Electrical source of surface plasmons
AMOLF researchers, together with colleagues at Twente University, have demonstrated that an electrically-driven source of light in the form of surface plasmon polaritons could be built inside silicon computer chips. These devices may someday be used to make lab-on-a-chip products that combine sensors and logic together to diagnose diseases or monitor chemicals. Their findings were reported on December 6, 2009 in the journal Nature Materials.
Modern computer chips are made of billions of transistors that are each so small that ordinary light cannot be squeezed down into comparable dimensions. This size mismatch has driven scientists to study optical circuits that are designed to use surface plasmon polaritons, a condensed form of light that is bound to a metal surface. Surface plasmon polaritons can be made as small as the transistors in electronic circuits.
Inside the laboratory, surface plasmon polaritons are typically created through the conversion of focused laser light using diffraction grating structures on the surface of the chip or by using glass prisms that couple the light into the surface waves at specific incidence angles. These methods work very well for research purposes, but are not suitable for densely integrated circuits that might contain millions of individual sensors. These new electrically-driven sources of surface plasmon polaritons are a significant advance towards these future devices.
The successful demonstration of this new device is the culmination of several years of collaboration between the group of prof. dr. Jurriaan Schmitz of the MESA+ Institute for Nanotechnology at the University of Twente and the group of prof. dr. Albert Polman of the Center for Nanophotonics at FOM Institute AMOLF.
Dr. Robb Walters, a postdoctoral scholar in the group of Albert Polman who worked on the project offered this view of the potential impact of the work: “You can buy a digital camera today for less than 30 euros that contains four million individual optical sensors. Our hope is that the same manufacturing technology will eventually be used to make active plasmonic sensor chips that can simultaneously run millions of diagnostic tests.”
Reference
A silicon-based electrical source of surface plasmon polaritons, Robb Walters, Rob van Loon, Ihor Brunets, Jurriaan Schmitz and Albert Polman, appeared on December 6, 2009 in the online edition of Nature Materials.
The research was carried out with financial support of FOM, STW, NANONED and the Smartmix program MEMPHIS.
For additional infomation, please contact:
Albert Polman, tel. (020) 754 7100
Electrical plasmon source. Plasmon waves propagate between two gold films. They are generated by silicon nanoparticles represented by the small balls. The plasmons escape though small holes made in the top gold film, and are then detected in a microscope. ®AMOLF/Tremani