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Frequency selective surface is interrogated using optical fibers in THz. Both the band diagram and S-parameter transmission calculations are used in our analysis. Transmission spectrum is explained using Fano resonances, slow light and surface modes.
We experimentally study THz evanescent wave coupling in an array of parallel-plate waveguides in close proximity. We observe stronger coupling with larger plate separations and longer propagation paths.
A modular set of compact corrugated wave-guiding components is presented as an alternative to rectangular waveguides in the WR-1.5 band (500 to 750 GHz). The components presented are designed to enable broadband and low loss operation. A high performance connection system between the components allows for modular path building and efficient power coupling to solid-state devices. The manufacturing...
A method for the in-situ characterization of spurious modes in high power microwave transmission lines is presented. It uses hole couplers, which are integrated into a mitre-bend. The signals are proportional to the field strength at the mirror and allow to partly reconstruct the mode spectrum in the waveguide. The theoretical background is presented as well as results from measurements on prototypes.
Balanced amplifier monolithic millimeter-wave integrated circuits (MMICs) for application in high resolution radar and wireless communication with an output power of up to 7.5 dBm at 210 GHz are shown in this paper. The small-signal gain is more than 13 dB from 200 to 270 GHz and more than 23 dB between 200 and 240 GHz, respectively. Airbridge microstrip transmission lines are used for matching, biasing...
A fundamental 1.9–2.8 THz Schottky diode mixer has been modified to enable high harmonic mixing, thus allowing use of the mixer for phase locking of a quantum cascade laser (QCL) to an stable external microwave source. Phase locking to a reference will transfer the spectral line profile of the reference to the THz source; this will control the phase precisely. Stabilizing a QCL for a single frequency...
We demonstrate the combination of phase-only optical pulse shaping and terahertz time domain spectroscopy. Temporal delay of pulses and generation of bit patterns is shown.
The dependence of the transmission spectra for the array composed of the planar split-ring and circular-ring on meta-atom orientation has been studied experimentally and by simulation in the terahertz region. We observe the systematic change of the spectra with the meta-atom orientation and interpreted it by the interaction among the meta-atoms in the periodic array structure.
The effect of the tilt of the electron beam axis on the gyrotron operation is investigated. It is commonly accepted that the tilt deteriorates the efficiency of cylindrical cavity gyrotrons. Our study showed that this deterioration can be mitigated by a proper displacement of the electron beam axis at the entrance. Also, in some cases, when the aftercavity interaction lowers the gyrotron efficiency,...
We develop a stacking technique for precisely measuring the terahertz (THz) refractive index and absorption coefficient of low-absorbing polyethylene. Due to an increased interaction length more reliable results with considerably smaller confidence intervals are obtained.
Numerical 3D PIC code simulations show that Slow-Wave-Structures SWSs demonstrate excellent potential as a virtual dielectric in a Cherenkov based Backward Wave Oscillator (BWO). CST Microwave Studio confirms internal mode coupling between a volume TM0,6 and surface HE20,1 modes resulting in the creation of a high-Q cavity, necessary for the Cherenkov mechanism to be exploited. MAGIC 3D demonstrates...
Cavities based on a periodic-surface-lattice (PSL) of cylindrical topology have been studied. The lattice perturbations have an amplitude much smaller than the operating wavelength of the structure, allowing the PSL to be described as an effective metadielectric or high impedance surface. Dispersive plots describing the electromagnetic (EM) properties of the PSL are presented and the potential for...
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