Extreme-ultraviolet light generation in plasmonic nanostructures
Plasmonic enhancement of high harmonic generation revisited
by Murat Sivis
Date of Examination:2013-11-13
Date of issue:2014-01-30
Advisor:Prof. Dr. Claus Ropers
Referee:Prof. Dr. Claus Ropers
Referee:Prof. Dr. Tim Salditt
Referee:Prof. Dr. Bernd Abel
Referee:Prof. Dr. Markus B. Raschke
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Abstract
English
The present (cumulative) thesis examines fundamentals of nanostructure-enhanced extreme-ultraviolet light generation in noble gases using two different nanostructure geometries for local field-enhancement. Specifically, resonant antennas and tapered hollow waveguide nanostructures are utilized to enhance low-energy femtosecond laser pulses, which in turn induce light emission from excited xenon, argon and neon atoms and ions. Spectral analysis of this radiation reveals that coherent high-order harmonic generation is not feasible under the examined conditions, contrary to former expectations and reports. Instead, the spectral characteristics unequivocally identify that incoherent fluorescence from multiphoton excited and strong-field ionized gas atoms is the predominant process in such schemes. Furthermore, novel nanostructure-enhanced effects are reported such as surface-enhanced fifth-order harmonic generation (from bow-tie nanoantennas) and the formation of a bistable nanoplasma (in a hollow waveguide). These effects offer intriguing links between nonlinear nano-optics, plasma dynamics and extreme-ultraviolet radiation.
Keywords: Nonlinear plasmonics; Nano-optics; Metallic nanostructures; extreme-ultraviolet light; high-order harmonic generation; atomic fluorescence; strong-field physics; waveguides; bow-tie antenna; surface-plasmon-polaritons; localized plasmons; optical bistability; plasma dynamics; noble gas atoms; multiphoton excitation; intensity gauging; spectral analysis