Perfect anomalous reflection with a multi-layer metasurface

Abnormal reflection is one of the most basic functions of metasurface and its efficiency is very important in practical application. The implementation of perfect anomalous reflection needs to meet both phase and amplitude requirements. However, due to the absorption loss of metal materials and transmission loss of dielectric materials, perfect abnormal reflection is difficult to be realized in optical frequency. Here, we propose a multi-layer all-dielectric metasurface structure, using the reflecting layer to reflect all of this energy back to meet the amplitude requirement of 100% reflectivity. As proof of this concept, a 30° perfect anomalous reflector at 1550 nm for TM polarized light is showed. It is worth noting that this approach is not limited to anomalous reflection but can be extended to more complex metasurface functions such as focusing.