Silicon Photonics Optical Transceiver for High-speed, High-density and Low-power LSI Interconnect

The next-generation servers and supercomputers with high performance and low power consumption require not only CPUs with an enhanced processing capability, but also signal transmission technology that connects CPUs with other CPUs or memories at high density and low power. It is becoming difficult for electrical signal transmission to satisfy the demand for the next-generation servers and supercomputers due to the decrease of transmission distance in high-speed transmission and the restriction of the numbers of pins. Therefore, there have been increasing expectations for optical interconnects enabling large-capacity (wide bandwidth) and long-distance transmission. Thus, there are high hopes that it will be a key technology. Especially, silicon (Si) photonic interconnects have been attracting much attention in recent years because they are considered to be promising for reducing the size, increasing integration density and lowering the power consumption of optical transceivers. This paper explains Fujitsu's and Fujitsu Laboratories' small, energy-efficient Si photonics optical transceiver technologies. The key factors for realizing a small, high-density optical transceiver with low power consumption involve enhancing optical devices and driver circuits, and optimizing the mounting structure to supply high-quality power and signals. We proposed a novel configuration for a Si photonic transceiver utilizing a bridge structure that enabled high-density integration without wiring, and we optimized the design of optical/electrical devices based on this structure. We achieved the world's best performance in terms of high signal density and low power consumption, and demonstrated the effectiveness of the technology.