The concept of the spaser was proposed in 2003, and realized in practice by a team at Norfolk State University in Virginia. They irradiated nanoparticles of gold, encased in silica capsules containing green organic dye, with light to excite surface plasmon oscillations, reports Nature magazine. The pumped in energy was released as greenish light with a wavelength of 531 nanonmeters.

The light, however, radiates in all directions, rather than in a tight laser beam. Co-author Vladimir Shalaev of Purdue University in West Lafayette, Indiana, adds that the team is yet to verify that the spaser emits coherent light – a key quality for quantum amplification devices. But the theory says that it does.

The device could be used as a light source for high-resolution near-field optical microscopes and in nanolithography. But Mikhail Noginov, who headed the research, says the spaser’s ability to generate coherent surface plasmons may be more important than its use as a nanolaser. Spasers can be used as amplifiers and generators in fast plasmon-based nanocircuits, which may replace microelectronic devices. So far, scientists have managed to build plasmonic wires, resistors and capacitors.