Optical waveguide switch (3 x 3) for an optical switching system

A new optical switch element is proposed for a switching system which exchanges optical signals in optical transmission lines without optoelectric conversion. It consists of three parallel equidistant straight singlemode waveguides fabricated of an electrooptic material with electrodes deposited on them. The element, whose interaction length is pi/(2)((1/2))k (k is the coupling coefficient of neighboring guides), serves as a 3 x 3 optical switch by control of the differences in propagation constants between those waveguides. Control conditions to realize all the six connecting states of a 3 x 3 switch are discussed with the solution of the coupling equation for those guides.