When lasers start getting down to the nanoscale, they run up against the diffraction limit where the size of the laser cannot be smaller than the wavelength of light it emits. But researchers have shown that nanoscale plasmonic lasers can reach an optical mode well below this limit by confining light of very short wavelengths through the use of surface plasmons oscillations of electrons that occur at the junction of a metal and an insulator. This has revitalized the hope that chips populated with these plasmonic nanolasers could make possible computer processors run by light rather than electrons.
Now researchers at Northwestern University have developed a new design for plasmonic nanolasers that are the size of a virus particle and capable of operating at room temperature.
"The reason can fabricate nanolasers with sizes smaller than that allowed by diffraction is because to made the lasing cavity out of metal nanoparticle dimers -- structures with a 3-D bowtie' shape"
The bowtie geometry allowed the nanoparticles to achieve an antenna effect and suffer only minimal metal “losses”. Typically, plasmon nanolaser cavities have suffered from both metal and radiation losses that required them to be operated at cryogenic temperatures. The antenna effect allows for lasing to occur from an "electromagnetic hot spot" found that when arranged in an array, the 3-D bowtie resonators could emit light at specific angles according to the lattice parameters,"
Dept. of Information Science & Engineering
Brindavan College of Engineering, Bangalore