Design and analysis of a hierarchical scalable photonic architecture

This paper introduces a hierarchical optical structure for processor interconnection and evaluates its performance. The architecture is based on wavelength division multiplexing (WDM) which enables multiple multi-access channels to be realized on a single optical fiber. The objective of the hierarchical architecture is to achieve scalability yet avoid the requirement of multiple wavelength tunable devices per node as with the WDM-based hypercube interconnection scheme. Furthermore, single-hop communication is achieved: a packet remains in the optical form from source to destination and does not require cross dimensional intermediate routing. The wavelength multiplexed hierarchical structure features wavelength channel re-use at each level, allowing scalability to very large system sizes. It employs acousto-optic tunable filters in conjunction with passive couplers to partition the traffic between different levels of the hierarchy without electronic intervention. A significant advantage of the proposed structure is its ability to dynamically vary the bandwidth provided to different levels of the hierarchy. The architecture is compared to a wavelength-flat architecture in terms of physical and performance scalability