Abstract-Multiplexing THz Vortex Beams With a Single Diffractive 3-D Printed Len

Federico Machado, Przemysław Zagrajek, Vicente Ferrando, Juan A. Monsoriu, Walter D. Furlan

https://ieeexplore.ieee.org/document/8550797

We present a novel method for experimentally generating multiplexed THz vortex beams by using a single three-dimensional printed element that combines a set of radially distributed spiral phase plates, and a binary focusing Fresnel lens. With this element, we have experimentally demonstrated that THz multiplexing can be tailored to fit within a small space on an optical bench. Results are presented beside numerical simulations, demonstrating the robust nature of the experimental method.

Abstract-Modeling of Silicon-Based Substrates of Patch Antennas Operating in the Sub-THz Range

Paweł Kopyt,  Bartłomiej Salski,  Przemysław Zagrajek, Dariusz Obrębski, Jacek Marczewski


http://ieeexplore.ieee.org/document/7938371/

The paper describes a convenient way to numerically model planar antennas dedicated to sub-terahertz (THz) radiation detectors while accounting for multiple oxide layers included in typical silicon-based substrates used in microelectronics. Several approaches are presented, including a solution based on calculations of effective permittivity of the layered substrate. The results suggest that this approach can work at lower frequencies, but will not be effective in the sub-THz range due to different mechanisms of dispersion occurring in transmission lines with either homogeneous or layered substrate. Therefore, an alternative approach based on anisotropic layers has been proposed, which proves to be efficient and easy to adopt in typical numerical models. It also explains well the results of experiments done using a set of patch antennas fabricated on thin membranes and operating at various frequencies from 240 GHz up to 370 GHz.

Abstract-Terahertz 3D printed diffractive lens matrices for field-effect transistor detector focal plane arrays

Krzesimir Szkudlarek, Maciej Sypek, Grzegorz Cywiński, Jarosław Suszek, Przemysław Zagrajek, Anna Feduniewicz-Żmuda, Ivan Yahniuk, Sergey Yatsunenko, Anna Nowakowska-Siwińska, Dominique Coquillat, Dmytro B. But, Martyna Rachoń, Karolina Węgrzyńska, Czesław Skierbiszewski, and Wojciech Knap
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-18-20119

We present the concept, the fabrication processes and the experimental results for materials and optics that can be used for terahertz field-effect transistor detector focal plane arrays. More specifically, we propose 3D printed arrays of a new type – diffractive multi-zone lenses of which the performance is superior to that of previously used mono-zone diffractive or refractive elements and evaluate them with GaN/AlGaN field-effect transistor terahertz detectors. Experiments performed in the 300-GHz atmospheric window show that the lens arrays offer both a good efficiency and good uniformity, and may improve the signal-to-noise ratio of the terahertz field-effect transistor detectors by more than one order of magnitude. In practice, we tested 3 × 12 lens linear arrays with printed circuit board THz detector arrays used in postal security scanners and observed significant signal-to-noise improvements. Our results clearly show that the proposed technology provides a way to produce cost-effective, reproducible, flat optics for large-size field-effect transistor THz-detector focal plane arrays.

© 2016 Optical Society of America

Full Article  |  PDF Article

Abstract-3D printed diffractive terahertz lenses

Walter D. Furlan, Vicente Ferrando, Juan A. Monsoriu, Przemysław Zagrajek, Elżbieta Czerwińska, and Mieczysław Szustakowski
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-41-8-1748

A 3D printer was used to realize custom-made diffractive THz lenses. After testing several materials, phase binary lenses with periodic and aperiodic radial profiles were designed and constructed in polyamide material to work at 0.625 THz. The nonconventional focusing properties of such lenses were assessed by computing and measuring their axial point spread function (PSF). Our results demonstrate that inexpensive 3D printed THz diffractive lenses can be reliably used in focusing and imaging THz systems. Diffractive THz lenses with unprecedented features, such as extended depth of focus or bifocalization, have been demonstrated.

© 2016 Optical Society of America

Full Article  |  PDF Article