摘要 本文提出了一种基于石墨烯超表面的效率可调太赫兹聚焦透镜。该超表面单元结构由两层对称的圆形镂空石墨烯和中间介质层组成,其中镂空圆形中间由长方形石墨烯片连接。该结构可实现偏振转换,入射到超表面的圆偏振波将以其正交的形式出射,如左旋圆到右旋圆偏振转换。利用几何相位原理,通过旋转长方形条的方向,透射波会携带额外的附加相位并能满足2π范围内覆盖。合适地排列石墨烯超表面的单元结构,以实现太赫兹聚焦透镜。仿真结果表明:通过改变石墨烯的费米能级,可以对超表面圆偏振转换幅度进行调节,进而超透镜的聚焦效率也可以动态调节。因此,这种基于石墨烯超表面的效率可调聚焦透镜不用改变单元结构的尺寸,只需通过改变费米能级便可实现,可以广泛地应用到能量收集、成像等太赫兹应用领域。 This paper proposes an efficiency-tunable terahertz focusing lens based on the graphene metasurface.The unit cell is composed of two symmetrical circular graphene hollows and an intermediate dielectric layer,wherein the hollow circular middle is connected by a rectangular graphene sheet.This structure can realize polarization conversion,for example,when an incidence with left-hand circular polarization emitted on the metasurface the polarization of the transmitted light is right-hand circular polarization.According to the principle of geometric phase,by rotating the direction of the rectangular bar,the transmitted wave will carry an additional phase and can cover the range of 2π.An THz focusing lens can be realized by properly arranging the unit structure of the graphene metasurface.The simulation results show that the conversion amplitude of circular polarized light can be adjusted by changing the Fermi level of graphene,and the focusing efficiency of the metalens can also be dynamically adjusted.Therefore,this graphene metasurface-based efficiency-tunable focusing lens can be realized by changing the Fermi level without changing the size of the unit cell,and can be widely used in terahertz applications such as energy harvesting and imaging.
机构地区 武汉科技大学信息科学与工程学院
出处 《光电工程》 CAS CSCD 北大核心 2021年第4期60-67,共8页 Opto-Electronic Engineering
基金 湖北省教育厅科技研究计划重点项目(D20181107) 武汉科技大学研究生创新基金项目(JCX201959) 大学生创新基金项目资助课题(20ZA083)。
