Small lasers that produce wavelengths of light larger than themselves could be used to explore the fundamentals of quantum electrodynamics, and they could also have practical uses, including chip-based optical communications and ultra-high-resolution imaging. Lasers can transmit information faster than traditional semiconductors, and they might be more practical than quantum computers (if those are even a possibility).

These new lasers are an efficient step in that direction because they don't require a high threshold to start lasing. They could even be designed to remove the threshold entirely.

A laser threshold is the energy level beyond which a laser's power increases rapidly. When the laser cavity - the place where light waves are amplified - is very small, the threshold energy must be very high, but a lot of this input energy is wasted. This makes the tiniest lasers impractical. 

To get beyond this limitation, Mercedeh Khajavikhan and colleagues at the University of California-San Diego used a cylindrical co-axial arrangement - co-axial as in the type of cable that runs from your wall to the TV. Khajavikhan and colleagues built nanoscale lasers whose co-axial arrangement allowed them to capture all the energy of the larger laser that was used to pump them up, a huge improvement in efficiency.

"These nanoscale resonators should provide a powerful platform for the development of other QED devices and metamaterials in which atom-field interactions generate new functionalities," the authors write. Their paper was published in Nature.

[via BBC]