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Numrering	Referens	Omslagsbild	Hitta
1.	Bevilacqua, Stella, 1981, et al. (författare) Fast room temperature THz bolometers 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174 ; , s. 1-2 Konferensbidrag (refereegranskat)abstract A responsivity of >100 V/W was measured at roomtemperature for nano scale bolometers integrated with planar spiral antennas covering a frequency range from 100 GHz to 3 THz. Currently a NEP of about 200 pW/Hz^0.5 was experimentally obtained.
2.	Drexler, C., et al. (författare) Reststrahlen Band assisted photocurrents in graphene 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174 Konferensbidrag (refereegranskat)abstract We report on the experimental and theoretical study of the Reststrahlen Band assisted photocurrents in epitaxial grown graphene on SiC. We show that excitation of graphene with infrared radiation results in a dc current. We demonstrate that photocurrent in response to linearly polarized radiation exhibit a resonance enhancement in the frequency range of the Reststrahlen Band of the SiC substrate. By contrast the photocurrent excited by circularly polarized radiation is suppressed in the same spectral range. The developed theory is in agreement with the data and reveals a strong influence of the Reststrahl Band on the high frequency transport in graphene.
3.	Ducournau, G., et al. (författare) 200 GHz communication system using unipolar InAs THz rectifiers 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174 Konferensbidrag (refereegranskat)abstract We report on the first use of a THz detector based on InAs rectifying nanochannels in a communication system. The transmitter is composed of an electronic multiplication chain, externally amplitude modulated at the input signal. The system has been driven at 200 GHz and up to 500 Mbps data signals have been transmitted in an indoor configuration. In contrast to most nanodevices, the InAs detector has a low impedance (580 ω) and is therefore easily loaded by 50 ω electronics. The data rate limitation is mainly coming from parasitics coupled in the board. © 2013 IEEE.
4.	Ganichev, S.D., et al. (författare) Magnetic quantum ratchet effect in graphene 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174 Konferensbidrag (refereegranskat)abstract We report on the observation of magnetic quantum ratchet (MQR) effect induced by electric field of terahertz radiation in single-layer graphene samples subjected to an inplane magnetic field. We show that the dc electric current stems from the orbital asymmetry of the Dirac fermions induced by an in-plane magnetic field, while the periodic driving comes from terahertz radiation. A microscopic theory of the observed effect is developed being in a good qualitative agreement with the experiment. The observation of the ratchet transport in the purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other 2D crystals, such as boron nitride, molybdenum dichalcogenides, and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field give strong evidence for the existence of structure inversion asymmetry in graphene.
5.	Auriacombe, Olivier, 1989, et al. (författare) Road Surface Characterization Using a Radiometer at 100 GHz 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 136-137 Konferensbidrag (refereegranskat)abstract A dual polarization super-heterodyne radiometer operating between 85 and 100 GHz has been developed and used for surface characterization. The instrument can detect changes from dry to icy road in many environmental conditions (night, fog, rain) by measuring the combination of reflected/transmitted radiation from the surface at two orthogonal polarizations. The difference in brightness temperature between those polarizations is an accurate tool to distinguish ice from dry road surfaces. Results from measurement of dry asphalt and ice layers on asphalt are presented in this paper.
6.	Bevilacqua, Stella, 1981, et al. (författare) High Sensitivity Terahertz Bolometers as Room Temperature Detectors 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956197- Konferensbidrag (refereegranskat)abstract High sensitivity room temperature THz direct detectors made of YBa2Cu3O7-x nano-bridges, with a broadband optical coupling (0.1-2THz) are presented. An optical responsivity (RV) up to 45 V/W was measured at 400 GHz. For bolometers with an electrical responsivity of 70 V/W a noise equivalent power (NEP) of 50 pW/Hz0.5 was experimental obtained.
7.	Blomberg, Patrik, 1992, et al. (författare) On-wafer characterisation of resonant-tunnelling diodes up to 1.1 THz 2023 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract This paper presents on-wafer S-parameter characterisation of resonant-tunnelling diodes between 0.5 THz and 1.1 THz. Diodes with a peak current density of 532 kA/cm2 and a clear negative differential region have been fabricated. An on-chip Multi-Thru-Reflect-Line calibration kit was developed and utilised to achieve accurate S-parameter measurements up to 1.1 THz.
8.	Bonmann, Marlene, 1988, et al. (författare) An Integrated 200-GHz Graphene FET Based Receiver 2018 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2018-September Konferensbidrag (refereegranskat)abstract A receiver composed by a graphene FET 200-GHz mixer and a 1-GHz intermediate frequency amplifier integrated on a silicon substrate was modelled, fabricated and characterized. This is the first demonstration of a millimeter wave integrated receiver based on graphene FETs. The receiver conversion loss is measured to be 25 dB across the 185-205-GHz band with 16 dBm of local oscillator pump power, which is in good agreement with the circuit simulations. The simulations show that the receiver conversion loss can be significantly reduced to 16 dB by reducing the contact resistance and by realizing a higher charge carrier mobility in the mixer transistor.
9.	Bryllert, Tomas, 1974 (författare) Sub-millimeter wave diode transceivers 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956019- Konferensbidrag (refereegranskat)abstract We present sub-millimeter wave transceiver modules intended for imaging radar applications. In particular a novel circuit architecture that operates in homodyne FMCW radar mode will be highlighted [1], and the trade-offs between performance and circuit complexity will be discussed. The transceiver units are based on monolithically integrated Schottky diodes fabricated on 3 μm thick membranes. Radar images with 60 dB of signal-to-noise at 220 GHz will be presented as well as design results for a 340 GHz unit.
10.	Bulcha, Berhanu, et al. (författare) Development of 3–5 THz harmonic mixer 2017 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781509060504 ; , s. Art no: 8067104- Konferensbidrag (refereegranskat)abstract There is a high need for >2 THz room temperature direct-detectors/harmonic-mixers to characterize THz optical sources, phase lock THz-QCLs as LO sources for multi-pixel receivers, and realize absolute frequency calibration sources for applications in astrophysics, earth science, and remote sensing. Thus, we have developed a WM-52 (WR-0.22) harmonic mixer for the 3–5 THz operation. The design, fabrication and assembly of the THz mixer are discussed.
11.	Buron, J. D., et al. (författare) Quantitative mapping of large area graphene conductance 2012 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467315975 Konferensbidrag (refereegranskat)abstract We present quantitative mapping of large area graphene conductance by terahertz time-domain spectroscopy and micro four point probe. We observe a clear correlation between the techniques and identify the observed systematic differences to be directly related to imperfections of the graphene sheet on the length scale of several micrometers.
12.	Cabello Sánchez, Juan, 1992, et al. (författare) Terahertz Planar Goubau Line Components on Thin Suspended Silicon Substrate 2022 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; August Konferensbidrag (refereegranskat)abstract The planar Goubau line is a low-loss planar single-conductor waveguide that holds promise for terahertz applications, where power efficiency is crucial. We present three circuit elements for planar Goubau line: a stopband filter, a matching load, and a power divider, which have been fabricated in a high-resistivity silicon membrane. Simulation results are presented for the matching load and the power divider. The filter’s performance is validated by comparing measurement results with simulations, showing good agreement.
13.	Cabello Sánchez, Juan, 1992, et al. (författare) Transmission Loss in Coplanar Waveguide and Planar Goubau Line between 0.75 THz and 1.1 THz 2018 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; , s. 1-2 Konferensbidrag (refereegranskat)abstract In many cases, metallic planar waveguides are required in the design of integrated circuits. However, at terahertz frequencies, metallic planar waveguides present high losses, which make necessary the use more efficient waveguides to avoid power limitations. In this work, the attenuation constant of two popular planar waveguides for terahertz frequencies, Coplanar Waveguide (CPW) and Planar Goubau Line (PGL), are compared between 0.75 THz and 1.1 THz. To measure the PGL, its transition is deembeded using a multiline Thru-Reflect-Line calibration standard. Measurement results show a lower attenuation constant across the band for a PGL (0.13 mm-1 < α < 0.39 mm-1) than for a CPW (0.68 mm-1 < α < 0.99 mm-1) when an ultra-thin substrate is used suspended in air, which greatly reduces the substrate mode coupling from the PGL. These results put the PGL as a less lossy metallic planar waveguide for terahertz applications.
14.	Cherednichenko, Serguei, 1970, et al. (författare) THz Hot-Electron Bolometer Mixers 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 Konferensbidrag (refereegranskat)abstract We overview the technology of superconductingHot-Electron Bolometer mixers in the field of terahertzheterodyne detection. HEB mixer performance is analyzed vs competing technologies and application fields, with emphasize on radio astronomy. We discuss materials which have been reported in the past to be used for such devices with both phonon-substrate and electron-diffusion cooling mechanisms. It caused a splash of interesting theories with attempts of describing both dc and RF characteristics of HEB mixers. Development of HEB mixers made possible to extend high spectral resolution radio astronomy beyond 1THz.
15.	Garcia Wernersson, Joakim, et al. (författare) Non-destructive density measurements of pharmaceutical products by THz imaging 2016 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467384858 ; 2016-November, s. Art. no 7758615- Konferensbidrag (refereegranskat)abstract In this paper, measurements with a THz imaging system at 346 GHz together with electromagnetic simulations have demonstrated the capability of THz sensing for the non-destructive density determination of intermediate products in the pharmaceutical industry. The results confirm the ability of THz imaging to detect density changes in pharmaceutical samples by measuring the phase variation of the wave transmitted through the sample.
16.	Generalov, Andrey, 1987, et al. (författare) A heterodyne graphene FET detector at 400 GHz 2017 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; , s. Artno:8067234- Konferensbidrag (refereegranskat)abstract We present a THz heterodyne detector based on a single layer graphene field effect transistor (GFET) integrated with a bowtie antenna at 400 GHz. The heterodyne detection is achieved by coupling RF and LO signals quasi-optically to the same GFET. The down converted IF signal is extracted via a coplanar stripline connected to the GFET source and drain terminals. The measured IF bandwidth is 5 GHz.
17.	Generalov, Andrey, 1987, et al. (författare) Distinction of the thermoelectric effect in graphene FET THz detectors 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 504-505 Konferensbidrag (refereegranskat)abstract This work presents an approach to distinguish the thermoelectric detection mechanism from the resistive mixing or plasma wave rectification in graphene FET THz detectors. Numerical full-wave simulations validate the asymmetric feeding of the existing antenna design and allow for comparison with a reference design of thermoelectric detectors. The experimental results verify quantitively the thermoelectric contribution to the overall rectification, which allows for more accurate modelling of the GFET THz detectors.
18.	Hanning, Johanna, 1981, et al. (författare) Single Flange 2-port Design For THz Integrated Circuit S-parameter Characterization 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; , s. 1-2 Konferensbidrag (refereegranskat)abstract A single flange 2-port TRL calibration and measurement setup for accurate THz S-parameter characterization of integrated membrane circuit devices is proposed. The proposed setup facilitates shorter access waveguides, which greatly improves the calibration uncertainty.
19.	Jayasankar, Divya, 1994, et al. (författare) A 4.7-THz fundamental Schottky diode mixer 2022 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract Fundamental mixers operating at ambient temperatures are essential for realising long-lifetime space missions aiming to measure gas spectra at terahertz frequencies. This paper presents the design and sensitivity analysis of a 4.7-THz fundamental mixer. At supra-THz frequencies, fabrication and assembly tolerances substantially affect the mixer performance, and it is essential to identify critical circuit parameters. This work presents the progress towards a room-temperature heterodyne supra-terahertz receiver.
20.	Jayasankar, Divya, 1994, et al. (författare) Development of Supra-THz Schottky Diode Harmonic Mixers 2021 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781728194240 ; 2021-August Konferensbidrag (refereegranskat)abstract In this paper, we report the development of single-ended, Schottky diode-based harmonic mixers operating at 3.5 THz and 4.7 THz, respectively. Both mixers utilize a sub-micron size Schottky diode fabricated with circuit elements on a suspended 2 um-thick GaAs stripline circuit and then assembled in a waveguide split-block. The diode is closely integrated with the RF-waveguide, resulting in an electrically small and compact circuit. For the 3.5-THz, x6-harmonic mixer, a conversion loss of about 60 dB was measured at an intermediate frequency (IF) of 200 MHz. The predicted mixer performance versus dc bias agrees well with the measurements. Based on these results, the preliminary design and simulation results of a 4.7-THz, x8-harmonic mixer, are presented.
21.	Jayasankar, Divya, 1994, et al. (författare) Effect of idler terminations on the conversion loss for THz Schottky diode harmonic mixers 2019 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2019-September Konferensbidrag (refereegranskat)abstract Efficient and reliable frequency converters, preferably operating at room temperature, are critical components for frequency-stabilizing terahertz sources. In this work, we present the analysis of optimum configurations for Schottky diode-based x4, x6, and x8 harmonic mixers operating at 2.3 THz, 3.5 THz, and 4.7 THz respectively. Detailed large-signal analysis of the two basic single-ended Z- and Y-mixers was carried out using a standard Schottky-diode model. For each case, the conversion loss was minimized by finding optimal embedding impedances at RF, LO, and IF frequencies. The analysis shows that the Y-mixer has less conversion loss at a low LO pump power. However, the Z-mixer provides reduced loss with increasing harmonic index and pump power due to the associated power dissipation in idler circuits. The results provide preliminary design guidelines for room- temperature frequency converters and their use in phase-locked loop applications.
22.	Kaltenecker, K. J., et al. (författare) Plasmonic Resonances Affecting Terahertz Generation in Laser-Induced Gas-Plasmas 2018 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - : Book Series: International Conference on Infrared Millimeter and Terahertz Waves. - 2162-2027 .- 2162-2035. ; 2018-September Konferensbidrag (refereegranskat)abstract We demonstrate that plasmonic resonances can be used to broaden the terahertz emission spectrum from two-color laser-driven gas-plasmas. This effect can be controlled by changing the polarization properties of elliptically shaped driving laser-pulses.
23.	Katona, Gergely, 1975, et al. (författare) Bayesian analysis of non-thermal structural changes induced by terahertz radiation in protein crystals 2016 Ingår i: 2016 41ST INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ). - New York : IEEE conference proceedings. - 2162-2027 .- 2162-2035. - 9781467384858 Konferensbidrag (refereegranskat)abstract We have periodically (25ms on - 25ms off) illuminated lysozyme crystals with 0.4 THz radiation and simultaneously monitored their X-ray diffraction intensity in order to study non-thermal structural changes in the protein. In this work we analyze the X-ray scaled and unmerged diffraction intensity observations using a multivariate Bayesian model in order to improve the accuracy of the intensity estimates. The diffraction intensity pairs of the illuminated and non-illuminated state show a predominantly positive correlation. The correlation decreases with increasing resolution suggesting that finer slicing and faster sampling of the rocking curve may further improve the accuracy and effect size of structure factor amplitude differences, making the interpretation of structural changes more straightforward. The improved analysis retains the most important structural features described previously (in helix 3) and provide addition details about the B-factor changes close to the substrate binding site.
24.	Komissarov, Ivan, et al. (författare) Femtosecond Circular Photogalvanic Effect in FeCo/graphene nanobilayers 2023 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract We demonstrate the generation of THz transients from FeCo/graphene heterostructure triggered by circular polarized femtosecond pulsed laser emission originated from the circular photgalvanic effect.
25.	Malko, Aleksandra, 1984, et al. (författare) Thermal Analysis of III-V HBV Diode Structures on InP, GaAs, Silicon and Diamond Substrates 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; , s. 1-2 Konferensbidrag (refereegranskat)abstract Thermal analysis of In0.53Ga0.47As and GaAs Heterostructure Barrier Varactors diodes on InP, GaAs, silicon and diamond substrates are presented. The physical dimensions of the analysed structures correspond to the dimensions of a high power integrated HBV frequency multipliers for W-band (70 – 110 GHz). It is shown that material transfer to substrates with higher thermal conductivity will reduce thermal resistance by 21 % and approximately 50 % for In0.53Ga0.47As and GaAs HBVs, respectively. Thus, an enhanced thermal handling capability of the HBV multiplier sources can be obtained.
26.	Marouf Rashid, Hawal, 1982, et al. (författare) Experimental Verification of the pumping of SIS mixer with an Distributed SIS Frequency Doubler 2016 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467384858 ; 2016-November, s. Art. no. 7758974- Konferensbidrag (refereegranskat)abstract In this paper, we present the performance of the first frequency multiplier using the non-linearity of distributed SIS junctions. The prototype doubler based on distributed SIS junction was for the first time able to pump an SIS mixer. The multiplication efficiency of the distributed SIS junction is 15-30 % for a fractional bandwidth of 10% with excellent spectral line purity. The measured -3 dB line width of the multiplied signal is better than 1 Hz, which was limited by the resolution bandwidth of the spectrum analyzer. The results attained in this work show that the distributed SIS junction frequency multipliers have considerable future potential, and could possibly be used in LO source in single-end and multi-pixel SIS mixer receivers.
27.	Marouf Rashid, Hawal, 1982, et al. (författare) Towards quantum limited frequency multiplication 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract This paper presents a tentative modelling of Superconductor-Insulator-Superconductor (SIS) junction used as frequency multiplier. The model is tested against the experimental data presented earlier and demonstrates good agreement between the measured data and simulation. Such a model will improve understanding of the SIS junction used as frequency multiplier and hopefully lead us to demonstration of the performance for such multiplier.
28.	Masyukov, Maxim, et al. (författare) A calibration-free method to assess the quality of standards for THz on-wafer measurements 2022 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract A method to assess the quality of the calibration standards has been developed and tested. The actual response of the tested transmission lines for LRRM-16 calibration approach has been simulated in HFSS environment, fabricated, and tested with on-wafer measurement setup. The method for quality assessment is based on the properties of similar matrices, that compares traces and determinants of the S-parameters products for fabricated and simulated structures.
29.	Maussang, K., et al. (författare) Temperature dependance of Intrinsic Spin Orbit Coupling Gap in Graphene probed by Terahertz photoconductivity 2023 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract Graphene is a quantum spin Hall insulator, with a nontrivial topological gap induced by the spin-orbit coupling. Such splitting is weak (∼ 45 μ eV) in the absence of external magnetic field. However, due to rather long spin-relaxation time, graphene is an attractive candidate for applications in quantum technologies. When it is encapsulated in hexagonal boron nitride, the coupling between graphene and the substrate compensates intrinsic spin-orbit coupling and decreases the nontrivial topological gap, which may lead to phase transition into a trivial band insulator state. In this work, we have measured experimentally the zero-field splittings in monolayer and bilayer graphene by the means of subterahertz photoconductivity-based electron spin resonance technique. The dependance in temperature of such splittings have been also studied in the 2-12K range. We observed a decrease of the spin splittings with increasing temperature. Such behavior might be understood from several physical mechanisms that could induce a temperature dependence of the spin-orbit coupling. These includes the difference in the expansion coefficients between the graphene and the boron nitride substrate or the metal contacts, the electronphonon interactions, and the presence of a magnetic order at low temperature.
30.	Moradikouchi, Anis, 1990, et al. (författare) Non-Destructive Characterization Of Pharmaceutical Tablets Using Terahertz Frequency Domain Spectroscopy 2019 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2019-September Konferensbidrag (refereegranskat)abstract In this paper, terahertz frequency domain spectroscopy (THz-FDS) in transmission mode is used to study the influence of porosity on effective permittivity in pharmaceutical tablets. Three sets of training tablets with different dielectric constants were generated using microcrystalline cellulose (MCC), Benzophenone and Succinic acid. In each set, various compaction forces have been applied to the powders to produce tablets with different porosity. The results show that the extracted effective permittivity is sensitive to the change of porosity in tablets. Moreover, the results confirm that THz-FDS is able to differentiate between tablets with different dielectric constant and a linear correlation between effective permittivity and tablet density is observed. Therefore, THz-FDS technique is shown to be a promising technique for quality inspection of pharmaceutical tablets. © 2019 IEEE.
31.	Moradikouchi, Anis, 1990, et al. (författare) Small Variation of Active Pharmaceutical Ingredient Concentration Can Be Observed with THz Frequency Domain Spectroscopy 2021 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2021-August Konferensbidrag (refereegranskat)abstract Terahertz frequency-domain spectroscopy (THz-FDS) has been employed to study the result of the variation of active pharmaceutical ingredients (API) on the effective refractive index of pharmaceutical tablets. A quasi-optical set-up with four off-axis parabolic mirrors was used to measure the effective refractive index of tablets in the frequency range of 500-750 GHz. It was observed that a small variation in API concentration can be detected using accurate measurements of the complex transmission coefficients. As a result, THz-FDS reveals to be an effective technique in monitoring the physical properties of pharmaceutical tablets
32.	Moradikouchi, Anis, 1990, et al. (författare) Terahertz radar sensing for real-time monitoring of powder streams 2023 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract In pharmaceutical manufacturing processes, the flow properties of powder streams moving in the manufacturing pipes directly impact the properties of the final drug product, and there is a need for real-time non-invasive monitoring of the powder flow properties with process analytical tools. In this study, we propose a frequency-modulated continuous wave (FMCW) Doppler radar system with a center frequency of 340 GHz to measure the flow properties of falling powder streams in a vertical transparent tube. We successfully measured the velocity profile and powder flow density variation along the height of the tube with a spatial resolution of about 5 mm. In conclusion, the terahertz FMCW Doppler radar system was shown to be highly promising for real-time sensing of flow properties of powder streams in the pharmaceutical manufacturing processes.
33.	Nagy, O., et al. (författare) Transient multi-THz spectroscopy of single and multilayer 2D perovskite single crystals 2022 Ingår i: IRMMW-THz 2022 - 47th International Conference on Infrared, Millimeter and Terahertz Waves. - 2162-2035 .- 2162-2027. - 9781728194271 ; 2022-August Konferensbidrag (refereegranskat)abstract With air-photonics THz platform, we investigated photo-induced carrier dynamics of single and multilayer 2D perovskite single crystals. Interesting novel features and physics are revealed with effective conductivity spectrum up to 12 THz and 40-fs time resolution.
34.	Nefedova, Irina, et al. (författare) Design of a quasioptical test bench for VNA extenders 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 552-553 Konferensbidrag (refereegranskat)abstract The CAD design, simulated optical performance, and test measurements of a quasioptical test bench for VNA extenders are presented. The system allows straightforward integration of off axis parabolic mirrors and VNA extenders. The mirror orientation reduces aberrations and results suggest optical properties are close to what is expected with geometric ray tracing.
35.	Nefedova, Irina, et al. (författare) Evidence of capillary action in multilayered fibrous media observed with THz spectroscopy 2023 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract Here we investigate the applicability of the stratified media model to complex, multilayered media. THz reflectivity spectra of drying cellulose-based material show pronounced, frequency dependent reflectivity reduction below dry reflectivity. Analysis suggests the remaining water is distributed at the top surface of the paper thus consistent with a capillary in opposition to gravity.
36.	Nefedova, Irina, et al. (författare) THz Frequency Quantification of Water Gradients in Drying Paper 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 844-845 Konferensbidrag (refereegranskat)abstract THz-reflection spectroscopy was used to extract time-varying water gradients in drying paper targets mounted on electrically thick dielectric substrates. The data showed a pronounced and prolonged drop below dry reflectivity when the water content that peaks at low weight (∼10%). A binomial distribution fitted to the acquired data confirms the existence of the time-varying water content gradient and suggests aqueous thin film hydration can be quantified even when the contrast between the film and backing material is low.
37.	Nefedova, Irina, et al. (författare) THz spectroscopy techniques for water gradient quantification 2022 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2022-August Konferensbidrag (refereegranskat)abstract Understanding depth dependent hydration, or gradients, is important for a wide range of applications from paper manufacturing to biological tissue imaging. However, in situ characterization, especially in a non-destructive, reflective measurement is difficult in practice. Moreover, uncontrolled sample drying, water migration, and surface warping create significant challenges towards experimental testing. In this work we show a simple scenario with a standard cleanroom wipe of around 350μm thickness being exposed to water and left for complete drying, while its reflectivity together with changing mass data were recorded. The reflectivity was measured using VNA-based quasioptical system. High dynamic range, frequency domain measurements show a non-trivial frequency dependence on reflectivity that cannot be explained by aqueous dispersion alone. Further, the measurements reveal complicated drying dynamics where broadband reflectionless behavior was observed even when the sample was still ~50% water by mass. These investigations are an important step towards model model-free based analysis of spectra that should provide direct extraction of water at depth.
38.	Neumaier, Philipp, 1984, et al. (författare) Molecular spectroscopy with a compact 557 GHz heterodyne receiver 2013 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. Konferensbidrag (refereegranskat)abstract In this work the results of spectroscopic and performance measurements with a compact heterodyne receiver in the frequency range between 520 and 590 GHz are presented.
39.	Novoselov, Evgenii, 1988, et al. (författare) Wideband THz HEB mixers using HPCVD MgB2 thin films 2016 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467384858 ; 2016-November, s. Arti no 7758933- Konferensbidrag (refereegranskat)abstract We present results of experimental study of the gain bandwidth (GBW) of MgB2 hot electron-bolometer (HEB) mixers at 0.1THz and 0.4THz. Antenna integrated 0.25-1.5um2 area devices were made from thin MgB2 films deposited with a custom made HPCVD system. Film as thin as 15-45nm had a Tc from 35K to 40K. The GBW was found to be independent on the bias conditions, the bath temperature, and the LO frequency. The maximum GBW of 6GHz was observed for 15nm thick HEBs. At an 0.7THz LO and a 23K bath temperature the receiver noise temperature of this mixer was 3000K (corrected for optical losses).
40.	Olbrich, P., et al. (författare) Terahertz radiation induced photocurrents in graphene subjected to an in-plane magnetic field 2012 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467315975 Konferensbidrag (refereegranskat)abstract We report on the observation of terahertz radiation induced photocurrents in single-layer graphene samples subjected to an in-plane magnetic field. The photosignal is observed for both, linearly and circularly polarized radiation. A remarkable effect is that the current inverts its sign not only by switching the magnetic field direction, but as well by changing the radiation helicity from left- to right-handedness. We demonstrate that the photocurrent stems from strong structure inversion asymmetry (SIA) of samples originating from the presence of substrate and/or adatoms on graphene. The analysis shows that the observed effect represents a new type of ratchet effects: magnetic field induced ratchets. A microscopic theory of the observed effect is developed being in a good qualitative agreement with the experiment. Furthermore, the experiments open a promising access to the investigation of SIA which is of particular interest for the understanding of graphene properties as well as applications.
41.	Richter, Heiko, et al. (författare) Phase Locking of 3.5-THz and 4.7-THz Quantum-Cascade Lasers Using a Schottky Diode Harmonic Mixer 2021 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 46 Konferensbidrag (refereegranskat)abstract High frequency accuracy and stability are important requirements for local oscillators in terahertz heterodyne spectrometers. We report on a phase-locked loop for quantum-cascade lasers (QCLs) operating at 3.5 and 4.7 THz, two very important frequencies in atmospheric science and astronomy. The QCLs are locked to the multiplied output of a frequency synthesizer using a Schottky diode harmonic mixer.
42.	Riepl, J., et al. (författare) Sub-cycle high-order nonlinearities in a terahertz quantum cascade laser 2022 Ingår i: IRMMW-THz 2022 - 47th International Conference on Infrared, Millimeter and Terahertz Waves. - 2162-2027 .- 2162-2035. - 9781728194271 ; 2022-August Konferensbidrag (refereegranskat)abstract Ultrafast electron dynamics in quantum cascade lasers hold enormous potential for the implementation of intense, compact mode-locked terahertz sources, squeezed terahertz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational terahertz quantum cascade lasers. Here we show the first field-resolved two-dimensional terahertz spectroscopy of a free-running quantum cascade laser, revealing its sub-cycle gain dynamics and disentangling resonantly enhanced high-order nonlinearities up to eight-wave mixing in a regime of negative absorption.
43.	Rindert, Viktor, et al. (författare) THz Spectroscopic Electron Paramagnetic Resonance of the Fe3+ Defect in GaN 2023 Ingår i: 2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ. - : IEEE. - 2162-2035 .- 2162-2027. - 9798350336603 - 9798350336610 Konferensbidrag (refereegranskat)abstract We present a recently developed method for electron paramagnetic resonance (EPR) measurements in the THz spectral range. The method is based on spectroscopic ellipsometry and thus requires no cavity, unlike conventional EPR. This permits us to scan the frequency parameters in addition to the magnetic field parameters. To showcase this, both frequency and magnetic field scans are performed on Fe-doped GaN, and the results are compared to previous work that used conventional EPR to study the same defect.
44.	Rodilla, Helena, 1982, et al. (författare) Millimetre-wave dielectric spectroscopy for cell analysis 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956057- Konferensbidrag (refereegranskat)abstract A millimeter-wave sensor based on a CPW line has been designed and fabricated as a first prototype for impedance spectroscopy to be combined with a multifunctional micropipette for cell and membrane analysis. The first mm-wave measurement results show the sensitivity of the layout by distinguishing the cells from the media and monitoring the attachment process of the cells to the sensor surface. Measurements were performed on umbilical cord stem cells and cartilage thumb cells.
45.	Siday, Thomas, et al. (författare) Ultrafast Nanoscopy of an Exciton Mott Transition in Twisted Bilayer WSe 2 2022 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; August Konferensbidrag (refereegranskat)abstract The density-driven transition of an exciton gas into a plasma of unbound electron-hole pairs has provided a compelling testbed for exploring many-body physics. Here, we use ultrafast polarization nanoscopy to trace a Mott transition of excitons in a twisted bilayer of WSe2. An initially monomolecular recombination of optically dark excitons continuously evolves into bimolecular recombination of unbound electrons and holes as the density is increased. Furthermore, we reveal directly how the Mott transition varies on nanometer length scales, demonstrating how the technique is indispensable in the study of intrinsically disordered van der Waals materials.
46.	Soltani, Amin, et al. (författare) Unveiling the plasma wave in the channel of graphene field-effect transistor 2019 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2019-September Konferensbidrag (refereegranskat)abstract Coupling an electromagnetic wave at GHz to THz frequencies into the channel of a graphene field-effect transistor (GFET) provokes collective charge carrier oscillations of the two-dimensional electron gas (2DEG) known as plasma waves. Here, we report the very first experimental and direct mapping of the electric field distribution in a gated GFET at nanometer length scales using scattering-type scanning near-field microscopy (s-SNOM) at 2 THz. Based on the experimental results we deduce the plasma wave velocity for different gate bias voltages, which is in good agreement with the theoretical prediction.
47.	Stake, Jan, 1971, et al. (författare) Graphene in Millimeter Wave Devices 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956168- Konferensbidrag (refereegranskat)abstract We present work on graphene devices and circuits for microwave and millimeter wave applications, including detectors, mixers and microwave amplifiers. Field effect transistors were fabricated from exfoliated graphene and graphene grown using chemical vapor deposition (CVD). Results from noise assessment in the microwave region, millimeter wave mixers and 0.6THz direct detectors are presented.
48.	Tang, Aik-Yean, 1980, et al. (författare) Geometry Optimization of THz Sub-harmonic Schottky Mixer Diodes 2012 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467315968 ; , s. 1-2 Konferensbidrag (refereegranskat)abstract We present a systematic analysis of geometry dependent parasitics for THz sub-harmonic Schottky mixer diodes. In particular, the diode RF power coupling bandwidth has been studied, showing a trade-off between the air-bridge finger length and finger separation for operating frequencies beyond 1 THz.
49.	Vassilev, Vessen, 1969, et al. (författare) Imaging front-end for thermal detection using an InP DHBT process 2014 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956217- Konferensbidrag (refereegranskat)abstract This paper presents a 153-162 GHz pre-amplified power detector receiver based on a 250 nm InP/InGaAs/InP double heterojunction bipolar transistor (DHBT) process. The front end consists of a double slot antenna followed by a five stage low noise amplifier and a detector. The receiver is characterized through measurements of its response to broadband hot and cold terminations. A simplified method is presented for calculation of the temperature resolution of the receiver from measurements of the detected DC voltage and the noise spectrum at the video output of the receiver. The calculated temperature resolution for the receiver is 2.7 K at 1 ms integration time. This work addresses the need for low cost compact solutions suitable for multi pixel thermal imaging systems.
50.	Viti, Leonardo, et al. (författare) High-speed, low-noise thermoelectric graphene detectors at terahertz frequencies 2020 Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 302-302 Konferensbidrag (refereegranskat)abstract We report room temperature terahertz detection in hBN/graphene/hBN heterostructures, integrated in top-gated field effect transistors. The record combination of high-speed (response time < 1 ns) and high sensitivity (noise equivalent power ~ 100 pWHz-1I2) is enabled by the photo-thermoelectric effect and paves the way for the design of ultrafast graphene arrays in the far infrared, opening concrete perspectives for targeting ultrafast applications.

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