Terahertz Spectroscopy and Imaging : Terahertz pulsed imaging in vivo: measurements and processing methods
This paper presents a number of data processing algorithms developed to improve the accuracy of results derived from datasets acquired by a recently designed terahertz handheld probe. These techniques include a baseline subtraction algorithm and a number of algorithms to extract the sample impulse response: double Gaussian inverse filtering, frequency-wavelet domain deconvolution, and sparse deconvolution. In vivo measurements of human skin are used as examples, and a comparison is made of the terahertz impulse response from a number of different skin positions. The algorithms presented enables both the spectroscopic and time domain properties of samples measured in reflection geometry to be better determined compared to previous calculation methods. ...
Terahertz Spectroscopy and Imaging : Resonance enhancement of terahertz metamaterials by liquid crystals/indium tin oxide...
This work fabricates a terahertz (THz) metamaterial device, whose structure consists of split ring resonator array/ plastic substrate/ Indium Tin Oxide (ITO) film/ liquid crystals/ ITO film/ plastic substrate. Experiment results show that the resonance of the THz metamaterial device can be enhanced as voltage is applied to the liquid crystals. The enhancement will be more significant as higher voltage applied. The resonance enhancement is attributed to the fact that the liquid crystals/ITO interfaces exhibit the large difference in terms of refractive index between the two materials in THz regime. The interfaces reflect the incident electromagnetic wave and cause the reflected wave to enhance the resonance of the metamaterials. As those frequency-tunable metamaterial devices show different resonant transmittance at different frequencies, which is undesired, the liquid crystals/ITO interfaces can improve those frequency-tunable metamaterial devices with a constant transmittance at different ...
Terahertz Technology: Abstract-Numerical and theoretical analysis on the absorption properties of metasurface-based terahertz...
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Terahertz Technology: Abstract-Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection
graphene (483) metamaterials (352) advanced photonix (166) time domain spectroscopy (147) terahertz spectroscopy (122) quantum cascade lasers (120) Time domain Terahertz (104) Terahertz communication (80) CMOS (79) cancer detection (77) teraview (74) picometrix (66) terahertz astronomy (63) Dr. Daniel Mittleman (60) luna innovations (60) metasurfaces (57) pharmaceutical inspection (55) Continuous wave Terahertz (50) Weili Zhang (46) Mona Jarrahi (45) NASA (44) carbon nanotubes (44) patent (42) Advantest (41) Lake Shore Cryotronics (41) Rice University (39) Edmund Linfield (37) photonic crystals (37) airport security (36) algorithms (36) Jiaguang Han (35) MIT (35) commercialization of terahertz (35) plasmonics (35) quantum dots (35) surface plasmon polaritons (35) surface plasmons (35) Verisante (31) Darpa (29) terrorism (29) Don Arnone (28) Junichiro Kono (28) T-Gauge (28) metamaterial absorber (28) Toptica (27) Irl Duling (26) Jianquan Yao (26) Qing Hu (26) A. G. Davies (25) Yan Zhang (25) ...
Terahertz spectroscopy for the isothermal detection of bacterial DNA by magnetic bead-based rolling circle amplification -...
The demand for rapid and sensitive bacterial detection is continuously increasing due to the significant requirements of various applications. In this study, a terahertz (THz) biosensor based on rolling circle amplification (RCA) was developed for the isothermal detection of bacterial DNA. The synthetic bact
Terahertz Spectroscopy on the Cutting Edge of Material Testing | Features | Aug 2018 | Photonics Spectra
Just a few years ago, the application of terahertz radiation seemed obscure at best. If experts were asked for killer applications, few could be named
Terahertz Spectroscopy - THZ2016
THz Generalized Ellipsometry and the Optical Hall Effect for Characterization of Novel Metamaterials, and Electronic and Optoelectronic Materials and Device Structures ...
SYSTEMS, METHODS, DEVICES, AND COMPUTER READABLE MEDIA FOR TERAHERTZ RADIATION DETECTION - Energy Innovation Portal
Systems, devices, methods, and computer-readable media relating to terahertz radiation detection are disclosed. A method of detecting terahertz radiation may include transmitting a reference beam and a signal beam through a common-path interferometer. The method may further include transmitting a terahertz beam through a target object. Furthermore, the method may include causing the signal beam and the terahertz beam to simultaneously propagate through an electro-optical element within the common-path interferometer after transmitting the terahertz beam through the target object to induce a phase delay between the signal beam and the reference beam. In addition, the method may include calculating the phase delay and calculating an amplitude of an electric field of the terahertz beam from the phase delay.
Terahertz imaging goes the distance
At the upcoming CLEO/QELS meeting in Baltimore, an MIT-Sandia team will demonstrate the first real-time THz imaging system that obtains images from 25 meters away. The technique takes advantage of the fact that there are a few windows, or frequency ranges, of the terahertz spectrum that do not absorb water very strongly. The MIT-Sandia group designed a special, semiconductor-based device known as a quantum cascade laser that delivers light in one of these windows (specifically, around 4.9 THz). They shine this light through a thin target with low water content (for example, a dried seed pod), and a detector on the other side of the sample records an image. A cryorefrigerator maintains the laser at a temperature of 30 Kelvin, where it produces 17 milliwatts of power (as opposed to the microwatts of power typical of pulsed terahertz sources) in order to provide enough terahertz radiation to obtain a decent image. Increasing the power of the lasers and sensitivity of the detectors can ...
Terahertz Radiation Systems: Technologies and Global Markets
Terahertz Radiation Systems: Technologies and Global Markets Terahertz Radiation Systems: Technologies and Global Markets The global market for terahertz radiation devices and systems reached - Market research report and industry analysis - 9103955
Detective work using terahertz radiation ( It was a special moment for Michael ...)
...It was a special moment for Michael Panzner of the Fraunhofer Institut...According to Panzer the special thing about the terahertz (THz) scann...The scientists used short electromagnetic pulses that penetrate the va...,Detective,work,using,terahertz,radiation,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
OSA | Terahertz metamaterial absorbers with an embedded resistive layer
A conductive layer of Ti, with a sheet resistance of about 220 Ω/sq, was placed in the dielectric spacer of an Al/SiOx/Al metamaterial terahertz absorber at various depths to probe the effect on the absorption of terahertz radiation. For a square size of 15 µm and a periodicity of 21 µm, and dielectric thickness approximately 1.6 µm, maximum absorption was 60%, 88%, and 94% for Ti layers 297, 765, and 1270 nm deep into the SiOx. Finite element simulations of the absorption correlated well with that of the measurements. This indicates that metamaterials with an embedded high temperature coefficient of resistance (TCR) conducting layer can be used for fabrication of microbolometers with tuned spectral sensitivity.. ©2013 Optical Society of America. Full Article , PDF Article ...
Terahertz Detectors with Carbon Nanotubes Improve Image Detection
The problem, Læonard said, is that terahertz radiation typically requires an antenna to achieve coupling into a single nanotube due to the relatively large size of terahertz waves. The Sandia, Rice University and Tokyo Institute of Technology research team, however, found a way to create a small but visible-to-the-naked eye detector, developed by Rice researcher Robert Hauge and graduate student Xiaowei He, that uses carbon nanotube thin films without requiring an antenna. The technique is thus amenable to simple fabrication and represents one of the teams most important achievements, Læonard said ...
OSA | Resonantly enhanced transmission of terahertz radiation through a periodic array of subwavelength apertures
We demonstrate resonantly enhanced transmission of freely propagating coherent terahertz radiation through free-standing metal foils perforated with periodic arrays of sub-wavelength apertures. These arrays consist of 400 µm diameter apertures periodically spaced by 1 mm and 600 µm diameter apertures periodically spaced by 1.5 mm. We measure absolute amplitude transmission coefficients of ~0.6 at the resonance wavelength. Correspondingly, the ratio of the absolute amplitude transmission coefficient to the fractional aperture area at these resonance frequencies is ~5. This value at terahertz frequencies is significantly larger than equivalent values measured at optical frequencies.. ©2004 Optical Society of America. Full Article , PDF Article ...
High-intensity terahertz radiation from a microstructured large-area photoconductor
We present a planar large-area photoconducting emitter for impulsive generation of terahertz (THz) radiation. The device consists of an interdigitated electrode metal-semiconductor-metal (MSM) structure which is masked by a second metallization layer isolated from the MSM electrodes. The second layer blocks optical excitation in every second period of the MSM finger structure. Hence charge carriers are excited only in those periods of the MSM structure which exhibit a unidirectional electric field. Constructive interference of the THz emission from accelerated carriers leads to THz electric field amplitudes up to 85 V/cm when excited with fs optical pulses from a Ti:sapphire oscillator with an average power of 100 mW at a bias voltage of 65 V applied to the MSM structure. The proposed device structure has a large potential for large-area high-power THz emitters ...
Parametric analysis of transient skin heating induced by terahertz radiation - Zilberti - 2014 - Bioelectromagnetics - Wiley...
This paper investigates the effect of relevant physical parameters on transient temperature elevation induced in human tissues by electromagnetic waves in the terahertz (THz) band. The problem is defined by assuming a plane wave, which, during a limited time interval, normally impinges on the surface of a 3-layer model of the human body, causing a thermal transient. The electromagnetic equations are solved analytically, while the thermal ones are handled according to the finite element method. A parametric analysis is performed with the aim of identifying the contribution of each parameter, showing that the properties of the first skin layer (except blood flow) play a major role in the computation of the maximum temperature rise for the considered exposure situation. Final results, obtained by combining all relevant parameters together, show that the deviation from the reference solution of the maximum temperature elevation in skin is included in the coverage intervals from −30% to +10% at 0.1 ...
Liquids take a shine to terahertz radiation
In a significant breakthrough, scientists at the Tata Institute of Fundamental Research (TIFR), Mumbai, have devised a high-power radiation source in the terahertz (THz) region of the electromagnetic spectrum. This study, done in collaboration with laboratories in Greece and France, will be published in the journal Nature Communications on Oct 30, 2017.
Advanced Solutions | Fiber Optic Test Equip | Terahertz Technologies
Since 1989, Terahertz Technologies Inc. has been a leading global manufacturer of fiber optic test equipment, photonic lab equipment, and analog/digital fiber optic links. We produce high quality OTDRs, optical spectrum analyzers, and more. All of our products are proudly made in the USA.
High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds - NASA/ADS
Two-dimensional networks of quantum dots connected by atomic bonds have an electronic structure that is distinct from that of arrays of quantum dots coupled by ligand molecules. We prepared atomically coherent two-dimensional percolative networks of PbSe quantum dots connected via atomic bonds. Here, we show that photoexcitation leads to generation of free charges that eventually decay via trapping. The charge mobility probed with an AC electric field increases with frequency from 150+/-15 cm|SUP|2|/SUP| V|SUP|-1|/SUP| s|SUP|-1|/SUP| at 0.2 terahertz to 260+/-15 cm|SUP|2|/SUP| V|SUP|-1|/SUP| s|SUP|-1|/SUP| at 0.6 terahertz. Gated four-probe measurements yield a DC electron mobility of 13+/-2 cm|SUP|2|/SUP| V|SUP|-1|/SUP| s|SUP|-1|/SUP|. The terahertz mobilities are much higher than for arrays of quantum dots coupled via surface ligands and are similar to the highest DC mobilities reported for PbSe nanowires. The terahertz mobility increases only slightly with temperature in the range of 15-290 K. The
US20060216743A1 - Methods and systems for detecting biomolecular binding using terahertz radiation - Google Patents
Provided herein are methods and systems for detecting biomolecular binding events using gigahertz or terahertz radiation. The methods and systems use low-energy spectroscopy to detect biomolecular binding events between molecules in an aqueous solution. The detected biomolecular binding events include, for example, nucleic acid hybridizations, antibody/antigen binding, and receptor/ligand binding.
Effect of Bias Electrode Position on Terahertz Radiation From Pentagonal Mesas of Superconducting - | IEEE Journals & Magazine ...
We examined the effect of the bias current position on the radiation of intense and coherent terahertz electromagnetic waves from the intrinsic Josephson juncti
Wavenumber-Domain Theory of Terahertz Single-Walled Carbon Nanotube Antenna - IEEE Journals & Magazine
A theoretical study is presented on the characteristics of terahertz antennas formed by metallic single-walled carbon nanotube (SWCNT) dipoles. The Boltzma
T-ray laser pulses advance imaging - Futurity
U. LEEDS (UK) - Researchers have produced terahertz ray pulses from a quantum cascade laser, the first time rays have been made to emit separate packets of radiation, rather than in a continuous beam.. The work, published online in Nature Photonics, could open up new ways for T-rays to image natural and synthetic materials.. T-rays, a band of radiation in the electromagnetic spectrum that falls between radio waves and visible light, can be used to detect impurities in chemical and biological materials, generating characteristic spectral fingerprints that are used to identify different substances.. Researchers have been working with a technique known as terahertz time-domain spectroscopy, a particularly sensitive way of probing materials using pulses of T-rays. Up until now, these pulses have been made using laser sources that generated very little power (around one millionth of a watt).. Harnessing the power of a quantum cascade laser that is almost 10,000 times more powerful, researchers ...
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Online Annual Review 2018: Scientific Highlights - Helmholtz-Zentrum Dresden-Rossendorf, HZDR
The logical next step in the development of innovative, ever-faster (opto-)electronic components is to access the terahertz frequency range. Until now, however, the materials and technologies required for the simple, efficient generation and conversion of spectral tunable terahertz radiation were lacking. Graphene - an ultrathin material consisting of a single layer of interlinked carbon atoms - has long been discussed as a potential material to achieve this. In a groundbreaking experiment, a team of HZDR researchers led by Dr. Sergey Kovalev and Prof. Michael Gensch (previously at HZDR, now at TU Berlin and Deutsches Zentrum für Luft- und Raumfahrt (DLR, German Aerospace Center) in collaboration with the Max Planck Institute for Polymer Research and the University of Duisburg-Essen (UDE), has managed for the first time to experimentally prove the theoretically predicted, strongly nonlinear properties of graphene in the terahertz range for the first time. With the aid of the unique experimental ...
Most recent papers in the journal AIP Advances | Read by QxMD
We present a polarization-insensitive plasmonic photoconductive terahertz emitter that uses a two-dimensional array of nanoscale cross-shaped apertures as the plasmonic contact electrodes. The geometry of the cross-shaped apertures is set to maximize optical pump absorption in close proximity to the contact electrodes. The two-dimensional symmetry of the cross-shaped apertures offers a polarization-insensitive interaction between the plasmonic contact electrodes and optical pump beam. We experimentally demonstrate a polarization-insensitive terahertz radiation from the presented emitter in response to a femtosecond optical pump beam and similar terahertz radiation powers compared to previously demonstrated polarization-sensitive photoconductive emitters with plasmonic contact electrode gratings at the optimum optical pump polarization ...
Hearing terahertz electromagnetic...
The enhancement of acoustic waves, from audible into the ultrasonic range, is a linear function of the THz intensity incident on a laser-induced plasma, making THz-enhanced acoustics (TEA) useful for THz detection. Using a dual-color laser field to control electron trajectory inside the plasma, THz spectroscopic information can be encoded into the acoustic emission, making it possible to obtain the electric field profile of a THz pulse by simply listening to the plasma. A nearly instantaneous heating of a gas emits a shock wave through photoacoustics that quickly relaxes into an acoustic wave. The acoustic pulse contains a broad spectrum of frequencies that extend well beyond the range of human hearing into the ultrasonic range. When a broadband THz pulse is focused collinearly and simultaneously onto the plasma region, the THz field serves to accelerate freed electrons, giving them additional kinetic energy. Subsequent electron acceleration and collision between neighboring air molecules ...
METHODS AND APPARATUS FOR GENERATING TERAHERTZ RADIATION - Patent application
0063] Because of subwavelength THz mode confinement in the waveguide, in one aspect the THz DFG output from the QCLs may be significantly divergent and THz out-coupling efficiency may be poor. Accordingly, in yet another embodiment, a silicon hyperhemispherical lens 390 optionally may be attached to or otherwise in optical communication with (e.g., suitably proximate to) the output facet 370, as shown in FIG. 12. In one exemplary implementation, the lens 390 may be a 2 mm-diameter, 1.19 mm-height high-resistivity silicon hyperhemispherical lens, positioned to within 5 μm of the output facet 370. For lens alignment, a mid-JR output from the QCL may be imaged with an MCT detector. In some implementations, QCLs with a lens demonstrated a 25-fold increase in collected THz DFG power output, compared to devices without a lens. In various aspects, the increase stems from improved collection efficiency (from estimated ,10% to approximately 100%) and improvements in THz out-coupling efficiency. Typical ...
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Centro de Ciencias de Benasque Pedro Pascual
The physics of artificial structures of reduced dimensionality is one of the main emerging areas of condensed matter physics, and may form the basis of future terahertz electronics, quantum computing technology and novel type of materials known as metamaterials. As it was recently established arrays of quantum dots and Josephson junctions represent the most illustrative example of artificial materials with highly nonlinear and reactive properties usually characterizing metamaterial media. The Conference aims to cover these developments; in particular, recent achievements in Josephson physics, terahertz radiation, metamaterials and other related phenomena. Topics will include: arrays of Josephson junctions, quantum dots and magnetic nanoparticles; metamaterials, superlattices and band gap materials; quantum computing and tunneling phenomena; THz radiation and associated phenomena; nanotubes and nanowires; Josephson vortex dynamics. The conference aims at reviewing the fundamentals and outlining ...
The Far Infrared Rays (FIR) or terahertz - Free Essay Examples
region of the electromagnetic spectrum is shown in Fig.1.. In spite of the difficulties in the generation, transmission and detection of these tremendously high frequency signals 16, due to its undisputed benefits and hardly any ill- ...
Competitive and synergistic adsorption of binary volatile organic compound mixtures on activated carbon
Abstract The adsorption of four substances and their binary mixture is investigated via the terahertz time domain spectroscopy (THz-TDS). The selected unary compound (ethanol, acetone, ethyl acetate, and n-propyl acetate) and binary mixture (solution 1 is composed of ethanol and acetone, and solution 2 is composed of ethyl acetate and n-propyl acetate) exhibit different adsorption behaviors with varied polarities. In comparison with single component, solution 1 shows shorter adsorption equilibrium time, faster adsorption rate, and stronger adsorption capacity, which conform to a synergistic adsorption mechanism, while the competitive behavior is attributed to the slower adsorption in solution 2. In addition, the pseudo-second-order equation with terahertz parameter is used to assess the rate of binary component organics. The present results indicate a further understanding of multicomponent adsorption mechanisms ...
Duplex/Dual-Channel Fiber Optic Links | Terahertz Technologies Inc. | Photonics Showcase | Nov 2010 | Photonics Showcase
The LTX7240 conveys two analog and three digital channels bi-directionally over a single fiber at distances exceeding 10 km. Analog channels are digi
DNA Destroying Chip Being Embedded Into Mobile Phones, page 1
Their synopsis: We consider the influence of a terahertz field on the breathing dynamics of double-stranded DNA. We model the spontaneous formation of spatially localized openings of a damped and driven DNA chain, and find that linear instabilities lead to dynamic dimerization, while true local strand separations require a threshold amplitude mechanism. Based on our results we argue that a specific terahertz radiation exposure may significantly affect the natural dynamics of DNA, and thereby influence intricate molecular processes involved in gene expression and DNA replication ...
Terahertz quantum cascade lasers in a magnetic field - Fingerprint - Princeton University
Powered by Pure, Scopus & Elsevier Fingerprint Engine™ © 2021 Elsevier B.V We use cookies to help provide and enhance our service and tailor content. By continuing you agree to the use of cookies. ...
Ultrafast & Terahertz Photonics: Publications
Nanotechnology 32 042003 (Nov 2020) [pdf] [ref]. This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo et al in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D ...
trendssoul by özlem (yan) devrim: Researchers develop key component for terahertz wireless
This blog is a non-commercial website. Whole content of this website is for inspirational purposes only. Photographs, that are published In this website and registered for the name of Özlem Devrim in Picasa Web Album, are personally shot by Özlem Devrim with the permission of their respective owners and/or copyright holders. Those photographs, that are published in Picasa Web Album and on this site in lower resolutions than actual, may be used for non-commercial purposes and relevant reference as to the actual source is provided.. Please also take note that all rights and/or copyrights for other photographs and visual materials, which are currently published on this site that are not shot by Özlem Devrim and therefore not published under Picasa Web Album, belongs to their respective owners. Such materials that are or may be reported as to infringe copyrights are removed forthright ...
Forward THz radiation emission by femtosecond filamentation in gases: theory and experiment - Ecole polytechnique
A transition-Cherenkov electromagnetic emission by a femtosecond laser pulse propagating in a self-induced plasma channel in air has been very recently proposed as mechanism for production of terahertz (THz) radiation in the forward direction. In this paper, we study in detail the theory of the transition-Cherenkov process. The theoretical model is developed and compared with recent experimental results for several gases.
Biological effects of in vitro THz radiation exposure in human foetal fibroblasts.
In recent years, terahertz (THz) radiation has been widely used in a variety of applications: medical, security, telecommunications and military areas. However, few data are available on the biological effects of this type of electromagnetic radiation and the reported results, using different genetic or cellular assays, are quite discordant. This multidisciplinary study focuses on potential genotoxic and cytotoxic effects, evaluated by several end-points, associated with THz radiation. For this...
Opportunity
Terahertz (THz) radiation is defined as electromagnetic radiation with frequencies ranging from 0.1 to 10 THz. In recent years, many THz sensing and imaging technologies have been developed that have revolutionized the landscape of this rapidly evolving research discipline. These innovative technologies are now finding increasing use for a host of medical, military, and security applications. The emergence of these innovative THz-based systems has opened the door for numerous exciting applications, but the introduction of these new systems has also prompted safety concerns regarding this new technology and has stimulated much interest and activity in the ever growing THz bioeffects research community.. The mission of AFRLs Radio Frequency Radiation Branch is to understand the fundamental effects of exposure to THz radiation not only to support the development of exposure standards to ensure the safety of our military personnel, but also to identify areas ripe for exploitation.. Specifically, we ...
Manifestation of propagation traits for polymer square lattice micro-structured optical fiber in THz regime: a simplified model...
To sustain the pace with immense prominence, interest in low-loss terahertz (THz) waveguides increases due to their particular applications in the multidisciplinary arena. This paper narrates a novel solid-core polymer-based square lattice micro-structured optical fiber (SL-MOF) with circular air...
Structure and dynamics in protic ionic liquids: A combined optical Kerr-effect and dielectric relaxation spectroscopy study -...
The structure and dynamics of ionic liquids (ILs) are unusual due to the strong interactions between the ions and counter ions. These microscopic properties determine the bulk transport properties critical to applications of ILs such as advanced fuel cells. The terahertz dynamics and slower relaxations of si
Ionic Liquids
A hybrid zinc-calcium-silicate polyalkenoate bone cement
A novel bone cement composed of sintered zinc-calcium-silicate phosphate and hybrid polyalkenoates has been developed. Synthesis and formulation of glass fillers, monomers and polymers as well as formulation of the cement were described. The effects of sintering, polymer content, glass powder/polymer liquid (P/L) ratio and comonomer on compressive strength (CS) and curing time (CT) were investigated. The effects of P/L ratio and comonomers on shrinkage as well as exotherm were also studied. Results show that the experimental cement was 61% higher in CS, 10% lower in diametral tensile strength, 35% lower in flexural strength, 62% less in exotherm, and 68% less in shrinkage, compared to conventional polymethylmethacrylate cement. With increasing polymer content and P/L ratio in the cement formulation CS of the cement increased but CT decreased. Curing time, shrinkage and exotherm of the cement decreased with increasing P/L ratio. It appears that this novel cement may be a potential candidate for ...
Improved Design and Microfabrication of H -Plane and E -Plane Loaded Rectangular Slow-Wave Structure for THz TWT Amplifier -...
This paper reports further investigation on a recently proposed H-plane and E-plane loaded slow-wave structure (SWS) for terahertz traveling-wave tube (TWT) amplifier. An improved input-output coupler is designed to enable easy fabrication by microfabrication technology, UV-lithography, electroplating, and molding (LIGA), and deep reactive-ion etching. The coupler shows very low reflection coefficient, S11 ,; -15 dB over a frequency range 360-450 GHz. To improve the beam-wave interaction and enhance the saturated output power of the TWT, the SWS with tapered design is implemented. By tuning the period, the wave is resynchronized with the beam at the end of the SWS, resulting in more than 60% increase in the saturated output power across the 80-GHz bandwidth. In addition, the sensitivity of the output power of the TWT to the fabrication tolerance of the individual geometrical parameters is also studied in detail. It is found that the output power reduces by 80% for approximately 2% variation in ...
KIT - Test Facility - Test Facility - Synchrotron - Beamlines - IR/THz, UV & Soft X-ray Spectroscopy - IR1
Due to ANKA-IRs innovative and influential design utilizing synchrotron edge radiation, characterization and optimization of this novel source is a major research theme of the ANKA infrared group. These studies also include the use of short electron bunches to produce stable coherent emission, resulting in a 5 orders of magnitude intensity enhancement in the far-infrared or terahertz range.. ...
THz Wave 3D Imaging and Tomography | SpringerLink
THz waves are transparent to most of the dry dielectric materials. This property makes THz wave a promising candidate for nondestructive evaluation of the internal structures of targets. THz wave...
THz based) advanced electron bunch diagnostic - Helmholtz-Zentrum Dresden-Rossendorf, HZDR
Figure: (a) Electro-optic measurement of a THz pulse from the TELBE undulator utilizing the developed high-reprate pulse-resolved detection scheme which allows to correct for arrivaltime jitter and intensity fluctuations at repetition rates of presently up to 100 kHz [1] A demonstrator device for the European XFEL is under construction . This detection scheme opens up characterize the superradiant THz sources at TELBE, (b) undulator and (c) diffraction radiator, with a time resolution of better than 13 fs (rms) and a dynamic range of up to 1000000. The main focus of the actual research activities at the HZDR within the program topic accelerator-research and development: subtopic 3 ps - fs photon and electron beams (ARD - ST3) is in the development of versatile (THz-based) diagnostic for electron bunches and superradiant THz sources. To this end (T)ELBE serves within ARD-ST3 as a testfacilitiy for diagnostics on quasi-cw electron and photon beams. Two Examples for recent breakthroughs are the ...
Directory
inproceedings{339fd584-84f8-4c55-935b-db4eb2d20dfa, title = {Investigations of room temperature bolometers for THz applications }, author = {Ben Mbarek, Sofiane and Baron, Thomas and Euphrasie, S\{e}bastien and Thiery, Laurent and Cretin, Bernard and Vairac, Pascal and Briand, Danick and Guillet, Jean-Pierre and Adam, R. and Chusseau, Laurent and Penarier, A.}, year = {2010}, address = {Rome, Italie}, booktitle = {35th International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz 2010)}, month = {sep}, pages = {We-P.27 (2 pages)}, doi = {http://dx.doi.org/10.1109/ICIMW.2010.5612833}, publisher = {IEEE ...
Noise-equivalent temperature - Wikipedia
Noise-equivalent temperature (NET) is a measure of the sensitivity of a detector of thermal radiation in the infrared, terahertz or microwave portions of the electromagnetic spectrum. It is the amount of incident signal temperature that would be needed to match the internal noise of the detector such that the signal-to-noise ratio is equal to one. Often the spectrum of the NET is reported as a temperature per root bandwidth. A detector that measures power is often interested in the analogous noise-equivalent power (NEP). If a relation between intensity and temperature is well defined over the pass band, as in the case of a blackbody, then the NET simply scales with the NEP. If a detector is limited by either shot noise or Johnson noise then the NET can be decreased by using an increased integration time. The NET of flicker noise limited detectors can not be reduced by increased integration time. Typically uncooled bolometric detectors have NET figures of 30-200 mK. Cooled photon detecting ...
PPT - ABSORPTION AND DIFFUSION MEASUREMENT OF BIOLOGICAL SAMPLES USING A FREE ELECTRON LASER PowerPoint Presentation - ID...
ABSORPTION AND DIFFUSION MEASUREMENT OF BIOLOGICAL SAMPLES USING A FREE ELECTRON LASER. M. DArienzo,A. Doria, G.P. Gallerano, E. Giovenale, A. Lai, G. Messina, D. Piccinelli ENEA C.R.Frascati, Via Enrico Fermi 45, 00044 Frascati (Italy). Why Terahertz?. Slideshow 5695767 by kineta
Structure and dynamics of polar liquids: a molecular dynamics investigation of N,N-dimethyl formamide - Publications of the...
A molecular dynamics study of liquid N,N-dimethyl formamide has been carried out. Orientational correlation functions suggest a stacked antiparallel ordering at short distances (, 5Å) and a perpendicular + configuration at intermediate distances. The proposed ordering is in agreement with the recent 13C NMR results of Konrat and Sterk and suggests a stronger association of CH3(t) with O than of CH3(c) with O. Both the translational and the rotational motions are anisotropic. The diffusion constants for rotation along the different directions are different, in agreement with the NMR results. ...
Most recent papers with the keyword musso g | Read by QxMD
The Brill transition is a phase transition process in polyamides related with structural changes between the hydrogen bonds of the lateral functional groups (CO) and (NH). In this study, we have used the potential of Raman spectroscopy for exploring this phase transition in polyamide 6,6 (nylon 6,6), due to the sensitivity of this spectroscopic technique to small intermolecular changes affecting vibrational properties of relevant functional groups. During a step by step heating and cooling process of the sample we collected Raman spectra allowing us from two-dimensional Raman correlation spectroscopy to identify which spectral regions suffered the largest influence during the Brill transition, and from Terahertz Stokes and anti-Stokes Raman spectroscopy to obtain complementary information, e ...
Interaction of methoxy- and methylenedioxyamphetamines with carbon and polymeric adsorbents in polar liquids
|p|Solid phase extraction (SPE) of methoxy- and methylenedioxyamphetamines from diluted aqueous solutions was investigated on carbon and polymeric adsorbents of different textures and chemical compositions. Those adsorbents were applied cartridges packed with three chemically modified carbons prepared from plum stones (initial A2PS, oxidized A2PS-O, and reduced A2PS-H) and commercially available adsorbents (polymeric LiChrolut EN, graphitized Hypercarb and Carboprep). Several factors influence the recovery rates of amphetamine derivatives such as the polarity of adsorbates (free energy of salvation), the specific surface area and surface composition of adsorbents, and the solvent characteristics. Different combinations of these factors affect the recovery rate (R1) for high- and low-surface area adsorbents. The minimal R1 values are observed for an amphetamine derivative at a maximal solvation effect and for a set of amphetamines adsorbed on graphitized carbons. |inline
Semiconductor excitons in new light | Read by QxMD
Excitons are quasi-particles that form when Coulomb-interacting electrons and holes in semiconductors are bound into pair states. They have many features analogous to those of atomic hydrogen. Because of this, researchers are interested in exploring excitonic phenomena, from optical, quantum-optical and thermodynamic transitions to the possible condensation of excitons into a quantum-degenerate state. Excitonic signatures commonly appear in the optical absorption and emission of direct-gap semiconductor systems. However, the precise properties of incoherent exciton populations in such systems are difficult to determine and are the subject of intense debate. We review recent contributions to this discussion, and argue that to obtain detailed information about exciton populations, conventional experimental techniques should be supplemented by direct quasi-particle spectroscopy using the relatively newly available terahertz light sources. Finally, we propose a scheme of quantum-optical excitation ...