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Chen Sun, Mark T. Wade, Yunsup Lee, Jason S. Ocrcutt, Luca Alloatti, Michael S. Georgas, Andrew S. Waterman, Jeffrey M. Shainline, Rimas R. Avizienis, Sen Lin, Benjamin R. Moss, Rajesh Kumar, Fabio Pavanello, Amir H. Atabaki, Henry M. Cook, Albert J. Ou, Jonathan C. Leu, Yu-Hsin Chen, Krste Asanovic, Rajeev J Ram, Miloš A. Popović & Vladmir M. Stojanović.


Data transport across short electrical wires is limited by both bandwidth and power density, which creates a performance bottleneck for semiconductor microchips in modern computer systems—from mobile phones to large-scale data centres. These limitations can be overcome by using optical communications based on chip-scale electronic–photonic systems enabled by silicon-based  nanophotonic devices. However, combining electronics and photonics on the same chip has proved challenging, owing to microchip manufacturing conflicts between electronics and photonics. Consequently, current electronic–photonic chips are limited to niche manufacturing processes and include only a few optical devices alongside simple circuits. Here we report an electronic–photonic system on a single chip integrating over  70 million transistors and 850 photonic components that work together to provide logic, memory, and interconnect functions.

This system is a realization of a microprocessor that uses on-chip photonic inputs and outputs to directly communicate with other chips using light. To integrate electronics and photonics at the scale of a microprocessor chip, we adopt a ‘zero-change’ approach to the integration of photonics. Instead of developing a custom process to enable the fabrication of photonics, which would complicate or eliminate the possibility of integration with state-of-the-art transistors at large scale and at high yield, we design optical devices using a standard microelectronics foundry process that is used for modern microprocessors. This demonstration could represent the beginning of an era of chip-scale electronic–photonic systems with the potential to transform computing system architectures, enabling more powerful computers, from network infrastructure to data centres and supercomputers. Read full publication here.

Real World Application:
The single-chip microprocessor with integrated photonic inputs and outputs offers the potential to seamlessly integrate energy-efficient, high-bandwidth optical communications in almost any application where microelectronics (specifically silicon-on-insulator employed in applications ranging from IBM’s Blue Gene supercomputer family [Watson uses the exact microelectronics process as our photonics] to the Nintendo WiI U’s Espresso Processor) technology is used. This alternative solution allows the processor to access data stored in off-chip memory at the speed of light with lower energy cost than sending signals over electrical wires.

Related Links:

Single-chip microprocessor with integrated photonic inputs and outputs (Nature)

Optoelectronic microprocessors built using existing chip manufacturing (MIT News)

Professor Rajeev Ram

RLE Physical Optics and Electronics Group