Biography
Gelon studied Physics at the University of Stuttgart receiving his diploma in 2011. During his diploma thesis he measured the phase change and group velocity dispersion at the resonance of different plasmonic structures. For his PhD project he currently performs ultrafast nonlinear spectroscopy of hybrid plasmonic-organic materials.
Project description
Nonlinear plasmonics [1] has gained a lot of interest lately due to its potential to tailor novel nonlinear optical materials. Our concept to create highly nonlinear materials is a hybrid plasmonic-organic system.
Small gold nanoparticles with dimensions around 100nm show a collective oscillation of their conduction band electrons. This oscillation is called particle plasmon or localised surface plasmon. The properties of the plasmon can be modified by the size and shape of the particle. This geometry control is provided by electron-beam lithography. Besides gold many other metals show a plasmonic behaviour.
If you excite a particle with a suitable laser at the resonance frequency of the plasmon electromagnetic energy is efficiently transferred from the light field of the laser to the plasmon. For his gold samples the resonance wavelength is typically around 800nm and the size of the particle is in the order of 100nm. This is one example for the possibility of sub wavelength focussing with plasmons. Furthermore a strong near field exists around the particle [2].
Gelon uses this strong near fields to create an efficient nonlinear material by placing organic materials in the vicinity of an array of plasmonic structures. Finally he determines the improved efficiency by second and third harmonic generation.
In addition he’s interested in the dynamic absorption properties of this hybrid materials compared to their constituents.
[1] M. Kauranen and A.V. Zayats, Nat. Photonics 6, 737 (2012)
[2] M. Hentschel, T. Utikal, H. Giessen, and M. Lippitz, Nano Lett. 12, 3778 (2012)
