Showing posts with label V. Apostolopoulos. Show all posts
Showing posts with label V. Apostolopoulos. Show all posts

Friday, May 18, 2018

Abstract-3D-printed polymer antiresonant waveguides for short-reach terahertz applications



L. D. van Putten, J. Gorecki, E. Numkam Fokoua, V. Apostolopoulos, and F. Poletti

http://www.etoponline.org/ao/abstract.cfm?uri=ao-57-14-3953

In this work, we present a 3D-printed waveguide that provides effective electromagnetic guidance in the THz regime. The waveguide is printed using low-cost polycarbonate and a conventional fused deposition modeling printer. Light guidance in the hollow core is achieved through antiresonance, and it improves the energy effectively transported to the receiver compared to free space propagation. Our demonstration adds to the field of 3D-printed terahertz components, providing a low-cost way of guiding terahertz radiation.
Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Saturday, December 24, 2016

Abstract-Terahertz properties of liquid crystals doped with ferroelectric BaTiO3 nanoparticles



U. Chodorow, E. Mavrona 
 N. Palka, O. Strzezysz, K. Garbat, S. Saitzek, J. F. Blach, V. Apostolopoulos, M. Kaczmarek & J. Parka

http://www.tandfonline.com/doi/abs/10.1080/02678292.2016.1271468?journalCode=tlct20

In this paper, we present the results of the terahertz measurements of liquid crystal (LC) ferroelectric BaTiO3nanoparticles (nps) suspensions in the range of frequency from 0.3 up to 3.0 THz. Two different sol-gel methods and the harvesting technique were used to fabricate the nanoparticles. Five LC materials served as hosts for the suspensions: two single compounds: 6CHBT and 2,3′,5′-trifluoro-4-(4-pentylcyclohexyl)-4′-(trifluoromethoxy)-1,1′-biphenyl, and three mixtures: 1867, 2037 and 2020. We characterise, for the first time, the refractive indices and absorption parameters of suspensions with harvested nps in the terahertz range and show how the process of the nps’ preparation affects their response. We observed the increase of birefringence for few LC suspensions in comparison with the pure LCs. The highest increase of birefringence was for 2020 suspension with one kind of ferroelectric nps. On the other hand in most cases the addition of ferroelectric nps to LC causes the increase of its absorption in the THz range. The measurements of LCs terahertz properties by using time-pulsed spectrometer were performed.

Wednesday, July 22, 2015

Abstract-Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region




We show that a hybrid LC-ferroelectric nanoparticle suspension of liquid crystal E7 doped with BaTiO nanoparticles leads to 10% increase in birefringence in the THz region of spectrum as compared to pure E7. Doped liquid crystals can be used to increase performance of THz modulators and waveplates. BaTiO nanoparticles used in the mixture were synthesised with the sol gel technique, and their refractive index has been measured in THz in powder form and in solution.