A research team from the University of California, San Diego (UC San Diego) has developed the tiniest room-temperature nanolaser till date, and a highly efficient ‘thresholdless’ laser capable of funneling all of its photons into a coherent beam of light or lasing.
Mercedeh Khajavikhan in the lab.
Nanolasers require more pump power to start lasing. However, these two novel lasers need very low power to work, paving the way to develop optical circuits for future computer chips where the lasers will be used to set up communication links between remote points on a chip. According to the research comprising Mercedeh Khajavikhan and her colleagues from UC San Diego Jacobs School of Engineering, the thresholdless laser may be useful in developing novel metamaterials such as super-lenses and cloaking devices.
A threshold point of a laser is the point where the lasing output is higher than any spontaneous emission generated. The UC San Diego research team’s novel design for its new lasers utilizes quantum electrodynamic effects inside coaxial nanocavities to reduce the threshold limit. The laser cavity comprises a metal rod encircled by a metal-coated, semiconductor material-based quantum wells. The team changed the cavity’s geometry to develop the thresholdless laser.
The novel design also helped the team to develop the tiniest room-temperature, continuous wave laser. The whole coaxial laser device has a diameter of nearly half a micron. According to the team, its innovative design is scalable, thus allowing the fabrication of even smaller nanostructures to harvest laser light.
This feature paves the way to create and study metamaterials with devices smaller than the wavelength of the laser light. Yeshaiahu Fainman, one of the researchers, said that these new lasers can also be used to develop high-resolution displays or small biochemical sensors. However, the research team is still working on understanding the operating mechanism of these tiny lasers. It is also working on finding a method to electrically pump the lasers rather than optically, Fainman concluded.
The study has been published in the journal Nature.