Principles of all-optical switching fabrics with minimum number of stages

The concept of all-optical minimum-stage switching fabrics is presented and compared with other competitors. The multilayer architecture is based on decomposing permutations into parallel transpositions. The O(1)-switching fabric requires the largest number of 2x2-switches, but offers a considerable reduction of the number of stages (NS) (in principle, 3 stages for any size of the switching fabric). Thus a low attenuation of signals passing the switch is expected. However, the (uniform) subdivision of the inputs by the 'splitters' and the crosstalk are further problems which will be analysed in a forthcoming paper.