Yagi-Uda antenna on the nanoscale

A nanoscale version of a classic 80-year-old radio antenna known as Yagi-Uda ― after its Japanese creators ― has been developed for use with light waves, as reported online in Nature Photonics. The nano-antenna could be used to enhance both the emission and detection of light from nanoscale sources such as individual molecules and semiconductor quantum dots. This could lead to more efficient sensing and spectroscopy, as well as improved sources for quantum information processing.

Rooftops around the world are graced with the classic Yagi-Uda antenna, consisting of several parallel metal rods, which pick up radiowaves. Traditionally these were used to pick up radar and radio signals but today more commonly send information to our television screens. Yutaka Kadoya and colleagues create a nano-antenna that consists of five gold nanorods, with a geometry and spacing carefully designed to interact with red light of wavelength 632 nm, allowing highly directional control of light at this wavelength.

Given the great success of its radiowave ancestor, the nanoscale Yagi-Uda antenna is expected to find many applications in the optical domain.