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Linear and nonlinear optical properties of high refractive index dielectric nanostructures

Abstract : Nano-photonic structures offer a highly interesting platform to enhance light-matter interaction on a nanometer scale. Recently, high-index dielectric structures have gained increasing attention as possible low-loss alternatives to plasmonic nano-antennas made from noble metals. Furthermore, since non-linear effects offer many unique functionalities like the coherent up-conversion of photons, including the generation of harmonics, many efforts are being made to exploit such phenomena in nano-photonics. In this thesis, an analysis is presented on nonlinear optical effects in individual dielectric structures, specifically in silicon nanowires (SiNWs). Nanowires develop strong optical resonances in the visible and infrared spectral range. In this context, strong enhancement of the optical near-field together with a large surface to volume ratio support the appearance of nonlinear effects. We show that, compared to bulk Si, a two orders of magnitude increase in second harmonic generation (SHG) is feasible and furthermore unravel different polarization and size-dependent contributions at the origin of the SHG. Numerical simulations are carried out to reaffirm these experimental findings for which a numerical technique is presented to describe nonlinear effects on the basis of the Green Dyadic Method (GDM). In the last part of the thesis, the GDM is used together with evolutionary optimization (EO) algorithms to tailor and optimize optical properties of photonic nano-structures. We eventually fabricate samples, based on EO design, and successfully verify the predictions of the optimization algorithm. It turns out that EO is an extremely versatile tool and has a tremendous potential for many kinds of further applications in nano-optics.
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Submitted on : Tuesday, September 5, 2017 - 4:17:08 PM
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  • HAL Id : tel-01582148, version 1


Peter Wiecha. Linear and nonlinear optical properties of high refractive index dielectric nanostructures. Micro and nanotechnologies/Microelectronics. Université Paul Sabatier - Toulouse III, 2016. English. ⟨NNT : 2016TOU30253⟩. ⟨tel-01582148⟩



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