Asymetrically dilated optical cross connect switches

摘要

A horizontally asymmetrically dilated optical switch comprising multiple stages of 2x2 optical switching units, especially electro-optic switching units such as acousto-optical tunable filters (AOTFs), which are electrically switchable between a bar state and a cross state to route and switch an optical signal through the switch. The switch is dilated that is, the switching units have an unused input or output so as to dump crosstalk terms into unused outputs. According to the invention, the interconnections between the switching units and their control are such that any optical signal and any crosstalk path passes through equal numbers of bar-state switches and of cross-state switches. Thereby, two advantages are gained. First, no switching path is transparent to a wide bandwidth so that noise cannot recirculate in an amplifying path and go into oscillation. Also, if one state or the other produces greater crosstalk, along no switching path is the larger term accumulated more than the smaller term.