Dynamic wavefront engineering via index-near-zero nonlinearities

This is a PhD research project in Physics. This project is focused on novel photonic devices for real-time engineering of the optical wavefront. This will be attained by using novel Transparent conducting oxides (TCOs) operating in their NIR epsilon-near-zero window. The work plan proposes to exploit TCOs' complex nonlinearities (i.e. optical modulation of both absorptive and dispersive properties) to design a new class of time-varying flat devices capable of performing real-time wavefront engineering on a sub-picosecond time scale and along propagation distance of few hundreds of nm. These components, will overcome the fundamental limit of static operation, outperform standard plasmonic metasurfaces in terms of energy efficiency, and enable a plethora of functionalities which are intrinsically unreachable by traditional flat optics (e.g. non-reciprocal components such as optical isolators and circulators). The proposed technology is relevant for optical imaging, pulse shaping, and enhanced sensing and it might be the key for the next generation optical neural networks for machine learning.