Abstract-Spoof surface plasmon polaritons in terahertz transmission through subwavelength hole arrays analyzed by coupled oscillator model

• 
  • Shan Yin
  • , Xinchao Lu
  • , Ningning Xu
  • , Shuang Wang
  • , Yiwen E.
  • , Xuecong Pan
  • , Xinlong Xu
  • , Hongyao Liu
  • , Lu Chen
  • , Weili Zhang
  •  & Li Wang

http://www.nature.com/articles/srep16440

• Both the localized resonance and excitation of spoof surface plasmon polaritons are observed in the terahertz transmission spectra of periodic subwavelength hole arrays. Analyzing with the coupled oscillator model, we find that the terahertz transmission is actually facilitated by three successive processes: the incident terahertz field first initiates the localized oscillation around each hole, and then the spoof surface plasmon polaritons are excited by the localized resonance, and finally the two resonances couple and contribute to the transmission. Tailoring the localized resonance by hole size, the coupling strength between spoof surface plasmon polaritons and localized resonances is quantitatively extracted. The hole size dependent transmittance and the coupling mechanism are further confirmed by fitting the measured spectra to a modified multi-order Fano model.

Abstract-Optical modulation of terahertz behavior in silicon with structured surfaces

Xiaojun Wu, Xuecong Pan, Baogang Quan, and Li Wang

http://apl.aip.org/resource/1/applab/v103/i12/p121112_s1?isAuthorized=no

Optically modulated terahertz (THz) transmittance through Si with various resistivities, in particular the high-resistivity samples with a structured surface showing nanosized pillars or split-ring resonators (SRRs), was investigated. The samples with nanosized pillars display an increased transmittance and an accordingly reduced modulation depth. With SRRs on the surface, strongly selective modulation can be realized at the resonant frequencies where the transmittance is vanishingly small, whereas at the non-resonant frequencies, where the transmittance is large, the modulation depth is much greater. These results demonstrate an alternative route for the modulation of THz wave in the all-optical devices.

© 2013 AIP Publishing LLC

Article & Abstract-Design of a polarization insensitive multiband terahertz metamaterial absorber

Fangrong Hu, Li Wang, Baogang Quan, Xinlong Xu, Zhi Li, Zhongan Wu,  Xuecong Pan
My Note: you can read the entire article here:
http://m.iopscience.iop.org/0022-3727/46/19/195103/

We design a terahertz (THz) metamaterial absorber having four narrowband high absorptivities of 98%, 97%, 98% and 97% at frequencies of 0.68 THz, 1.27 THz, 2.21 THz and 3.05 THz, respectively. The absorber consists of three metallic layers, which are separated by two dielectric spacers. The absorption performances are simulated using a commercialized full-wave electromagnetic simulation software, and the mechanism of absorption is theoretically investigated. The result shows that the absorber is insensitive to the polarization of THz wave and the position of every absorption peak can be effectively tuned by the geometries of the absorber. The potential applications of the absorber include spectrally selective detecting, THz sensing and thermal imaging.

Abstract-Self-referenced sensing based on terahertz metamaterial for aqueous solutions

http://apl.aip.org/resource/1/applab/v102/i15/p151109_s1?isAuthorized=no

Xiaojun Wu¹, Xuecong Pan¹, Baogang Quan¹, Xinlong Xu^1,2, Changzhi Gu¹, and Li Wang¹

¹Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
²Nanobiophotonic Center, State Key Laboratory for Incubation Base of Photoelectric Technology and Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710069, China 

We demonstrated a self-referenced sensing method in reflection geometry for characterizing aqueous solutions based on terahertz metamaterials. The sensing signal and the reference signal are taken in one measurement from different interfaces of the substrate. For ethanol-water mixture and aqueous solution of NaCl, the line-shape of the modulated response shows distinct polarity, while the peak-valley value near resonant region depends linearly on the solution concentration. These observations result from the variation of dielectric environment near the interface between the metamaterials and the aqueous solutions. This method holds promise for future application in monitoring real aqueous biosystems and ecological water systems.