Researchers at nanoGUNE have discovered that infrared light can be transmitted and nanofocused using nanosized transmission cables that feature two metal nano wires placed close together in a ladder structure. These cables steer the infrared light as a surface wave packed tightly together. The ladder structure when used at MHz frequencies delivers energy in waveguides of nano scale diameter.

The infrared light can be transmitted by reducing the size of the cable to below 1micrometer. Two metal nanowires were developed and linked to an infrared antenna that absorbed infrared light and changed it into a surface wave along the cable. The width of the cable was gradually diminished, to compress the infrared surface wave to a nanospot at the taper apex measuring 60nm in diameter. The free-space wavelength is about 150 times bigger than the nanospot, revealing the sub-wavelength-scale focus derived. The team has developed a near-field microscopy method to identify multiple electrical field units with nano scale resolution.

A cable linked to the antenna, helps the light absorbed by the nanoantenna to be transmitted over long distances and nanofocused in a distant spot. Rainer Hillenbrand, who led the Nanooptics Group said this discovery proved that the idea of classical radiofrequency can be applied at infrared frequencies. Martin Schnell, who did the clinical testing, says this frequency is 30THz.