金属光栅异常透射增强黑磷烯法拉第旋转的理论研究  

Enhancement of Faraday rotation of black phosphorus by extraordinary optical transmission of the metal grating

作　　者：董大兴 刘友文[1] 伏洋洋 费越 Dong Da-Xing;Liu You-Wen;Fu Yang-Yang;Fei Yue(Department of Applied Physics,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]南京航空航天大学应用物理系,南京210016

出　　处：《物理学报》2020年第23期243-251,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61675095,11904169)资助的课题.

摘　　要：黑磷是一种具有直接带隙的二维材料,其较宽的带隙填补了石墨烯和二维过渡金属硫化物之间的带隙空白,其特殊的褶皱状晶体结构导致了其独特的面内各向异性,使其具有了独特的力电磁响应特性.本文基于单层黑磷设计了一种金光栅/黑磷/硅的混合等离子体结构的磁光器件.通过金属光栅诱导异常透射显著增强透射率,同时通过TE模式和TM混合等离子体模式匹配耦合增强了法拉第旋转效应.在1.5 THz工作频率点,对器件参数进行优化后,施加5 T的外部磁场,法拉第旋转角度可以达到2.7426°,增益为14.434倍,同时透射率能够保持在85%以上.此外,研究了黑磷的载流子密度和外部磁场对磁光器件的调谐特性.最后,讨论了金属光栅的类等离子模式对本征波导模式和法拉第磁光效应的影响.Black phosphorus(BP)is a kind of two-dimensional(2D)material with direct bandgap.Its adjustable bandgap fills the gap between graphene and transition metal dichalcogenides(TMDCs).At the same time,the black phosphorusalso has a higher charge carrier mobility.The unique fold-like crystal structure of the black phosphorus leads to in-plane anisotropy and it makes the photoelectric response anisotropic.It shows that the properties of black phosphorus can be dynamically adjusted by various methods.These characteristics make black phosphorus a two-dimensional material with great potential applications in the visible light to midinfrared region and even terahertz bands.In view of this,this paper focuses on the magneto-optical response of black phosphorus.In this paper,we design a magneto-optical device in Au grating/black phosphorus/silicon hybrid plasmonic structures.The inducing of abnormal transmission through the metal grating significantly enhances the transmittance,while the Faraday rotation effect is enhanced through the mode coupling between the TE and TM in the THz range.The rigorous coupled wave analysis(RCWA)is used to calculate the transmittance of the grating.The finite element software COMSOL Multiphysics is used to calculate the transmittance and simulate the electric field distribution of the magneto-optical device.Under the optimal parameters,the Faraday rotation can increase 14.434 times,reaching to 2.7426°,and the transmittance is more than 85%with an external magnetic field of 5 T at the operation frequency(1.5 THz).We plot the electric profiles of the magneto-optical device with and without BP to prove that the Faraday rotation is a result of the magneto-optical property of the monolayer phosphorus and that the enhancement is due to the mode coupling between the TE and TM.Moreover,we extract the tunable character of the magneto-optical device with the external magnetic field and the carrier density of the black phosphorus.The external magnetic field can effectively tune the Faraday rotation angle w

关 键 词：黑磷 异常透射 法拉第旋转 

分 类 号：TB34[一般工业技术—材料科学与工程] O482.55[理学—固体物理]