基于柱对称梯度折射率体系的可调控光束传输  

Tunable beam propagation based on cylindrically symmetric gradient index system

作　　者：温广锋 赵领中 张琳 陈毅云 罗圻林 方安安 刘士阳 Wen Guang-Feng;Zhao Ling-Zhong;Zhang Lin;Chen Yi-Yun;Luo Qi-Lin;Fang An-An;Liu Shi-Yang(Institute of Information Optics,Zhejiang Normal University,Jinhua 321004,China;Xiangsihu College,Guangxi University for Nationalities,Nanning 530225,China)

机构地区：[1]浙江师范大学信息光学研究所,金华321004 [2]广西民族大学相思湖学院,南宁530225

出　　处：《物理学报》2022年第14期102-111,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11574275);浙江省自然科学基金(批准号:LR16A040001);广西高校中青年教师科研基础能力提升项目(批准号:2022KY1604)资助的课题.

摘　　要：采用磁性电磁超构材料,设计了具有柱对称梯度折射率分布的二维体系,根据梯度的不同可以实现光束的不同调制功能.通过等效介质理论,可以计算磁性电磁超构材料的等效电磁参数,从而获得等效折射率.而且,随着磁性柱半径的变化,可以实现等效折射率的灵活调制.尤为特别的是,通过改变外加偏置磁场的空间分布,可以实现不同的折射率梯度,这也是磁性电磁超构材料相对于普通介质体系的优越性.基于多重散射理论,对光束在二维体系中的传输行为进行了模拟计算,研究结果表明通过调制外加偏置磁场可以实现光束的囚禁、光束的内偏折和外偏折、以及分束等功能.而且,通过改变外加磁场可以实现不同功能间的切换,这种灵活的调制能力为光束传输提供了新的自由度.In this work, a cylindrically symmetric gradient-refractivity two-dimensional electromagnetic system is constructed by using the magnetic metamaterials consisting of an array of ferrite rods. With the change of the bias magnetic field, the different gradient-refractivity systems can be obtained, based on which a tunable flexible beam is demonstrated. Based on the effective-medium theory, the effective electric permittivity and the effective magnetic permeability can be retrieved and thus the effective refractive index is obtained straightforwardly. It is shown that with the variation of the ferrite rod radius, an effective refractivity profile with particular gradient can be realized, which exhibits the electromagnetic “black-hole-like” effect. Especially,the gradient refractivity profile is also designed by introducing the gradient bias magnetic field, which, in principle, results in the refractivity profile with many different gradients. Finally, the propagation of a Gaussian beam in the gradient-refractivity system is simulated by using the multiple scattering theory. A few different phenomena are observed such as the “ black-hole” effect, the interior beam deflection, the exterior beam deflection, and the beam splitting. Furthermore, the functionalities can be switched between each other by controlling the bias magnetic field and adding an additional degree of freedom for beam propagation.

关 键 词：电磁黑洞 梯度折射率 等效介质理论 多重散射理论 

分 类 号：O441.4[理学—电磁学]