Dr. Will Green
IBM Thomas J. Watson Research Center

Today’s fastest high-performance supercomputing systems are comprised of over 10,000 individual processors, with each processor containing multiple cores on a single die. Because these vast arrays of discrete processing units require an extremely high-bandwidth, low-latency interconnect network to achieve parallel operation, optical fiber- based interconnects have already replaced copper wires for communication at the rack-to-rack level. As multi-core microprocessors continue to scale up to a larger number of cores, an additional set of challenges emerges for the global interconnects between cores. The limited throughput and large power consumption of electrical interconnects become dominant factors limiting the continued scaling of power performance, this time at the chip level.

One possible solution is to replace conventional global interconnects with a CMOS-compatible intra-chip optical network, based on Silicon-On- Insulator (SOI) photonic integrated circuits. Silicon nanophotonic wires have immense capacity for low-loss, high-bandwidth data transmission, and can confine light within sub-micron dimensions, enabling the design of ultra-compact optical devices for all necessary functions within such optical networks. In this seminar, I will provide an overview to motivate the opportunities and technical challenges associated with implementing silicon on-chip optical interconnects. The recent demonstration of various critical components at IBM will be reviewed, including low-loss silicon waveguides, wavelength division (de)multiplexers, broadband multi-channel optical switches, and electrooptic modulators.

Dr. Will Green is a Research Staff Member at the IBM Thomas J. Watson Research Center in Yorktown Heights, New York. His current research activities encompass the investigation of silicon nanophotonic wire and photonic crystal-based electrooptic devices and systems for low- power optical switching and high-speed modulation in on-chip optical networks. Previously, he was a Visiting Scientist at IBM, studying the optical properties of self-assembled multi-component nanoparticle superlattices. Dr. Green was awarded the degree of Ph.D. in Electrical Engineering from the California Institute of Technology in June of 2005, for his work on III-V semiconductor annular Bragg resonator lasers and optical modulators.