A laser occurs when light is confined between two partially reflecting mirrors and amplified by some material in between them. The resulting beam can be extremely bright and of a single colour. Lasers are used in all areas of modern life, from DVD players to operating theatres.
Researchers at the Federal Institute of Technology (ETH) in Zurich have now developed a miniature device that applies the same principle to surface plasmons. The electromagnetic waves created by such a surface plasmon laser – or ‘spaser’ – can be focused much more tightly than light, making them interesting for both fundamental research and technical applications such as sensors, explains ETH Zurich.
Previous attempts have been made to realize spasers, but these used a metallic particle as the cavity, which did not allow extraction of the spaser beam. The procedure developed at ETH Zurich, in contrast, uses a planar film with integrated mirrors, giving the researchers more freedom of choice regarding the size and geometry of the cavity. It also allows them to study the surface plasmons directly.
“Our fabrication methods are very reproducible and versatile, so we can now think about creating integrated circuits with multiple elements: spasers, amplifiers, sensing regions, and so forth,” said ETH Zurich professor David Norris.