Researchers at the A*STAR Singapore Institute of Manufacturing Technology (SIMTech) have developed an unusual electromagnetic wave that does not bend or diffract as it travels, which could become an important component in fast, highly-efficient computer chips that use beams of light to carry and process data.
Jiao Lin, a physicist at SIMTech, helped to develop the electromagnetic wave, which can travel approximately 80 micrometers in a straight line without diffracting. The wave developed by Lin and his colleagues is reportedly “a previously unknown solution to Maxwell’s equations, which describe how electromagnetic fields behave.”
According to Lin, the electromagnetic wave is formed when light hits the surface of a metal, creating ripples in the “sea” of electrons, known as surface plasmons, that combine with the incoming light to create electromagnetic waves. These waves—surface plasmon polaritons—adhere tightly to the metal surface as they move and can travel just as fast as light along metal waveguides much smaller than the average optical component.
However, Lin added, while an attractive option for data transmission, surface plasmon polaritons diffract as they travel over the metal, which affects the quality of the signals they carry. Earlier attempts to prevent this diffraction were somewhat successful, but caused the polaritons to change direction.
By shining near-infrared laser light at two sets of tiny grooves carved into a thin layer of gold attached to a glass backplate, the team generated two surface plasmon polaritons that “converged and interfered constructively with each other.” The result was a tightly-focused beam that skimmed the surface of the gold without bending or diffracting and covered a larger distance than previous efforts had achieved.