Open AccessAnalysis of the thickness dependence of metamaterial absorbers at terahertz frequencies
Author(s) -
Guangwu Duan,
Jacob Schalch,
Xiaoguang Zhao,
Jingdi Zhang,
R. D. Averitt,
Xin Zhang
Publication year - 2018
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.26.002242
Subject(s) - metamaterial , materials science , metamaterial absorber , split ring resonator , ground plane , optics , terahertz radiation , absorption (acoustics) , reflection coefficient , attenuation coefficient , terahertz spectroscopy and technology , dielectric , optoelectronics , tunable metamaterials , antenna (radio) , physics , composite material , telecommunications , computer science
Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ interference theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.