Computing Through Silicon Photonics
The explosive growth of the internet has been accompanied by a similar increase in the amount of data that is transmitted and processed. Much of the burden of this growth has been shouldered by datacenters, one of the largest and fastest growing consumers of electricity in the country. Datacenters in 2013 consumed an estimated 91 terawatt-hours of electricity, about 2% of electricity produced in the United States, and demand is rising rapidly. Reducing datacenter power consumption is a significant energy efficiency and environmental challenge.
Project Innovation + Advantages:
Columbia University will develop a new platform for generating multiple simultaneous optical channels (wavelengths) with low power dissipation, thereby enabling optical interconnects for low power computing. Optical interconnect links communicate using optical fibers that carry light. Wavelength-division multiplexing (WDM) is a technology that combines a number of optical carrier signals on a single optical fiber by using different wavelengths. This technique enables bidirectional communications over strands of fiber, dramatically increasing capacity. Low-power lasers generate the wavelengths used in a WDM system, but it is important to stabilize the wavelength for each channel to allow for precise separation and filtering. The importance of stabilization increases when the number and density of wavelength channels increases. Energy use also increases because each of the laser sources must be individually stabilized. In contrast, the Columbia team proposes using a single high-powered stabilized laser to generate greater than 50 wavelength sources with high efficiency using an on-chip comb. This approach can improve laser energy efficiency from 0.01% to 10%.