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Focus: Research news IBM lights up silicon chips to tackle Big Data


t the IEEE International Electron Devices Meeting in Washington DC in December, IBM’s Dr Solomon Assefa presented a major advance in the ability to use light instead of electrical signals to transmit data for computing. The breakthrough technology, called ‘silicon nanophotonics’ is able to transport information via pulses of light through optical fibres in order to deal with the growing volumes of data being created and transmitted over enterprise networks. Due to an explosion of new applications and services, businesses are entering a new era of computing that requires systems to process huge volumes of information known as Big Data. Silicon nanophotonics provides answers to Big Data challenges by allowing the integration of different optical components side-by-side with electrical circuits on a single silicon chip using, for the first time, sub-100nm semiconductor technology. This seamlessly connects various parts of large systems, whether a few centimetres or a few kilometres

‘ The technology provides a super highway for

apart from each other, and enables terabytes of data to be transmitted via pulses of light through optical fibres. The technology provides a super highway for large volumes of data to move at rapid speeds between computer chips in servers, large data centres, and supercomputers, thus alleviating the limitations of congested data traffic and high-cost traditional interconnects.

large volumes of data to move at rapid speeds’

Building on its initial proof of concept in 2010, IBM has solved the key challenges of transferring the silicon nanophotonics technology into the commercial

foundry. By adding a few processing modules into a high-performance 90nm complementary metal-oxide-semiconductor (CMOS) fabrication line, a variety of silicon nanophotonics components such as wavelength division multiplexers (WDM), modulators and detectors are integrated side-by-side with a CMOS electrical circuitry. As a result, single-chip optical communications transceivers can be manufactured in a conventional semiconductor

MIT eye scanner to aid early detection of retinal diseases

A new optical device that could aid primary care physicians in the early detection of a host of retinal diseases has been developed by researchers at the Massachusetts Institute of Technology (MIT). The device is about the size of a handheld video camera and scans a patient’s entire retina in seconds. The researchers describe

their new ophthalmic-screening instrument in a paper published in the open-access journal Biomedical Optics Express, published by The Optical Society (OSA). The new design is the first to combine cutting-edge technologies

such as ultra high-speed 3D imaging, a tiny micro-electro-mechanical systems (MEMS) mirror for scanning, and a technique to correct for unintentional movement by the patient. These innovations, the authors say, should allow clinicians to collect comprehensive data with just one measurement. Normally, to diagnose retinal diseases such as diabetic retinopathy, glaucoma and macular degeneration, an ophthalmologist or optometrist must examine the patient in his or her office, typically with tabletop instruments. However, few people visit these specialists


regularly. To improve public access to eye care, the MIT group, in collaboration with the University of Erlangen and Praevium/Thorlabs, has developed a portable instrument that can be taken outside a specialist’s office. ‘Handheld instruments can enable screening a wider population outside the traditional points of care,’ said researcher James Fujimoto of MIT, an author on the Biomedical Optics Express paper. For instance, they can be used at a primary-care physician’s office, a pediatrician’s office or even in the developing world. The instrument uses a technique

called optical coherence tomography (OCT), which the MIT group and collaborators helped pioneer in the early 1990s. The technology sends beams of infrared light onto the retina. Echoes of this light return to the instrument, which uses interferometry to measures changes in the time delay and magnitude of the returning light echoes, revealing the cross sectional tissue structure of the retina. Tabletop OCT imagers have become a standard of care in ophthalmology, and current generation handheld scanners are used for imaging infants and monitoring retinal surgery.

@electrooptics |

Cross-sectional view of an IBM Silicon Nanophotonics chip combining optical and electrical circuits

foundry, providing significant cost reduction over traditional approaches. IBM’s CMOS nanophotonics technology is capable of feeding a number of parallel optical data streams into a single fibre by utilising compact on-chip wavelength-division multiplexing devices. The ability to multiplex large data streams at high data rates will allow future scaling of optical communications capable of delivering terabytes of data between distant parts of computer systems.


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