The target of the PhD thesis is to use thin film layers with very high optical nonlinearities in order to surpass the diffraction limit of a focused Gaussian beam.

Very recently, our team performed studies of the nonlinear optical response of Sb2Te3 layers. The target of these studies was the optimization of the saturable absorption of the thin film layers in order to use them for Super-Resolution applications. Moreover, nanofabrications have been performed with a resolution of about 400 nm, using an IR laser beam.

The target of this thesis is the improvement of this performance, by combining self-focusing and saturable absorption in order to achieve resolutions lower than 100 nm. The following tasks will be performed:

a) Wavelength dependent nonlinear optical studies of Indium Tin Oxide (ITO) and chalcogenide thin film layers by means of the Z-scan technique, in the femtosecond regime. For these studies, an Optical parametric amplifier will be added to a currently existing laser system and properly calibrated in order to obtain wavelengths between 200nm and 11μm. Tuning the wavelength will be of significant importance during the laser-matter interaction studies.

b) A nanoinscription setup providing large scale (typically several mm2) inscriptions will be built. The main objective will be to obtain the possibility to fabricate optical components which can be integrated in optical systems.

c) Photonic component fabrication (as for example optical filters, phase masks and diffractive elements) will be performed.

Consequently the PhD student will have the possibility to perform photoinscriptions using an experimental technique based on a femtosecond laser with tunable wavelength. The inscriptions will be performed in thin film layers that the PhD student will be able to deposit by using the thin film deposition techniques existing in Institute Fresnel. The thin films will be characterized by several techniques as for example AFM, SEM, Nomarski microscopy, ellipsometry, XRD and Raman spectroscopy.

A good background in optics/nonlinear optics and Labview/ MATLAB programming will be appreciated.

References:

[1] C. Moisset, A. Bourgade, J. Lumeau, F. Lemarchand, C. Perrin-Pellegrino, H. Akhouayri, J.-Y. Natoli, K. Iliopoulos, Optical Materials 86, 7 (2018).

[2] K. Iliopoulos, A. El-Ghayoury, H. El Ouazzani, M. Pranaitis, E Belhadj, E. Ripaud M. Mazari, M. Sallé, D. Gindre, B. Sahraoui, Optics Express 20, 25311 (2012).