Quad-band THz frequency selective surface based on a split ring resonator loaded with multiple slots

Abstract

A quad-band terahertz (THz) frequency selective surface with bandstop response is designed, fabricated, and characterized. The unit cell of the filter consists of a split ring resonator (SRR) and surrounding four groups of slots. Each group of slots has three slots with different lengths. The lowest frequency band is determined by the resonance of the SRR and the other three upper bands are selected by the resonance of the slots which exhibit bandstop characteristics rather than bandpass characteristics. The filter transformation characteristic originates from the slits placed between the unit cells which act as series-connected capacitive components. The fabricated quad-band THz filters exhibited bandstop characteristics with attenuation higher than 20 dB in all the operating frequency bands.

The quad-band FSSs were characterized using TeraView's time domain spectroscopy system - the TPS Spectra 3000.

http://www.tandfonline.com/doi/abs/10.1080/09205071.2015.1053576

Properties of two-component nematic liquid crystal mixtures in the range of 0.3–3.0 THz

TeraView's TPS Spectra 3000 was used to investigate nematic liquid crystals in the range of 0.3–3.0 THz.


http://www.tandfonline.com/doi/abs/10.1080/02678292.2015.1036816#.VYvdFvlViko


Abstract

In this work, we present the results of terahertz measurements of five nematic liquid crystal materials. Optical properties like refractive indices, birefringence and absorption coefficients of liquid crystals (LCs) for ordinary and extraordinary polarisation were compared. The aim of this study was to check the impact of the structure of LC molecules on above properties. The compounds with different core structure and various number of laterally substituted fluorine atoms were chosen. A standard terahertz Time-Domain Spectrometer to measurements from 0.3 THz to 3 THz was used.

TeraView TPS 3000 unit for time domain spectroscopy was used to investigate spectral properties of nematic liquid crystal mixtures

Article

Spectral Properties of Nematic Liquid Crystal Mixtures Composed with Long and Short Molecules in THz Frequency Range

ABSTRACT In this paper the influence of short and long molecules added to liquid crystal
6CHBT were investigated. Change of refractive indices and absorption coefficients
for 6CHBT mixtures were compared in the 0.3 - 3 THz frequency range. Influence of
temperature on the mentioned parameters of liquid crystal were investigated. Our study
show that even a slight change in shape and the composition of the molecules dopants
affects the macroscopic properties of liquid crystal. These properties depend on the
length of chains, the number of benzene or cyclohexane rings or the spatial distribution
of molecules and the interactions between them in the liquid crystal mixture. Spectra
measurements on the terahertz time-domain spectrometer were performed.
Spectral Properties of Nematic Liquid Crystal Mixtures Composed with Long and Short Molecules in THz Frequency Range (PDF Download Available). Available from: http://www.researchgate.net/publication/235218799_Spectral_Properties_of_Nematic_Liquid_Crystal_Mixtures_Composed_with_Long_and_Short_Molecules_in_THz_Frequency_Range [accessed Jun 23, 2015].

Hybrid SRRs Design and Fabrication for Broadband Terahertz Metamaterials

Pan, Z.Y. Zhang, P. ; Chen, Z.C. ; Vienne, G. ; Hong, M.H.

IEEE Photonics Journal 4(5), 1267 – 1272, (2012)

Data Storage Inst., Agency for Sci., Technol. & Res. (A*STAR), Singapore, Singapore

ABSTRACT

Hybrid metamaterials comprising split-ring resonator (SRR) structures with different gap dimensions are fabricated on polyethylene naphthalate (PEN) films by parallel laser micro-lens array (MLA) lithography and a liftoff process. The unit cell of hybrid metamaterials consists of four SRRs with the same SRR core side length but different gap sizes. The different-gap-size SRRs in each unit cell correspond to different but successive resonance dips, which are coupled to form a significantly broader band with enhanced resonance. The hybrid SRRs design is numerically and experimentally demonstrated, showing a much broader bandwidth to cover all narrowband induced by each SRR and enhanced resonance as compared with a uniform SRR design.

......The pitch p of the samples is defined by the pitch size of the MLA, which is fixed at 100 m. The sample characterization is carried out with a THz time-domain spectroscopy (THz-TDS) system (TPS3000, Teraview Inc.) in ..


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Surface relief structures for a flexible broadband terahertz absorber

Dong-Hyun Kim,1 Dae-Seon Kim,1 Sehyun Hwang,2 and Jae-Hyung Jang1,2,3,*

1School of Information and Communications, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea

2Research Institute for Solar and Sustainable Energies, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea

3Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea

Abstract

Terahertz (THz) absorbers with surface relief structures (SRSs) were designed and fabricated on a flexible polydimethylsiloxane(PDMS) substrate by using a stamping method. The silicon mold used for the stamping process was prepared by using a crystallographic wet etching method with 45% KOH solution at 80°C. The flexible THz absorber, consisting of micropyramids with a base width of 240 μm, demonstrated nearly perfect absorbance higher than 99% owing to the dramatically reduced surface reflectance of the SRS. The reflectance of the PDMS with the SRS was less than 1%, which is only 1/100th of that measured from a bare PDMS at frequency higher than 1 THz.

... of 240 μm. The reflectance and transmittance of the fabricated flexible PDMS-based SRS samples were measured with a terahertz time-domain spectroscopy (THz-TDS) system (TPS spectra 3000, TeraView). The THz-TDS ...

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THz spectroscopy and imaging in security applications

Palka, Norbert; Szustakowski, Mieczyslaw ;  Kowalski, Marcin ;  Trzcinski, Tomasz ;  Ryniec, Radoslaw ;  Piszczek, Marek ;  Ciurapinski, Wieslaw ;  Zyczkowski, Marek ;  Zagrajek, Przemyslaw ;  Wrobel, Janusz

Institute of Optoelectronics, Military University of Technology, Warsaw, Poland  

19th International Conference on Microwave Radar and Wireless Communications (MIKON), 2012 

Volume 1, pages 265-270

ABSTRACT

We compared terahertz transmission spectra of explosives measured by means of Time Domain Spectroscopy (TDS) and an Optical Parametric Oscillator-based system (OPO). Reflection spectra of pure explosives were measured in reflection configuration by means of TDS in the range 0.3–2.5THz. We also analyzed influence of the surface roughness on reflectance and phase spectra of RDX plastic based explosives. Next, we present a thermal phantom of human body working in THz range, which was developed for testing of THz cameras. We demonstrate the possibility of improvement of the quality of the image captured by a commercially available passive THz camera.

for full paper click here

... In our investigations we exploited a commercially available spectrometer TPS 3000 from Teraview -  Fig.1a [9]. The heart of the system is a 800 nm femtosecond Ti:Sapphire laser (a pulse duration  less than 100 fs, repetition rate of 80 MHz, and average power of 300 mW). ...

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