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The concept of a CW THz range gyrotrons operated at the second or third cyclotron harmonic is presented. To suppress the mode competition effects a double beams scheme is applied. The helical electron beams are formed in a double-beam triode magnetron-injection gun (MIG), where both emitters of the electron beams are located on a common cathode of the conventional MIG. Results of numerical simulation...
We report the experimental design and initial experimental results on high power RF generation at W-band based on coherent wakefield from the metallic periodic structure of 91 GHz, excited by intense electron beam at the Argonne Wakefield Accelerator (AWA) facility. The recently output RF power is 0.7 MW, with 67 MeV, 1.4 nano-column (nC) single electron beam go through the 12cm structure. The RF...
Nanostructured NiCr thin film was prepared by a combination of magnetron sputtering and reactive ion etching (RIE) in 80 × 60 uncooled infrared focal plane arrays (IRFPA). The surface morphologies and THz absorption characteristics of the IRFPAs were tested with NiCr absorption layers prepared by magnetron sputtering and the combined process respectively. The tests suggested that THz absorption could...
In the following article the measurements performed at CIEMAT on several silica samples are described. The samples were treated in both N2 and O2 atmosphere, in a temperature range from 500 to 1000 °C. The measurements include UV — VIS — NIR absorption spectroscopy, FT-IR transmission and reflectance spectroscopy, and visual inspection of the treated samples with a confocal microscope.
The effect of rough surface scattering on the contrast observed in THz medical imaging is explored. A Frequency Modulated Continuous Wave (FMCW) THz imaging system operating at a center frequency of 650 GHz with a time averaged bandwidth varied between ∼ 0.01% and 1% bandwidth was used to image rough surface targets to explore the effect of rough surface scattering on the contrast observed in THz...
The functionality of terahertz metamaterials can be dramatically increased through judicious materials integration. In addition to semiconductors, materials ranging from graphene to superconductors can enhance or enable new functionality. Following a brief review, we present recent results creating nonlinear metamaterials using InAs and YBa2Cu3O7, and discuss the broad range of possibilities to explore...
This research represents experimental use of a pulsed terahertz time-domain imaging system to obtain time of flight (in-depth) reflection scans from three-dimensional ex-vivo breast cancer tumor tissue. Image processing and volumetric techniques are performed on these THz scans to analyze and enhance the tumor image and assess its boundaries.
We measured the bandwidth of a terahertz detector using an InAlAs/InGaAs high-electron-mobility-transistor by heterodyne mixing with UTC-PD and a frequency multiplier as a radio frequency (RF) and local oscillator (LO), respectively. The intensity of the intermediate signal was measured by changing the frequency of UTC-PD, and a very high bandwidth of up to 26 GHz was obtained.
Studies of a rat blood and skin were carried out using THz-TDs. The transmission and the attenuated total internal reflection geometries have been used for measuring the dielectric properties of the water solutions and biological samples with high glucose concentration. We discuss the reasons for the observed THz sensitivity to diabetes mellitus in the context of changes in the bounded water caused...
It has been about 15 years, since the first demonstration of terahertz (THz) communications using both impulse and continuous waves. To meet an ever-increasing demand for the speed of wireless communications, THz communications have recently gained lots of interest and expectation. This paper overviews a latest trend of THz communications research, and discusses the future perspective with respect...
The fifteen-unity coupled ridge waveguide quantum cascade laser (QCL) arrays integrated in parallel were present. In-Phase mode of operation is provided by both the index-guided nature and the strong coupling between lasers inherent in this structure. Single-lobe lateral far-field with a nearly diffraction limited beam pattern was obtained. The simplicity of this structure and fabrication process...
Considered possibility of application of terahertz waves at geological researches. Investigations of anisotropy of electrical properties of rocks are conducted. Coefficients of transmission, reflection and permittivity for plane samples of rocks are obtained.
A waveguide window is designed for W-Band folded waveguide TWT. The window performance is initially designed by the transmission line theory and then optimized by 3D EM simulation code CST MWS, HFSS and MTSS. The results of these codes are in agreement and all show us that the waveguide window has excellent transmission performance from 90GHz to 102GHz with VSWR less than 1.1 and S11 less than −30dB.
High quality Mn1.56Co0.96Ni0.48O4 films with different layers have been prepared on Pt//Ti/SiO2/Si substrate. Infrared optical properties of the films have been investigated using infrared spectroscopic ellipsometry. The optical constants have been obtained by fitting the measured ellipsometric parameter data with classical infrared model.
In this paper, a novel optical frequency 24-tupling scheme for THz signal generation is proposed and demonstrated. Based on two cascaded Dual-Parallel Mach-Zehnder Modulators (DPMZM) and three phase shifters, optical signal with only ±12th-order sidebands is achieved without optical filter. Theoretical analysis and simulation results show that the scheme can generate 0.12THz signal from a 5GHz radio...
Optical properties of nonlinear Ga2S3 are studied to reveal possibility for THz applications. The results establish that 3-d (bulky) Ga2S3 is a strong potential competitor to a layered GaSe and its solid solutions those possess outstanding optical properties.
A precise and stable THz Measurement Platform is proposed in this paper. The displacement precision and angle precision of the platform are 0.02mm and 1° respectively. With OML or VDI extension module and Agilent N5245A PNA-X network analyzer, the THz Measurement Platform can measure waveguide components and antennas precisely in 0.2–1.1THz.
The radial sheet beam traveling wave tubes can work at the frequency of millimeter wave band, have the properties of high efficiency, broad bandwidth, miniaturized dimensions, and easily to be integrated and so on. The radial divergent sheet beam electron optical system with cylindrical emission surface is designed for the Ka band radial sheet beam traveling wave tubes in this paper. The radial divergent...
A new method of spatial separation of electrons with different initial energies in the helical electron beams of gyrotrons is reported. This method is based on the radial drift of electrons in the presence of crossed azimuthal magnetic and axial electric fields. The possibility of application of this method of electron sorting for effective multistage depressed collectors in gyrodevices is shown through...
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