Metasurfaces, as two-dimensional metamaterials, display fascinating ability in electromagnetic (EM) modulation within a sub-wavelength scale, opening up a new way for manipulating the properties of EM wave in a plane. Owing to the flexible modulation of EM wave, metasurfaces have spawned a number of enchanting applications, such as perfect absorbers, cloaking devices, planar meta-lens and meta-hologram.