Charles Moisset will defend his Ph.D. thesis entitled : "Étude des propriétés optiques de chalcogénures en couches minces pour la photo-inscription super-résolue par processus non-linéaires" on thursday 21st november, 2019 at 10:30 am in Ponte Amphithéater.
The jury will be composed of:
Pr. Sahraoui Bouchta, Université d’Angers, referee
Pr. Lionel Canioni, Université de Bordeaux, referee
Pr. Natalie Destouches, Université de Jean Monnet, examinator
Pr. Stelios Couris, Université de Patras, examinator
Dr. Julien Lumeau, Université d’Aix-Marseille, examinator
Pr. Jean-Yves Natoli, Université d’Aix-Marseille, director
Dr. Konstantinos Iliopoulos, Université d’Aix-Marseille, co-director
Abstract :
Nowadays, the laser nano-patterning is of great importance for highly integrated systems. The resolution of the laser patterning can be improved by employing nonlinear optical effects, as for example the saturable absorption. This thesis details the preparation of a super-resolution mask based on a chalcogenide material (Sb2Te3), which can offer a sub-wavelength patterning. In order to obtain that, a thin Sb2Te3 film is deposited on a thin inscription layer. The crystallization obtained by laser and oven annealing has been controlled by XRD measurements and resulted to an optimal nonlinear optical response. The Z-scan technique, developed for the study, allowed us to quantify the mask’s nonlinear optical properties, under femtosecond and nanosecond irradiation (visible and infrared). Two theoretical models have been used to determine the nonlinear optical properties. The Sb2Te3 mask efficiency has been investigated under femtosecond irradiation. Two different modification regimes have been identified, one reversible, the other non-reversible, resulting to a beam size reduction of about 25% and 35%, respectively. The employed multilayer structure (Sb2Te3/inscription layer), has required a determination of the laser flux resistivity of the materials used for both layers, to assure their compatibility. Finally, a direct laser inscription technique has been built. By means of this technique, inscriptions without a mask have been performed. Based on the results obtained in this thesis, spots smaller than 50 nm can be obtained by using the mask, under UV irradiation.
Key words : Direct laser inscription, nonlinear optics, super-resolution, chalcogenides, thin films, saturable absorption, Z-scan
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