Russian scientists have developed a new way to solve a key problem with cooling plasmonic components, which makes optical chips and super-fast light-based computers a definite possibility.

We dream of a world where super-fast computers are possible, but there are still several obstacles to solve before this is possible, including how to create optical chips that can send information at ultra-fast speeds.

To make optical chips possible, scientists need to harness photons instead of electrons, since photons travel at the speed of light and electrons are much slower. But while it is possible to shrink conventional electronic microprocessors, it's difficult to get tiny photonic components to work because it is difficult to get light to turn corners in conventional chips in the same way that electrons can.

To get around this, many scientists are now researching into plasmonics to create new 'metamaterials' that can exploit the way photons and electrons oscillate and interact on the surface of metal to achieve optical properties not seen in nature – self-sustaining, propagating, nanoscale electromagnetic waves known as surface plasmon polaritons (SPP), which are much shorter in wavelength compared with incident light, and are able to ripple along metal-dielectric materials.

But the optic chip still won't work unless you figure out how to keep the plasmonic components cool, because as the SPPs move they cause temperature increases of 100 Kelvin, overheating the metal in the plasmonic components so much so that they will fizzle out and die. Since the plasmonic components are tiny and can be as small as 10 nanometres in size, the cooling system would need to be just as tiny. Which is why, until now, it hasn't been possible to fix this problem.

Using thermal materials to cool plasmonic components

However, researchers from the Moscow Institute of Physics and Technology (MIPT) claim to have found a solution – they have inserted tiny high-performance thermal interfaces made from thermally conductive materials into the components that act as a buffer from the metal to absorb the heat, together with a conventional cooling system, so the components only increase by a few degrees kelvin.

"We need only to remove the heat from the chip's surface. The problem is similar to that of a CPU or GPU, so we need to use a good heat sink attached to the chip with a solder to improve the chip's conductivity," said Andey Vshnevyy, a postdoctoral research at MIPT's Laboratory of Nanooptics and Plasmonics. "This approach gives a possibility to decrease the temperature rise to only about two kelvin, contrary to the 100-kelvin temperature rise in air. This result is very optimistic and demonstrates that we can win over the temperature rise."

The researchers' findings are explained in the paper Self-Heating and Cooling of Active Plasmonic Waveguides, which is published in the journal ACS Photonics.

Harvard scientists have also found a way to solve the problems with optic chips by inventing a new type of metamaterial with a phase velocity of light that is infinite, so the optic chip can control light so that it flows infinitely faster than the speed of light.