Research Article

Wood zone plate fishnet metalens

¹ Antennas Group-TERALAB, Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona, Spain
² Institute of Smart Cities, Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona, Spain
³ Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2BT, UK
⁴ School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK

^* e-mail: b.orazbayev@unavarra.es

Received: 14 September 2015
Accepted: 12 November 2015
Published online: 23 December 2015

Abstract

Fresnel-zone plate lenses provide focusing performance while having low profile. Unfortunately, they usually display higher reflection losses than conventional dielectric lenses. Here, we demonstrate a low-profile Wood zone plate metalens based on the fishnet metamaterial working in a near-zero regime with an equivalent refractive index less than unity (n_f = 0.51). The metalens is made of alternating dielectric and fishnet metamaterial concentric rings. The use of fishnet metamaterial allows reducing the reflections from the lens, while maintaining low profile, low cost and ease of manufacturing. The lens is designed to work at the W-band of the millimeter-waves range with a focal length FL = 22.8 mm (7.5 λ₀) aiming at antenna or radar system applications. The focusing performance of the lens along with its radiation characteristics in a lens antenna configuration have been studied numerically and confirmed experimentally, showing a gain improvement of ~2.5 dB with respect to a fishnet Soret metalens.