Multi‐Channel Vortex Beam Generation by Simultaneous Amplitude and Phase Modulation with Two‐Dimensional Metamaterial

An ultrathin metasurface is proposed to generate multi-channel vortex beams with equal energy distribution. The phase and amplitude can be separately modulated by tuning the photonic spin-orbit interaction in a rectangular holes array perforated in a nanometer-thin metallic film. This design may enable miniaturized and high-capacity on-chip multiplexing and de-multiplexing vortex beam generators.