Dynamic wavefront engineering via index-near-zero nonlinearities

这是一个物理学博士研究项目。该项目的重点是用于光学波前实时工程的新型光子器件。这将通过使用在其NIR ε近零窗口中操作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面器件，该器件能够在亚皮秒时间尺度上和沿着几百nm的传播距离执行实时波前工程。这些组件将克服静态操作的基本限制，在能量效率方面优于标准等离子体超颖表面，并且实现传统平面光学器件（例如，诸如光学隔离器和环行器的非互易组件）本质上无法实现的过多功能。所提出的技术与光学成像、脉冲整形和增强传感相关，它可能是下一代机器学习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.