IBM creates 1Tbps Holey Optochip

Researchers at IBM have created an optical computer chip that can transmit and receive data at up to one terabit per second (1Tbps). To put this into perspective, the DDR3 interconnect between CPU and memory is rated at around 100Gbps; some 10 times slower than IBM’s new chip. Even L2 cache, which shares the same die as your CPU, generally peaks around 200Gbps in the latest Intel processors. 1Tbps equates to 128 gigabytes per second, which is fast enough to transfer three or four Blu-ray discs per second, or the entire 235-terabyte Library of Congress in about 30 minutes.

The chip, dubbed the Holey Optochip, is basically a conventional silicon chip with 48 holes drilled into it (pictured above), and an array of lasers and photodiodes on the back (pictured below). Each hole allows a laser beam (VCSELs; vertical-cavity surface-emitting lasers) to pass through from the beneath the chip to the switching circuitry on top, and then back down to a photodiode, effectively creating a 48-channel optical transceiver. Each channel is rated at 20Gbps, for a total bandwidth of 960Gbps. You’d be right in thinking that 20Gbps per optical channel isn’t all that exciting, but in this case it’s all about the density of the chip, and a power efficiency that is four times that of existing optical chips.

The chip is primarily of importance because it has been built using a standard 90nm CMOS process; these chips could be found in your computer within the next year or two. More realistically, though, IBM’s optical chip will probably find a home in supercomputers, which already use optical interconnects between racks (they’re faster and more efficient than copper wiring). As processor performance increases, optical interconnects between CPUs are the next logical step. IBM’s optical chip could also be used in telecommunications — first to speed up existing fiber networks, and eventually (when the stars align) to bring these kinds of speeds to your home.

This news follows on from last month’s news that MIT has almost produced an optoelectronic chip (where the entire chip’s bus is optical, rather than just an interconnect in IBM’s case), and of course IBM’s own quantum computer chip.

IBM creates 1Tbps Holey Optochip