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2015
Book Article
Titel
Nanophotonic applications of fs-laser radiation induced nanostructures and their theoretical description
Abstract
We present the analysis of the optical properties of two different fs-laserinduced nanostructures which possess great potential for near-field applications due to their sub-100nm features. The first structures are standing gold nanojets generated by irradiation of thin gold films with single pulses of fs-laser radiation. Due to their upright standing orientation, the characteristic extinction resonances of these nanojets are studied by grazing incidence infrared spectroscopy with ppolarized radiation. The resonance wavelength strongly depends on the lateral extent of the nanojet and can be tailored by adjusting the focusing numerical aperture and the applied pulse energy. The observed correlation between the lateral extent of the nanojet and the resonance wavelength is described by the monopole model of a linear antenna. The second type of structures under investigation are fs-laserinduced sub-wavelength ripples on silicon. Ripple structures of different geometrical shape are generated and coated with a thin gold film. Here, the metallic cover layer allows for the excitation of surface plasmons. Based on the generated surface profiles, the corresponding plasmonic resonances are simulated. Angle-resolved UV-VIS spectroscopy measurements are performed and the resulting plasmonic dispersion relation of these structures is compared to the calculated resonance conditions. The plasmonic resonances and additional experiments of the surface structures reveal insights into the localized or propagation nature of the plasmonic modes excited on generated surface profiles.