Random-access memories have low power consumption

The January issue of Nature Photonics features an ultra-small, ultra-fast, electrically pumped, all-optical memory on a silicon chip, said to have record-low power consumption.

This result, achieved by Imec and its associated laboratory Intec at the Ghent University, paves the way for optical packet switching with reduced overall power consumption in high-speed, high-data-rate optical-telecommunication systems.

Fibre-optic communication systems have revolutionised the telecommunications industry and play a crucial role in today's information age where long-distance and high-data rate communication is indispensable.

While the transportation of the data bits between different points in such networks normally makes use of light pulses, it is a different story for the switching and routing of the data at the network nodes.

Due to the absence of good optical random-access memories, up to now, the data needed to be converted from the optical to the electrical domain and electronic switches with micro-electronic processors were needed.

However, with the ever increasing amount of data, the power consumption of such optoelectronic switches increases dramatically.

Researchers from Imec and Ghent University in Belgium realised extremely fast and small optical random-access memories with record-low power consumption.

This discovery paves the way to do the switching in optical-fibre networks or optical-interconnect systems completely optically and to no longer rely on optoelectronic conversions.

The optical random-access memory has been achieved with ultra-compact micro-disk lasers with a diameter of 7.5um.

The laser light can either propagate in the clockwise or counter-clockwise direction and one can switch between these two laser modes using short optical pulses.

The lasers, implemented in Indium Phosphide membranes, are heterogeneously integrated onto passive silicon waveguide circuits.

This allows optical interconnection of different memory cells using silicon wires.

It also allows the use of strongly developed silicon-based microelectronics fabrication technology, making it a cost-effective solution.

These results were achieved in collaboration with TU Eindhoven and INL in the framework of the European FP7 projects Historic and Wadimos, coordinated by Imec-Intec.

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