Portland, Ore. - IBM Corp. will team with Agilent Technologies Inc. to pursue "terabit per second optical interconnect" technology for multiprocessing servers, under a four-year, $30 million contract with the Defense Advanced Research Projects Agency (Darpa).
The goal is to build chip-sized modules that interconnect high-speed microprocessors at aggregated data rates of up to a Tbit/second.
"We are looking beyond cabled rack-to-rack technology to very high levels of integration, and to do that we need [optical] modules about 2 centimeters2 right on the board next to the microprocessor," said Marc Taubenblatt, senior manager of optical communications at IBM Research. "We will increase per-channel speed, but probably our most aggressive goal is to reduce power to 5 to 10 milliwatts per gigabit."
The director of Agilent's Communications and Optics Research Laboratory, Waguih Ishak, said the goal was Tbit/s speeds in a size small enough for chip-to-chip interconnects. "This will only be achieved," he said, "by developing miniature optical components, pushing their operating speeds to 40 Gbits/s and higher, and by clever integration and packaging techniques."
By combining many separate channels into modules, the team hopes to aggregate data rates up to 1 Tbit/s/module, with each high-speed channel optimized for dramatically less cost and power consumption than discrete components used today (up to 15 Gbits/s for parallel links and up to 40 Gbits/s for components).
By integrating the modules directly on the board with the microprocessors much higher levels of integration (microprocessors/foot3) will use very short runs of electrical lines to optical modules that interconnect the computer chips with optical transceivers and waveguides. The team's basic technology for optical interconnects will be to use vertical-cavity surface-emitting laser (VCSEL) diode arrays to transmit and conventional photo diodes and waveguides to receive (and free-space optics for interconnect paths).
The benefits of optical interconnects are only enjoyed by communications between large computer systems, but 2-cm2 optical modules will transfer the technology inside the box. IBM estimates that the total communications bandwidth inside servers will continue to rise tenfold every four years, increasing the processors per system until 2010, when IBM predicts a bandwidth of about 40 Tbits/s will be needed between microprocessors.
IBM and Agilent's long-term goal is to develop optical-interconnect technology that delivers 40-Tbit performance by 2010 and in a low-power, low-cost, high-density form factor.