Thursday, 18 December 2014

Permittivity and Loss Characterization of SU-8 Films for mmW and Terahertz Applications

Ghalichechian, N. ; Sertel, K.

Abstract


The dielectric permittivity measurement of thick SU-8 dielectric film is presented for entire frequency band of 1 GHz to 1 THz. SU-8 is a high-resolution UV-patternable photoresist that can be used for fabrication of high-aspect-ratio 3D structures for millimeter-wave and terahertz devices. Here, we report the measured dielectric constant and loss tangent of SU-8 films using terahertz time-domain spectroscopy. A quadratic polynomial model is established for the accurate calculation of complex permittivity up to 1 THz. The loss tangent of fully-cross-linked 430-μm-thick SU-8 film was measured to be 0.015, 0.027, and 0.055 at 1, 200, and 1000 GHz, respectively. Similarly, relative permittivity was found to be 3.24, 3.23, and 2.92. The fabrication process and level of cross-linking were demonstrated to have significant impact on the loss behavior of this material and the impact of cross liking on dielectric permittivity is quantified across a wide frequency band. The characterization results reported in this work is a platform for developing next-generation millimeter-wave and terahertz devices.

Merry Christmas from TeraView!

TeraView would like to wish everyone a merry Christmas and a happy new year from our offices in Cambridge!

 

Tuesday, 16 December 2014

Investigation of UV optical fibers under synchrotron irradiation

Dan Sporea, Laura Mihai, Adelina Sporea, Alin Lixandru, and Elke Bräuer-Krisch




Abstract


The focus of the present paper deals, for the first time, with commercial UV optical fibers, characterizing their behaviour as they are subjected to very high flux wiggler generated synchrotron radiation. Five distinct types of UV optical fibers, produced by three manufactures, were exposed to total doses between 5 Gy and 2000 Gy. The exposure to synchrotron radiation was performed in two campaigns. The tests were run off-line and considered the dependence of the radiation induced attenuation (RIA) as function of the total dose. The recovery of the radiation induced colour centres was studied at room temperature and after heating the samples up to 560 K. As a première, we also investigated through THz imaging and spectroscopy the irradiated optical fiber samples. Under these conditions, three of the optical fibers proved to be radiation resistant. The two optical fibers sensitive to synchrotron radiation exhibited a linear variation of the optical absorption at the wavelengths of λ = 229 nm, λ = 248 nm, and λ = 265 nm, for total doses between 60 Gy and 2000 Gy. These two samples showed also an increase of the optical absorption in the UV spectral range when heated to 560 K. The optical fibers sensitive to synchrotron radiation can potentially be used for on-line radiation dosimetry.


Wednesday, 10 December 2014

Positions at TeraView - Software Contractors

TeraView Limited is the world's leader in the design and manufacture of terahertz (THz) products to the pharmaceutical, security, medical and materials characterisation markets. Our products continue to yield many ground-breaking applications such as tablet coating thickness and uniformity, cracks, defect analysis, foreign materials and analysis of solid-state structure to be exploited by our customers. Based in Cambridge UK, we have a global client base and a highly-skilled workforce.

We are seeking a Software Development Specialist to join our team; an individual who is able to meet the existing operational needs of the company, as well as planning for the future needs of the company as we grow.

For a full job description and more information on the role, please visit: http://www.teraview.com/about/careers-jobs.html


Tuesday, 9 December 2014

Investigation of thermal degradation of vegetable oils by spectroscopic methods and its mathematical analysis

M. Tobolova, V. Kresalek, H. Vaskova and M. Buckova

Abstract


In this paper, relatively new spectroscopic methods were used for investigation of edible oils and their thermal degradation. There were included the samples of refined rapeseed and sunflower oil and the same oils heated for specified time interval at the temperature 200 °C. The optical characteristics of oils have been investigated with Terahertz Time Domain Spectroscopy (THz-TDS). The refractive indices were calculated in the specified terahertz frequency range, processed and statistically evaluated. The Wilcoxon matched pairs test was carried out for comparison of unheated and heated oil samples. The results measured by THz-TDS were supplemented by Raman spectra analysis. Both methods seem to be capable analyzing tool for oil investigation. 

Tuesday, 2 December 2014

Feasibility of Using Terahertz Spectroscopy To Detect Seven Different Pesticides in Wheat Flour

Maeng, Inhee; Baek, Seung Hyun; Kim, Hwa Yeon; Ok, Gyeong-Sik; Choi, Sung-Wook; Chun, Hyang Sook

Abstract


This study investigated the feasibility of detecting pesticides using terahertz (THz) spectroscopy in high-density polyethylene and/or wheat flour mixtures. The absorption spectra of seven pesticides (dicofol, chlorpyrifos, chlorpyrifos-methyl, daminozide, imidacloprid, diethyldithiocarbamate, and dimethyldithiocarbamate) were measured in the frequency range 0.1 to 3 THz at room temperature. Five of the seven pesticides exhibited specific absorption peaks in the low-energy THz range. The two remaining pesticides had no specific absorption peaks in this frequency range, but they exhibited different frequency-dependent refractive indices. The absorption coefficients of imidacloprid increased with its increasing weight ratio in high-density polyethylene, and the fitted power absorptions and refractive indices using a Maxwell-Garnett effective medium model were comparable to the measured data. Imidacloprid was also identified from its characteristic absorption peaks in wheat flour mixtures, and a linear relationship between the absorption coefficient and the weight ratio was observed. Our results show the potential of detection of selected pesticides in foods, such as wheat flour, using THz spectroscopy.

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

Full Article: http://www.ingentaconnect.com/content/iafp/jfp/2014/00000077/00000012/art00010

Thursday, 20 November 2014

TeraHertz: New opportunities for industry

TeraView are happy to confirm that Dr. Philip Taday will be speaking at the upcoming event: TeraHertz: New opportunities for industry - Special Focus Session: THz Materials Measurements, on the 3rd-5th of February 2015.

Event Overview:

TeraHertz (THz), the frequencies between electronics and optics, was until recently the last unexploited part of the electromagnetic spectrum. The harnessing of THz-based technologies has the potential of impacting globally a vast number of industries, like both electronics in the 70’s and optics in the 80’s did. THz applications span over a wide array of fields, including:

• Quality Control and Non-destructive testing
• Surface analysis
• Security
• Chemical and Bio-Medical analysis
• Telecommunications

Filling the TeraHertz “gap” has led to unprecedented creativity in the development and commercialization of TeraHertz sources, transmission components and detectors. This year’s edition will focus on THz materials measurements and applications.

For more information on the event and a full list of speakers visit:
http://www.formation-continue-unil-epfl.ch/thz
http://www.formation-continue-unil-epfl.ch/wp-content/uploads/12215091-teraherz-new-opportunities.pdf

Wednesday, 19 November 2014

TeraView at ISTFA 2014

TeraView are Proud to have recently attended ISTFA 2014 on the 9th-13th of November!

'ISTFA is where you’ll find researchers, engineers, technicians and others who work on discrete components, dies, wafer fabrication, packages, board assembly and systems.'

TeraView had a booth at the event, pictured below with Martin Igarashi.

TeraView at ISTFA 2014 

Thursday, 13 November 2014

THz structures fabricated in laser direct patterning

Koziol, P.E. ; Antonczak, A.J. ; Walczakowski, M. ; Palka, N. 










Abstract


In this paper two different methods of the manufacture of metamaterial structures using a laser treatment were presented. One of them is related to direct metallization of the surface of aluminum nitride ceramics (AlN) by interaction of laser radiation. The second method involves a process of selective removal of the conductive layer (silver) in the laser ablation process. It has been proved that both proposed methods allow to produce a structure of SRR type showing its properties in THz range. Obtained results allow to implement these methods for the manufacture of more complex structures. An advantage of the process of laser radiation interaction on the surface of a material is the ability to produce any shape without having to adapt further process components.

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

Full Article: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6948562&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6948562

Wednesday, 12 November 2014

Flat THz leaky wave antennas: Analysis and experimental results

Beaskoetxea, Unai ; Beruete, Miguel ; Zehar, Mokhtar ; Agrawal, Amit 

Abstract


Here, two different THz radiating structures are analyzed, consisting both of a central slot surrounded by annular or straight corrugations. Concentrically grooved antenna presents a moderately high gain. Its radiation and temporal properties are analyzed both numerically and experimentally. For the second case, no appreciable differences in terms of radiation characteristics are observed when the grooves' profile is changed from square to triangular. Manufactured triangular grooves antenna shows good performance for the experimental measurements at 0.5THz. These results could be of interest for the development of new THz sources and detectors.

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

Full Article: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6948592&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6948592

Tuesday, 11 November 2014

Wavelet denoising and reconstruction of a microneedle embedded in human skin ex-vivo using terahertz pulsed reflectance

Mueller-Holtz, Martin ; Smith, Geoff

Abstract


Biological tissue can show promising features in the terahertz region of the electro-magnetic spectrum but face the problem that the signal to noise ratio can be poor due to the low energy output from the measurement instrument coupled with the high absorbance of water in biological tissue. Wavelet denoising and reconstruction are known to be suitable digital signal processing filters for reflected terahertz energy when appropriate thresholds, scales and mother-wavelets are chosen. In this article, we therefore describe a Wavelet transform-based method for denoising reflections of THz energy from ex-vivo human skin with an embedded microneedle. The wavelet reconstruction was then successfully used to identify the microneedle from the reflected waveform. This technique is potentially useful to enhance in-depth analysis and visualisation of underlying skin layers, lesions and penetration depth for targeted drug delivery.

Thursday, 6 November 2014

Applications of terahertz pulsed technology in non destructive testing



TeraView would like to remind you that TeraView's Dr. Philip Taday will be presenting on the 26th of November.

Technisches Kolloquium - Terahertz technology for NDT will be held on the 26th of November 2014 in the conference/class room in Zorneding, Munich.

This event will be open to all our customers and to contacts of our partner Allianz.'

The event is free of charge and will be attended by Dr. Philip Taday who will be presenting a talk on: “Applications of terahertz pulsed technology in non-destructive testing”

Link to event details - (PDF in German): 




Wednesday, 15 October 2014

Assignment of the Terahertz Spectra of Crystalline Copper Sulfate and Its Hydrates via Solid-State Density Functional Theory

Michael Thomas Ruggiero , Tiphaine Bardon , Matija Strlic , Phil F. Taday , and Timothy Michael Korter

Abstract


Terahertz (THz) vibrational spectroscopy is a promising tool for the non-destructive and potentially non-invasive characterization of historical objects, which can provide information on the materials used for their production as well as identify and monitor their chemical degradation. Copper sulfate (CuSO4) has drawn interest due to its inclusion in the preparation of iron gall inks found in historical artwork and documents. Copper sulfate rapidly forms hydrates which contribute to the formulation of these ink species, and may influence their corrosive nature. In this study, copper sulfate has been studied using a combination of THz time-domain spectroscopy, powder X-ray diffraction (PXRD), and solid-state density functional theory (DFT) in order to better understand the spectral absorbances in the THz region. The results have revealed that the THz spectrum of commercially available “anhydrous” copper sulfate results from the presence of not only the anhydrous form, but also the monohydrate (CuSO4⋅H2O) and trihydrate (CuSO4⋅3H2O) forms. Complete assignment of the experimental spectrum was achieved through a comparison of density functionals and extensive investigation of the influence of basis set polarization functions on the bonding interactions, lattice parameters, and low-frequency motions in these crystalline solids.

Thursday, 9 October 2014

Polarization-insensitive metamaterial absorber of selective response in terahertz frequency range

B Grześkiewicz, A Sierakowski, J Marczewski, N Pałka and E Wolarz

Abstract


We present an experimental and numerical analysis of a planar metamaterial that selectively absorbs terahertz radiation. The metamaterial is produced as a planar two-dimensional network of electromagnetic resonators and is characterized by electric and magnetic responses in a narrow frequency range. The unit cell of the metamaterial has fourfold symmetry about the axis perpendicular to the planes containing the metallic resonators. Such a planar metamaterial is polarization-insensitive to the electromagnetic waves. A good agreement of the absorption characteristics obtained from the numerical simulations and from the spectroscopic experiments is shown. The analysis of wave impedance, refractive index, permittivity and permeability of the metamaterial allows the identification of the characteristic electromagnetic resonance and antiresonance in the system. It is shown that the absorption is mostly the result of the electric field energy accumulation in the metamaterial absorber.

Thursday, 2 October 2014

THz Metal Mesh Filters On Electrically Thick Fused Silica Substrates

William Otter, Fangjing Hu, Stepan Lucyszyn, Jonathan Hazell,

Abstract


This paper shows simulated and measured results of ultra-low cost metal mesh filters on electrically thick substrates for millimeter-wave and THz bands. It provides a broad overview of metal mesh filters currently available and suggest why it is worth moving to an electrically thick substrate for ultra-low cost applications. We demonstrate scalable traditional metal mesh filters on 525 µm thick fused silica substrates. In addition, trapped-mode excitation is exploited to improve out-of-band rejection at higher frequencies. The measured results prove that these filters are scalable in the THz range using cost-effective micromachining manufacturing. This work opens up the possibility of using electrically thick metal mesh filters for ultra-low cost applications. 


Tuesday, 30 September 2014

Complementary optical and neutron vibrational spectroscopy study of bromanilic acid: 2,3,5,6-tetramethylpyrazine (1:1) cocrystal

Katarzyna Łuczyńska, , Kacper Drużbicki, Krzysztof Lyczko, Wojciech Starosta

Abstract


Complementary structural and vibrational spectroscopy study of bromanilic acid:2,3,5,6-tetramethylpyrazine (BrA:TMP) 1:1 cocrystal is reported. The crystallographic structure was determined by means of single-crystal X-ray diffraction and can be described as a stacked net of hydrogen-bonded TMPH+⋯BrA⋯BrA⋯TMPH+ moieties. The structural analysis was supported by 13CP/MAS NMR study. The complementary vibrational analysis was performed by combining optical (infrared, Raman, terahertz) and inelastic neutron scattering spectroscopy with the state-of-the-art solid–state density functional theory (DFT) computations, which have proven to be superior to the hybrid cluster modeling approach. An excellent agreement between theoretical and experimental data was observed over the entire spectral range, allowing for deep understanding of the vibrational properties. While the primary hydrogen-bonding interactions are limited to the above quoted structural units, the system revealed very little dispersion of the phonon branches, manifested mainly in the intermolecular vibrations range. Moreover, the studied phase does not exhibit any mechanical instability, which could suggest a displacive structural transformation tendency.

Friday, 26 September 2014

Polarization independent broadband terahertz antireflection by deep-subwavelength thin metallic mesh

Lu Ding*, Qing Yang Steve Wu andJing Hua Teng*

Abstract


Broadband antireflection coatings for passive terahertz (THz) components are extremely important in the application of THz technology. Metallic nano-films are commonly used for this purpose. Here a new approach to realize polarization independent broadband antireflection in THz range, based on a meta-surface design is experimentally demonstrated. The internal reflection of a broadband THz pulse (spectral bandwidth of 0.06 – 4 THz) at a Si/air interface can be fully suppressed with a Cr square mesh with deep-subwavelength dimensions. Small nonuniformity of the meta-surface structure can enhance the tolerance on structural parameters for achieving the AR condition. The design concept is applicable to other metals and frequency ranges as well, which opens a new window for future AR coatings.

Friday, 19 September 2014

Congressman Tours Electrical Engineering Lab

Earlier this month, Congressman Steve Womack visited the lab of Magda El-Shenawee, professor of electrical engineering, to learn about terahertz imaging research at the College of Engineering.

During his visit, Womack learned about a potential medical application of terahertz imaging for breast cancer treatment. Researchers in El-Shenawee’s lab are developing a process to test tissue from lumpectomies during surgery in order to improve patient outcomes.

A second application of El-Shenawee’s system is in the field of security. Terahertz imaging is not harmful to humans, and it has the potential to identify narcotics, explosives and plastic or ceramic weapons. This makes it ideal for security screening. Researchers demonstrated this capability for Womack, concealing weapons and gun powder on a manikin, then revealing the hidden weapons with the imaging system.

“We are very pleased that Congressman Womack took the time to learn about this timely research,” said Juan Balda, head of the Department of Electrical Engineering. “Dr. El-Shenawee’s work has potential to contribute to advances in several different fields ranging from biomedical to security, and the congressman’s interest shows that he understands the importance of innovative engineering projects like this one to the economic development of our state.”

For the full article visit: http://newswire.uark.edu/articles/25171/congressman-tours-electrical-engineering-lab

Wednesday, 17 September 2014

High-Speed and Broadband Terahertz Wave Modulators Based on Large-Area Graphene Field-Effect Transistors

Qi-Ye Wen, Qi Mao, wee tian, Tian-Long Wen, Zhi Chen, Qing-Hui Yang, and Huaiwu ZHANG

Abstract


We present a broadband terahertz wave modulator with large modulation depth and fast switch speed by cautiously selecting the gate dielectric materials in a large-area graphene field-effect transistor (GFET). An ultrathin Al2O3 film (~60 nm) is deposited by atomic-layer-deposition technique as a high-ĸ gate dielectric layer, which reduces the Coulomb impurity scattering and cavity effect thus greatly improves the modulation performance. Our modulator has achieved a high modulation depth of 22 % and modulation speed of 170 kHz in a frequency range from 0.4 to 1.5 THz, which is vital for many THz technology applications as well as for fundamental researches.

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

Full Article: http://www.opticsinfobase.org/ol/upcoming_pdf.cfm?id=216913

Tuesday, 16 September 2014

TeraView at IRMMW-THz 2014

TeraView are currently at IRMMW-THz 2014!

Both Dr Philip Taday and Rob May are in attendance and will be at the TeraView booth (#21) throughout the event.

If you would like to arrange a meeting please contact Dr Philip Taday:

Dr Philip Taday
Head of Applications
TeraView Limited
Cambridge

E-mail: philip.taday@teraview.com
Tel: +(44) 1223 435380
Cell: +(44) 7887 994018

www.teraview.com

Friday, 12 September 2014

Terahertz time-domain spectroscopy for measurement of particle sizes of fexofenadine hydrochloride

Anna Sadloňová, Vojtech Kresalek, Tomas Bata

Abstract

Time domain spectroscopy is one of the new methods of terahertz radiation used for wide spectrum of the industry. More extended sector is the security system much like the sector of the medicine. The main focus is orientated to detection and identification of the substances. This study is focused on the measurement of the particle size of pharmaceuticals. The characteristic absorption features will be studied experimentally by Terahertz time-domain spectroscopy. The results are identified for processing by one of the statistical method usable for such variable groups. The three samples of the pharmaceutical– Fexofenadine Hydrochloride (antihistamine) will be compared between themselves. Mentioned samples are supplied by different suppliers. The main focus will be put on the pharmaceutical differences of the same pharmaceutical that are commonly available on the markets. Terahertz time-domain spectroscopy setup was used to measure absorbance spectra of each sample in the range from 1 THz to 3 THz (it was used the device TPS Spectra 3000 produced by TeraView Ltd . The device that belongs to the first commercial machine developed in this company for measurement of the substances by transmission spectroscopy method.). During the testing was used the vacuum for purging the measurement chamber from water vapors.

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

Wednesday, 10 September 2014

TeraView Continues to Make Waves at IRMMW-THz 2014

TeraView invites you to visit us at IRMMW-THz 2014!

Dr. Philip Taday and Rob May will both be attending the event, with Rob May giving a keynote talk on Monday the 15th of September - 11:30 in the Tuscon Room:

Terahertz Car Paint Thickness Sensor: Out of The Lab and Into the Factory

Don't miss out on this opportunity to learn more about TeraView's recent development and applications!

TeraView will be at Booth #21

If you would like to pre-arrange a meeting, please e-mail Dr. Phil Taday.

Tuesday, 9 September 2014

Broadband Terahertz Sensing on Spoof Plasmon Surfaces

Binghao Ng , Stephen M. Hanham , Jianfeng Wu , Antonio I. Fernández-Domínguez , Norbert Klein , Yun Fook Liew , Mark B.H. Breese , Minghui Hong , and Stefan A. Maier

Abstract

In this paper, we show that broadband spectral data can be experimentally extracted from corrugated metallic surfaces consisting of a linear array of subwavelength grooves supporting tightly confined spoof plasmons. Using a combination of the scattering edge coupling method and short-time Fourier transform, we are able to discern the group velocity characteristics of a spoof plasmon pulse which in turn allows for the extraction of broadband dispersion data from 0.4 THz to 1.44 THz in a single measurement. Refractive index sensing of various fluids is demonstrated at microlitre volume quantities by monitoring changes in not only the dispersion relation but also the frequency dependent attenuation of the spoof plasmons. This gives information about both the real and imaginary part of the refractive index of an analyte, indicating the potential for spoof plasmon surfaces to fully characterise substances in the terahertz regime. Lastly, we show that the strong electromagnetic field confinement near the effective spoof plasmon frequency allows for surface enhanced absorption spectroscopy, demonstrated here with α-lactose monohydrate powder. This allows us to take a more spectroscopic approach to THz sensing whereby substances can be uniquely identified by their spectral fingerprints. The enhanced light-matter interactions that occur in the vicinity of the spoof plasmon surface allows for a more efficient use of the limited power of current terahertz sources. Together with the ability to integrate spoof plasmon surfaces with microfluidics and to freely design its electromagnetic properties, we believe that these surfaces can be a very versatile platform on which chip-scale terahertz sensing can be performed.

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

Full Article: http://pubs.acs.org/doi/abs/10.1021/ph500272n

Thursday, 28 August 2014

Split-ring resonators manufactured on conductive layer by selective laser ablation

Paweł Koziol ; Arkadiusz J. Antończak ; Patrycja E. Szymczyk ; Bogusz Stępak ; Łukasz Łazarek ; Michał R. Wójcik ; Michał Walczakowski ; Krzysztof M. Abramski

Abstract

In this paper an alternative method of manufacturing SRR structures through the selective removal of a thin layer of silver-palladium deposited on the surface of the Al2O3 ceramic by laser ablation process using nanosecond Nd:YAG laser (1064 nm) was presented. The SRR structures array were subject to transmittance measurements using the TDS (Time Domain Spectroscopy). Both electric and magnetic resonances were observed at frequencies determined by the structural parameters of the SRR. In case of the E field perpendicular to an SRR structure and one resonance area for 0.56 THz with the E field parallel to the structure, two characteristic resonant dips for 0.31 THz and 0.62 THz were obtained. Studies have confirmed that using selective laser removal process enables the preparation of the resonant structure in the range of THz. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.


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

Full Article: http://www.sciencedirect.com/science/article/pii/S0939641114002203

Tuesday, 19 August 2014

CLEO: 2015 - Laser Science to Photonic Applications

The submissions for CLEO: 2015 (12-14 May 2015 in San Jose, California, USA) Abstract and Summary Submission Deadline will be 16 December 2014, 12:00 EST (17:00 GMT)


CLEO: 2015 is well known for its high quality, peer-reviewed research, and bridges fundamental science all the way through to technology development and uses of technology and applications. 



More information about CLEO: 2015 can be found on the website at www.cleoconference.org.

Thursday, 31 July 2014

TeraView's Dr. Philip Taday will be attending 'Technisches Kolloquium' - 26th of November 2014

TeraView are happy to announce that we will be attending Technisches Kolloquium - Terahertz technology for NDT


'Technisches Kolloquium - Terahertz technology for NDT will be held on the 26th of November 2014 in the conference/class room in Zorneding, Munich.

This event will be open to all our customers and to contacts of our partner Allianz.'


The event is free of charge and will be attended by Dr. Philip Taday who will be presenting a talk on: 
“Applications of terahertz pulsed technology in non-destructive testing”