New switching element for large optical interconnection networks

Optical interconnection networks for linking a large number of users require the use of particular switching elements. For the classical 2 X 2 switching elements, in order to maintain the control voltage as low as possible, the length of the element cannot be less than a few millimeters. For this reason, the total number of stages implementable on a single LiNbO3 crystal must be contained and the number of users N cannot be above 8. In order to extend the network dimensions, a different network architecture must be chosen which requires a new type of (alpha) X (beta) switching element. Generally speaking, (alpha) equals 2n and (beta) equals 2m with n does not equal m. In this paper we present a 4 X 4 switching element for which two different solutions are considered. The design criteria of these structures are presented and the insertion loss and crosstalk are evaluated.