A Simple Design Rule for Light Concentrator Using Polymer Metamaterial
Abstract
Transformational optics is a powerful approach for designing optical elements using metamaterials, where geometrical transformations of space can be transferred into the material parameters. In this context, metamaterial based light concentrators have recently attracted much attention. Such structure can efficiently focus the light coming from infinity into a tight spot in the immediate vicinity of the metamaterial layer, making them attractive for integration purpose. Here, we propose a simple design rule to create efficient light concentrators using a thick layer of transparent metamaterials exhibiting a lateral gradient of effective index. The lateral effective index profile is simply determined so as to convert the incoming plane wave into a spherical one focusing at an arbitrary distance from the layer. The resulting structure exhibits an easily achievable porosity gradient considering the use of polymer blocks in the Infrared range. The focusing properties are compared with previously reported hyperbolic secant index profiles. Simulation, fabrication and characterization of the designed 3D flat gradient index (GRIN) metamaterial lenses are presented.