Optical Characterization of Plasmonic Nanostructures: Near-Field Imaging of the Magnetic Field of Light

Denitza Denkova

abr. de 2016 · Springer

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This thesis focuses on a means of obtaining, for the first time, full electromagnetic imaging of photonic nanostructures. The author also develops a unique practical simulation framework which is used to confirm the results.

The development of innovative photonic devices and metamaterials with tailor-made functionalities depends critically on our capability to characterize them and understand the underlying light-matter interactions. Thus, imaging all components of the electromagnetic light field at nanoscale resolution is of paramount importance in this area. This challenge is answered by demonstrating experimentally that a hollow-pyramid aperture probe SNOM can directly image the horizontal magnetic field of light in simple plasmonic antennas – rod, disk and ring. These results are confirmed by numerical simulations, showing that the probe can be approximated, to first order, by a magnetic point-dipole source. This approximation substantially reduces the simulation time and complexity and facilitates the otherwise controversial interpretation of near-field images. The validated technique is used to study complex plasmonic antennas and to explore new opportunities for their engineering and characterization.

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Denitza Denkova completed her Bachelor (2008) and Master (2010) studies in Physics at Sofia University, Bulgaria. During her studies she also worked part-time as an engineer at Melexis, a microelectronics company. In a joint project between these institutions she studied specific malfunctions in microelectronics circuits via various structural, optical and electrical characterization techniques, including the development of a cathodoluminescence add-on to a scanning electron microscope. Denitza then moved to KU Leuven, Belgium to further develop her interest in nanoscale characterization as a PhD. There she developed and applied a novel approach for imaging the magnetic field of light with nanoscale resolution, in the context of characterization of plasmonic and metamaterial devices.