Nanoantenna effect has potential for optical switching

A team investigating the properties of very small antennae has produced a fast optical transistor capable of changing the physical state of a metal oxide from insulator to conductor.

The team is looking at nanostructures that interact strongly with light; an area of interest because it could allow optical devices to be used for a very wide variety of applications, for example in computing and medicine. Such structures are smaller than the wavelength of visible light, yet allow light energy to be concentrated to a very high level.

Working with teams with specialised capabilities at Salford University and the University of the Basque Country in San Sebastien, Spain, the Southampton researchers used gold nanoantennae to achieve a phase transition in vanadium oxide (VO₂). At room temperature, VO₂ is an insulator, but if heated above 68°C its structure changes and it conducts electricity; this makes it potentially useful in optical transistors, because light energy can be used to rate its temperature.