IBM scientists have created a tiny device that could lead to the eventual use of light in place of electricity in the connection of electronic components, for potentially significant improvements in computer and electronic systems performance, the company reported today.
Scientists have slowed light down to less than one-three-hundredth its usual speed by directing it down a carefully designed channel of perforated silicon called a photonic crystal waveguide. The unique design of the device also allows the light’s speed to be varied over a wide range simply by applying an electrical voltage to the waveguide, IBM explained.
The company noted that its researchers have known for some years how to slow light under laboratory conditions, but doing it on a silicon chip using standard silicon with standard micro- and nanoelectronic fabrication technology, is a first.
The device’s small size, use of standard semiconductor materials, and ability to more closely control this “slow light” could make the technology useful for building ultra-compact optical communications circuits that are practical for integration into computer systems, IBM believes.
“This work is an example of our continued commitment to push the limits of exploratory science,” said T.C. Chen, VP of science and technology for IBM Research, located in Yorktown Heights, N.Y., in a statement.
“We are constantly exploring new technologies that might enhance our systems and storage products. We believe this brings real value to both our clients, who rely on these products to enhance their business, and to their customers, who ultimately benefit from the new and improved services they make possible,” he added.
IBM believes this work could speed the movement of information in electronic systems – one of the biggest bottlenecks in electronic design today.
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While scientists have searched for practical ways to use light to speed communication between the components within a computer, the components to support such an optical network would need to provide excellent control over the light signal and be very small and inexpensive to manufacture. IBM said its work addresses several of these issues.
Using a photonic crystal waveguide – a thin slab of silicon punctuated by regular arrays of holes that scatter light, the IBM team has slowed light. The pattern and size of the holes gives the material a very high refractive index -- the higher the refractive index, the slower the light. Heating the waveguide locally with a small electrical current alters the refractive index, allowing the speed of light to be quickly tuned over a large range with very low applied electric power.
The active area of IBM’s device is microscopically small, indicating the possibility of complex light-based circuits with footprints not much larger than semiconductor circuits, the company said.
The manufacturing processes used to build the device are available in nearly any semiconductor factory and could be applied to create a variety of nanophotonic components such as optical delay lines, optical buffers, and even optical memory – all of which would be useful in building computer systems knitted together by powerful optical communications networks, IBM concluded.
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