Flat nanophotonic devices hold a great potential to process diffractive optical information within ultra-thin submicron thickness. In particular, optical filtering of transmissive angular spectrum in the free space is an essential functionality in diffractive optics. Here, we propose a novel configuration and theoretical study of an ultrathin transmissive angular filtering metamaterial for the first time to the best of our knowledge. Based on the adiabatically tapered plasmonic waveguide metamaterial in the visible regime, full color angle-selective transmission is achieved near the optic axis including the representative blue (473 nm), green (532 nm), and red (633 nm) colors. By providing further analysis on bandwidth extension, we envision that the proposed flat angular filtering mechanism in the visible range promises practical value and potential for a variety of metamaterial-assisted compact diffractive imaging and sensing applications such as augmented or virtual reality displays and biomedical optical sensors.

平面纳米光子器件在处理超薄亚微米厚度内的衍射光学信息方面具有巨大的潜力。特别地，自由空间中的透射角光谱的光学滤波是衍射光学中的基本功能。在此，根据我们的知识，我们首次提出了一种超薄透射角过滤超材料的新颖配置和理论研究。基于处于可见状态的绝热锥形等离子体波导超材料，可以在光轴附近实现全色角度选择性透射，包括代表性的蓝色（473 nm），绿色（532 nm）和红色（633 nm）。通过进一步分析带宽扩展，