Large phase modulation of THz wave via an enhanced resonant active HEMT metasurface

Zhang, Yaxin, Yuncheng Zhao, Shixiong Liang, Bo Zhang, Lan Wang, Tianchi Zhou, Wei Kou et al. "Large phase modulation of THz wave via an enhanced resonant active HEMT metasurface." Nanophotonics (2018).

Abstract

Terahertz (THz) science and technology promise unique applications in high-speed communications, high-accuracy imaging, and so on. To keep up with the demand for THz systems, THz dynamic devices should feature large phase shift modulation and high speed. To date, however, only a few devices can efficiently manipulate the phase of THz waves. In this paper, we demonstrate that efficient phase modulation of THz waves can be addressed by an active and enhanced resonant metamaterial embedded with a nanostructured 2D electron gas (2DEG) layer of a GaN high electron mobility transistor (HEMT). The enhanced resonant metaunit couples the traditional dipolar and inductance-capacitance resonances together to realize a coupling mode with enhanced resonance. Embedded with the nanostructured 2DEG layer of GaN HEMT, the resonance intensity and surface current circuit of the enhanced resonant mode in the metamaterial unit can be dynamically manipulated by the electrical control of the carrier distribution and depletion of the 3 nm 2DEG, leading to a phase shift greater than 150° in simulation. In the dynamic experiments, a 137° phase shift was achieved with an external controlling voltage of only several volts in the THz transmission mode. This work represents the first realization of a phase shift greater than 100° in a dynamic experiment in transmission mode using an active metamaterial structure with only a single layer. In addition, given the high-speed modulation ability of the HEMT, this concept provides a promising approach for the development of a fast and effective phase modulator in THz application systems.

for full paper see https://www.degruyter.com/view/j/nanoph.ahead-of-print/nanoph-2018-0116/nanoph-2018-0116.xml

This group uses a terahertz spectrometer supplied by TeraView, Cambridge, UK  for more information visit their new web site at www.teraview.com

Complex Permittivity Measurement of Paraffin Phase-Change Material at 26 GHz–1.1 THz Using Time-Domain Spectroscopy

Ghassemiparvin, Behnam, and Nima Ghalichechian. "Complex Permittivity Measurement of Paraffin Phase-Change Material at 26 GHz–1.1 THz Using Time-Domain Spectroscopy." Journal of Infrared, Millimeter, and Terahertz Waves (2018): 1-9.

Abstract

We report complex permittivity measurement of hexatriacontane films at the frequency range of 26 GHz–1.1 THz. Hexatriacontane (C36H74) has a melting point of 75 °C that exhibits a 15% volumetric change which is crucial in developing low-loss RF microactuators with large displacement. In this work, we employ time-domain spectroscopy to measure the transmission coefficient of the paraffin samples in the frequency range of 0.3–1.1 THz. In order to extract the dielectric constant and accurately estimate the small values of loss tangent, we developed a propagation model which measured data are fitted to through a new least-squares minimization method. A Debye relaxation model is used to model the frequency dependence of the permittivity. Described method is rapidly convergent with minimum amount of signal processing. This method can be used to determine the complex permittivity of the materials by devising an appropriate function for the frequency dependence of the complex permittivity. Transmission through 20 samples of paraffin with various thicknesses is measured and the average permittivity is found to be 2.25 with standard deviation of 0.028. The loss tangent is monotonically increasing with frequency and the maximum value is 6.32 × 10− 3 at 1.1 THz. Our study demonstrates that paraffin is a low-loss dielectric which makes it an attractive candidate for development of electro-thermo-mechanical actuators for sub-millimeter- and millimeter wave (mmW) variable capacitors, low-loss reconfigurable antennas, and phase shifters.

For full paper see https://link.springer.com/article/10.1007/s10762-018-0556-5

This group uses a terahertz spectrometer supplied by TeraView, Cambridge, UK  for more information visit their new web site at www.teraview.com

Tuning of Topological Dirac States via Modification of van der Waals Gap in Strained Ultrathin Bi2Se3 Films

Yang, Won Jun, Chang Woo Lee, Da Sol Kim, Hyun Sik Kim, Jong Hyeon Kim, Hwan Young Choi, Young Jai Choi, Jae Hoon Kim, Kyungwha Park, and Mann-Ho Cho. "Tuning of Topological Dirac States via Modification of van der Waals Gap in Strained Ultrathin Bi2Se3 Films." The Journal of Physical Chemistry C 122, no. 41 (2018): 23739-23748.

Robust massless Dirac states with helical spin textures were realized at the boundaries of topological insulators such as van der Waals (vdW) layered Bi2Se3 family compounds. Topological properties of massless Dirac states can be controlled by varying the film thickness, external stimuli, or environmental factors. Here, we report single-crystal-quality growth of ultrathin Bi2Se3films on flexible polyimide sheets and manipulation of the Dirac states by varying the vdW gap. X-ray diffraction unambiguously demonstrates that under uniaxial bending stress the vdW gap substantially changes with interatomic-layer distances unaltered. Terahertz and photoelectron spectroscopy indicate tuning of the number of quantum conducting channels and of work function, by the stress, respectively. Surprisingly, under compressive strain, transport measurements reveal dimensional crossover and suppressed weak antilocalization. First-principles calculations support the observation. Our findings suggest that variation of vdW gap is an effective means of tuning the Fermi level and topological Dirac states for spintronics and quantum computation.

For full see https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.8b06296

This group uses a terahertz spectrometer supplied by TeraView, Cambridge, UK  for more information visit their new web site at www.teraview.com

Flexible terahertz and FarIR polymer‐supported filter

Sanphuang, Varittha, and Niru K. Nahar. "Flexible terahertz and FarIR polymer‐supported filter." Microwave and Optical Technology Letters.

Abstract

We present the design, fabrication, and measurement of a terahertz (THz) polymer‐supported filter. A periodic structure, frequency selective surfaces (FSS) is employed to provide bandpass characteristic for this filter design with polyimide (PI) film as a substrate. This PI film (13 μm thick) is very thin and thus provides a flexible support to the filter. The average extracted dielectric constant ε r is 3.35 and the average refractive index n s is 1.84. The final filter structure was fabricated using standard microfabrication process. The measured transmission response shows high percentage of transmission (~80%) with the peak at 0.58 THz and sharp roll‐off that covers the broad range of frequency from 0.1 to 1 THz (wavelength of 300 μm‐3000 μm).

For full paper see https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.31414

For more information about TeraView visit www.teraview.com 

Hydration of gelatin molecules studied with terahertz time-domain spectroscopy

Fan, S., Z. Qian, and V. P. Wallace. "Hydration of gelatin molecules studied with terahertz time-domain spectroscopy." In Infrared, Millimeter-Wave, and Terahertz Technologies V, vol. 10826, p. 1082604. International Society for Optics and Photonics, 2018.

Abstract

Gelatin is an irreversible hydrolyzed form of collagen having similar amino acid compositeswith its parent collagen. The hydrogen atoms on the side chains of the long peptide strings can weakly bond with their surrounding gelatin as well as water molecules in aqueous environment, forming a cross-linked 3D matrix. Gelatin has been used as a model for soft tissue phantoms in several medical imaging studies including in terahertz imaging. In the terahertz regime, the dielectric property of the gelatin relies largely on its hydration status and the relationship has been shown to be non-linear. It is therefore essential to study the change of the dielectric properties with respect to the hydration status so as to accurately mimic the properties of fresh biological tissues in the terahertz spectrum. .....

for full paper see https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10826/1082604/Hydration-of-gelatin-molecules-studied-with-terahertz-time-domain-spectroscopy/10.1117/12.2502287.short?SSO=1

… The heated gelatin solutions were poured into a liquid holder with a window made of
z-cut quartz as the bottom material. The sample holder was set on the reflection imaging stage of the TeraPulse 4000 system (TeraView Ltd, Cambridge, UK) …

For more information about TeraView visit https://teraview.com/terapulse/

Application of THz spectroscopy for localisation of fibre optics embedded into glass fibre reinforced composite

Mieloszyk, Magdalena, Katarzyna Majewska, and Wieslaw Ostachowicz. "Application of THz spectroscopy for localisation of fibre optics embedded into glass fibre reinforced composite." Composite Structures (2018).

Abstract

Recently, in many industrial branches (e.g. aviation, marine or civil engineering) metal elements are replacing by composite ones. To ensure their reliability structural health monitoring systems also based on fibre optics sensors (embedded into or mounted on composite structure) are widely applied.

In the paper THz spectroscopy technique was proposed for detection and localisation of glass fibre optics embedded into a glass fibre reinforced polymer. The analysis was performed on a four-layer sample manufactured by infusion method. During this investigation both the sample surfaces roughness as well as fibre optics arrangements (according to the THz spectrometer axes) were examined. For this purpose THz images of internal structure of the sample were presented. Additionally two methods (in time and frequency domains) for quick determining of fibre optics location are presented. The first one is based on local changes in signal amplitudes while the second – on differences in power spectrum.

for full paper see https://www.sciencedirect.com/science/article/pii/S0263822318315423

… 2.1. THz unit. During the experimental investigation the THz spectrometer (TPS Spectra 3000 THz Pulsed Imaging and Spectroscopy from TeraView ® ), presented in Fig. 2, was used. The system contains two main parts: a measurement chamber and a scanning unit …

Visit TeraView's new web site site at www.teraview.com

Polarizability of Aspirin at Terahertz Frequencies Using Terahertz Time Domain Spectroscopy (THz-TDS)

Zhang, Tianyao, Zhaohi Zhang, and Mark Arnold. "EXPRESS: Polarizability of Aspirin at Terahertz Frequencies Using Terahertz Time Domain Spectroscopy (THz-TDS)." Applied Spectroscopy (2018): 0003702818815177.

A novel application of terahertz time-domain spectroscopy (THz-TDS) is described for the determination of permittivity and polarizability of organic crystals, as exemplified by measurements with the polymorph I form of crystalline aspirin (acetylsalicylic acid). The coherent nature of the THz pulse experiment, coupled with gated-detection, permits direct measure of differences in the phase angle of the electric field vector after passing through a pellet composed of the aspirin crystals embedded within an inert polymer matrix. An effective …

For full paper see https://journals.sagepub.com/doi/10.1177/0003702818815177

… Relevant crystal structure information for this aspirin polymorph is listed in Table II. The

THz spectra were collected by using a TeraView TPS Spectra 1000D THz time- domain spectrometer (TeraView Limited, Cambridge, UK). Details of the instrument can be..

Visit TeraView new web site at www.teraview.com

Non-Destructive Fault Localization in Fan Out Wafer Level Packages Using Electro Optical Terahertz Pulse Reflectometry

Rho, Kyungsoo, Jongmin Lee, Daejin Kim, Thomas White, and Jesse Alton. "Non-Destructive Fault Localization in Fan Out Wafer Level Packages Using Electro Optical Terahertz Pulse Reflectometry." In 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA), pp. 1-4. IEEE, 2018.

Abstract:

Here, we demonstrate how electro optical terahertz pulse refiectometry (EOTPR), a time-domain refiectometry technique that utilizes terahertz frequency electrical pulses to identify device faults, can be used to quickly and non-destructively isolate faults in advanced fan-out wafer level (FOWL) packages. We present a case study to show how EOTPR can accurately locate faults in the densely spaced redistribution layers (RDLs) of the package.

For full paper see https://ieeexplore.ieee.org/abstract/document/8452600/

For more information about TeraView see www.teraview.com

Study of plant fibre composites with damage induced by laser and mechanical impacts

Malinowski, Paweł H., Wiesław M. Ostachowicz, Fabienne Touchard, Michel Boustie, Laurence Chocinski-Arnault, Pedro Pascual Gonzalez, Laurent Berthe, Davi Silva de Vasconcellos, and Luigi Sorrentino. "Study of plant fibre composites with damage induced by laser and mechanical impacts." Composites Part B: Engineering 152 (2018): 209-219.

Abstract

Polymer composite materials provide good strength to weight ratio and tailored mechanical properties thanks to the reinforcing fibres. Until recently, the need for taking into account the whole life cycle of a composite structure was neglected and only the service aspects were important. Today, the designers of a new composite structure have to take into account the environmental aspects from the sustainability of raw materials to the management of end life products. There are recycling issues related to the most popular composites. A solution for the recycling issue can be sought in green composites with reinforcing fibre originating from plants. The behaviour of eco-composites, when subjected to laser or mechanical impactloadings, is not well known yet. Short fibre composites were made with spruce fibres. Another set of samples was made of flax fibres. Also a woven hemp fabric-based eco-composite was investigated. A fully synthetic woven composite was used for comparison with green composites. Mechanical impacts were performed by means of a falling dart impact testing machine. Laser impacts were made with high power laser source. Four assessment techniques were employed in order to analyse and compare impact damage. Damage detection thresholds for each material and technique were obtained.

… The terahertz spectrometer used was TPS Spectra 3000 from TeraView (Cambridge, United Kingdom) with radiation in the 0.1–3 THz range. The spectrometer is equipped with a moving table to apply xy movements and scan large objects (Fig … 

For full paper see https://www.sciencedirect.com/science/article/pii/S1359836818303524

For more information about TeraView see www.teraview.com

Terahertz Multivariate Spectral Analysis and Molecular Dynamics Simulations of Three Pyrethroid Pesticides

Qu, Fangfang, Lei Lin, Yong He, Pengcheng Nie, Chengyong Cai, Tao Dong, Yi Pan, Yu Tang, and Shaoming Luo. "Terahertz Multivariate Spectral Analysis and Molecular Dynamics Simulations of Three Pyrethroid Pesticides." Journal of Infrared, Millimeter, and Terahertz Waves (2018): 1-14.

Abstract

The terahertz (THz) multivariate spectral characteristics and the molecular dynamics of three pyrethroid pesticides, including deltamethrin, fenvalerate, and beta-cypermethrin, were studied in this paper. THz spectra of the pesticides were measured in frequency range of 0.06–3.5 THz by using THz time-domain spectroscopy (THz-TDS). To improve the THz spectral quality, the wavelet threshold de-noising (WTD) method was used to remove spectral noise and the spectral baseline correction (SBC) method was used to remove baseline drift. Specific absorption peaks were observed in the processed THz spectra of the three pesticides. Deltamethrin showed three peaks at 0.90, 1.49, and 2.32 THz. Fenvalerate had five peaks at 1.13, 1.43, 1.61, 1.98, and 2.58 THz. Beta cypermethrin had four peaks at 1.27, 1.84, 2.12, and 2.92 THz. The density functional theory (DFT) was used to characterize the molecular dynamics and formation mechanism of the absorption peaks. Results showed that there was a good matching effect between the THz experimental spectra and the DFT quantum calculation spectra. Based on the characterized fingerprint absorption peaks, the linear addition model was used to simulate the THz spectra of mixed pesticides. The simulated spectra of multicomponent pesticides were demonstrated to be in good agreement with those obtained by THz-TDS. By analyzing the absorption peaks of THz spectra, the composition and concentration of multicomponent pesticides could be determined. The proposed strategy presented an analytical methodology for studying the THz spectral characteristics of pesticides. In addition, this work provided experimental and theoretical basis for the detection potential of pesticides in agricultural products based on THz technology. 

for full paper see https://link.springer.com/article/10.1007/s10762-018-0519-x

… 2.2 THz Spectral Acquisition The TeraPulse 4000 THz-TDS system, Inc. (Teraview, UK), was applied to the spectral acquisition of the pesticide....

For more information about TeraView see www.teraview.com

Dynamic Photoinduced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures

Zhao, Yuncheng, Yaxin Zhang, Qiwu Shi, Shixiong Liang, Wanxia Huang, Wei Kou, and Ziqiang Yang. "Dynamic Photoinduced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures." ACS Photonics 5, no. 8 (2018): 3040-3050.

for full paper see https://pubs.acs.org/doi/abs/10.1021/acsphotonics.8b00276

… THz-TDS). The THz-TDS system is produced by Teraview company (Teraview TPS 3000). In this system, the Terahertz transmitter and detector are laser gated photo-conductive semiconductor devices. The femtosecond pulse … 

Abstract

Utilizing terahertz (THz) waves to transmit data for communication and imaging places high demands on phase modulation. However, until now, it is difficult to realize a more than 100° phase shift in the transmission mode with one-layer structure. In this paper, a ring-dumbbell composite resonator nested with VO2 nanostructures is proposed to achieve the large phase shift. It is found that in this structure a hybrid mode with an enhanced resonant intensity, which is coupled by the L-C resonance and dipole resonance has been observed. Applying the photoinduced phase transition characteristics of VO2, the resonant intensity of the mode can be dynamically controlled, which leads to a large phase shift in the incident THz wave. The dynamic experimental results show that controlling the power of the external laser can achieve a phase shift of up to 138° near 0.6 THz using this one-layer VO2 nested composite structure. Moreover, within a 55 GHz (575–630 GHz) bandwidth, the phase shift exceeds 130°. This attractive phase shift modulation may provide prospective applications in THz imaging, communications, and so on.

Assessment of Terahertz Imaging for Excised Breast Cancer Tumors with Image Morphing

Chavez, Tanny, Tyler Bowman, Jingxian Wu, Keith Bailey, and Magda El-Shenawee. "Assessment of Terahertz Imaging for Excised Breast Cancer Tumors with Image Morphing." Journal of Infrared, Millimeter, and Terahertz Waves (2018): 1-20.

Abstract

This paper presents an image morphing algorithm for quantitative evaluation methodology of terahertz (THz) images of excised breast cancer tumors. Most current studies on the assessment of THz imaging rely on qualitative evaluation, and there is no established benchmark or procedure to quantify the THz imaging performance. The proposed morphing algorithm provides a tool to quantitatively align the THz image with the histopathology image. Freshly excised xenograft murine breast cancer tumors are imaged using the pulsed THz imaging and spectroscopy system in the reflection mode. Upon fixing the tumor tissue in formalin and embedding in paraffin, a formalin-fixed paraffin-embedded (FFPE) tissue block is produced. A thin slice of the block is prepared for the pathology image while another THz reflection image is produced directly from the block. We developed an algorithm of mesh morphing using homography mapping of the histopathology image to adjust the alignment, shape, and resolution to match the external contour of the tissue in the THz image. Unlike conventional image morphing algorithms that rely on internal features of the source and target images, only the external contour of the tissue is used to avoid bias. Unsupervised Bayesian learning algorithm is applied to THz images to classify the tissue regions of cancer, fat, and muscles present in xenograft breast tumors. The results demonstrate that the proposed mesh morphing algorithm can provide more effective and accurate evaluation of THz imaging compared with existing algorithms. The results also showed that while THz images of FFPE tissue are highly in agreement with pathology images, challenges remain in assessing THz imaging of fresh tissue.

Funding Information

This work was funded by the National Institutes of Health under Award No. R15CA208798. It was also funded in part by the National Science Foundation under Award Nos. 1408007 and 1711087.

… 2 Pulsed THz Imaging and Spectroscopy System The THz system is a TPS Spectra 3000 (#TeraView, Ltd.) pulsed terahertz imaging and spectroscopy system at the #University of Arkansas [5–8]. A diagram of the system is given in Fig …

Proton irradiation induced changes in glass and polyethylene terephthalate substrates for photovoltaic solar cells

Čermák, J., L. Mihai, D. Sporea, Y. Galagan, J. Fait, A. Artemenko, P. Štenclová, B. Rezek, M. Straticiuc, and I. Burducea. "Proton irradiation induced changes in glass and polyethylene terephthalate substrates for photovoltaic solar cells." Solar Energy Materials and Solar Cells 186 (2018): 284-290.

… The results are presented in the form of the ratio S irradiated non-irradiated . THz spectroscopy was performed by a TPS3000 spectrometer (TeraView) in the spectral range 0.06–2 THz using a spectral …

Abstract

An alkaline earth boro-aluminosilicate glass (Eagle XG), a soda-lime glass, and a light-weight polyethylene-terephthalate (PET) foil, used as typical substrates for photovoltaics, were treated by an energetic proton beam (3 MeV, dose 106–107 Gy) corresponding to approx. 30 years of operation at low Earth orbit. Properties of the irradiated substrates were characterized by atomic force microscopy, optical absorption, optical diffuse reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and terahertz (THz) spectroscopy. Minimal changes of optical and morphological properties are detected on the bare Eagle XG glass, whereas the bare PET foil exhibits pronounced increase in optical absorption, generation of photoluminescence, as well as mechanical bending. On the other hand, the identical substrates coated with Indium-tin-oxide(ITO), which is a typical material for transparent electrodes in photovoltaics, exhibit significantly higher resistance to the modifications by protons while ITO structural and electronic properties remain unchanged. The experimental results are discussed considering a potential application of these materials for missions in space.

for full paper https://www.sciencedirect.com/science/article/pii/S0927024818303568

Visualization of subsurface damage in woven carbon fiber-reinforced composites using polarization-sensitive terahertz imaging

Dong, Junliang, Pascal Pomarède, Lynda Chehami, Alexandre Locquet, Fodil Meraghni, Nico F. Declercq, and D. S. Citrin. "Visualization of subsurface damage in woven carbon fiber-reinforced composites using polarization-sensitive #terahertz imaging." NDT & E International (2018).

for full paper see https://www.sciencedirect.com/science/article/pii/S0963869518301610

Abstract

Polarization-sensitive #terahertz imaging is applied to characterize subsurface damage in woven carbon fiber-reinforced composite laminates in this study. #Terahertz subsurface spectral imaging based on #terahertz deconvolution is tailored and applied to detect, in a nondestructive fashion, the subsurface damage within the first ply of the laminate caused by a four-point bending test. Subsurface damage types, including matrix cracking, fiber distortion/fracture, as well as intra-ply delamination, are successfully characterized. Our results show that, although the conductivity of carbon fibers rapidly attenuates terahertz propagation with depth, the imaging capability of #terahertz radiation on woven carbon fiber-reinforced composites can nonetheless be significantly enhanced by taking advantage of the #terahertz polarization and terahertz deconvolution. The method demonstrated in this study is capable of extracting and visualizing a number of fine details of the subsurface damage in woven carbon fiber-reinforced composites, and the results achieved are confirmed by comparative studies with X-ray tomography.

… thickness direction). The commercial THz time-domain spectroscopy (TDS) system (Teraview TPS Spectra 3000), which was employed in this study, is shown schematically.....

for more information about TeraView see: teraview.com

Experimental Gouy phase shift compensation in Terahertz time-domain spectroscopy

Koleják, Pierre, Kamil Postava, Martin Micica, Petr Kuzel, Filip Kadlec, and Jaromír Pištora. "Experimental Gouy phase shift compensation in Terahertz time-domain spectroscopy." Photonics and Nanostructures-Fundamentals and Applications(2018).

Abstract

Terahertz time-domain spectroscopy experiments are usually carried out with focused beams. In this case the Gouy phase shift modifies the retrieved dielectric spectra of thick samples [Opt. Express 18, 15338 (2010)]. We show that a significant influence of the Gouy shift occurs also in commercial THz spectrometers where the focusing conditions may be a priori unknown. A method of experimental compensation of the Gouy shift influence is described and demonstrated.

… In this work we use the time domain spectrometer TeraviewTPS Spectra 3000, which uses 90 fs pulses at 780 nm delivered by the second harmonic of Er:doped fiber laser …Scheme of the measuring system (TPS spectra 3000 from Teraview company) with the … 

For more information about TeraView see teraview.com

for full paper see https://www.sciencedirect.com/science/article/pii/S1569441017303048

Predicting the Structures and Associated Phase Transitions Mechanisms in Disordered Crystals via a Combination of Experimental and Theoretical Methods

Ruggiero, Michael T., Johanna Kölbel, Qi Li, and J. Axel Zeitler. "Predicting the Structures and Associated Phase Transitions Mechanisms in Disordered Crystals via a Combination of Experimental and Theoretical Methods." Faraday Discussions (2018).

Abstract

Disordered materials make up a large portion of condensed phase systems, but the difficulties in describing their structures and molecular dynamics limit their potential applications. Disordered crystalline systems, also known as plastic crystals, offer a unique perspective into these factors because the system retains a degree of crystallinity, reducing the degrees of freedom that must be explored when interpreting the results. However, while disordered crystals do diffract X-rays, it is difficult to fully resolve a meaningful crystalline structure, with the best scenario resulting in lattice parameters. In this study, we use a combination of experimental terahertz time-domain spectroscopy, and theoretical solid-state ab initio density functional theory and molecular dynamics simulations to fully elucidate the structures and associated dynamics of organic molecular solids. The results highlight that this combination provides a complete description of the energetic and mechanistic pathways involved in the formation of disordered crystals, and highlights the importance of low-frequency dynamics on their properties. Finally, with structures fully determined and validated by the experimental results, recent progress into anharmonic calculations, namely the quasi-harmonic approximation method, enables full temperature and pressure-dependent properties to be understood within the framework of the potential energy hyper-surface structure.

for full paper see http://pubs.rsc.org/en/content/articlepdf/2018/FD/C8FD00042E

"A corresponding pellet containing pure polyethylene was also made to act as a standard blank for absorption measurements. All experimental THz-TDS spectra were obtained using a commercial TeraPulse 4000 spectrometer (TeraView Ltd., Cambridge,UK). Variable-temperature measurements were performed using a liquid nitrogen cryostat (Janis, Massachusetts, USA) equipped with a externally controlled heating element (Lakeshore 330, Ohio, USA)."

For information about TeraView see: teraview.com

For information about Janis see https://www.janis.com/

A quantitative comparison of in-line coating thickness distributions obtained from a pharmaceutical tablet mixing process using discrete element method and terahertz pulsed imaging

Pei, Chunlei, Hungyen Lin, Daniel Markl, Yao-Chun Shen, J. Axel Zeitler, and James A. Elliott. "A quantitative comparison of in-line coating thickness distributions obtained from a pharmaceutical tablet mixing process using discrete element method and terahertz pulsed imaging." Chemical Engineering Science (2018).

Abstract

The application of terahertz pulsed imaging (TPI) in the in-line configuration to monitor the coating thickness distribution of pharmaceutical tablets has the potential to improve the performance and quality of the spray coating process. In this study, an in-line TPI method is used to measure coating thickness distributions on pre-coated tablets during mixing in a rotating pan, and compared with results obtained numerically using the discrete element method (DEM) combined with a ray-tracing technique. The hit rates (i.e. the number of successful coating thickness measurements per minute) obtained from both terahertz in-line experiments and the DEM/ray-tracing simulations are in good agreement, and both increase with the number of baffles in the mixing pan. We demonstrate that the coating thickness variability as determined from the ray-traced data and the terahertz in-line measurements represents mainly the intra-tablet variability due to relatively uniform mean coating thickness across tablets. The mean coating thickness of the ray-traced data from the numerical simulations agrees well with the mean coating thickness as determined by the off-line TPI measurements. The mean coating thickness of in-line TPI measurements is slightly higher than that of off-line measurements. This discrepancy can be corrected based on the cap-to-band surface area ratio of the tablet and the cap-to-band sampling ratio obtained from ray-tracing simulations: the corrected mean coating thickness of the in-line TPI measurements shows a better agreement with that of off-line measurements.

For full paper see https://www.sciencedirect.com/science/article/pii/S0009250918304172

… the terahertz in-line measurement. A TPI Imaga 2000 system (TeraView Ltd., Cambridge, UK) was used to perform the off-line measurements as described in detail by Shen and Taday (2008). During the measurement, each...... 

Investigating elastic relaxation effects on the optical properties of functionalised calcium carbonate compacts using optics-based Heckel analysis

Bawuah, Prince, Anssi-Pekka Karttunen, Daniel Markl, Cathy Ridgway, Ossi Korhonen, Patrick Gane, J. Axel Zeitler, Jarkko Ketolainen, and Kai-Erik Peiponen. "Investigating elastic relaxation effects on the optical properties of functionalised calcium carbonate compacts using optics-based Heckel analysis." International journal of pharmaceutics 544, no. 1 (2018): 278-284.

for full paper see https://www.sciencedirect.com/science/article/pii/S0378517318302710

The group used a terahertz  a Terapulse 4000 spectrometer (Teraview Ltd., Cambridge, UK) in transmission mode.

Abstract

Heckel analysis is a widely used method for the characterisation of the compression behaviour of pharmaceutical samples during the preparation of solid dosage formulations. The present study introduces an optical version of the Heckel equation that is based on a combination of the conventional Heckel equation together with the linear relationship defined between the effective terahertz (THz) refractive index and the porosity of pharmaceutical tablets. The proposed optical Heckel equation allows us to, firstly, calculate the zero-porosity refractive index, and, secondly, predict the in-die development of the effective refractive index as a function of the compressive pressure during tablet compression. This was demonstrated for five batches of highly porous functionalised calcium carbonate (FCC) excipient compacts. The close match observed between the estimated in-die effective refractive index and the measured/out-of-die effective THz refractive index supports the validity of the proposed form of the equation. By comparing the measured and estimated in-die tablet properties, a clear change in the porosity and hence, the effective refractive index, due to post-compression elastic relaxation of the FCC compacts, has been observed. We have, therefore, proposed a THz-based compaction setup that will permit in-line monitoring of processes during tablet compression. We envisage that this new approach in tracking powder properties introduced in this preliminary study will lead to the onset of further extensive and detailed future studies.

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII @ Photonics West 2019

Important
Dates

SHOW | HIDE

Abstract Due:
25 July 2018

Author Notification:
1 October 2018

Manuscript Due Date:
9 January 2019

Conference
Committee

SHOW | HIDE

Conference Chairs

• Laurence P. Sadwick, InnoSys, Inc. (United States)
• Tianxin Yang, Tianjin Univ. (China)

Program Committee

• René Beigang, Technische Univ. Kaiserslautern (Germany)
• Jianji Dong, Huazhong Univ. of Science and Technology (China)
• Frank Ellrich, Technischen Hochschule Bingen (Germany)
• Fabian Friederich, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
• Robert H. Giles, Univ. of Massachusetts Lowell (United States)
• R. Jennifer Hwu, InnoSys, Inc. (United States)

Program Committee continued...

• Mona Jarrahi, Univ. of California, Los Angeles (United States)
• J. Anthony Murphy, National Univ. of Ireland, Maynooth (Ireland)
• Créidhe O'Sullivan, National Univ. of Ireland, Maynooth (Ireland)
• Kyung Hyun Park, Electronics and Telecommunications Research Institute (Korea, Republic of)
• Alessia Portieri, TeraView Ltd. (United Kingdom)
• Jinghua Teng, Institute of Materials Research and Engineering (IMRE) (Singapore)
• Michael Weibel, Joint Research and Development, Inc. (United States)
• Jiangfeng Zhou, Univ. of South Florida (United States)

Call for
Papers

This conference brings together researchers and engineers from academia, industry, and government laboratories to explore and present work in the frequency range covering approximately less than 1 GHz (300 mm) to greater than 3 THz (100 μm) as well as infra-red including near, mid and far infrared. Papers on RF and millimeter and infrared technology including advances in wireless communications, radar, lidar, microwave and mm-wave photonics, metamaterials, antennas, phased array radar, modulation, security, monitoring, detection, imaging are encouraged. Papers in photonic-related fields including, but not limited to, radio over fiber (RoF) RF photonics including photonic generation of microwave signals, photonic processing of microwave signals, and photonic distribution of microwave signals and semiconductor (including Si, SiC, SOI, GaAs, GaN, InP, SiGe, diamond, graphene and other materials) RF, mm-wave and terahertz devices and related applications are also encouraged, as well as the hybrid photonic systems and applications. Terahertz (THz) technology deals with the generation and utilization of electromagnetic energy covering what is also known as the sub-millimeter wave region of the spectrum. In this region, which lies between the millimeter wave and far infrared spectral regions, materials exhibit properties that can be exploited to advantage for use over a broad range of important technologies and applications. Papers on terahertz photonics including photonic generation and detection of terahertz waves to/or infrared, THz to/or infrared lasers are also encouraged. 

This conference includes low- to high-power sources, detectors, amplifiers, systems, including both photonic and electronic modulated sources, detectors, and systems as well as nanodevices, nanomaterials, nanotechnology, nanostructures, etc. At THz frequencies, the primary difficulty encountered by scientists and engineers working in this field is the lack of convenient and affordable sources and detectors of terahertz radiation, but this difficulty is gradually changing as new sources and improved detectors are being developed as the technology continues to mature and broaden. At RF and millimeter frequencies, more and more hybrid systems are being integrated with photonic devices that enhance the functions, specifications and stabilities tremendously compared to their traditional counterpart systems. The purpose of this conference is to gather scientists and engineers from a diverse set of disciplines, who are interested in either learning more about terahertz and sub-millimeter and millimeter wave and RF technology and related and coupled technologies, or who are contributing to the field through their own research, development, or manufacturing activities. 

This conference also includes hybrid technologies including, for example, microwave to THz wearable devices of any type and form as well as microwave to THz communications and data links, Artificial intelligence in microwave toThz imaging, etc. 

Disciplines utilizing terahertz technology include physical chemistry (certain molecules or molecular segments exhibit strong resonances in the 10 cm-1 to 100 cm-1 spectral region), military, and homeland security (terahertz radiation can penetrate clothing and packing materials but is reflected by metals and other materials), biomedical technology (tissue exhibits reflection and absorption properties that change dramatically with tissue characteristics), medical and dental, secure short-distance wireless communications (atmospheric water content prevents terahertz radiation from traveling very far), astronomy (the cold background of the universe exhibits a peak in this spectral region), space communications (where the terahertz region is wide open for use) and other disciplines where new, yet-to-be-discovered applications will undoubtedly come forth. Since the low energy associated with terahertz radiation is expected to be no more harmful than infrared or microwave radiation, safety issues are not expected to limit the use of terahertz radiation at low-power levels. 

Papers on power supplies and electronic power conditioners and associated power protection systems including energy-efficient power supplies are also encouraged. 

Papers are solicited in the following and related areas: 

Terahertz sources

• solid-state sources, electron-beam sources, vacuum electronics sources, frequency mixers, frequency multipliers, parametric oscillators, hybrids, graphene, FET and HEMT sources, gas lasers, quantum cascade lasers and related sources, p-germanium sources, photoconductive switches, resonant tunneling diodes, backward wave oscillators
• novel stabilized photonic THz sources
• fabrication processes
• high bandwidth devices, structures, sources, detectors, sensors, etc.
• wearables
• systems and systems integration.

RF, sub-millimeter-wave and millimeter-wave sources

• power sources of all types in the range of 1 GHz to 300 GHz and 300 GHz and higher (i.e. from S-band to the higher end of the millimeter-wave frequencies and all of the sub-millimeter-wave frequency region)
• novel stabilized photonic RF, millimeter-wave, sub-millimeter-wave sources.

Detectors

• bolometers and other thermal detectors, Schottky and other mixers, thermopiles, quantum devices, antenna integrated detectors, heterodyne detection techniques, hybrid detection, direct detection techniques
• transistor-based detectors including graphene, silicon, III-V, II-VI, nitride-based, etc.
• theoretical modeling
• novel detectors.

High-power sources, modules, and systems

• THz, RF, millimeter-wave and sub-millimeter-wave high power sources
• THz, RF, millimeter-wave and sub-millimeter-wave modules
• THz, RF, millimeter-wave and sub-millimeter-wave systems
• power supplies and support circuits, electronics, optoelectronics, systems.

Terahertz, RF, millimeter-wave, and sub-millimeter-wave passive components

• optics, lenses, gratings, waveguides, photonic crystal structures and metamaterials, couplers, wire guides, other components.

Materials for THz and GHz devices

• linear and nonlinear optical materials and devices
• organic and inorganic source and modulator materials and devices
• RF, millimeter-wave and sub-millimeter-wave materials, devices and fabrication processes
• THz and/or GHz material systems
• silicon (Si)-based
• silicon carbide (SiC)-based
• silicon-on-insulator (SOI)-based
• gallium arsenide (GaAs)-based
• gallium nitride (GaN)-based
• indium phosphide (InP)-based
• silicon germanium (SiGe)-based
• quantum dot-(QD) based including for QDs for sensors, detectors and sources
• diamond-based
• graphene-based
• other-based.

Enhancements, improvements and advances in RF, millimeter-wave and sub-millimeter wave generation, modulation and detection

• RF, millimeter-wave and sub-millimeter-wave integrated photonic devices
• RF, millimeter-wave and sub-millimeter-wave and photonic integration process development
• RF, millimeter-wave and sub-millimeter-wave performance characterization
• phased-array and single-element photonically-driven antennas
• phased-array and single-element antennas, systems, concepts, approaches
• low-Vp and wide-bandwidth modulators
• direct-driven millimeter-wave lasers and amplifiers
• millimeter-wave, sub-millimeter and THz photonic crystal devices and applications
• RF, millimeter-wave, sub-millimeter-wave and THz photonic up- and down-converters
• photonic phase locked loops
• RF, millimeter-wave, sub-millimeter-wave, and THz MMICs
• wearables
• RF, millimeter-wave, sub-millimeter-wave, high power solid-state and electronic vacuum devices.

Simulations and modeling

• simulations and/or modeling of RF devices, components, and/or systems
• simulations and/or modeling of millimeter-wave devices, components, and/or systems
• simulations and/or modeling of sub-millimeter-wave devices, components, and/or systems
• simulations and/or modeling of THz devices, components, and/or systems
• modeling of optical components, optical systems, imaging systems, wave propagation, modes, Gaussian beam characteristics, couplers, antennas, performance limitations, software designs
• artificial intelligence, augmented reality, virtual reality.

Spectroscopy

• terahertz and/or sub-millimeter spectroscopy, DNA segment identification, cell abnormalities, cancer identification and screening, imaging, medical and dental detection
• infrared spectroscopy
• identification of biological and chemical detection and fingerprinting
• identification of hazardous, explosive, and/or dangerous materials
• identification of chemical or biological threats
• scalar and vector network analysis at sub-millimeter and terahertz frequencies
• measurement techniques at sub-millimeter, millimeter, and terahertz frequencies
• identification of organic and inorganic compounds using terahertz and/or sub-millimeter wave spectroscopy
• high-speed and/or high-resolution spectroscopic techniques, methods, approaches
• artificial Intelligence, augmented reality, virtual reality, etc.
• novel approaches, systems, designs, techniques, reflection, sensitivity, applications.

Biomedical applications

• DNA identification, burn analysis, tissue abnormality identification, pharmaceutical, dentistry, medical, clinical, commercial applications
• cancer, burn, and/or water content detection; high sensitivity, high contrast, etc.
• biological and/or physiological aspects and/or related effects of RF, millimeter-wave, sub-millimeter-wave and/or THz
• artificial Intelligence, augmented reality, virtual reality, etc.
• imaging techniques, methods, hardware design, strategies, technologies and techniques.

Communication and sensing systems

• terahertz, RF, millimeter-wave and sub-millimeter-wave communications, media characteristics, wireless communications, inspection systems, detection systems, screening systems
• RF, millimeter, sub-millimeter-wave and microwave links
• RF, millimeter-wave, sub-millimeter-wave photonic communication and sensing systems
• Internet of things (IOT) sensors, detectors and communication interfaces, protocols and implementations including but not limited to wireless sensors and wireless communications.

Imaging and security

• RF imaging devices, components, and/or systems
• millimeter-wave imaging devices, components, and/or systems
• sub-millimeter-wave imaging devices, components, and/or systems
• THz imaging devices, components, and/or systems
• RF, millimeter-wave and sub-millimeter-wave active and passive imaging systems
• artificial Intelligence, augmented reality, virtual reality, etc.
• x-ray imaging including components, systems, power supplies, applications, techniques, etc.

Astronomy and space and other areas of photonics, light, and matter

• imaging techniques, ultra-sensitive detection, applications, programs
• artificial Intelligence, augmented reality, virtual reality, etc.
• satellite communications
• space based electronics and devices
• satellite components and systems
• space and satellite qualifications and testing
• radiation hard electronics
• high-energy physics and related topics
• fusion and related topics
• fission and related topics.

Innovations

• new or novel terahertz, RF, millimeter-wave and sub-millimeter, microwave concepts, systems, applications
• new or novel developments in THz or sub-millimeter waves including teaching, instruction, course offerings, simulations, conceptional and/or experimental procedures, implementations, concepts, etc.
• wearables, implantable, etc.

Power supplies and electronic power conditioners

• high-power power supplies
• low- and ultra-low-power power supplies
• low-noise power supplies
• high- and ultra-efficient power supplies
• associated power protection systems
• energy-efficient power supplies
• novel designs and architectures
• specialized power electronics
• portable power supplies
• power supplies tailored for photonics and/or RF, mm-wave and/or THz applications
• power supplies for lighting applications including solid state lighting such as LEDs, OLEDs and quantum dots.

Organic electronics

• DC and low frequency
• high frequency
• novel designs and architectures
• passive and active addressable arrays
• low power
• modulated configurations
• sensing, detection and/or emitting
• organic light emitting diodes and associated electronics
• lighting therapy using solid state lighting including OLEDs.

Infrared devices, communications, sources, sensors, detectors

• infrared amplifiers
• infrared imaging devices, components, and/or systems
• infrared sources devices, components, and/or systems
• infrared sensors, detectors and/or associated devices, components, and/or systems
• infrared communications devices, components, and/or systems
• infrared active and passive components and/or systems
• infrared advances including components, systems, power supplies, applications, techniques, etc.
• infrared applications
• wearables
• artificial Intelligence, augmented reality, virtual reality,