Dynamic wavefront engineering via index-near-zero nonlinearities

这是一项物理学博士研究项目。本项目致力于用于光学波前实时工程的新型光子器件。这将通过使用工作在近红外近零窗口的新型透明导电氧化物(TCO)来实现。该工作计划提出利用TCO的复杂非线性(即吸收和色散特性的光学调制)来设计一类新的时变平板器件，能够在亚皮秒时间尺度上进行实时波前工程，并沿数百nm的传播距离进行实时波前工程。这些组件将克服静态操作的基本限制，在能效方面优于标准等离子体变表面，并实现传统平板光学本质上无法实现的过多功能(例如，光学隔离器和环行器等非互易性组件)。所提出的技术与光学成像、脉冲整形和增强传感相关，它可能是用于机器学习的下一代光学神经网络的关键。

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.