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The goal of our work was to study the capability of field effect transistors to measure high power THz radiation at frequencies from 0.1 up to 3 THz and to determine the linear detection limits. We observed different types of the photoresponse dependence on the incident radiation power. We qualitatively explain the unusual sub-linear behavior observed in high intensities.
We demonstrated a reciprocal planar chiral metamaterials in the THz spectral regime exhibiting asymmetric electromagnetic transmission in opposite propagation directions for circular polarization. We also measured dichroism for counter propagating linear polarized light, which is identical with measured dichroism from its mirror image.
Test structures comprehending several combinations of FET detector sizes and bow-tie antennas were designed and fabricated in a 0.13 µm standard CMOS technology. Measurement results from these structures provide a quantitative comparison basis for the design of a future real-time high-frame rate THz camera, providing an insight on the optimization of the FET size.
Development and applications of one-pulse time-domain spectroscopy on terahertz Novosibirsk free-electron laser is described. Spectrometer with Fabry-Perot etalon in reference branch is used for NovoFEL pulse diagnostics with measuring time of 0.4–0.5 ns. More long HCN-gas reference was applied for high resolution (38 MHz; 1.8·10−5) gas spectroscopy. Spectral resolution of the method as expected to...
The detailed characterization of a modular 260GHz, frequency-tunable, CW-gyrotron equipped with a matching optics unit allowing full-polarization control of the rf-wave is presented. The integration of the gyrotron-system with the NMR spectrometer is outlined.
A Broadband frequency tunable gyrotron operating at fundamental resonance for 600 MHz DNP-NMR has been developed. A cavity resonator and a magnetron injection gun are newly designed. In the preliminary experiments, the continuously frequency tuning bandwidth was 1.3 GHz and the output power was increased up to 100 W.
A terahertz absorption spectrometer with a quantum-cascade laser (QCL) for high-resolution molecular spectroscopy is realized. The spectrometer is based on high-frequency (up to 50 MHz) modulation of the QCL frequency. This allows for the determination of the absorption coefficient and dispersion of the absorbing medium along with a very precise measurement of the line shape of the absorption feature...
The reflection properties of porcine skin are examined in the terahertz (THz) frequency range utilizing a Fourier transform infrared spectrometer with a reflection unit. Their dependence on the frequency and other parameters such as the surface structure is analyzed in order to determine whether porcine skin can be used as surrogate for human skin in the THz frequency range.
The measurement of the wavefront of a terahertz (THz) beam is essential for the development of any optical instrument operating at THz frequencies. We have realized a Hartmann wavefront sensor for the THz frequency range. The sensor is based on an aperture plate consisting of a regular square pattern of holes and a microbolometer camera. The performance of the sensor is demonstrated by characterizing...
We investigate the photothermoelastic response of ZnTe and GaP crystals irradiated by THz-frequency radiation from a quantum cascade laser. We present a full theoretical description of this interaction that agrees well with the measured response.
This paper presents a method of improving the transmission characteristics of a terahertz step attenuator. The transmittance of the step attenuator was measured using a terahertz time-domain spectrometer (THz-TDS). Flat transmittances at each attenuation step were obtained at frequencies up to 3 THz by combining several 6-µm-thick metalized film attenuators (MFAs). The attenuator had no significant...
Complex dielectric susceptibilities of MWCNT/PE composites with various contents of nanotubes were measured using THz-TDS and cw THz BWO-spectrometer in the frequency range 100 GHz – 2.2 THz and THz peak powers from microwatts to hundred kilowatts.
We studied salt effects on hydration water of protein using terahertz time-domain spectroscopy (THz-TDS). The number of hydration water molecules at the protein surface was observed to decrease by addition of ammonium sulfate, while ammonium thiocyanate increases it.
A self-consistent code is introduced to develop a continuous frequency tunable gyro-BWO. A cavity is designed with TE8,5 mode for 400 GHz band second harmonic oscillation. The experimental verification has been carried out and 2 GHz tunability is observed with output powers of higher than 40 W.
The term metrology refers to the art and science of measurement. In the last three hundred years approaches and tools have been developed that allow for precise and reliable measurements with known measurement uncertainty in a multitude of disciplines in physics and technology. Trust in measurement results, comparability and interoperability are crucial for technology in everyday life. With the advent...
We demonstrated a frequency measurement of CW-THz wave referring to THz frequency comb. Effectiveness of the proposed method is demonstrated by measurement of sub-THz test sources. The achieved precision of frequency measurement was 2.0*10−11.
We report on the first demonstration of a quartz enhanced photo-acoustic (QEPAS) sensor in the Terahertz (THz) range. The sensor is based on a QCL emitting at 3.93 THz and a customized quartz tuning fork. For methanol detection we reached a normalized noise-equivalent absorption of 2×10−10 cm−1W/Hz½ comparable with the best result of mid-IR QEPAS.
This paper presents the use of Terahertz (THz) SPR near-field sensor based on array of sub-wavelength metallic holes and Bull's eye structure to characterize materials such as PMMA and those used in organic light emitting diode (OLED). The measurement results confirmed the theoretical SPR frequencies for metal-silicon mode and demonstrate a shift to 0.9211 THz from 0.9375 THz due to 2 µm of PMMA layer...
We present a compact high-Q photonic crystal resonator for 1 THz based on a micro-structured metallic ridge waveguide. The simulated Q-factor of 150 is compared to broadband transmission measurements of a fabricated prototype.
Performance of the antenna-coupled detectors was measured by the quasi-optical setup in wide frequency range from 0.1 to 1.0 THz. Studied sensors were based on the titanium microbolometers coupled with the double-dipole- or log-periodic-type antenna for room temperature THz detection. The THz radiation of the selectively filtered broadband LTG-GaAs photoconductive emitter and the system generating...
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