Silicon Photonics Optical Transmitter Technology for Tb/s-class I/O Co-packaged with CPU

摘要

In the near future, Tb/s-class large-capacity input/output (I/O) circuits are considered to be necessary for high-end CPUs used in high-performance computing (HPC) systems and high-performance servers due to the progress in processing performance of the CPUs.A high-performance I/O using optical transmission technology is attracting public attention as a technology to overcome the limitations of a conventional electric I/O in terms of size and power consumption.Particularly, an integrated optical I/O chip based on silicon (Si) photonics technology is a very promising candidate to realize a Tb/s-class large-capacity I/O chip of a size that allows it to be co-packaged with a CPU.This paper describes the current status of progress in Fujitsu Laboratories' approaches to develop the Si optical transmitter for a large-capacity optical I/O chip.To realize the co-packaging of a large-capacity optical I/O chip in a CPU package, it is essential to realize a Si optical transmitter that ensures stable operation with low power even under drastic fluctuations of operation temperature.Therefore, the authors proposed a novel Si optical transmitter scheme using a highly energy-efficient Si ring modulator to operate stably without a complex wavelength-tuning procedure.A prototype integrated optical transmitter based on this scheme was fabricated and evaluated.The evaluation results showed that an integrated Si optical transmitter chip could operate at 10 Gb/s without any wavelength tuning over a temperature range of 25 to 60°C.Further, supported by successful developments of a compact-size, high-performance laser source using flip-chip bonding technology as well as a 4-ch integrated Si hybrid laser array for wavelength division multiplexing, there are certain prospects for application of a Si optical transmitter for large-capacity optical I/O chips.