4 May 2012Jamie Stokes from the Photonics group in Electrical and Electronic Engineering won the Best Paper prize at The Festival of Radio Science organised by the International Union of Radio Science (URSI) at Durham University. His paper was entitled “Analysis of Sub-Wavelength Optical Antennas” by J.L. Stokes, N. Ahmad, J. R. Pugh and M.J. Cryan. This is an annual event aimed at PhD students and young researchers to give them the opportunity to present their work to their peers. URSI is an international organisation aimed at furthering the understanding and use of Radio Science. Dr Cryan has recently taken on the role of UK representative for Electronics and Photonics (Commission D) and is particularly interested in engineering applications that cross the boundary between photonics and electronics.
Optical antennas are an excellent example of this since they are closely related to their more conventional Radio Frequency(RF) counterparts, but with some important differences, the main one being that at optical frequencies metal can support a particular type of surface wave known as a Surface Plasmon. This is a coupled electromagnetic-electron wave which consists of oscillations in the free electrons at the metal surface combined with an electromagnetic surface wave. This has the effect that standard RF design approaches have to be slightly modified to account for this. Optical antennas are set to revolutionise many fields in optics including solar cells and sensors where they can dramatically enhance the absorption or emission of light. Like RF antennas they are approximately the size of a wavelength, so for visible light this means they are typically a few 100 nanometres in size. The picture below shows a dipole optical antenna made recently at Bristol using Focused Ion Beam etching of a gold coated glass microscope slide.
An optical antenna