近日，河海大学Mengyuan He团队研究了等离子体螺旋表面晶格共振的非极化螺旋二色性。2025年12月8日出版的《物理评论A》杂志发表了这项成果。

在与轨道角动量相关的光学手性研究中，光子自旋角动量及高阶跃迁矩的参与长期被视为不可或缺的因素。迄今为止，完全由轨道角动量决定的螺旋二色性现象仍难以实现。

通过激发等离激元表面晶格共振，研究组报道了一种无需电四极矩参与的、与偏振无关的螺旋二色性，这一现象曾被认为不可能实现。借助旋转对称性修正的偶极子求和模型，他们成功将表面晶格共振理论框架拓展至等离激元螺旋结构。研究结果表明，任意等离激元螺旋结构均可通过构型优化同时实现窄带表面晶格共振峰和与偏振无关的螺旋二色性。

值得注意的是，表面晶格共振激发能同时产生高度局域的近场约束和准直的远场辐射，分别促进手性相互作用中的轨道角动量传递和定向轨道角动量投射。这项工作有望阐明轨道角动量介导的手性内在物理机制，或将对映选择性检测和涡旋增强光谱技术发展产生推动作用。

附：英文原文

Title: Polarization-independent helical dichroism via surface lattice resonance of plasmonic helices

Author: Mengyuan He, Xuefen Kan, Cheng Yin, Qilin Jin, Qiubo Ye, Xiaobin Wang, Jian Wu

Issue&Volume: 2025/12/08

Abstract: In the context of orbital angular momentum (OAM) associated optical chirality, the involvement of photonic spin angular momentum and higher-order transition moments has long been regarded as essential. To date, the existence of helical dichroism that is exclusively determined by OAM remains elusive. Through the excitation of plasmonic surface lattice resonances (SLRs), we report a polarization-independent helical dichroism without the, engagement of electric quadrupole momentsa scenario previously deemed implausible. Using a modified dipole sum under rotational symmetry, the theoretical framework of SLRs is successfully generalized to plasmonic helices. Our results reveal that the arbitrary plasmonic helix can be structurally optimized to exhibit both narrowband SLR peaks and polarization-independent helical dichroism. Notably, SLRs excitation can simultaneously generate tightly confined near-fields and collimated far-field radiation, which facilitate the OAM transfer in the chiral interaction and directional OAM projection, respectively. This work may clarify the intrinsic physics governing OAM-mediated chirality, potentially enabling advances in enantioselective detection and vortex-enhanced spectroscopy.

DOI: 10.1103/rqh7-qjg2

Source: https://journals.aps.org/pra/abstract/10.1103/rqh7-qjg2