Aug. 24, 2009
Jeremy Craig, 404-413-1357
Lasers have been part of scientific and everyday life for 50 years, from large beaming devices aimed at the moon to small supermarket barcode readers. Thanks to the research of a Georgia State University professor, scientists have developed an even tinier laser which may lead to huge advances in optical computing and other technologies.
The spaser (which stands for Surface Plasmon Amplification by Stimulated Emission of Radiation) was first conceived by Georgia State's Mark Stockman, professor of physics, and David Bergman of Tel Aviv University in Israel.
The first spaser, gold nanoparticles encapsulated in a silica sphere that is only 44 nanometers wide - forty thousand times less than the width of a human hair - has been created by scientists at Norfolk State University, Purdue University and Cornell University. Their research appears online in the journal Nature.
The spaser, first introduced by Stockman and Bergman in the journal Physical Review Letters in 2003, has the potential to replace the transistor - the foundation of all modern electronics, including the world's fastest computers, Stockman said.
Transistors, contained in computer chips and integrated circuits, work by turning off and on, creating binary signals that are the basis of electronic data. Lasers can also turn off and on by generating light particles, called photons, but they can't be made small enough to integrate into chips like transistors because of their size - half a micron or more, which is hundred times bigger than a transistor.
"A spaser generates quanta of electron oscillations known as surface plasmons, which have the same frequency as light and are as fast as light, but they can be squeezed into almost any size, down to almost the atomic level, or the nanoscale," Stockman said.
Moreover, transistors have reached the limits of miniaturization and speed in "flipping" between off and on, which is responsible for the speed of a computer chip. By contrast, surface plasmons produced by spasers are very fast. These fast excitations can be used to produce off-and-on signals necessary for electronics - working thousands of times faster than today's transistors.
"You will be able to build many things that were impossible before," said Stockman, who added that the first spaser-based processors could be on the market within a decade. "You can build better sensors, better detectors and better markers for biomedical research."
The spaser also may lead to technology which can withstand a nuclear explosion.
"If you take a transistor and irradiate it, it's dead, almost immediately," he said. "So there's a nuclear explosion, the planes will fall, the cars will stop and electronics will stop working," Stockman said. "But spasers are as resistant as any metals, which are very stable and resistant to radiation. They can even work inside nuclear reactors."
Stockman's and Bergman's pioneering work was published as "Surface Plasmon Amplification By Stimulated Emission of Radiation: Quantum Generation of Coherent Surface Plasmons in Nanosystems" in the January 2003 edition of Physical Review Letters. Recently the spaser has been also recognized as an invention protected by a U.S. patent belonging to Georgia State University and Tel Aviv University.
The creation of the spaser is described in "Demonstration of a spaser-based nanolaser," by M.A. Noginov, et al., published online this week in Nature.