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Ac conductivity and dielectric permittivity of bovine serum albumin, cytochrome c and extracellular matrix synthesized by electrogenic bacteria Shewanella oneidensis MR-1 are measured at frequencies 1–1012 Hz and temperatures 10–300 K. Two types of conductivity mechanisms are observed as well as nearly constant loss (NCL) phenomenon, universal dielectric response (UDR) and signatures of boson peak...
In this article we introduce a new type of frequency diverse antenna based on a leaky waveguide. We have shown with simulated experiment that the antenna can achieve 2cm spatial resolution at K-band frequencies.
Second-order nonlinear coefficients (X2)) and refractive indices (n(2)) of crystals were measured at THz frequencies at the FELIX free-electron laser facility. Maker Fringes were used to obtain χ(2) and Z-scan to obtain n(2). The results wer found to differ from the published values measured in the visible and near-IR.
In this work, we explore a room-temperature measurement of photon correlations in the THz range based on electro-optic sampling. We apply this technique to a THz quantum cascade laser and measure below and above threshold first- and second-order degree of coherence with a subcycle temporal resolution of 146 fs.
On the basis of previous theoretical and experimental investigation there proposed and described the technical decision about examined possibility to do the receiver-frequency-meter-tuner of generators on the Josephson junctions (JJ) working in super wide band. It can be especially convenient for the experimental purposes with new generation structures when radiate power is small and frequency are...
This paper presents a broadband terahertz (THz) high-temperature superconducting (HTS) mixer based on a log-periodic antenna-coupled YBa2Cu3O7−x (YBCO) step-edge Josephson junction. The THz thin-film antenna, as well as the microwave coupling circuits, have been carefully designed to optimize the power transmission from and into the junction while realizing good isolation between the DC bias, local-oscillator...
We propose a novel concept for water-based black-bodies to be used as calibration sources in microwave remote sensing instruments. In order to obtain a low electromagnetic reflectivity, a curved conical interface between water and air has been developed by means of numerical simulations. A blackbody prototype consisting of a 3D printed conical low-loss plastic shell was manufactured and experimental...
We investigate hydration of series of simple alcohol molecules using time-domain THz and FTIR spectrometers. We show that accurate measurements using the THz-TDS setup capable of 70 dB dynamic range in 30 s, can be combined well with traditional THz-FTIR measurements and that the spectra obtained by both setups are consistent with each other. Further, the difference absorption spectra between the...
We implemented pressure-dependent terahertz time-domain spectroscopy. Compared with traditional far-IR spectroscopy with a diamond anvil cell, we can measure at much lower frequencies, down to 0.1 THz, giving us access to many interesting dynamics. The pressure tuning range is from room pressure to 5 kpsi, while the temperature tuning range is from 77 to 473 K. With this large range of tuning parameters,...
The ferroelectric cathode is a cold cathode based on surface plasma, that is not widely known to the gyrotron community. It was assembled and operated is several setups of gyrotrons. Radiation was obtained in the Ka band and the W band. Power in the range of 1–30 kW with interaction efficiency of 10–15% were measured. Experiential results and the potential exploitation of the cathode will be presented.
Polar oxides are natural candidates for use in tunable mm-wave devices. Using different quasi-optical characterization setups, we present the complex dielectric constant of two ferroelectrics and the electrical tunability of one of them at 90GHz.
In ultra-wideband non-destructive testing of large multilayered polymers, data collection and reduction can be achieved by applying compressed sensing techniques. In this work, using effective modelling of possible defects, such as air gaps between layers, we construct defect dictionaries and use them as support data for a signal similarity-based classifier, which will automatically extract the main...
This work explores a rapid design and manufacturing approach to realize complex 3D pillar type filter and transmission line structures for applications in the 220 GHz–325 GHz range, which cannot be economically reproduced by conventional machining processes or present rapid prototyping methods. The significance of this investigation is that at THz frequencies, the exact conductor shape and surface...
We report on a detector-free on-chip dual frequency comb setup based on terahertz quantum cascade lasers. The presented dual-comb covers a bandwidth of 630 GHz with a centre frequency of 2.5 THz. Instead of a fast detector one of the lasers has been used as a fast detector itself. The frequency comb spacing was analysed using frequency counting techniques revealing an accuracy down to δfrep/fcarrier...
Broadband laser based terahertz systems for multilayer thickness inspections are getting established in industrial environments, such as in the quality control for paint processes in the automotive industry. Within this contribution we address another highly attractive and complementary industrial terahertz application by the thickness and density inspection of thick and multilayer plastics as for...
We proposed and fabricated a novel resonant-tunneling-diode (RTD) terahertz (THz) oscillators for circularly polarized wave radiation, which is convenient for THz wireless communication without the alignment of polarization direction. The oscillator is composed of an RTD, crossed slots for resonator and in-plane radiation, radial line slot pairs for output radiation in the upward direction from the...
We introduce a method for estimating the permittivity of liquid samples measured using integrated microfluidic/planar Goubau line terahertz waveguides, in which simulation results are combined with practical data to enable more accurate frequency-dependent analysis.
A high power 300 GHz band pulse gyrotron has been developed based on the design concept for stable and single mode oscillation verified with a prototype gyrotron. The oscillation frequency is 303.3 GHz and the power target is 300 kW. Oscillation test has been carried out and a maximum single mode oscillation power higher than 320 kW was attained. No competing mode was observed during the turn on and...
The water relaxation dynamics is measured for DMPC vesicle solution and LMPC micelle solution from the dielectric spectroscopy. Both lipid have a same headgroup, which is interacting parts with the surrounding water molecules, but the change of the water relaxation time with increasing lipid concentration shows opposite trend. The result suggests that one needs to consider the lipid structure in water...
In this paper, a two-section folded waveguide (TSFW) structure for generating prebunching beam in terahertz (THz) extended interaction oscillator (EIO) is presented and demonstrated. For the realized aim of prebunching beam in the TSFW, it is split into two halves. With help of high speed numerical mill, the TSFW is manufactured. To avoid the effects of size deformation on the interaction of beam-wave...
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