WDM Optical Interconnects: A Balanced Design Approach

In this paper, we develop a new design approach to wavelength division multiplexing (WDM) optical interconnects with the objective of designing cost-effective and scalable interconnects. Our design philosophy strikes a balance between switching and conversion costs, and requires wavelength conversion only between two fixed and predefined wavelengths. The proposed design approach exploits the potential of the wavelength exchange optical crossbar (WOC) - a device that can switch signals simultaneously and seamlessly both in space and wavelength domains. We propose a novel crossbar switch that minimizes hardware and control complexity and use it as a building block for developing a new class of three-stage Clos-like WDM optical interconnects. The design space of the proposed interconnect is characterized and its hardware complexity is analyzed. We also show that the proposed crossbar switch and the new class of WDM interconnects admit most existing routing algorithms with simple modifications. In addition, we show that our design approach can be generalized to develop a class of k-stage interconnects, 3 < k les 2 log₂ N-1.