三维非线性异向介质的频率特性

Frequency features of a 3-D nonlinear metamaterial

为了实现异向介质的可调性,推导了埋入在非线性介质中的由金属线和谐振环构成的具有三维周期性结构的Metamaterial有效磁导率表达式,计算了Metamaterial的有效磁导率实部和虚部对外场频率的响应.结果表明,当外场频率与这种Metamaterial的线性本征频率相差越小时,材料的左右手特性的跳变点就越小,且在非线性区材料的磁响应呈现双稳特性,这种现象可能被用于实现光学双稳态和光学开关器件.

In order to create a tunable metamaterial we derived an expression of the effective magnetic permeability of a 3-D metamaterial created by periodical arrays of wires and split-ring resonators（SRRs）embedded into a nonlinear dielectric.We also calculated the dependencies of the real part and imaginary part of the effective permeability of the structure on varying external magnetic field strengths and different frequencies.The results showed that the characteristic magnetic field strength for switching of the structural property was proportional to the difference between the external field frequency and the linear eigen-frequency of the metamaterial.In the nonlinear regime the magnetic response of the metamaterial may become bistable.This phenomenon may be used to create optically bistable behavior,and hence optical switching devices,although as yet this has only been demonstrated at microwave frequencies.