基于无刻蚀铌酸锂薄膜波导阵列合成参数空间中外尔点的转角拓扑特性  

Topological Characteristics of Rotation Angle of Weyl Point in Parameter Space Based on Unetched Lithium Niobate Thin Film Waveguide Array Synthesis

作　　者：李浩 刘子怡 赵玉乐 王强 肖彦玲 刘辉[1] Li Hao;Liu Ziyi;Zhao Yule;Wang Qiang;Xiao Yanling;Liu Hui(National Laboratory of Solid State Microstructures,Collaborative Innovation Center of Advanced Microstructures,School of Physics,Nanjing University,Nanjing 210093,Jiangsu,China)

机构地区：[1]南京大学物理学院固体微结构物理国家重点实验室,人工微结构科学与技术协同中心,江苏南京210093

出　　处：《光学学报》2024年第20期110-120,共11页Acta Optica Sinica

基　　金：国家自然科学基金(12334015,92163216,92150302,62288101)。

摘　　要：利用拓扑光子学中人工合成维度的概念,在无刻蚀薄膜铌酸锂上,通过将波导阵列结构参数视为额外维度,实现在一维波导阵列系统中模拟三维外尔晶格,并考虑不同外尔结构层间相对扭转的影响,通过调控外尔晶格层间扭转角度,实现了对拓扑界面态间的耦合调控。所提方法不仅降低了样品制备难度,还提高了系统的可控性。此外,在新型无刻蚀薄膜铌酸锂上设计新颖的拓扑波导阵列光学器件,利用合成维度方法,对多层外尔晶格间的相对扭转进行调控,探索其传输效果及丰富的物理特性,包括实现多外尔晶格的拼接和拓扑界面态的耦合调控。通过调节波导阵列长度灵活控制光输出,丰富了光调控的自由度,特别是在光学开关和逻辑器件领域,为片上大规模光子器件集成提供了新的设计思路。Objective Topological photonics,a novel method for controlling light flow,exploits topologically protected photonic states at interfaces between topologically trivial and nontrivial structures.These states can maintain robust light transmission even in the presence of structural defects.An ideal integrated optical platform for realizing topological photonics is lithium niobate on insulator(LNOI).However,the challenges in etching lithium niobate pose a hurdle to achieving mass production.Recently,a new type of LNOI that requires no etching has been proposed.This technology,by avoiding complex etching steps,shows tremendous potential to become the nextgeneration optical integration platform.Nevertheless,research on topological devices using this platform is still rare.Here,we report the design of a onedimensional waveguide array using the concept of synthetic dimensions.This design enables the coherent coupling of topological interface states between multiple layers of threedimensional Weyl lattices by adjusting the relative twist angles between different Weyl lattices.We aim to flexibly control light output by designing waveguide arrays of different lengths,thereby enriching the freedom of light control.This approach provides new design ideas for the integration of largescale photonic devices on chips,particularly in the fields of optical switches and logic devices.Methods We employ a combination of experimental and theoretical methods to investigate the topological characteristics of Weyl points in thin film unetched lithium niobate waveguide arrays.Theoretically,a tightbinding model is employed to design different waveguide spacings,which are considered synthetic dimensions.This approach aims to realize threedimensional Weyl points within a onedimensional waveguide array system.Multiple layers of Weyl lattices are crafted,and by adjusting the relative twist angles between different layers,the coherent coupling of topological interface states is achieved.Experimentally,unetched waveguides are fabricated using ele

关 键 词：集成光学 铌酸锂 无刻蚀波导 人工合成维度 拓扑光子学 

分 类 号：O436[机械工程—光学工程]