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A double-sided phase-reversal binary zone plate is numerically investigated and experimentally characterized at the frequency of 1 THz. The double-sided zone plate has a novel design based on a binary phase-reversal zone plate, in which the total zone thickness is split into two halves located at a distance optimized by means of numerical simulations. The samples are fabricated by a three-axis milling technique on slabs of an ultralow-loss cyclo-olefin polymer. The lenses' characterization at the frequency of 1 THz is performed by means of a terahertz time-domain spectrometer, in terms of both focal length and spatial resolution. The focusing properties of the double-sided zone plate are compared with those of a conventional binary zone plate. The double-sided zone plate features 2.4× smaller focal spot, 1.25× higher focusing efficiency, and an approximately 10λ 0 longer depth of field than the conventional …
Publication date: 
20 Nov 2018

Silvia Tofani, Dimitrios C Zografopoulos, Mauro Missori, Renato Fastampa, Romeo Beccherelli

Biblio References: 
Volume: 31 Issue: 2 Pages: 117-120
IEEE Photonics Technology Letters