Photonic 2×2 switching node for 160 Gb/s interconnection networks

A modular photonic interconnection network based on a combination of basic 2×2 all-optical nodes where a photonic combinatorial network manages the packet contention, is presented. The proposed architecture is synchronous, can operate Optical Time Division Multiplexing (OTDM) packets up to 160Gb/s and exhibits self-routing capability and very low switching latency. In such a scenario, OTDM has to be preferred to Wavelength Division Multiplexing (WDM), because in the former case the instantaneous packet power carries the information related to only one bit, making more simpler the signal processing based on instantaneous nonlinear interactions between packets and control signals. Moreover OTDM can be utilized in interconnection networks without caring about the propagation impairments, since these networks are characterized by a very limited size (< 100m). Finally, in such a limited domain, the packet synchronization can be solved at the network boundary in the electronic domain, without the need of complex optical synchronizers. The 2×2 switching element is optically managed by exploiting a photonic combinatorial network able to carry out contention detection, and to drive the contention resolution and the switching controller blocks. The implementation of such photonic combinatorial network is based on semiconductor devices, making the solution very promising in terms of compactness, stability, and power consumption. The network performances have been investigated for bit streams at 10 Gb/s in terms of Bit Error Rate (BER) and Contrast Ratio. Moreover, the suitability of the 2×2 photonic node architecture exploiting the above mentioned combinatorial network, has been verified up to 160 Gb/s, demonstrating the potentialities of photonic digital processing in the next generation broad-band and flexible interconnection networks.