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Sub-wavelength coaxial aperture has been demonstrated as a simple technique for coupling terahertz (THz) radiation on a cylindrical metal wire. From the practical point-of-view, the structure of a coaxial aperture may have a misalignment of the inner conductor, which leads to an eccentric coaxial aperture. Making use of finite difference method (FDM) in bipolar coordinate system (BCS) and finite element...
We have investigated the THz superfocusing effect using a metal tapered parallel waveguide and THz dielectric response of plastic tubes sandwiched between parallel plates of the waveguide. We observed that about 20% amplitude of terahertz wave can be transmitted through a 20-µm slit of the waveguide.
This paper presents a tomographic system at 100 GHz for imaging based on MST technique. At 100 GHz, a good compromise is obtained between penetration and resolution for biomedical and non-destructive testing applications. Moreover, this system just requires low frequency wiring and reduces the RF equipment necessary for performing real-time imaging. The system has been built and successfully validated...
Conversion from static electric fields to periodic terahertz waves has been experimentally demonstrated at 0.38THz using an optically controlled array of coplanar strip lines on a semi-insulator GaAs substrate.
We studied the parameters that affect terahertz wave generation via optical rectification in nonlinear crystals. We used simulations based on one-dimensional propagation equations of Maxwell in GaAs to consider the effect of these parameters on conversion efficiency. In order to study the effect of nonlinear absorption, we used Drude-model.
The paper describes the method of modelling a microstrip transmission line fabricated on FR-4 substrate in the GHz frequency range. The model is based on the real part of high frequency complex electric permittivity of the dielectric measured with THz time domain spectrometer. The microstrip measurement results are used to analyse the model accuracy.
A dual-frequency laser coupled to a unitravelling carrier photodiode is used to produce a highly coherent THz wave. THz signal is detected by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature and no active stabilization is used. The measured linewidth is better than 30 kHz and tunable from DC to 1 THz. The dynamic...
We have demonstrated THz wave detection using an ultra-compact THz probe. Our THz probe is based on an electro-optic-sampling method, which has been developed as an electric field prober in the microwave frequency range. The THz probe is a fiber-based system operating at the 1.5 µm-band. The dimensions of the EO probe unit were 10mmφ × 60mm-long. By using the EO probe, a 2 THz-wide THz wave was successfully...
Concerning several attacks using letter bombs within Europe in the last couple of years and the highly rising number of new drugs, there is a need for new kinds of detection devices for explosives and drugs. We present a postscanner on basis of Terahertz (THz) spectroscopy using novel chemometric methods for the evaluation of detected THz fingerprints.
CEA-Leti has developed a real-time reflection imaging system: it combines illumination by QCL sources and a telescope that focuses the reflected radiation onto a camera that houses an uncooled 320×240 antenna-coupled micro-bolometer array driven by a FPGA card. We present first high resolution images of illuminated surfaces acquired in real-time.
We report on a magnetospectroscopy study of a set of four HgTe quantum wells of different thickness. In quantizing magnetic fields, intraband and interband transitions have been observed. The obtained results are compared with the allowed transition energies calculated using the 8 × 8 Kane model.
A variety of buffers are commonly used in biochemistry and molecular biology to maintain functions of various biomolecules such as nucleic acids and proteins. We present the high-precision terahertz (THz) time domain spectroscopy (TDS) of buffer and water to clarify differences between both liquids in complex dielectric functions and determine a dielectric relaxation of both liquids.
A 0.14THz point to point communication system based on all solid-state electronic devices has been developed. The carrier frequency is 140.3GHz with output power of −1dBm. 16 QAM modulation has been applied in signal processing to achieve 2.75 bit/Hz spectrum efficiency. It has successfully transmitted 10Gbit/s data over 1.5km with bit error rate (BER)<1e-6 based on non-realtime software demodulation...
We have controlled the curvature of silicon microlens by changing the amount of photoresist in order to microfabricate hemispherical silicon microlens which can improve the directivity and reduce substrate mode losses.
New degrees of freedom in optical design are attained by introducing in the optical path abrupt phase changes over the scale of the wavelength. In this talk, I will discuss experiments on optically thin components based on phase discontinuities and applications
It has been observed that Terahertz (THz) wave was radiation from nanostructured metal gratings and metal films, which was illuminated by femtosecond laser pulse. In this paper, we got more than 60µJ intense single THz pulse, and the maximum spectrum was distributed from 0.3 to 149 THz.
We report electromagnetic radiation covering a spectral range between radio and THz frequencies from a thin metal wire excited by ns, ps, and fs laser pulses. The transient current induced by the pondermotive force of the laser and photoemission from the wire is responsible for the radiation from the thin wire.
To rectify high frequency AC bias, the characteristics and the structure of asymmetric tunneling metal-insulator-metal (MIM) diode has been studied. Needle like nanometer level electrode structure makes a high probability of electron tunneling due to high electrical field density on the electrode structure. The result enhances the asymmetric characteristic of current-voltage at negative to positive...
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