Abstract-Multiband terahertz absorber and selective sensing performance

Yue Wang, Zijian Cui, Dongying Zhu, Xinmei Wang, Suguo Chen, and Pengcheng Nie

Fig. 1 (a) Illustration of multiple-band THz metamaterial absorber. (b) Photograph of the metamaterial absorber. (c) Optical microscopy image of the absorber. (d) Reflection time-domain waveforms in the TE and TM polarization cases. Inset: Designed structure and geometric parameters of the unit cell.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-10-14133

Multiband terahertz absorbers are essential photonic components for responding to, manipulating, and modulating terahertz waves. In this work, improved electric split resonant ring arrays are used to demonstrate multiband terahertz wave absorption. The proposed design strategy is simple, practical, and significant. Experiments and simulations reveal perfect absorption at 0.918 THz and 1.575 THz for the transverse magnetic (TM) polarization and at 0.581, 1.294, and 1.556 THz for the transverse electric (TE) polarization. In addition, the weak resonant peaks that occurred in the experiments in both polarization states have been verified by the simulations. Furthermore, five concentration gradients of 2, 4-dichlorophenoxyacetic acid solutions and six concentration gradients of chlorpyrifos have been detected using the absorber. The lowest detectable concentration that could be monitored was 0.1 ppm. The absorption, intensity, and frequency shift values for the different solution concentrations at the resonant peaks were analyzed. The highest linear regression coefficients were 0.9862 and 0.9565 for the TE and TM polarizations, respectively. This multi-band absorber was demonstrated to be highly efficient in detecting pesticides for food safety applications.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Tailoring terahertz surface plasmon wave through free-standing multi-walled carbon nanotubes metasurface

Yue Wang, Zijian Cui, Dongying Zhu, Xianbin Zhang, and Li Qian

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-12-15343

Surface plasmons have a fundamental role in the dynamics of photon–electron interactions and in optical metamaterials. Terahertz (THz) time-domain spectroscopy was used to characterize the complex dielectric constant, index of refraction, and conductivity of super-aligned, free-standing, multi-walled carbon nanotube films over the range 0.2-2.5 THz. These complex parameters were in excellent agreement with Maxwell-Garnett and Drude-Lorentz models. In addition, surface plasmon excitations in engineered, subwavelength, multi-walled carbon nanotube metasurfaces were examined. The observed surface plasmon resonances, reproduced by simulation, could be changed over the THz frequency range by altering the lattice constant of the arrays. The THz transmission was enhanced at the resonance peak. Overall, the results indicate potential applications for THz metasurfaces based on super-aligned, free-standing multi-walled carbon nanotubes.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement