure where two normal modes propagate and not as two coupled single-mode guides. Switching arises from a large electrooptically controllable propagation phase difference phi between the modes, which accumulates throughout the interaction region.