Lieb光子微结构中平带光局域与布洛赫振荡效应的研究

可调可控的人工光子学材料平台对研究物理学与材料科学的交叉学科问题具有重要意义。本项目采用光诱导的方式，通过对光子晶格诱导光的光学整形，在非线性晶体中制备具有折射率梯度的Lieb光子晶格微结构。紧束缚近似下，该结构不仅具有石墨烯中的狄拉克锥形能带，同时还存在无色散平坦能带(平带)。特殊的晶格和能带结构使得该系统中波传输特性变得新颖而有趣。本项目首先通过选择性激发该人工材料的晶格格点，发现由平带能带结构带来的模式局域。在此基础上，改变折射率梯度场的大小，研究梯度场对平带及其光局域效应的影响。最后，深入探究Lieb光子晶格中由梯度折射率势场引起的光学布洛赫振荡效应，揭示平带局域效应、锥形能带和多能带间能量隧穿效应的结合带来的新颖量子现象及其规律。本研究不仅能够很好的帮助我们认识和理解物理学与材料科学的交叉学科问题，同时也能够为开发新型人工材料在光信息传输等方面的应用提供新的技术原理。

Artificial photonic microstructures bring about an exciting interdisciplinary field of physics and material sciences, which has profound significance in both fundamental research and applications. In this project, we propose to develop innovative techniques to optically induce Lieb photonic structures fabricated by evanescently coupled waveguide arrays. In the tight-binding approximation, the band structure of Lieb lattice consists of three bands: two dispersive bands that touch a flat middle band via a cone-like dispersion point. By launching a laser beam into an optically induced lattice with a superimposed index gradient, we explore localized states of the flat band and focus on the understanding of their interaction with lattice index gradient. After these studies, we will further investigate the Landau-Zener Bloch oscillations in such a flat band system. The combination of the physics of Bloch oscillations, Landau-Zener tunneling, and of flat band networks opens promising directions for control of unconventional quantum and photonic transport through properly designed lattice structures. These studies will advance the knowledge and understanding of these fundamental concepts and phenomena in the interdisciplinary areas of physics and material sciences. Furthermore, results from our work may lead to new development of techniques for various photonic applications of artificial photonic lattices.