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We report on intense, tunable, continuous, and coherent THz electromagnetic waves observed from differently shaped triangular mesas of the intrinsic Josephson junctions in single crystalline high-Tc superconducting Bi2Sr2CaCu2O8+δ. All samples are fabricated by focused ion beam milling.
The plasmon resonances in GaN and InGaAs-based heterojunction field effect transistors (FETs) are investigated by using the finite-difference method in combination with finite-element solution of electron densities, potential and carrier velocities. Our results predict a resonant behavior of photoresponse in the channel of these FETs at terahertz frequencies indicating potential application of these...
A tunable double-channel narrowband terahertz filter integrated with parallel plate waveguide cavities is described. The filter is formed by machining two rectangular grooves into upper and bottom plates of parallel plate waveguide, respectively. Tuning is achieved by a relative lateral shift of two metal plates with rectangle grooves. Simulation results show that both the resonance frequency and...
This paper proposes a characterization method for the electromagnetic properties of thin films, based on the resonance properties of a slow-wave coplanar strips resonator. It is shown that using the resonant frequency and the quality factor of the resonator, permittivity and loss tangent of an unknown thin film at high frequencies such as mm-wave frequencies can be accurately determined. The method...
Results on identification of liquids by a Josephson detector with a dielectric waveguide coupling are presented. Broadband and frequency-selective modes of the Josephson detector were used to extend a spectral bandwidth from 1 GHz to 500 GHz. A characterization of a liquid identifier was demonstrated for alcohols, acetone and water.
We present two designs of planar terahertz metamaterials for strain sensing. A series of resonance frequency shifts are obtained with differing gap widths when the sensor is under mechanical compression. The subwavelength metamaterial structures exhibit a high-Q resonance resulting in a good sensitivity to mechanical deformation. Because of the penetrability and relatively high spatial resolution...
It is important to keep the frequency of higher-frequency operating mode twice or triple as large as that of the lower-frequency operating mode in the dual-frequency operation terahertz coaxial gyrotron with two electron beams. From the practical point of view, the effects of a possible tilted or shifted inner rod of a coaxial gyrotron cavity on the ohmic loss distribution, the resonant frequency,...
We present a metamaterial-based sensor for use at terahertz (THz) frequencies that is suitable for the measurement of the thickness and the refractive index of a dielectric sample material. The sensor is designed to operate in reflection geometry in the frequency range between 1 THz and 1.6 THz. Deep-subwavelength sample thicknesses as small as 1/16000 of the operating wavelength can be resolved as...
A longitudinal computer-generated hologram is incorporated into the Fabry-Pérot cavity of a terahertz quantum cascade laser which displays two distinct spectral gain peaks. The combined cavity and hologram feedback mechanisms lead to digitally selective dual-mode emission with a difference frequency which may be electronically tuned from 190 GHz to 267 GHz.
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