Testing the mettle of photonics

Pierre Berini

“Rapid, inexpensive disease detection is one of the leading applications of this technology.”

– Pierre Berini

Mention the science of optics to most people and they will likely think about glass, usually in the form of lenses that we use to focus and transmit light in one way or another. Bring up the subject with Pierre Berini, however, and he thinks about metal.

The professor at the School of Electrical Engineering and Computer Science studies what happens when light travels along a metal surface.  An extremely brief wave of electrons, called a surface plasmon, carries a coherent bundle of energy along this metallic guide. When the phenomenon was first discovered more than 50 years ago, the distance travelled by a typical plasmon was in the order a millionth of a metre — far too short to be of much practical or even experimental value.

More recently, Berini and his colleagues have added an entirely new perspective to plasmons. By altering the geometric shape of the metallic surface at the nanometre scale, they have been able to coax plasmons to travel as much as several centimetres at a time. That is far enough for them to transfer data within an optical computer chip, a prospect that Berini is now actively exploring.

“These are essentially small antennas that work with light,” he explains, describing an application that would have been unimaginable to the scientists who first identified plasmons, and was still a major challenge when he began his career in plasmonics more than 15 years ago.  Nevertheless, the growing accessibility that researchers now have to powerful lithography systems, employing tools such as electron or focused ion beams, has made it possible for him to work at unprecedented scales.

“These technologies, which enable you to make ‘nano-things’ cheaply, have really pushed the area forward,” he says.

Berini, who holds a University Research Chair in Surface Plasmon Photonics, employs this technology to manufacture exotic plasmon guides from gold, silver or copper, which could become the foundation for an entirely new class of biosensor.

“The optical fields that interact with metallic structures develop very high field strengths near the metallic surface itself,” he observes. “If you have small biomolecules that are accumulating on that surface, this will appreciably change the optical field on that surface. “

The result could be a handheld electronic device capable of measuring contaminants in a waterway or pollutants in the air. He points to a working example of this approach, a plasmonic detector that can determine the presence of life-threatening dengue infection in an individual’s blood sample within a matter of minutes.

“Rapid, inexpensive disease detection is one of the leading applications,” Berini suggests. “This sort of technology replaces lab techs who work for several hours to try to come up with a similar diagnosis.”

He is looking forward to even more exciting developments that should emerge from the laboratories of the Advanced Research Complex (ARC), the new home of the University’s Centre for Research in Photonics (CRPuO). His research in plasmonics will benefit from cutting-edge infrastructure, which will include shared nanofabrication facilities that no single member of the CRPuO could have otherwise afforded.

“As an individual researcher it’s great, because we’re moving into better quality lab space,” he says, adding that he is also looking forward to the synergy that is bound to emerge within the shared work spaces.  “That’s what’s huge. If you bump into someone on your way to the cafeteria, or in the hallway or the common lab, that helps to foster some spontaneous interaction. A few minutes here and a few minutes there can actually go a long way to getting things done.”

Last year, Berini became director of the CRPuO, which gives him a much broader perspective — and much greater responsibility — over the movement of various research groups into ARC.

“I like to be involved at this stage, where you’re building something new,” he says. “There’s a lot of planning work to be done. At this point I can come in and help develop a vision for the whole thing.”

 

by Tim Lougheed

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