Antennas have been used for over a century as emitters, scatterers and receivers of electromagnetic waves. All wireless communication devices, such as radio, mobile phones and satellite communication are strongly dependent on the capability of an antenna to localize propagating electromagnetic waves to a fraction of its wavelength. Because Maxwell's equations are scale-invariant the principles of antenna designs at radio frequencies (106 Hz) can also be applied at optical frequencies (1014 Hz) . Over the course of the last two decades, novel developments in nanotechnology have enabled the fabrication of antennas in the optical regime, and various optical antenna structures have been developed that have the potential to advance many light based technologies [2-5]. The power of optical antennas lies in their capability to manipulate light at the nanoscale. This freedom of controlling light at the nanoscale enables the creation of novel field distributions, where light can be focused to a fraction of the wavelength. Controlling the polarization state of these sub-wavelength spots is of interest for many future applications, including quantum computing. In this thesis the far- and near-fields of optical antennas are experimentally and numerically studied. We determine and manipulate several parameters which determine the resonance behavior of single and coupled antenna systems. With a newly developed optical technique, we are able to measure and manipulate the optical state of the near- and far-field of an array of optical antennas. With this technique we can make a phased antenna array for light, and manipulate the optical state of light at the nanoscale. We experimentally demonstrate how the fundamental properties of light at any point in space have become programmable parameters.
|Award date||30 Sep 2015|
|Place of Publication||Enschede|
|Publication status||Published - 30 Sep 2015|