Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article Citation - WoS: 3Citation - Scopus: 4Terahertz Wavefront Engineering Using a Hard-Coded Metasurface(Springer, 2023) Noori, Aileen; Demirhan, Yasemin; Akyürek, Bora; Özyüzer, Lütfi; Demirhan, Yasemin; Aygün, Gülnur; Özyüzer, Lütfi; Güven, Kaan; Altan, Hakan; Aygün, Gülnur; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyDuring the past few years, coding metamaterials (MM) drew significant attention, where the far-field scattering/transmission pattern of the electromagnetic wave (particularly in the THz regime) can be encoded into a single or few-bit digitized phase-response of the metasurface, thereby enabling a full digital control. Single-bit MMs contain two types of unit cells where the phase becomes 0 and 1 (in units of ?), respectively. By arranging these unit cells into a 2D surface pattern, the THz wavefront can be shaped. In this work, a novel hard-coded metasurface was designed, fabricated, and experimentally investigated for multi-beam reflection of incident THz beam. The design employs stripe and checkerboard patterns of bilayer MM unit cells consisting of square gold patches with a polymer spacing layer from a gold backplane. Experimental and simulation results show that the incident wave in the 0.500–0.750 THz range can be reflected with > 95% efficiency in uniform amplitude and 1-bit coded phase. For the checkerboard metasurface pattern, the measured and analytically calculated reflection angle shows good agreement. The metasurface design is suitable for large-scale fabrication and can potentially be used as a template in the development of actively coded metasurfaces. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Conference Object Terahertz Transmission Through Patterened Vanadium Oxide Thin Films on Dielectric Substrates(SCITEPRESS, 2017) Akkaya, M.; Aygün, Gülnur; Demirhan, Yasemin; Yüce, Hürriyet; Yüce, Hürriyet; Özyüzer, Lütfi; Aygün, Gülnur; Demirhan, Yasemin; Özyüzer, Lütfi; Sabah, Cumali; Altan, Hakan; 04.05. Department of Pyhsics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyPatterned and unpatterned films of vanadium oxide grown on dielectric substrates such as fused silica and sapphire were grown and analysed by varying the temperature using terahertz time domain spectroscopy. After investigating the critical transition temperature near 340K, a well-known cross-shaped pattern was studied to observe any resonances upon transmission. Due to the poor conductivity of the films the frequency selective nature of the structure was not observed, however an etalon effect could be seen in the sapphire substrate as opposed to the fused silica substrate above the critical temperature. Dependence of the refractive index difference between substrates upon transmission of the THz pulse is likely in explaining this observed difference.