Current progress of advanced high speed parallel optical links for computer clusters and switching systems

This paper discusses the present state of the art of parallel optical links for interconnection systems required e.g. in computer clusters and telecom terabit switching systems. The dramatic growth of bandwidth demand in interconnection systems drives the throughput of parallel optical links to over 30 Gbit/s per optical module. The system architecture, the electro-optical components and the performance of an asynchronous 12 channel parallel optical link, PAROLI(R), that carries data at 1.25 to 2.5 Gbit/s per channel is described. Methods of system performance evaluation by eye diagram analysis and BER scan techniques are discussed and measurement results are shown. In addition, a parallel link for synchronous data transmission, attractive for computer systems, is presented for data rates up to 1.25 Gbit/s per channel (DC-PAROLI(R)). Channel-to-channel skew limits the data rate and transmission distance of such a system. Therefore, concepts for active skew-compensation are described to overcome the bandwidth-distance limitations.