Phase Discretization Influence on the Performance of Focusing Metasurface

In this paper, we discuss the effect of phase discretization on the electromagnetic performance of a planar focusing metasurface. Under the same focusing parameter settings, metasurfaces with different phase discrete levels approximating the ideally constant phase profile to be compensated by the metasurface are constructed. Their beam qualities, such as individual beam shape and focusing efficiency, are comparatively analyzed. It is demonstrated that the metasurface with the limit fine phase map can obtain higher focusing efficiency, more compact and symmetric focal spot shape, and smaller side lobe level.