基于二维导模共振效应的光轨道角动量产生和操控机制研究

Orbital angular momentum (OAM)is one of the most fundamental physical quantities of photon that is not well explored and utilized yet. OAM state represents the light beam with helical phase fronts and an azimuthal component of the wave vector. Similar with amplitude, phase, and other physical quantities of light, OAM can carry information. Recently, OAM based techniques have attracted great attention in wide-ranging applications of optical-microscopy, micromanipulation, and quantum information processing. In particular, OAM-multiplexing will upgrade freespace optical communication systems with high-capacity,high-reliability, and high-security. In this project, we proposed to utilize two-dimensional (2D) guided mode resonance (GMR) effect to generate and manipulate OAM states. GMR effect is excited in multi-layered waveguide structure with periodic refractive-index modulation when phase-matching happens between waveguide mode and Bloch modes. Due to the 2D distributed coupling mechanism and the confinement of high-contrast dielectric interface, 2D-GMR effect has great potential to perform sophisticated manipulation of light beams. In this project, we will study the 2D-GMR effect in the structures with large-area, high-contrast, finite-size and chirped-modulation. An accurate and efficient theoretical model will be developed to depict the physics of 2D-GMR, and hence, to realize completed controlling upon the amplitude, phase, and polarization of light. We will design novel 2D-GMR based devices for generation and manipulation of OAM states, and fabricate the devices using standard semiconductor processes. A testing platform will be established to experimentally evaluate the performance of devices, and validate our design. The exploring of novel OAM devices will boost the development of optical communication systems with OAM-multiplexing.

光的轨道角动量（OAM）表征了光波相位的空间分布，与波长、偏振等一样，也是光子的内在物理性质之一。作为一个新的、未探索的自由度，基于OAM的光通信技术已成为国际、国内研究的热点。本项目拟利用二维导模共振效应实现OAM的产生和操控。该效应是指具有周期性折射率的介质波导结构中，波导模式与Bloch模式相位匹配彼此耦合而产生的共振效应。特别地，利用二维分布式耦合机制，二维导模共振效应具有光束精细操控的潜力，有望成为理想的OAM操控机制。本项目将研究大尺寸、高对比、有限面积、复杂啁啾结构中的二维导模共振效应，建立精确、高效的理论模型及其物理图像；运用其光束操控能力，实现对光的相位、幅度、偏振及其空间分布的控制，设计新型的OAM产生和操控关键器件，突破器件制备和测试的关键技术，验证器件可行性。本项目在器件层面的前瞻研究将为发展基于OAM复用的光通信系统奠定基础。

光子具有幅度、相位、波长、偏振等多种物理特性，在多维度上实现光子调控是光电子领域的前沿问题，也是国际、国内研究的热点。本项目利用导模共振效应实现操控能力。该效应是折射率周期性分布的多层介质结构中，波导模与Bloch波相位匹配彼此耦合而产生的共振效应。利用二维分布式耦合机制，导模共振效应具有精细的光束操控的潜力。在课题支持下，我们对光子系统中导模共振效应及其相关幅度、相位响应机理进行了系统性研究，建立了导模共振解析理论模型，发现并澄清了“导模共振”与“光连续区束缚态”，即BIC态的内在关联。从导模共振效应出发，我们发现了基于“偶然对称性”和“垂直抵消”机制的可调BIC态，可作为幅度、相位多维度调控。这一系列成果建立了光子系统与量子系统的有效类比。课题的研究揭示了光子系统深刻的物理本质，导模共振及BIC态可成为光场约束的全新方法。BIC态相关研究处于学术前沿方向，正逐渐成为国内外研究的热点，具有重要的科学意义。在光电子、光通信、光量子器件等方面具有广阔应用前景。