Highly efficient asymmetric optical transmission by unbalanced excitation of surface evanescent waves in a single-layer dielectric gradient metasurface

摘要

Asymmetric optical transmission has recently been demonstrated using Lorentz. reciprocal devices with patterned photonic structures of linear materials by breaking spatial inversion symmetry. However, it is a huge challenge to fabricate such devices due to their sophisticated multilayer configurations. In this letter, we show that a simple single. layer dielectric gradient metasurface (GM) enables high-efficiency asymmetric optical transmission under the oblique incidence. The underlying mechanism is ascribed to the unbalanced excitation of surface evanescent waves for forward and backward light. Our results provide strategies for creating compact, integrated and high performance asymmetric optical transmission devices. (C) 2019 The Japan Society of Applied Physics