11 December 2013 Many multipoles make light go right

Ultracompact nanoantenna for directional photon emission published in NanoLetters. Novel nano-antenna research carried out by Ion Hancu, Alberto Curto, Marta Castro and Martin Kuttge in the Molecular NanoPhotonics group led by Niek van Hulst, has been published in NanoLetters.

Antennas are widely used to steer electro-magnetic radiation. The phased array Radar and the TV-antenna are well known examples, based on control of phase in a row of dipole antennas. Unfortunately such multi-element antennas are bulky and operate in a narrow bandwidth, making them critical to scale down to the optical regime. In this NanoLetters paper Ion Hancu and co-authors exploit interference between electric dipole, quadrupole and magnetic dipole modes to realize directional emission of light. Putting quantum dots on a compact single-element split-ring antenna the luminescence simultaneously in both even and odd modes yields strongly directional emission, moreover with broad bandwidth.

The concept of the multipolar interference antenna combines simplicity, compactness (λ/3 x λ/3), broad band operation and superior directivity, making the novel design promising for the integration of directional nanoantennas in light-emitting and harvesting devices.