Experimental characterization of the dispersive behavior in a uniaxial metamaterial around plasma frequency
Experimental characterization of the dispersive behavior in a uniaxial metamaterial around plasma frequency
复制标题
单轴超材料在等离子体频率附近色散行为的实验表征
DOI：
10.1364/oe.18.022631
复制
发表时间：
2010-10-25
期刊：
影响因子：
3.8
通讯作者：
Ran, Lixin
中科院分区：
文献类型：
--
作者：
Ye, Dexin;Qiao, Shan;Ran, Lixin
实验研究了磁单轴超材料中等离子体频率附近的色散行为。通过理论分析、参数反演和实验表明，当考虑材料损耗时，当等离子体频率由磁导率的真实的部分趋近于零的频率定义时，由于色散图的改变，超快相速度实际上出现在稍低的频率处。参数反演和实验数据表明，在等离子体频率左边的窄频带内，固有损耗保持有限，且远小于相应共振区的固有损耗。在真实的超材料样品中，测量到自由空间中光速的24，440倍的超快相速度，并且观察到由于唯一的负磁导率引起的负相传播。这种具有有限损耗的超快相速度的存在完美地解释了基于近零折射率超材料的高方向性天线的工作原理，并可进一步用于同相分波器和相干波源等其他应用。(C)2010年美国光学学会
In this paper, the dispersive behavior around the plasma frequency in a magnetically uniaxial metamaterial is experimentally investigated. We show by theoretical analysis, parameter retrieval and experiment that when material loss is considered, while the plasma frequency is defined by the frequency where the real part of permeability approaches zero, ultra fast phase velocity actually appears at a slightly lower frequency, due to the change of the dispersion diagram. Both parameter retrieval and experimental data show that within a narrow frequency band to the left of the plasma frequency, the inherent loss keeps finite and is much less than that in the corresponding resonant region. In a real metamaterial sample, an ultra fast phase velocity of 24,440 times the speed of light in free space is measured, and negative phase propagation due to the only negative permeability is observed. The existence of such ultra fast phase velocity with finite loss perfectly explains how the highly directivity antennas based on near-zero refractive index metamaterial work, and can be further used in other applications such as in-phase wave divider and coherent wave sources. (C) 2010 Optical Society of America