Researchers at nanoGUNE have conducted a series of experiments to prove that infrared light with narrow transmission lines can be focused to small spots of nanometer-scale dimensions.
Unlike mirrors and lenses, which allow light to travel as a propagating wave, transmission lines enables the infrared light to travel in the form of a surface wave.
Concept and Design of Transmission Lines
The researchers utilized the typical transmission line theory to the frequency range of the infrared light. Using experiments, it was proved that the infrared light can be transmitted in the similar manner by reducing the size of the transmission lines to less than 1 mµ. To prove this concept, the researchers developed two metal nanowires that were linked to an antenna for capturing infrared light. The light then changed into a propagating surface wave that travelled along the transmission line. The near-field microscopy technique was used by researchers to capture the various electric field components of infrared light at the nanoscale level. The researchers showed that by reducing the size of the transmission lines, the infrared surface wave could be compressed to a very minute spot at the narrow apex with 60 nm diameter.
The device could help develop biological and chemical sensing tools such as lab-on-a-chip integrated biosensors and compact infrared spectrometers.