Miniature Laser Operates at Room Temperature

A team of researchers at the Northwestern University has found a way to manufacture miniature single-laser devices that are the size of a virus particle and more importantly, can function at room temperature.

It is reported that these plasmonic nanolasers could be readily incorporated into silicon-based photonic devices, all optical circuits and nanoscale biosensors. The small size helps in ultra-fast data processing and ultra-dense information storage.

"Coherent light sources at the nanometer scale are important not only for exploring phenomena in small dimensions but also for realizing optical devices with sizes that can beat the diffraction limit of light," said Teri Odom, a nanotechnology expert who led the research, a professor of Chemistry in the Weinberg College of Arts and Sciences and the McCormick School of Engineering and Applied Science.

"The reason we can fabricate nano-lasers with sizes smaller than that allowed by diffraction is because we made the lasing cavity out of metal nanoparticle dimmers -- structures with a 3-D 'bowtie' shape," Odom said.

The localized surface plasmons that have no fundamental size limits when it comes to confining light are supported by the metal nanostructures.

The use of the bowtie geometry has two significant benefits over previous work on plasmon lasers: Firstly, the bowtie structure provides a well-defined, electromagnetic hot spot in a nano-sized volume because of an antenna effect, and secondly, the individual structure has only minimal metal "losses" because of its discrete geometry.

"Surprisingly, we also found that when arranged in an array, the 3-D bowtie resonators could emit light at specific angles according to the lattice parameters," Odom said.

The results are published in the journal Nano Letters.