Dynamic wavefront engineering via index-near-zero nonlinearities

这是一个物理学博士研究项目。本项目主要研究用于光波前实时工程的新型光子器件。这将通过使用新型透明导电氧化物（tco）在其近红外ε -近零窗口中工作来实现。工作计划建议利用tco的复杂非线性（即吸收和色散特性的光调制）来设计一类新的时变平面器件，能够在亚皮秒时间尺度上执行实时波前工程，并沿着几百纳米的传播距离。这些组件将克服静态操作的基本限制，在能量效率方面优于标准等离子体超表面。并且实现了传统平面光学本质上无法实现的大量功能（例如光学隔离器和循环器等非互易组件）。所提出的技术与光学成像、脉冲整形和增强传感相关，它可能是下一代用于机器学习的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.