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Terahertz radiation has emerged as a prominent solution for imaging and detection beyond visible and infrared. Active terahertz imaging is a widely used technology in this context especially for security applications and screening. Such systems are built around an illuminating source, a detecting module and a beam shaping system to match the detectors geometry. The overall system performance is largely dependent on an optimized choice of these modules. In this work, an active sub-terahertz scanning system working at 100 GHz frequency is proposed to detect concealed objects in parcels and mail. The system is optimized based on an adapted design of the beam shaper and a preprocessing correction of the images to ensure uniformity of response and cleanness. The proposed system demonstrated through experimentation improved resolution with a uniform response along its detection area.

The purpose of this work is to design and manufacture low cost, efficient terahertz (THz) diffraction gratings using a 3D printing technique. We performed theoretical modeling and numerical simulations to determine the components' optimal parameters; then, we proceeded to 3D printing and final production of the desired component. Experimental characterization has shown that the components that we manufactured offer very satisfactory performances despite their insignificant cost, which is promising for providing THz components with a very high quality/price ratio. [ABSTRACT FROM AUTHOR]

We discuss the design and the optimization of interband cascade infrared photodetectors (ICIPs) based on type-II InAs/GaSb superlattices. Our study explores matched-absorbers configuration in ICIPs made up of multiple stages. An effective and enhanced computational approach is presented for determining the subsequent absorbers thicknesses in the matched-absorbers configuration. The first absorber thickness controls that of the following active layers, ensuring uniform quantum efficiency (QE) throughout all stages. Thus, we have demonstrated that selecting the initial absorber thickness is an important factor that can improve the performance of ICIP detectors. Furthermore, we have established that the accurate calculation of the subsequent absorber thicknesses leads to a significant high QE, with potential improvements of over 80% in certain cases. [ABSTRACT FROM AUTHOR]

The aim behind this work is to design and manufacture a beam shaping lens for active terahertz imaging systems that boosts their performance in terms of sensitivity and image quality. The proposed beam shaper is based on an adaptation of the original optical Powell lens, where a collimated Gaussian beam is converted into a uniform flattop intensity beam. The design model for such a lens was introduced, and its parameters were optimized by a simulation study conducted using COMSOL Multiphysics software. The lens was then fabricated using a carefully chosen material [polylactic acid (PLA)] through a 3D printing process. The manufactured lens was implemented in an experimental setup to validate its performance using a continuous-wave sub-terahertz source around 100 GHz. Experimental results demonstrated a high-quality flattop beam maintained along the propagation path, which is highly recommended for terahertz and millimeter-wave active imaging systems to produce high-quality images.