Transmissive focusing meta-surface with nearly 100% efficiency
- PDF / 2,391,989 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 34 Downloads / 153 Views
Transmissive focusing meta-surface with nearly 100% efficiency B.-C. Lin1
•
G.-M. Wang1 • T. Cai1
Received: 20 June 2017 / Accepted: 9 September 2017 Ó Springer-Verlag GmbH Germany 2017
Abstract Planar lens is one of the most important components of both microwave and optical frequency regimes. However, current available transmissive lenses are limited by their low efficiency, complex configurations and large sizes. Here, we propose a general strategy to design focusing meta-surface by using carefully designed Huygens elements. Each element on the meta-surface can realize very high transmission due to the electric and magnetic currents deduced by electric and magnetic structures, respectively. As proof of the concept, a metalens, working at frequency of 10 GHz is designed, fabricated and measured. Our meta-lens consists of 31 9 25 Huygens elements, occupying a total area of 155 9 164.3 mm2. Numerical and experimental results agree well with each other. The measured absolute efficiency of our meta-lens is higher than 86.7% (90.6% for simulation) at the working frequency. Moreover, the bandwidth is about 30.7% (32.5% for simulation). Our finding opens up a new avenue to design high-performance microwave meta-devices working in transmission geometry.
& T. Cai [email protected] G.-M. Wang [email protected] 1
Air and Missile Defend College, Air Force Engineering University, Xi’an 710051, China
1 Introduction In recent years, meta-surfaces (MSs) have become a research topic for their strong capabilities in manipulating electromagnetic (EM) wave-front, especially for the phase gradient meta-surfaces. Great advantages in meta-surfaces have led to various fascinating phenomena and practical applications, such as anomalous refraction/reflection [1–11], conversion between propagation wave and surface wave [12–14], vortex beam [15, 16], holograms [17–21], and so on. As a kind of MSs, Huygens elements have been widely used in metadevices design (i.e. metasurface realizing beam bending effect) due to its high transmission property [3–5]. Planar meta-lens, exhibiting unique converging property for the incident EM wave, has attracted a lot of attention, especially since the proposal of Pendry’s super lens [22]. For instance, an ultrathin and flat metasurface working in reflection geometry has been engineered, which solves the impedance mismatch problem and can realize focusing effect efficiently [23]. What’s more, bifunctional reflective lens has been designed to achieve simultaneously the Luneburg lens and Maxwell-fisheye [24]. However, transmissive lens is more useful in practice. Currently available transmissive lenses usually consist with multilayer structures, and their working efficiency is limited because of the imperfect elements with large reflection and imprecise phase distributions on the meta-surface. Therefore, one issue is that, how to design transmissive meta-lens with very high efficiency? In this paper, we propose a two-step method to enhance the working efficiency. For the first step, also the most import
Data Loading...
