Abstract-Terahertz Probing Irreversible Phase Transitions Related to Polar Clusters in Bi0.5Na0.5TiO3‐Based Ferroelectric

Jiyue Wu, Wenfeng Sun, Nan Meng, Hangfeng Zhang, Vladimir Koval, Yan Zhang, Robert Donnan, Bin Yang, Dou Zhang, Haixue Yan

https://onlinelibrary.wiley.com/doi/abs/10.1002/aelm.201901373

Electric‐field‐induced phase transitions in Bi0.5Na0.5TiO3‐based relaxor ferroelectrics are essential to the control of their electrical properties and consequently in revolutionizing their dielectric and piezoelectric applications. However, fundamental understanding of these transitions is a long‐standing challenge due to their complex crystal structures. Given the structural inhomogeneity at the nanoscale or sub‐nanoscale in these materials, dielectric response characterization based on terahertz (THz) electromagnetic‐probe beam fields is intrinsically coordinated to lattice dynamics during DC‐biased poling cycles. The complex permittivity reveals the field‐induced phase transitions to be irreversible. This profoundly counters the claim of reversibility, the conventional support for which is based upon the peak that is manifest in each of four quadrants of the current–field curves. The mechanism of this irreversibility is solely attributed to polar clusters in the transformed lattices. These represent an extrinsic factor, which is quiescent in the THz spectral domain.

Abstract-Hollow complementary omega-ring-shaped metamaterial modulators with dual-band tunability

Hairun Chen, Bin Yang, Yan Gui, Jiaqi Niu,  Jingquan Liu,

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-16-3913

In this Letter, we report two kinds of metamaterial modulators based on hollow complementary omega-ring-shaped (HCΩ) structures, which are fabricated on parylene-C thin film with high flexibility and can realize dual-band amplitude tunability. The first type of structure (HCΩ-I) consists of identical unit cells along a similar direction, achieving different tunability under different compression directions but suffering from polarization dependence. To investigate the effect of unit cell direction on polarization direction, the unit cells in the HCΩ-I device are rotated by 90° in sequence to form a symmetrical type of structure (HCΩ-II), which successfully produces reverse dual-band variation of transmission with good polarization independence. These two developed flexible modulators with varied tunable ability will have a promising application in terahertz detection, sensing, and imaging.

© 2018 Optical Society of America

Abstract-Quality-control of UV offset lithographicaly printed electronic-ink by THz technology

Yang Zeng, Robert Donnan, Marc Edwards, Bin Yang,

http://ieeexplore.ieee.org/document/8068504/

In this paper, a novel quality-monitor method of inkjet-printed electronics based on terahertz (THz) sensing is presented. Specifically, two different approaches, namely THz reflection spectroscopy and THz near-field scanning, are proposed.

Abstract-Flexible omega-ring metamaterial sensor with ultrahigh sensitivity in the terahertz region

Yan Gui, Hairun Chen, Bin Yang, Jingquan Liu, Xiang Chen, Xiaolin Wang, and Chunsheng Yang

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-7-11-4123

This article presents a dual-band tunable metamaterial sensor in the terahertz region, which has a high sensitivity and can work on curved surface with good flexibility. The proposed metamaterial sensor is composed of omega-ring arrays with two types of omega-shape structures fabricated on parylene-C thin substrates. An omega-I structure is developed from unit omega cells arranged along the same direction. Meanwhile, in order to investigate the effect of the unit cell direction on THz transmission, each unit cell is rotated by 90° in sequence to configure omega-II structure. Compared to the omega-I structure, the omega-II structure achieves a 31.1% intensity change when only 4% length is changed and the strain change is around 1.3 × 10−4. Moreover, the omega-II structure is insensitive to the polarization angles of incident waves, which will be beneficial for the potential application of the new flexible THz sensing technology.

© 2017 Optical Society of America

Abstract-Introducing quasi-optical terahertz circular dichroism spectroscopy

Junyi Qui, Yang Zeng,  Richard Pickersgill,  Robert Donnan, Oleksandr Sushko, Bin Yang,

http://ieeexplore.ieee.org/document/7972579/

A sub-Terahertz circular dichroism spectrometer is developed and built based on a vector network analyzer driven quasi-optical system at 220–325 GHz sub-THz frequency domain (VNA-CD). The main goal is to explore the potentially significant absorption features in THz signatures of aqueous protein samples.

Abstract-A 'T' shaped flexible multiband ultra-thin terahertz metamaterial with consistent curved transmission spectra

Hairun Chen1,2, Bin Yang1,2, Xiaoqing Zhao1,2, Yan Gui1,2, Jingquan Liu1,2, Xiang Chen1,2,
 Xiaolin Wang1,2and Chunsheng Yang1,2


http://iopscience.iop.org/article/10.1088/2053-1591/aa7434


In this paper, we designed a flexible multiband ultra-thin terahertz metamaterial with four 'T' shaped beams deposited on parylene-C substrate to achieve sensing. The simulated and experimental investigations of transmission spectra showed two resonant peaks, respectively, which demonstrated a good numerical and experimental agreement. Due to this special 'T' shaped structure, the transmission spectra were nearly unchanged in the first resonant peak and slightly fluctuant in the second resonant peak after bending with a constant step, which successfully confirmed a pretty consistent curved transmission performance. A further study about the effect of polarization and incident angle direction of terahertz wave on transmission spectra indicated that the transmission of the sample did not vary with the change of polarization angles but would be influenced by incident angles. In order to explore the performance of the structure in terms of sensing phenomenon, a final contrast simulation on different surface analytes and without analyte was carried out, consequently suggesting a promising and remarkable function in sensing applications especially in detecting biomolecules.

Abstract-Structural changes of Bombyx mori fibroin from silk gland to fiber as evidenced by Terahertz spectroscopy and other methods

• Xu Wu^a, 
• Xiaodong Wu^a, 
• Min Shao^b, 
• Bin Yang^a, b, , 

• ^a College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018, China
• ^b Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, China

http://www.sciencedirect.com/science/article/pii/S0141813017311303

Here we investigated the structural changes of silk fibroin during Bombyx mori silkworm spinning and reconstitution process. X-ray diffraction, Fourier transform infrared spectroscopy, polarized optical microscopy, and terahertz (THz) spectroscopy were applied to monitor the structural features of silk fibroin from posterior, middle silk glands, to cocoons, and then to reconstituted silk.

Abstract-Accurate determination of terahertz optical constants by vector network analyzer of Fabry–Perot response

Wenfeng Sun, Bin Yang, Xinke Wang, Yan Zhang, and Robert Donnan  »View Author Affiliations

Abstract

We present a method based on a Fabry–Perot model to efficiently and accurately estimate optical constants of wafer samples in transmission-only measurements performed by a vector network analyzer (VNA). The method is demonstrated on two separate wafer samples: one of silicon and the other of polymethylmethacrylate. Results show that the method can not only acquire optical constants accurately and simply over a broad frequency domain but also overcome the limitations of calculation for dispersive and lossy materials to which existing methods are susceptible, such as those based on VNA-driven quasi-optical transmissometers and terahertz time-domain spectrometry.

© 2013 Optical Society of America

Abstract-Determination of silk fibroin secondary structure by terahertz time domain spectroscopy

 

Chao Yan,^a Bin Yang*^a and Zhicheng Yu^ab

Show Affiliations

      http://pubs.rsc.org/en/Content/ArticleLanding/2014/AY/C3AY41358F#!divAbstract

*

Corresponding authors

^a

Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Zhejiang Sci-Tech University, Hangzhou, China
E-mail: yangbin665959@gmail.com

^b

Ecological Engineering Research Center of Dyeing and Finishing Technology, Hangzhou, China

Anal. Methods, 2014, Advance Article

DOI: 10.1039/C3AY41358F
Received 08 Aug 2013, Accepted 08 Oct 2013
First published online 10 Oct 2013

Silk fibroin membranes with different secondary structures were fabricated, and subsequently employed as an ideal system model for the investigation into the conformational transition of native proteins by terahertz time domain spectroscopy (THz-TDS). In comparison to conventional Fourier Transform Infrared (FTIR) Spectroscopy, THz spectroscopy presents distinct features for each kind of secondary structure with narrower bandwidths. Based on the theoretical calculation, absorption features observed in the range of 2.0–2.6 THz may be attributed to intramolecular modes of peptide chain. Three bands centered at 1.84 THz, 1.68 THz, and 1.55 THz are attributed to random coil, α-helix, and antiparallel β-pleated sheet, respectively. The results indicate that THz-TDS presents great potential as a complementary method to FTIR in determining the secondary structure of silk fibroin.

Abstract-Determination of silk fibroin secondary structure by Terahertz time domain spectroscopy

Chao Yan,   Bin Yang and   Cheng Zhi Yu  

http://pubs.rsc.org/en/content/articlelanding/2013/ay/c3ay41358f#!divAbstract

Silk fibroin membranes with different secondary structure were fabricated, and subsequently employed as an ideal system model for the investigation on conformational transition of native protein by Terahertz time domain spectroscopy (THz-TDS). In comparison to conventional Fourier Transform Infrared (FTIR) Spectroscopy, THz spectroscopy present distinct feature for each kind of secondary stucture with narrower bandwidth. Based on the theoretical calculation, absorption features observed in the range of 2.0-2.6THz may be attributed to intramolecular modes of peptide chain. Three bands centered at 1.84 THz, 1.68 THz, and 1.55 THz are attributed to random coil, α-helix, and antiparallel β-pleated sheet, respectively. The results indicate that THz-TDS present great poential as complementary method to FTIR in determining secondary structure of silk fibrion.

 

Terahertz spectroscopy: a powerful new tool for the chemical sciences?

http://pubs.rsc.org/en/content/articlelanding/2012/cs/c1cs15277g

Terahertz spectroscopy is only now beginning to make its transition from initial development by physicists and engineers to broader use by chemists, materials scientists and biologists, thanks to the increasing availability of commercial terahertz spectrometers. With the unique insights that terahertz spectroscopy can provide into intermolecular bonding and crystalline matter, it could prove to be an invaluable addition to the chemist's analytical toolset. This tutorial review aims to give an introduction to terahertz spectroscopy, its techniques, equipment, current applications and potential for the chemical sciences to a broad readership.