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We present a current study of mid-IR isolator using nonreciprocal (NR) magnetoplasmonic InSb mirror. The reflectivity of n-type InSb surface was calculated using Rigorous Coupled Wave Algorithm (RCWA) method. We report magnetooptical (MO) effect for low external magnetic field (B=0.1T), which can be enhanced by a plasmonic grating.
A combination of circular polarizer and polarization rotator at 170 GHz were designed and constructed by General Atomics (GA) and tested at MIT for Electron Cyclotron Heating in ITER. Cold test measurements were performed using a Vector Network Analyzer to determine the relative amplitudes and phase shifts between two orthogonal components of the reflected field. Measured polarization parameters,...
We discuss the improved performance of a microfluidic cell for chemical detection. The sensitivity is increased by placing the microfluidic cell in photonic crystal cavity. The insecticide methomyl is used as an exemplary chemical.
A multi-megawatt Electron Cyclotron Resonance Heating (ECRH) system is in routine operation at the ASDEX Upgrade (AUG) tokamak. It applies four step-tunable gyrotrons at 105 and 140 GHz with 10 s pulse length and output powers close to 1 MW. An upgrade with four more gyrotrons is underway which will double the installed power. The first two-frequency gyrotron of the new series has recently been installed...
In this report we demonstrate a high-spectral-resolution terahertz (THz) imaging system on the basis of a THz quantum-cascade laser (QCL), a fast scanning mirror (FSM), and a cryogenic-cooled Ge:Ga detector. During the scan through an absorption cell filled with methanol (CH3OH), spectral information is obtained through QCL frequency tuning within a range that covers the feature of interest. Our results...
We investigate the impact of periodic sampling time errors of terahertz time-domain waveforms and analytically calculate the influence on the spectrum of the measurement. We assess the effects on optical parameter extraction.
The Smith-Purcell radiation is a promising alternative to make Terahertz wave be development and utilization. Measure the spectrum of Terahertz can reflect the source performance and stability indirectly. The design and construction of a simple THz Fourier transform spectrometer (FTS) is described. The spectrometer is operation at frequencies between 0.1 and 5 THz with a frequency resolution of 3...
This paper presents a novel scheme for generation of high power short THz pulses using optical rectification. The procedure consists of two main steps. In the first step, generation of a chirped broadband THz pulse is proposed using a chirped aperiodically poled lithium niobate (APLN) crystal. In order to design a crystal with optimum generation efficiency, we take advantage of binary optimization...
We report on a fast self-mixing approach for real-time, coherent terahertz imaging based on a quantum-cascade laser and a scanning mirror. Due to a fast deflection of the THz beam, images with frame rates up to several Hz are obtained. By applying a phase-modulation technique, the amplitude and the phase information can be separated.
Microwave diagnostics will play an increasingly important role in burning plasma fusion energy experiments like ITER and beyond. The Collective Thomson Scattering (CTS) diagnostic to be installed at ITER is an example of such a diagnostic with great potential in present and future experiments. The ITER CTS diagnostic will inject a 1 MW 60 GHz gyrotron beam into the ITER plasma and observe the scattering...
We investigate optical resonant cavities using metallic mirror in order to increase the absorption in low-temperature-grown GaAs (LT-GaAs) based photoconductors operating at telecom wavelength. Two different semi-transparent front mirrors are compared: the first one is a thin gold layer whereas the second one consists of a gold periodic array. We show that the generated photocurrent is 3 times higher...
We report on first results obtained with the use of a new setup for direct passive measurements of the low temperature terahertz emissivity of different materials — metals, superconductors, and others. The setup allows estimating the level of noise originating from the thermal radiation of mirrors in terahertz space missions. This setup also makes it possible to develop the passive terahertz emissivity...
The aim of this work is to improve high-frequency calibration data on long baseline observations for the ALMA antennas. A dual-frequency atmospheric phase error calibration method is proposed and will be implemented by the simultaneous observation in two ALMA Bands, specifically 6 and 9, coupled by means external optics in a few baselines. This method is envisioned to demonstrate the advantage of...
We demonstrate real-time mapping of high-frequency phonon-polariton dispersions up to 7 THz in ferroelectric LiNbO3 using a single-shot spectroscopic setup with an echelon mirror. The echelon mirror provides a spatially encoded time delay for the probe pulse, and therefore, ultrafast transient behavior of materials can be detected on a single-shot basis. Using optical Kerr gate apparatus, the E-mode...
Scattered millimeter waves entering from the collective Thomson scattering diagnostic at ASDEX Upgrade fusion device are generally elliptically polarized. In order to convert the millimeter waves to linearly polarized waves (required for the detector), birefringent window assemblies (sapphire) have been developed to replace grooved metal mirrors. This allows a significantly more compact receiver design...
A THz laser source based on stimulated polariton scattering (SPS) in an intracavity RbTiOPO4 (RTP) crystal is reported, with frequency-tunable output from 3.10 to 3.16 THz and from 3.50 to 4.15 THz. The gap exhibited from 3.17 to 3.49 THz is located in the vicinity of the 104 cm−1 absorbing mode in RTP. A maximum average output power of 16.2 μW was measured at 3.80 THz.
Experiments with terahertz surface plasmons (SPs) excited by a free electron laser demonstrated that SPs are totally reflected from a plain mirror slightly inclined to the normal of the guiding surface. With larger angles, the SP reflection decreases gradually, which indicates that the wave vector of SPs on a real metal surface is not constant but is spread over a rather wide interval due to SP scattering...
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