Wood zone plate fishnet metalens

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 k 0 ) 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.

On the Performance of the Zoned Fishnet Metamaterial Lens With Positive and Negative Reference Phase

“…As shown there, the best performance is achieved when q = 0.35 in terms of the FL, DF and power enhancement, as happened in the metalenses we studied before with a FL of 4.50 [19]. Also, note that the power enhancement for these metalenses is below the values obtained with our previous reported fishnet metalenses [16], [17] and other advanced designs [21], due to the fact that more plates are used at their center, increasing the loss in the structures. However, these results demonstrate that the reference phase can be also applied in the design of metalenses with small FL obtaining the best performance for positive values of q, reducing the lateral lobes at the focal position.…”

Effective medium concept in temporal metamaterials

“…Within this context, metamaterials [and metasurfaces as their two-dimensional (2D) version] have been studied and demonstrated at different spectral ranges such as microwave, terahertz, and optics [2][3][4][5][6][7][8][9][10][11] achieving extreme parameters of permittivity (ε) and permeability (μ) such as near-zero or negative [12][13][14][15][16][17][18][19]. Metamaterials have opened new paths to tailor and engineer wave propagation at will giving rise to new and improved applications such as sensors [20][21][22], antennas [23][24][25][26][27], beam shaping, [28][29][30] and mathematical operators [31], to name a few.…”