AWG-Based Non-Blocking Copy Networks For Optical Multicast Switching

Three-stage AWG-based copy networks for optical multicast switching are examined with regard to properties of scalability and non-blocking routing.The optical multicast switch architecture under consideration is a cascaded combination of an AWG-based non-blocking copy network and a point-to-point switching network.First,the AWG-based copy network simultaneously generates required copies for the optical signals at different input wavelength channels,and then the AWG-based point-to-point network routes these copies to their requested output wavelength channels.Firstly,we present the rank-based route and wavelength assignment algorithm in the proposed three-stage AWG-based copy networks,and prove that if the set of copy requests input to the network is monotonic,non-blocking routing can be achieved in the three-stage AWG-based copy network according to this algorithm.Due to the wavelength routing property of the AWG modules,the ordering of the numberings sequence of the input/output channels in the middle-stage subnetwork of three-stage AWG-based copy has been cyclically shifted.To retain the original ordering of these channels,we define a mapping on the set of input and output wavelengths of each subnetwork.Based on this mapping,we reveal the Order-Preserving property of the three-stage AWG-based copy networks.Secondly,based on the rank-based route and wavelength assignment algorithm and the Order-Preserving property,we propose a recursive decomposition scheme of the three-stage AWG-based copy networks,and discuss the architecture of central modules when the recursive decomposition process ends.We also quantitatively analyze the relationship between the wavelength granularity and the number of decompositions,and the relationship between number of active components and the number of decompositions.Taking advantages of the wavelength routing property of the AWG modules,we then discuss the further decomposition scheme of the AWG-based copy networks.Finally,we demonstrate that an AWG-based multicast switch can be constructed by two cascaded AWG-based copy networks.We compare this new optical switch architecture with previously proposed optical multicast switching networks.Comparing with previous works,our new design requires less active and passive components than most other switching networks,and has the smallest wavelength granularity and requires smallest size of AWGs among all AWG-based designs,and the time complexity of the required routing algorithm is only comparable to that of a unicast switch.