标题： 通过多目标策略在二维光声拓扑绝缘体中定制声波和电磁波的赝自旋单向态 显示英文标题

标题： Customizing pseudospin unidirectional states of acoustic and electromagnetic waves in two-dimensional phoxonic topological insulators via multi-objective strategies

摘要： 拓扑材料在经典波应用中展现出显著的潜力，如传感、波导和信号处理，利用了诸如强鲁棒性、对背向散射的免疫性和单向传输等拓扑保护效应。 本工作提出了二维$C_{\textrm{6v}}$光声晶体中声波和电磁波的伪自旋依赖的拓扑边缘态的同时逆向设计。 光声晶体是通过在空气背景中周期性排列硅柱而制成的。 我们提出了一种基于NSGA-II与有限元方法协同的多目标优化框架，其中声波和电磁波的带隙分别作为目标值进行处理。 通过模态场计算分析成对简并模态的位置关系来确定带隙的拓扑性质，从而实现在同一单元内定制其中一个带隙。 与传统方法依赖带隙反转来诱导拓扑相变不同，所提出的方法直接为两种波类型生成具有不同拓扑特性的两个单元，从而在每种情况下实现最大的带隙匹配。 我们进一步证明了声波和电磁波的伪自旋依赖的拓扑边缘态的存在，验证了它们的单向性和对背向散射及缺陷的鲁棒性。 本工作建立了一种定制光声拓扑态的系统性策略，为基于声波和光波的多功能器件的逆向设计提供了一条新途径。 显示英文摘要

摘要： Topological materials for classical waves offer remarkable potential in applications such as sensing, waveguiding and signal processing, leveraging topological protection effects like strong robustness, immunity to backscattering and unidirectional transmission. This work presents the simultaneous inverse design of pseudospin-dependent topological edge states for acoustic and electromagnetic waves in two-dimensional $C_{\textrm{6v}}$ phoxonic crystals. The phoxonic crystals are created by arranging the silicon columns periodically in the air background. We propose a multi-objective optimization framework based on the NSGA-II collaborated with the finite element approach, where the bandgaps of acoustic and electromagnetic waves are treated separately as the objective values. The topological nature of bandgaps is determined by analyzing the positional relationships of paired degenerate modes through the modal field calculations, enabling the customization of one of the two bandgaps within the same unit cell. Unlike traditional approaches relying on the band inversion to induce topological phase transitions, the proposed approach directly generates a pair of unit cells with distinct topological properties for both wave types, achieving the maximum bandgap matching in each case. We further demonstrate the existence of the pseudospin-dependent topological edge states for both acoustic and electromagnetic waves, verifying their unidirectionality and robustness against backscattering and defects. This work establishes a systematic strategy for customizing phoxonic topological states, offering a new avenue for the inverse design of multi-functional devices based on both sound and light.