#18 APR 2016
Special

STORY

Silicon Photonics Technology to Innovate
Future Computing/Data Communication

Dr. Gyungock Kim, Principal Researcher of the Nano Interface Device Research Section

ETRI to develop world’s first single-chip optical transceiver based on bulk silicon

If silicon electronic-circuit chips such as CPU and memory can exchange data through light, a new paradigm for computing and data communication could appear in the future. Capable of contributing to such innovation is the bulk silicon-based single-chip optical transceiver recently developed by ETRI to enable optical communication between silicon chips. Silicon photonics technology can converge electronics and photonics, and has emerged as a leading future technology to enable next-generation high-performance computers and future data optical communications. This can realize optical computer chips that optically exchange data between silicon chips within a computer or even within a chip, dramatically accelerating the data transmission speed and reducing power consumption.

The latest technology helps produce optical I/O (input/output) devices on a low-cost bulk silicon wafer, thereby considerably improving the integrity with electronic ICs (integrated circuits). In addition, by enabling practical optical data transmission between chips, the technology is anticipated to bring a significant impact upon electronics-photonics convergence in the areas of high-performance computers, CPU, memory, 3D IC, data centers, and network optical communication applications. As a monolithic-integrated platform technology to add an optical data I/O function to the existing silicon chips of electronic circuits, the newly developed technology is expected to find wide industrial applications, encompassing computer chips, network optical communication components, and mobile devices and sensors.

 

Next-generation technology to strengthen semiconductor competitiveness and lead the future computer market

The research result was published on June 10 in Scientific Reports of the Nature Publishing Group. In September, the technology was exhibited at the ECOC international exhibition in Spain, and related patents have been applied both in and outside Korea. The silicon optical I/O integrated platform technology adopts the bulk silicon wafer used in common electronic circuit chips. This platform technology is also based on selective germanium epitaxial growth and silicon CMOS processing. The additional fabrication process of optical sources after transplanting the thin active layer of III-V compound semiconductor laser epilayer on the surface of a silicon wafer enables the monolithic-integrated vertical optical I/O devices including laser sources. Further, as a new integration scheme to overcome the three major issues (silicon-on-insulator substrate, device size and performance, and chip-level optical sources) that currently impede the practical implementation of silicon photonics technology in electronic chips, this technology is anticipated to enhance device performance as well as integration and practical use of electronic circuits. If this newly developed technology is adopted as high-speed, high-density optical I/O platforms for future computer chips including memory and CPU, it will enable wafer-level mass-production and contribute to rapidly improved data I/O speed and bandwidth. In addition, it is advantageous not only for 2D data communication, but also for communication between 3D-stacked ICs. It is therefore possible to apply the technology to 3D-chip memory and 3D-chip computer system.

In this research, ETRI demonstrated the prototype for 20Gps/channel low-power optical interconnects between silicon chips, which is expected to have a significant impact on practical realization of electronic-photonic monolithic integration. Furthermore, on the basis of the merits of small size, low-cost, high-performance, and low power consumption of single-chip silicon optical transceivers, the technology is expected to find practical applications for optical communication and mobile components, sensors, and displays; dominate the global market; and lead the domestic and overseas markets.
 

Silicon photonics technology to vitalize silicon optical components market

In addition to recently developed compact, high-performance silicon single-chip optical transceiver technology, ETRI also holds world-class silicon photonics technology obtained through continued research and development efforts. Some representative achievements are as follows: 40Gb/s monolithic silicon photonic integrated circuits (Si-PICs) based on the SOI (silicon on insulator) wafer; compact silicon Mach-Zehnder optical modulator operating up to 50Gb/s; 40Gb/s hybrid-integrated silicon EPIC (electronic-photonic IC); high-performance vertical illumination-type Ge-on-Si PD (germanium photodetector) with a speed of 50Gbps and high responsivity in the wavelength range of 650nm-1600nm; high-sensitivity Ge-on-Si avalanche photodetector (APD) operating at 10-25Gb/s; 36Gb/s all-silicon photonic transmitter and receiver; high-performance 28/43Gbps germanium photoreceivers; and WDM (wavelength division multiplexing) devices. Many of these silicon photonics R&D results have been published in a number of internationally prominent journals such as Optics Express and Optics Letters. They were also invited to present at the SPIE Photonics West 2015 held in the United States, and registered and applied for multiple domestic and international patents. In addition, high-performance germanium photodetectors, high-sensitivity germanium APDs, and other silicon photonics core devices developed by ETRI show performance levels surpassing those of the existing commercial products. Since this technology can replace the conventional optical devices based on expensive III-V compound semiconductors with low-cost, high-performance silicon optical communication devices, it is expected to have a remarkable ripple effect in the coming years.

Summary

“The bulk silicon single-chip optical transceiver technology is a smart development further toward realizing electronic chips for optical data communication. Once it is applied to next-generation computer chips, the technology will contribute to significantly improving the performance of computing systems.” explained Dr. Gyungock Kim, the project manager. “This achievement is expected to strengthen national competitiveness in semiconductor technology for next-generation photonic-electronic convergence and contribute to leading the new semiconductor technology market and future computer market.” Dr. Kim added, “In response to the rapidly growing silicon optical interconnection market, ETRI has secured highly competitive low-cost silicon photonics technology applicable to active optical cable, high-performing optical connectors, network optical transceivers, and mobile devices.” The new technology will be commercialized soon, together with other technologies developed by ETRI to the level of commercialization, such as silicon photonics-based germanium photodetectors and high-sensitivity APDs. This technology was developed solely in ETRI as part of the silicon photonics technology research project of the Ministry of Science, ICT and Future Planning’s program for developing original technology for a silicon nanophotonics-based next-generation computer interface platform.