Comparison between holographic and guided-wave interconnects for VLSI multiprocessor systems

Abstract

The performance of guided-wave and holographic optical interconnects are compared to each other and to conventional electrical interconnects for use in high-performance very-large-scale integration (VLSI) parallel computing systems. The comparison is based on chip-to-chip communication within and between VLSI thermal-conduction multichip modules. The interconnects are evaluated in terms of maximum data transmission rate, power dissipation, crosstalk, and connection density as a function of the number of processors in the system. Previous comparisons between optical and electrical interconnects1 for intrachip communication neglected transmission line effects. Because of the range of interconnect lengths (1–10 cm), both transmission-line and lumped RC line effects must be taken into account for electrical connections. Also, the light propagation delay for both holographic and guided-wave connections are significant. Owing to the high index of refraction of guided-wave systems, they have a longer propagation delay than do free-space systems. Advantages and disadvantages of multiplexing several signals over the optical connections have been analyzed. Detector circuit amplifiers, optimal in the sense that they minimize total power dissipation, have been designed.