Optical interconnects for information distribution networks

Optical interconnections for information distribution provide advantages of a high distance-bandwidth product, high density, immunity to EMI and in some cases reduced weight and volume. This paper describes several interconnect technologies being developed at Honeywell. Serial, high speed (approximately 1 Gbit/sec) fiber optic data communication modules are being developed for applications including local area networks, links to peripherals and supercomputer cabinet-to-cabinet interconnects. These modules are being incorporated onto boards under the "PRISM" program to be inserted in the Intel Paragon supercomputer in order to enable this machine to be expanded to two rows of cabinets separated by 10-20 meters. Polymer waveguides are used to provide high density board and backplane integrated optical interconnects, and are also used to package optoelectronic devices together with conventional electronic die in multichip modules (MCM) using conventional fabrication procedures. An expanded beam parallel waveguide connector allows 32 optical channels to replace one electrical pin in a standard SEM-E connector. Polymer waveguides have interconnect densities 50/mm, and have been integrated with conventional circuit board material in industry-standard flamination processes. Systems in the next 3 to 5 year time frame will need optical interconnects at the board and backplane level if the interconnects are not to force undesirable compromises in system performance. We show that board-integrable waveguides represent the optimum choice for embedded systems. An interconnect figure-of-merit is given which shows that polyimide waveguides promise a factor of 20 speed-density-power improvement over copper interconnects.