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Semiconductor nanowires and nanostructures have a great potential for Terahertz generation and detection, especially because certain materials properties such as optical absorption, high electron and hole mobility, and short carrier lifetime can be engineered through structural changes and material compositions. In such structures, the variation in geometry and surface charge characteristics can greatly...
The analysis of petrochemical samples by Terahertz (THz) spectroscopy is investigated. THz spectroscopy is a nondestructive, contact-free analysis method for the study of many different materials. In this work, we show that the THz spectra can be used to get different chemical and structural information from a potential hydrocarbon source. Density of the geological samples has the potential for valuable...
By using existing metal mesh technology we propose a new lens design that behaves in a similar way to a Wollaston Prism. That is, a device that separates out the two linear polarised states of the incident field and then focuses them separately on same focal plane. The design is an evolution of an existing GRIN lens based on the same technology. The proposed lens design has a diameter of 75mm while...
Terahertz ellipsometric and polarimetric measurement systems have been commissioned with the Novosibirsk free electron laser (FEL) being a source of monochromatic radiation. Calibration experiments with semiconductors and metamaterials showed correct operation of these systems. Blood films, monosaccharide, amino acids, and culture medium were studied.
We report on the terahertz analysis of the internal structure of ultra-high molecular weight polyethylene composite materials. The visualisation of interfaces between the perpendicularly arranged plies and the identification of stacking faults is possible because the THz refractive index depends on the orientation of fibres in the plies. Thicknesses of all plies in a composite material were determined...
Using terahertz time-domain spectroscopy (THz-TDS), we measured optical constants of nine different types of common natural stones: slate, gneiss, marble, mudstone, sandstone, dolomite, granite, tuff, and diorite. The result shows that most natural stones are fairly transparent in THz frequency range, and dolomite, in particular, exhibits a nearly uniform refractive index of 2.7 over frequency range...
Refractive indices of a 1 mol % MgO-doped stoichiometric LiTaO3 (SLT) crystal in the region of 0.85 ∼ 1.59 THz and for the temperature range of 80 ∼ 300 K were deduced via the terahertz generation process using a fanned-out periodically poled SLT. In addition, temperature-dependent Sellmeier equation was derived.
The optical parameters (refractive index, absorption coefficient) of opaque dielectric materials can be measured with terahertz (THz) Time-Domain spectroscopy (TDS). By using a THz beam of known polarization and measuring both components of the transmitted THz field, it is possible to determine the birefringence present in an anisotropic material. In this work we used polarization sensitive (PS) TDS...
The far-field divergence of Tapered THz quantum cascade lasers is studied experimentally and theoretically. A abnormal increase of the divergence has been found with either increasing the tapered angle or the device's length. Then we want to answer either the thermal accumulation or the nonlinearity of the material account for it. Theoretical analysis suggests that the field-induced change of the...
The qualitative and quantitative analysis of amino acids by terahertz (THz) refractive index spectra is discussed. The frequency band of anomalous dispersion emerging in the spectra is unique for the amino acids, L-glutamine (Gln) and L-histidine (His). The refractive indices of the amino acids were found to be linearly proportional to the concentrations. The calibration models were established to...
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