IBM Scientists Harness 'Slow Light' for Optical Communications

November 3, 2005

IBM Scientists Harness 'Slow Light' for Optical Communications
Researchers at IBM have created a tiny device that represents a big advance toward the eventual use of light in place of electricity in the connection of electronic components, potentially leading to vast improvements in the performance of computers and other electronic systems.

Image: Photonic crystal composed of a periodic array of holes etched in silicon slab. False-colored SEM image.

As described in today’s issue of the journal Nature, IBM scientists were able to slow light down to less than 1/300th of its usual speed by directing it down a carefully designed channel of perforated silicon called a “photonic crystal waveguide.” Further, the unique design of the device allows the light’s speed to be varied over a wide range simply by applying an electrical voltage to the waveguide.

Researchers have known for some years how to slow light to a crawl under laboratory conditions, but actively controlling the light speed 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.

“This work is an example of our continued commitment to push the limits of exploratory science,” said Dr. T.C. Chen, vice president of Science and Technology for IBM Research. “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.”

SOI 200mm wafer processed on a standard CMOS fabrication line with numerous nanophotonic circuits
Image: SOI 200mm wafer processed on a standard CMOS fabrication line with numerous nanophotonic circuits

While chip performance has continued to increase, electronic systems don’t always reap the full benefits. Just as traffic congestion can hinder commerce by limiting the flow of products and materials within a busy city, the inability to more quickly move information around within electronic systems is one of the biggest bottlenecks in electronic design today. The work announced by IBM could help relieve such constraints.

Scientists have searched for practical ways to use light to speed communication between the components within a computer. But, to be practical, the components to support such an optical network will need to provide excellent control over the light signal, while also being very small and inexpensive to manufacture. The IBM work addresses several pieces of this puzzle.

The IBM team succeeded using a photonic crystal waveguide – a thin slab of silicon punctuated by regular arrays of holes that scatter 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 the IBM device is microscopically small, indicating the possibility of complex light-based circuits with footprints not much larger than semiconductor circuits. The manufacturing processes used to build the device are available in nearly any semiconductor factory. The capabilities demonstrated in today’s Nature article 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.


Animation: Active Control of Slow light on a chip (REFRESH the page to play again)

The report on this work, “Active control of slow light on a chip with photonic crystal waveguides” by Yurii A. Vlasov, Martin O’Boyle, Hendrik F. Hamann, and Sharee J. McNab of IBM’s T.J.Watson Research Center in Yorktown Heights, N.Y. is published in the November 3 issue of Nature. This work was partially supported by the Defense advanced Research Agency (DARPA) through the Defense Sciences Office program “Slowing, Storing and Processing Light”.

Source: IBM

Explore further: Sandwich structure of nanocrystals as quantum light source

Related Stories

Sandwich structure of nanocrystals as quantum light source

November 8, 2018

Excited photo-emitters can cooperate and radiate simultaneously, a phenomenon called superfluorescence. Researchers from Empa and ETH Zurich, together with colleagues from IBM Research Zurich, have recently been able to create ...

Slower light could mean faster computers

December 22, 2006

IBM today announced its researchers have built a device capable of delaying the flow of light on a silicon chip, a requirement to one day allow computers to use optical communications to achieve better performance.

Silicon nanophotonics: Using light signals to transmit data

December 10, 2012

(Phys.org)—IBM announced today a major advance in the ability to use light instead of electrical signals to transmit information for future computing. The breakthrough technology – called "silicon nanophotonics" – allows ...

Nanophotonic switch device for routing light on a chip scale

March 17, 2008

IBM scientists today took another significant advance towards sending information inside a computer chip by using light pulses instead of electrons by building the world’s tiniest nanophotonic switch with a footprint about ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

Paleontologists report world's biggest Tyrannosaurus rex

March 22, 2019

University of Alberta paleontologists have just reported the world's biggest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. The 13-metre-long T. rex, nicknamed "Scotty," lived in prehistoric Saskatchewan ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.