光频三维各向同性左手超材料结构单元模型的仿真设计

Numerical study of three-dimensional isotropic left-handed metamaterials at visible frequencies

基于树枝结构单元思想,提出了光频三维各向同性左手超材料球刺结构单元模型.采用金属的Drude原理,运用等效媒质理论,仿真研究了结构的电磁响应特性.在晶格间距与工作波长的比值满足等效媒质理论要求的前提下,通过调节结构单元的几何参数,发现它能在光波段出现介电常数和磁导率同时为负值的区域,实现折射率小于零的左手超材料响应特性.该模型结构简单,具有各向同性特点.研究结果为采用"由下向上"方法制备光波段的三维左手超材料指出了新的途径.

In this paper,we design a three-dimensional isotropic left-handed metamaterial（LHM） composed of sphere-thorn shaped cells at visible frequencies.Adopting the metallic Drude＇ s principle,we simulate and study its transmission properties for the incident plane electromagnetic wave.The dimension of unit cell here is far below the resonant wavelength,and thus the effective medium theory is well satisfied.With appropriate geometric parameters,this structure can realize negative refractive index with simultaneous negative permittivity and permeability at visible frequencies.The LHM proposed in this paper has advantages of simplicity and isotropy,moreover,our numerical model provides a new method for ＇top-to-bottom＇approach to preparing visible three-dimensional metamaterials.