IBM controls light speed; faster computers possible

By Control Engineering Staff December 1, 2005

Light’s speed can be slowed in dispersive materials; and prior laboratory efforts aimed at decelerating light employed “cooled” light, using billows of ultra-cold atoms, and requiring extensive infrastructure. Now, IBM scientists have successfully slowed light to 3.3% of its normal 186,000-miles/sec speed with a bit of silicon called a crystal waveguide.

Researchers created waveguides with conventional chip-manufacturing processes: fabricated 200-mm silicon-on-insulator wafers with 2-seconds. The light was slowed additionally applying an electric field to the waveguide.

Pulses of “slow” light could carry data efficiently for all-optical storage and switching. Furthermore, the technology has the potential to allow computers to substitute light for electricity andrun at terahertz speeds—likely initially on the motherboard.

Historically optical components tended to be large and pricey—defying the economies of large-scale production. Indeed, some see the manufacture of optical components as much art as science. And such optically based equipment throws off less heat.

A crystal waveguide would allow optical components to be scaled down resulting in significant cost savings. Moreover, manufacturing waveguides from silicon would allow a merging of the optics and the electronics on the same silicon chip.

Nearly concurrently another group ofscientists announced a new silicon-based microtransmitter that can send optical data at 100 Gbps or 10% of a terahertz.

— Richard Phelps, senior editor, Control Engineering