Terahertz Switching Focuser Based on Thin Film Vanadium Dioxide Zone Plate

Petr M. Solyankin, Mikhail N. Esaulkov, Igor A. Chernykh, Ivan V. Kulikov, Maxim L. Zanaveskin, Andrey R. Kaul, Artem M. Makarevich, Dmitrii I. Sharovarov, Oleg E. Kameshkov, Boris A. Knyazev, Alexander P. Shkurinov

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

In this paper, we propose a switchable focuser device based on a Fresnel zone plate (FZP) structure for terahertz (THz) applications. Each FZP contains seven rings, etched in thin VO2 film with the designed focal lengths of 50 and 100 mm for 3.7-THz frequency. Temperature-induced VO2 phase transition leads to the change in dielectric susceptibility of the material, which allows one to switch on and off the focusing properties of the device. The devices were tested with radiation of 3.1 and 3.7 THz emitted by quantum cascade lasers. Experimental results were compared with numerical simulations. In this article, we compare the FZP based on VO2 films with different properties and show that a thicker VO2 film reveals higher focusing efficiency, while a thinner one reveals a higher modulation ratio for the peak intensity at the focal point of FZP. We demonstrate experimentally the near-diffraction-limited size of the beam in the focal point of the device. Switching between two phase states of the VO2 films results in up to the 38-fold change of intensity in the focal point.

Original languageEnglish
Pages (from-to)1203-1210
Number of pages8
JournalJournal of Infrared, Millimeter, and Terahertz Waves
Volume39
Issue number12
DOIs
Publication statusPublished - 1 Dec 2018

Keywords

  • Fresnel zone plates
  • Phase transition
  • Terahertz radiation
  • Vanadium dioxide
  • TRANSITION
  • LENS

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