High-Efficiency Dual-band Orbital Angular Momentum Generation Based on Trilayer Metasurface

Metasurface has drawn much attention for its extraordinary ability of manipulating wavefronts at will. However, the wavelength-dependent behavior of the metasurface greatly hinders its design freedom. In this work, a novel highly efficient 2-bit dual-band metasurface unit cell is proposed, which is composed of three metallic layers separated by two spacers. As a proof of concept demonstration, a dual-band orbital angular momentum generator based on the proposed unit cells is designed and numerically verified.