平面手性石墨烯超表面的等离激元近场手性响应  

Plasmonic Near-Field Chiral Responses of Planar Chiral Graphene Metasurfaces

作　　者：胡莉[1] 席锋[1] 代洪霞[1] Hu Li;Xi Feng;Dai Hongxia(Department of Applied Physics,College of Artificial Intelligence,Chongqing Technology and Business University,Chongqing 400067,China)

机构地区：[1]重庆工商大学人工智能学院应用物理系,重庆400067

出　　处：《光学学报》2024年第23期226-235,共10页Acta Optica Sinica

基　　金：重庆市自然科学基金(CSTB2022NSCQ-MSX1536,2024NSCQ-MSX0683);重庆市教委科学技术研究重点项目(KJZD-K202200805);国家自然科学基金(11804035)。

摘　　要：为了实现手性传感和对少量分子或单分子的手性识别和检测,将单层非手性石墨烯纳米片组成平面手性超表面,利用石墨烯等离激元共振响应及纳米片之间的耦合效应,获得单一手性、分布较均匀且强烈的近场手性响应。利用COMSOL软件对电磁波与超表面的相互作用进行数值模拟分析。模拟结果显示:相对于非手性超表面,平面手性超表面所产生的手性近场更强且分布更均匀;随着错位位移的增加,光学近场强度逐渐增加,对应的手性峰(谷)位置变化很小;随着纳米片宽度增加,手性峰(谷)位置蓝移,当纳米片所围面积不变时,手性增强强度有微小变化,而当纳米片所围面积增加时,平均近场手性增强减小;随着纳米片长度的增加,光学手性近场强度基本保持不变,但对应的手性峰(谷)位置明显红移;随着石墨烯纳米片费米能级增加,光学手性强度增大且对应的手性峰(谷)位置明显蓝移;当纳米片包围区域填入相反手性的手性分子时,其吸收谱相对于非手性分子呈对称分布。此理论研究有望为在实验中实现手性传感、对少量分子或单分子检测提供理论参考。Objective Chirality is a geometric property of objects that cannot be superimposed on their mirror images through simple rotation or translation.Many biomolecules,such as nucleic acids,DNA,and carbohydrates,exhibit chirality.Molecules with different handedness often show different physiological activities and biological toxicities.Therefore,accurate and efficient identification,detection,and separation of chiral molecules are essential in fields like analytical chemistry and biopharmaceuticals.Research has shown that the ultra-strong chiral near-field generated by metasurfaces can significantly amplify the weak chiral response of chiral molecules,making it highly valuable for chiral sensing,molecular recognition,and separation.Various chiral,achiral,2D,and 3D metal nanostructures have been designed to produce chiral near-fields.Some of these near-fields exhibit opposite chirality in different regions,limiting the enhancement of volume-averaged optical chirality;some structures are complex to fabricate;others generate background chiral signals.In addition,the response wavelength of metal nanostructures is usually restricted to the visible and near-infrared regions.However,important drugs and biomolecules exhibit chiral signals in the mid-infrared range.Graphene nanomaterials,with advantages such as low loss and dynamic tunability,have thus gained significant attention.We theoretically design a planar chiral metasurface composed of simple graphene nanosheets to achieve a single-handed,more uniform,and stronger chiral near-field distribution.Methods A rotating planar chiral metasurface composed of three rectangular graphene nanosheets is proposed to generate a single-handed,uniform,and strong chiral near-field response.Graphene nanosheets are deposited on a silicon substrate,and the entire metasurface is placed in air.Simulations are conducted using COMSOL software based on the finite element method.Circularly polarized light(CPL)propagates along the-Z direction,with an electric field intensity of 1 V/m.The graphene

关 键 词：应用光学 纳米光子学 手性传感 石墨烯 

分 类 号：O439[机械工程—光学工程]