Abstract
A broad range of terahertz (THz) metamaterials have been developed for refractive index sensing. However, most of these metamaterials barely make sufficient use of the excited electric field which is crucial to achieve high sensitivity. Here, we proposed a metamaterial sensor possessing electromagnetically induced transparency (EIT) resonance that is formed by the interference of dipole and quadrupole resonance. In particular, the strengthening of light-matter interaction is realized through substrate etching, leading to a remarkable improvement in sensitivity. Hence, three kinds of etching mode were presented to maximize the utilization of the electric field, and the corresponding highest sensitivity is enhanced by up to ~2.2-fold, from 0.260 to 0.826 THz/RIU. The proposed idea to etch substrate with a strong light-matter interaction can be extended to other metamaterial sensors and possesses potential applications in integrating metamaterial and microfluid for biosensing.
Highlights
In recent years, the trends of metamaterial research have progressed toward the realization of particular functions by constructing customized metasurfaces to control its optical properties [1,2,3,4,5], thereby creating extraordinary opportunities in the field of various functional devices like modulators, absorbers, and sensors [6,7,8,9]
By controlling the coupling between two resonant modes, highly desirable electromagnetically induced transparency (EIT) resonance can be obtained with high quality (Q) factor, which is capable of detecting weak shifts in the resonance frequency [17]
We proposed a novel scheme for the formation of EIT resonance at THz frequencies in planar metamaterial which is composed of a cut wire (CW) and a U-shaped split ring (U-SRR)
Summary
The trends of metamaterial research have progressed toward the realization of particular functions by constructing customized metasurfaces to control its optical properties [1,2,3,4,5], thereby creating extraordinary opportunities in the field of various functional devices like modulators, absorbers, and sensors [6,7,8,9]. By controlling the coupling between two resonant modes, highly desirable EIT resonance can be obtained with high quality (Q) factor, which is capable of detecting weak shifts in the resonance frequency [17] Such excellent properties make EIT effective in metamaterials with great attraction for its potential in serving as a biochemical sensing platform [18]. A significant enhancement of the sensitivity is realized due to the fact that the electric field that permeates the substrate interacts with the analyte after etching.
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