An E cient Signal Distinction Scheme for Large-scale Free-space Optical Networks Using Genetic Algorithms

Free-space optical interconnection networks can be classi ed into two types, space variant and space invariant, according to the degree of space variance [1]. The degree of space variance determines the network's complexity and regularity. A totally space variant network allows a completely arbitrary interconnection between nodes, whereas a totally space invariant network has a de nite, regular structure with all the nodes having the same connection patterns. In terms of physical implementations, the degree of space variance can be interpreted as the degree of sharing beam steering optics among the nodes of a given network. In other words, all nodes in a totally space-invariant network can share a single beam steering optics (considering multiple fanouts as one steering optics) to realize the given network topology, whereas, in a totally space variant network, each node requires a distinct beam steering optics. This is one of the reasons why space variant networks require complex optical implementations that often result in low interconnection density and high cost.