微纳能谷光子晶体中的拓扑态光传输研究

Disorder-induced uncontrollable optical scattering limits the development of micro-nano-photonic structures to achieve high-efficiency light propagation, which is one of basic physics principles of photonic devices. The exploration of topological photonics into micro-nano-photonic structures will break the limitation and provide a new way to solve such scattering loss. However, there is lack of systematic and in-depth study, as the coalescence between topological photonics and micro-nano-photonics is in the start-up stage. In preliminary work, the proposer has realized valley-induced topological photonic crystal in micro-nano scale, and experimentally characterized topological-protected edge states along sharp-bending geometry at telecommunication wavelength. This project will study the propagating properties of topological micro-nano-photonic states in valley photonic crystal slab, both in theory and in experiment. The proposer will deeply explore the topological phases of photonic Dirac cones, so as to develop the novel principle of topological photonics suitable for micro-nano-slab structures. The proposer will further explore the intrinsic mechanism of valley-path locking effect to realize disorder-insensitive robust transport. Based on such topologically-protected robustness, beam splitting/combining in topological multichannel will be realized at telecommunication wavelength. In brief, we expect this project can make a clear picture and deep learning on topological micro-nano-photonics and the new mechanisms herein. In addition, it may open a new door on the exploration in micro-nano-photonic structures and their device prototypes based on topologically robust transport.

微纳光子结构中对光的有效传输是促进光子器件发展的物理基础之一，但是其进展受限于缺陷、无序引起的不可控的光学散射。将拓扑光学理论引入微纳光子结构设计中，有望从物理源头解决上述散射损耗问题。然而，目前拓扑光子学与微纳光子学的融合才刚刚起步。申请人在前期工作中已经成功制作了基于能谷自由度的微纳拓扑光子结构，通过大角度转弯初步实验表征了光通信波段的抗散射光传输。本项目拟围绕能谷光子晶体平板，深入、系统开展微纳拓扑光子态传输行为的理论和实验研究。系统研究光学狄拉克锥的拓扑相，发展适用于微纳平板结构的新型拓扑光学理论；研究拓扑边界态中的能谷-传播路径锁定效应，实现更普适的结构偏差不敏感的抗散射光传输；进一步基于抗散射机制，实现拓扑多通道中的光分束/合束行为。期望通过本项目的实施，能够清晰地理解微纳拓扑光子学中若干新效应，探索基于拓扑抗散射机制的微纳光子结构及器件原型设计的新思路。

光作为信息载体，具有速度快、频带宽、信息处理能力强等优势，人们希望在微纳光子结构中获得高效光传输，以促进新一代信息技术的快速发展。本项目围绕微纳能谷光子晶体等体系，开展拓扑光子态传输行为的理论和实验研究。按照执行计划，本项目顺利完成了项目全部研究内容，实现了全部研究目标：1）从麦克斯韦方程出发，利用三维空间矢量场实现了光子晶体平板结构的贝里曲率计算，构建了微纳平板体系的能谷霍尔、双偏振能谷、二维扎克等拓扑相图，实现了双偏振光学狄拉克锥及其偏振依赖光子能谷霍尔效应；2）通过不同材料组分和空间构型优化，实现了能谷光波导与鲁棒性拓扑角态微腔，并分析了它们的空间傅里叶谱分析，验证了能谷拓扑相的结构偏差抗散射特性，并利用谷间散射抑制原理实现了光学抗散射与单向耦合；3）基于能谷-传播路径锁定机制，设计了两种拓扑四通道结构，分析了拓扑边界态在多个通道间的光耦合和抑制机理，实现光分束与合束结构，并用于高可见度的量子干涉效应实验演示。上述微纳能谷光子晶体成果，不仅展示了诸多微纳光传输新效应，也为微纳光子器件原型设计及其在光子量子芯片应用提供新思路。.项目执行期内，标注资助的研究论文无论在质量和数量两方面都超过预期目标，已发表论文10篇，项目负责人均为第一作者/通讯作者（含共同）。这些论文成果包括Physical Review Letters、Laser & Photonics Reviews、Photonics Research、SCIENCE CHINA Physics, Mechanics & Astronomy、Physical Review Applied共5篇代表性论文。申请发明专利1项（已授权）。PRL论文入选Editors’ Suggestion，Photonics Research论文入选Editors’ Pick。项目负责人在多个国内外会议上作口头报告。此外，项目负责人何辛涛博士获得广东省杰出青年基金资助（2022年获批），本青年项目密切相关后续研究计划继续得到国家自然科学基金面上项目资助（2022年获批）。