Dual-band electromagnetically induced transparency (EIT) terahertz metamaterial sensor

Abstract

We propose a dual-band terahertz metamaterial sensor (MS), which exhibits the low loss and high quality (Q) factor of electromagnetically induced transparency (EIT) effects at the frequencies of 0.89 THz and 1.56 THz simultaneously. The physical natures of EIT effects are analyzed by using numerical simulations and a “two particle” model. Further, THz sensing is performed based on the shifts of two EIT resonances when the analyte is coated at the metamaterial surface. The sensitivities of the sensor are investigated with respect to different thicknesses, cover areas and refractive indexes of the coated analyte film. Results show that the first EIT resonance is suitable for sensing the analyte with the refractive index from 1.5 to 2, while the second EIT resonance is more suitable for sensing the refractive index of the analyte from 1 to 1.5. The sensitivity is 280.8 GHz/RIU, the average Q value is 14.3, and the figure of merit (FOM) value is 4 for the first EIT resonance. Meanwhile, the sensitivity is 201.6 GHz/RIU, the average Q value is 56.9, and the FOM value is 11.5 for the second EIT resonance. Such a metamaterial sensor with high refractive index sensitivity and dual-band would have great potentials for promoting the developments of multi-band/broadband terahertz sensing and detection technology.

A Dual-Band High-Sensitivity THz Metamaterial Sensor Based on Split Metal Stacking Ring

“…The first resonance was suitable for sensing the refractive index of an analyte from 1 to 2, but the second resonance was only suitable for sensing the refractive index from 1 to 1.5, since further enhancement of the refractive index for the analyte raised the overall loss of metamaterial and degraded the performance of the second resonance band. In contrast, the proposed sensor in this paper has the following advantages: firstly, the two resonances are far apart and thus the sensor has a wider working frequency band of 0.2-3 THz; secondly, the refractive index sensitivity of the two resonances achieves 304 GHz/RIU at resonance 1 and 912 GHz/RIU at resonance 2, respectively, which is superior to previous works [24,31], making the sensor easier to identify kinds of substances with similar refractive indices; finally, both resonances can be used for sensing the refractive index between 1 and 2, enabling one to identify a specific substance at multiple frequency bands simultaneously, which can better meet the specificity of the substances to be measured.…”

“…Zhu L. et. al [ 24 ] proposed a kind of metamaterial with refractive index sensitivity of 280.8 GHz/RIU at 0.89 THz and 201.6 GHz/RIU at 1.56 THz. The first resonance was suitable for sensing the refractive index of an analyte from 1 to 2, but the second resonance was only suitable for sensing the refractive index from 1 to 1.5, since further enhancement of the refractive index for the analyte raised the overall loss of metamaterial and degraded the performance of the second resonance band.…”

“…Furthermore, a dual-band terahertz metamaterial was proposed to realize detection at two electromagnetically induced transparency (EIT) resonances. The refractive index sensitivity was 280.8 GHz/RIU for sensing the refractive index in the range 1.5–2 at the first EIT resonance and 201.6 GHz/RIU for sensing the refractive index in the range 1–1.5 at the second EIT resonance [ 24 ]. With the development of high-powered stable terahertz sources, it is more relevant than ever to broaden the terahertz band availability for metamaterials, allowing the detection of the substance over a wider range of frequency bands.…”

Inversely-designed terahertz metadevice with ultrafast modulation of double electromagnetically induced transparency windows

“…As of late, the metasurface-based electromagnetically induced transparency (EIT) analog has drawn in impressive consideration, attributed to an assortment of promising applications in the field of quantum information storage [1][2][3] , novel optical communication [4,5] , slow-light devices [6][7][8] , and sensing [9][10][11] . Usually, in metasurfaces, the EIT effect has been obtained via the near-field coupling between bright and dark modes or superradiant and sub-radiant modes [12][13][14][15][16][17] .…”

Dynamically Tunable and Multifunctional Polarization Beam Splitters Based on Graphene Metasurfaces

“…Consequently, it has significant applications in optical storage, optical communication, and integrated optical circuits [ 1 , 2 , 3 ], and has become a popular research topic in recent years. Electromagnetically induced transparency (EIT) [ 4 , 5 ] is a unique optical phenomenon in which light is destructively interfered with between atomic energy levels, making EIT applicable to the fields of sensing [ 6 , 7 ] and slow light [ 8 , 9 ]. However, EIT requires rigorous experimental conditions, severely restricting its optical application.…”