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Optics faster than copper, study finds

Recently, Duke University electrical engineers have designed a way to replace copper in electronic devices with an optical device that would use light to carry information.

Although the use of optics has been somewhat overlooked as a valuable means of transmitting data until now, replacing copper allows engineers to increase connection speed in order to produce smaller and faster electronics.

“The work we are doing is primarily to replace electrons with photons,” said Sabarni Palit, who received her Ph.D. while working with Dr. Nan Marie Jokerst, who oversaw the research.

Palit found that optical signals are actually more efficient than copper, which has traditionally been used for transmitting information in computers and other electronic devices. Palit’s device integrates microscopic semiconductor lasers and light guides to transmit data from its source to its next component all on silicon in electronic devices. The lasers and guides helped the scientists create small-scale light that could be efficiently transmitted.

The lasers and channels are connected to the other structures and the silicon by microscopic layers of polymer. The layers of lasers and light channels are given their functions through nano- and micro-fabrication processes and chemical removal of portions of the surface on which the lasers and channels rest.

Jeremy Kirch of the University of Wisconsin at Madison helped with the design of the lasers used in the devices.

“Primarily my function was to fabricate the actual laser structures that [Palit] was lifting off and then putting them onto the circuit,” Kirch said.

The lasers are about 3.5 microns thick and fit on top of the silicon. Light propagates from the lasers into tiny channels, which then translate it to the target chip or other component.

Jokerst, J.A. Jones Distinguished Professor of Electrical and Computer Engineering in the Pratt School of Engineering, hopes to apply the results of the study to chip-scale medical diagnostics.

“One of the next goals that we have is to integrate this with a sensor,” Jokerst said, noting that currently medical professionals draw blood samples and send them away to labs for lengthy diagnostic testing. “With one or two drops of blood, one would be able to do a whole host of diagnostic tests right in the doctor’s office,” she said.

The study also could have applications in consumer electronics and environmental sensing as well.

Other members of the team included Professor Luke Mawst of the University of Wisconsin at Madison and Duke’s Mengyuan Huang.


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