Nanoantennas for visible and infrared radiation

Nanoantennas for visible and infrared radiation can strongly enhance the interaction of light with nanoscale matter by their ability to efficiently link propagating and spatially localized optical fields. This ability unlocks an enormous potential for applications ranging from nanoscale optical microscopy and spectroscopy over solar energy conversion, integrated optical nanocircuitry, opto-electronics and density-ofstates engineering to ultra-sensing as well as enhancement of optical nonlinearities. Here we review the current understanding of optical antennas based on the background of both well-developed radiowave antenna engineering and the emerging field of plasmonics. In particular, we address the plasmonic behavior that emerges due to the very high optical frequencies involved and the limitations in the choice of antenna materials and geometrical parameters imposed by nanofabrication. Finally, we give a brief account of the current status of the field and the major established and emerging lines of investigation in this vivid area of research.Comment: Review article with 76 pages, 21 figure

Waveguide approach to plasmonic antennas

The thesis aims to investigate select problems of practical interest in plasmonic systems primarily from a viewpoint of guided wave dynamics. After providing theoretical foundation of the fundamental concepts, it re-examines the problem of quasi-static resonance in plasmonic nano-particles and demonstrates its equivalence with the standing wave model. Thereafter, it presents an approach to designing cylindrical metallic antennas tailored to sustain resonances at both fundamental and second harmonics for enhanced nonlinear frequency conversion. Lastly, it visits plasmonic slot waveguides with a view to identify the possibility of phase-matched interaction between fundamental and second harmonic which is necessary for steady nonlinear frequency conversion