Light on silicon better than copper?

Oct 21, 2010
This is Nan Jokerst, left, and Sabarni Palit in the lab. Credit: Duke University Photography

Step aside copper and make way for a better carrier of information -- light.

As good as the metal has been in zipping information from one circuit to another on inside computers and other , optical signals can carry much more, according to Duke University electrical engineers. So the engineers have designed and demonstrated microscopically small lasers integrated with thin film-light guides on silicon that could replace the copper in a host of electronic products.

The structures on silicon not only contain tiny light-emitting lasers, but connect these lasers to channels that accurately guide the light to its target, typically another nearby chip or component. This new approach could help engineers who, in their drive to create tinier and faster computers and devices, are studying light as the basis for the next generation information carrier.

The engineers believe they have solved some of the unanswered riddles facing scientists trying to create and control light at such a miniscule scale.

"Getting light onto silicon and controlling it is the first step toward chip scale ," said Sabarni Palit, who this summer received her Ph.D. while working in the laboratory of Nan Marie Jokerst, J.A. Jones Distinguished Professor of Electrical and Computer Engineering at Duke's Pratt School of Engineering.

The results of team's experiments, which were supported by the Army Research Office, were published online in the journal Optics Letters.

"The challenge has been creating light on such a small scale on silicon, and ensuring that it is received by the next component without losing most of the light," Palit said.

"We came up with a way of creating a thin film integrated structure on silicon that not only contains a that can be kept cool, but can also accurately guide the wave onto its next connection," she said. "This integration of components is essential for any such chip-scale, light-based system."

The Duke team developed a method of taking the thick substrate off of a , and bonding this thin film laser to silicon. The lasers are about one one-hundreth of the thickness of a human hair. These lasers are connected to other structures by laying down a microscopic layer of polymer that covers one end of the laser and goes off in a channel to other components. Each layer of the laser and light channel is given its specific characteristics, or functions, through nano- and micro-fabrication processes and by selectively removing portions of the substrate with chemicals.

"In the process of producing light, lasers produce heat, which can cause the laser to degrade," Sabarni said. "We found that including a very thin band of metals between the laser and the silicon substrate dissipated the heat, keeping the laser functional."

For Jokerst, the ability to reliably facilitate individual chips or components that "talk" to each other using light is the next big challenge in the continuing process of packing more processing power into smaller and smaller chip-scale packages.

"To use light in chip-scale systems is exciting," she said. "But the amount of power needed to run these systems has to be very small to make them portable, and they should be inexpensive to produce. There are applications for this in consumer electronics, medical diagnostics and environmental sensing."

Explore further: Laser makes microscopes way cooler

Related Stories

Photoluminescence in nano-needles

Apr 22, 2008

Silicon is the workhorse among semiconductors in electronics. But in opto-electronics, where light signals are processed along with electronic signals, a semiconductor that is capable of emitting light is needed, which silicon ...

Time Lens Speeds Up Optical Data Transmission

Sep 28, 2009

(PhysOrg.com) -- Researchers at Cornell University have developed a device called a "time lens" which is a silicon device for speeding up optical data. The basic components of this device are an optical-fiber ...

Creating light sources for nanochips

Aug 25, 2010

(PhysOrg.com) -- "One of the most important goals in the optics community is to create and manipulate light on chip," Yinan Zhang tells PhysOrg.com. "This is especially important when it comes to improving the performance of sem ...

Photonics: Pump up the bandwidth

Jun 21, 2006

U.S. scientists say they've developed an optical amplifier based on silicon that works across a wide range of frequencies.

Recommended for you

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

mg1
not rated yet Oct 27, 2010
Sure nanotubes could transport the light of the future. Just have each tubes inside coated with a nice reflective substance and voila little wires. But that would be a waste.

"their drive to create tinier and faster computers and devices"

No it isnt...Their "drive" is more computations per second. Building tinier faster serial components is just a means to an end in todays industry which means maintaining market share and increasing profits.

lightronics will allow parallesim to an unprecedented level, "devices" are likely to be bigger and do more.