TY - JOUR

T1 - Terahertz Switching Focuser Based on Thin Film Vanadium Dioxide Zone Plate

AU - Solyankin, Petr M.

AU - Esaulkov, Mikhail N.

AU - Chernykh, Igor A.

AU - Kulikov, Ivan V.

AU - Zanaveskin, Maxim L.

AU - Kaul, Andrey R.

AU - Makarevich, Artem M.

AU - Sharovarov, Dmitrii I.

AU - Kameshkov, Oleg E.

AU - Knyazev, Boris A.

AU - Shkurinov, Alexander P.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - 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.

AB - 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.

KW - Fresnel zone plates

KW - Phase transition

KW - Terahertz radiation

KW - Vanadium dioxide

KW - TRANSITION

KW - LENS

UR - http://www.scopus.com/inward/record.url?scp=85054543884&partnerID=8YFLogxK

U2 - 10.1007/s10762-018-0540-0

DO - 10.1007/s10762-018-0540-0

M3 - Article

AN - SCOPUS:85054543884

VL - 39

SP - 1203

EP - 1210

JO - Journal of Infrared, Millimeter, and Terahertz Waves

JF - Journal of Infrared, Millimeter, and Terahertz Waves

SN - 1866-6892

IS - 12

ER -