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

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.

Nominated as an outstanding Ph.D. thesis by the Catholic University of Leuven, Belgium Fills the last gap in achieving full electromagnetic imaging of photonic nanostructures Proposed technique offers numerous advantages including use of commercially available platform and no requirement for data post-processing Unique practical simulation framework using an approximation that greatly reduces the simulation time, memory and complexity Includes supplementary material: sn.pub/extras

Autorentext
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.

Inhalt
Introduction.- Imaging the Magnetic Near-eld of Plasmon Modes in Bar Antennas.- A Near-Field-Aperture Probe as an Optical Magnetic Source and Detector .- Magnetic Near-Field Imaging of Increasingly Complex Plasmonic Antennas.- Plasmon-Enhanced Sub-wavelength Laser Ablation: Plasmonic Nano-Jets.- Conclusions and Outlook.