Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the California Institute of Technology have developed a whispering gallery microcavity based on plasmons - electromagnetic waves that race across the surfaces of metals. This plasmonic whispering gallery microcavity consists of a silica interior that is coated with a thin layer of silver and could prove to be a significant breakthrough in the ultra-miniaturization of lasers. Such lasers promise applications including superfast communications and data handling, and optical microchips for instant and detailed chemical analyses.
The main obstacle to working with plasmonic materials for creating nanoscale lasers has been a low quality or Q factor, which is a measure of power loss in the lasing cavity. A laser cavity with a high-Q factor has a low power loss. Using the whispering gallery phenomenon, the researchers boost the Q factor of dielectric microcavities. Whereas previous plasmonic microcavities achieved a best Q factor below 100, the whispering gallery plasmonic microcavity allows Q factors of 1,376. Cal Tech researcher Bumki Min says, "We need a good, high-Q plasmonic microcavity to make a plasmonic nanolaser. Our work paves the way to accomplish the demonstration of a real plasmonic nanolaser."
