Optoelectronic Integration Overcoming Processor Bottlenecks

"Your domestic PC these days can have a processor of two GHz andfaster -- this is quite common -- but the processor power will often bewasted because the real bottleneck in computer processing is thememory." That is John Snowdon of Heriot-Watt University in Edinburgh,speaking about the objectives of the HOLMS project.

"Optoelectronic technologies are the only way to bridge the presentgap between processor speed and memory bandwidth," says John Snowdon ofHeriot-Watt University in Edinburgh, of the HOLMS IST project. "Thishas been documented by the SIA, the Semiconductor Industry Associationin the US."

"Your domestic PC these days can have a processor of two GHz andfaster -- this is quite common -- but the processor power will often bewasted because the real bottleneck in computer processing is thememory," he says.

As a result participants in HOLMS set out to make the use ofboard-level optical interconnection in information systems practicaland economical. They aimed to develop optoelectronic technology to thepoint where it would be compatible with standard electronic assemblyprocesses. HOLMS focused on two key areas of optical technology: aseamless opto-mechanical interface to commercial parallel-fibre arrays,and low-cost optical waveguides that could be easily integrated intoconventional printed circuit boards (PCBs).

"What is key about HOLMS is our work on optoelectronic packaging --how to make optoelectronic technologies more compatible with market andindustry needs," he continues. "We were able to take the signals from afibre and push them into a high-bandwidth free-space opticalconnection, one which is capable of addressing many electronicprocessors simultaneously. So the latency is as low as you can get --essentially we're working at light speed with many thousands ofchannels."

The key achievement of HOLMS, believes Snowdon, was the project'ssuccess in integrating fibre-optics with free-space technologies andoptical PCBs -- to form a powerful three-part optoelectronic interface."We started from a pioneering research point-of-view, but with acommercial goal -- that's why we have so many industrial partners. Thislevel of integration has not been achieved before outside thelaboratory."

HOLMS ends in September 2005, and the participants have developedtwo working demonstrators to show the functional aspects of thetechnology. The two main university partners, Hagen University(Germany) and Heriot-Watt, are both integrating the knowledge gainedinto their academic research.

Several of the industrial partners, including ILFA (PCBmanufacturer) and Siemens of Germany, and Thales in France, haveincorporated the results into their product development. Thales isinvestigating the potential of HOLMS' optoelectronics technology foruse in very-high-speed embedded systems in defence applications, whileSiemens is believed to be developing a high-bandwidth optical waveguidePCB that could be on the market in as little as two years.

"It is the potential of this technology for the domestic marketsthat is so exciting," says Snowdon. "This kind of technology could bebuilt into the everyday PC within just two generations of development,which is no time at all."