TI

Le domaine térahertz aussi appelé « infrarouge lointain », reste une zone du spectre électromagnétique peu utilisée par les industriels. La cause principale est un manque certain de sources et de détecteurs compacts et performants, compatibles avec les exigences industrielles. Avec les avancées sur l’électronique ultra-haute fréquence et l’optique, des équipements deviennent plus performants sur une large bande de fréquences avec plus de puissance pour l’émission et plus de sensibilité en détection. Cet article propose d’éclairer des nouveautés récentes qui enrichissent l’exploitation de cette onde. De nombreuses applications industrielles seront détaillées

THz pulse generation and single shot detection in a single ZnTe Crystal IRMMW- THz 2022

Single-cycle THz signal of few picoseconds duration, have been simultaneous generated via optical rectification and detected by electro-optic effect in the same ZnTe crystal. An unbalanced seemingly single shot detection scheme was performed to characterize the signal. The added simplicity of this scheme aided the independent analysis of the horizontal and vertical polarization arm of the chirped probe beam to explain the associated nonlinearities in the detected THz signal

THz Spectroscopic Characterization of Oil Shales, IRMMW-THz 2022

Grey to dark-grey samples reported to be oil shales have been analyzed under the THz reflection and transmission spectroscopy. In order to examine the organic and mineral stratification of the oil shales, samples at varying height above the ground level were excavated from stream banks and hilly terrains. The constituent of these aquatic and terrestrial-based oil shales were further correlated to investigate any correspondence or dissimilarities in their composition by examining the refractive index, absorption and optical path length maps of the samples

Investigation on reconstruction methods applied to 3D terahertz computed tomography

International audience3D terahertz computed tomography has been performed using a monochromatic millimeter wave imaging system coupled with an infrared temperature sensor. Three different reconstruction methods (standard back-projection algorithm and two iterative analysis) have been compared in order to reconstruct large size 3D objects. The quality (intensity, contrast and geometric preservation) of reconstructed cross-sectional images has been discussed together with the optimization of the number of projections. Final demonstration to real-life 3D objects has been processed to illustrate the potential of the reconstruction methods for applied terahertz tomography

Terahertz Nondestructive Testing with Ultra-Wideband FMCW Radar

This paper presents the development, performance, integration, and implementation of a 150 GHz FMCW radar based on a homodyne harmonic mixing scheme for noncontact, nondestructive testing. This system offers high-dynamic-range measurement capabilities up to 100 dB and measurement rates up to 7.62 kHz. Such interesting characteristics make this system attractive for imaging applications or contactless sensing. Numerous samples of different materials and geometries were imaged by taking advantage of the radar’s performance. By taking into account the nonionizing capability of the system, new applicative fields such as food industry and pharmaceutical packaging were explored

Tunable ultra-fast infrared generation in a gas-filled hollow core capillary by a four-wave mixing process: erratum

This erratum reports corrections to the temporal axes in Figs. 12 and 13 of J. Opt. Soc. Am. B 39, 662 (2022)JOBPDE0740-322410.1364/JOSAB.444574

Single-scan multiplane phase retrieval with a radiation of terahertz quantum cascade laser

Terahertz phase retrieval from a set of axially separated diffractive intensity distributions is a promising single-beam computational imaging technique that ensures the obtention of high spatial resolutions and phase wavefronts, but remains restricted by time-consuming data acquisition processes. In this work, we have adopted an approach, relying on the radiation of a quantum cascade laser and the implementation of an express single-scan measurement of intensity distributions through the continuous on-the-go displacement of a high-sensitivity antenna-coupled microbolometer sensor array. In addition to the simplicity of this practical implementation and the minimization of measurement times, such an approach overcomes the problem of preliminary optimal selections of transverse intensity distributions used in the iterative phase retrieval algorithm and guarantees the required data diversity for high-quality wavefront reconstruction

Spectroscopie et imagerie THz dans le domaine temporel

International audienc

Terahertz spectroscopy imaging for oncology studies

National audienc