Cascading switching nodes in data vortex optical packet interconnection network - Electronics Letters

Introduction: Ultra-high capacity optical interconnection networks are considered as a potential solution to the immense processormemory access communications bottleneck, which is expected to dominate high-performance supercomputers [1, 2]. Optical packet switching fabrics have the potential to supply this next-generation technology with the performance characteristics necessary for efficient communications between supercomputer processor, memory and storage elements, even within systems containing thousands of such elements [3, 4]. The data vortex is one optical packet network designed specifically for large-scale processor-memory interconnections [5]. Its unique synchronous implementation and distributed control scheme not only eliminate the necessity for internal optical buffering, but also enable low switching latency and high throughput. Most large-scale optical packet switches recently considered, including the data vortex, share the semiconductor optical amplifier (SOA) as the central active optical switch component. The potential benefits of the SOA-based switching elements are well known and include: high-speed switching, high extinction ratios, sizable operating bandwidth, and relatively compact footprint [6, 7]. It follows that the physical layer scalability of large SOA based switches will depend primarily upon the successful propagation of optical packets through multiple cascaded SOA elements. Recent simulations of the data vortex have shown that a moderately loaded interconnection network with over 10 k ports requires fewer than 45 node ‘hops’ for 99.99% of the injected packets [8]. Researchers have examined the performance of cascaded SOAs as in-line amplifiers in a transmission system both numerically and experimentally [9, 10]. Numerical studies on the performance of cascaded SOAs specifically configured as switching gates have shown that the initial signal dynamic range and the number of cascaded gates are the two critical system parameters [11, 12]. In this Letter, we demonstrate the routing of 10 Gbit=s optical packets through 72 SOAbased data vortex switching nodes in a re-circulating test-bed. The input power dynamic range can be greater than 15 dB for 50 cascaded nodes. The results indicate the potential physical layer scalability of the data vortex to port counts relevant for high-performance computing interconnection networks.