Thursday, 27 February 2014

Xi-Cheng Zhang Named As American Association for the Advancement of Science Fellow

TeraView would like congratulate Xi-Cheng Zhang on being named a fellow of the American Association for the Advancement of Science for his contributions to the generation and detection of broadband terahertz waves, after being elected by his peers in the association.

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Friday, 21 February 2014

Orbital-selective metal–insulator transition and gap formation above TC in superconducting Rb1−xFe2−ySe2

Zhe Wang, M. Schmidt, J. Fischer, V. Tsurkan, M. Greger, D. Vollhardt, A. Loidl & J. Deisenhofer


Understanding the origin of high-temperature superconductivity in copper- and iron-based materials is one of the outstanding tasks of current research in condensed matter physics. Even the normal metallic state of these materials exhibits unusual properties. Here we report on a hierarchy of temperatures Tc<Tgap<Tmet in superconducting Rb1−xFe2−ySe2 observed by THz spectroscopy (Tc=critical temperature of the superconducting phase; Tgap=temperature below which an excitation gap opens; Tmet=temperature below which a metallic optical response occurs). Above Tmet=90 K the material reveals semiconducting characteristics. Below Tmet a coherent metallic THz response emerges. This metal-to-insulator-type, orbital-selective transition is indicated by an isosbestic point in the temperature dependence of the optical conductivity and dielectric constant at THz frequencies. At Tgap=61 K, a gap opens in the THz regime and then the superconducting transition occurs at Tc=32 K. This sequence of temperatures seems to reflect a corresponding hierarchy of the electronic correlations in different bands.

Thursday, 20 February 2014

Terahertz dual-band pass filter using double-layer reformative complementary metamaterial structures

Feng Lan, Ziqiang Yang, Limei Qi, Xi Gao, and Zongjun Shi


A dual-band frequency selective surface filter in the THz range that uses double-layer modified complementary metamaterial structures is proposed in this paper. The band-pass filter, with dual bands centered at 0.315 THz and 0.48 THz, uses a single crystal quartz substrate and is simulated, fabricated and measured. To minimize the manufacturing risks of working with fragile and thin quartz substrates, efforts have been made to improve the transmission frequency response features at realizable substrate thicknesses. Experimental results from 0.1 THz to 0.6 THz measured by THz time-domain spectroscopy show excellent agreement with the simulation results.

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Wednesday, 19 February 2014

New Insight into the Effect of the Formation Environment of Fh on Its Structure and Property

Hui Liu,   Xiuling Li,   Yan Wang,   Xin Yang,   Zhen Zhen,   Rufen Chen,   Denglu Hou and    Yu Wei  


Ferrihydrite(Fh) is a naturally occurring nanoscale iron oxyhydroxide mineral. It is of great interest in soil science and environmental science due to its extremely high surface area and reactivity. In this work, Fh samples were prepared by three procedures (named Fh-1, Fh-2, and Fh-3). The formation of Fh-1 went through a pH change from acidic to neutral, and the formation of Fh-2 went through a pH change from alkaline to neutral, while Fh-3 was formed at a constant neutral pH. The three Fhs were characterized by high-resolution transmission electron microscopy (HRTEM), terahertz (THz) spectroscopy, nitrogen adsorption isotherms, and low-temperature magnetic techniques. All these techniques indicate that the microstructure and formation process of Fh are strongly coupled. More importantly, the differences of the three Fhs in microstructure are reflected not only in their bulk structure but also in their surface properties. The adsorption and degradation of azo dye Mordant Yellow 10 (MY10) on the three Fhs were investigated. On the one hand, comparing with Fh-1 and Fh-2, Fh-3 exhibits a high density of active site per area, which leads to a large adsorption capacity. On the other hand, a strong affinity between Fh-3 and MY10 results in a more irreversible adsorption and a low degradation rate. The results from current study shed new light on synergetic effects of porosity and the variations of local structure on photocatalysis by iron oxide particles.

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Tuesday, 18 February 2014

Low-Bias THz Amplitude Modulator Based on Split-Ring Resonators and Graphene

Riccardo Degl'Innocenti , Davide Stephan Jessop , Yash Diptesh Shah , Juraj Sibik , J Axel Zeitler , Piran Ravichandran Kidambi , Stephan Hofmann , Harvey E Beere , and David Ritchie


Split-ring resonators represent the ideal route to achieve optical control of the incident light at THz frequencies. These sub-wavelength metamaterial elements exhibit broad resonances that can be easily tuned lithographically. We realized a design based on the interplay between the resonances of metallic split-rings and the electronic properties of a monolayer graphene integrated in a single device. By varying the major carrier concentration of graphene, an active modulation of the optical intensity was achieved in the frequency range between 2.2 THz and 3.1 THz, achieving a maximum modulation depth of 18\%, with a bias as low as 0.5 V.

This study was performed using TeraView's TPI Imaga 2000 system. (TeraView, Cambridge, UK)

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Thursday, 13 February 2014

TeraView Supplies Two Terahertz Systems to Leading Research Institutes in China

Press Release: 

The University of Electronic Science and Technology of China (电子科技大学), Chengdu, and The National Institute of Metrology (中国计量科学研究院) have both recently installed TeraView’s TPS Spectra 3000 spectrometers. The systems were selected due to their superior performance, ease of use and the Company’s track record with its existing customers in Asia.
The system at UESTC will be used by Prof Xiaodong Chen Visiting Professor from Queen Mary University London. Prof. Chen, who heads the department of Microwave Engineering in the Department of Electronic Engineering at QMUL, has a long standing history in the area of terahertz radiation research and has been a key contributor to the international terahertz community. The second TPS Spectra 3000 system at the National Institute of Metrology is supplied with TeraView's unique medical probe which provides three-dimensional information revealing structures beneath the surface with spatial resolution precision of 20 μm axial resolution of 40 μm.
“The growing interest in terahertz science and technology from China and recent developments in the area by prominent Chinese researchers have been remarkable” commented TeraView’s CEO, Don Arnone. “The success of our Asian business is evidence of our commitment to provide these customers with total solutions to their business needs, which is of up-most importance to users in this region. Being selected by such high-profile institutions strengthens TeraView’s position in the region as the leading supplier of turn-key terahertz systems. “

Tuesday, 4 February 2014

Terahertz Imaging for Nondestructive Evaluation of Packaged Power Electronic Devices

Nathan M. Burford1, Magda O. El-Shenawee2, Chad B. O’Neal3, Kraig J. Olejniczak4


Terahertz (THz) time-domain imaging of power electronic devices is performed using the commercial TPSTM Spectra 3000 THz imaging and spectroscopy system. The dimensions of bond wires within power transistor packages are extracted and the time-of-flight tomography is used to illustrate depth profiling of features in the device package. The devices under test in this paper are plastic encapsulated. The encapsulation measures a few millimeters thick. The THz images obtained in the reflection mode demonstrate a potential tool for the non-destructive inspection of packaged power electronic devices.

This study was performed using TeraView's TPS Spectra 3000 system. (TeraView, Cambridge, UK)

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