Open AccessExperimental characterization of the dispersive behavior in a uniaxial metamaterial around plasma frequency
Author(s) -
Dexin Ye,
Shan Qiao,
Jiangtao Huangfu,
Lixin Ran
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.022631
Subject(s) - metamaterial , phase velocity , optics , refractive index , plasma , frequency band , directivity , plasma oscillation , physics , group velocity , materials science , dispersion relation , phase (matter) , low frequency , antenna (radio) , telecommunications , quantum mechanics , astronomy , computer science
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.