Broadband gradient phase discontinuity all-dielectric metasurface

In recent years, metasurfaces have widely been studied due to their ability to offer a spatially varying phase response, low losses, ultrathin size, and easy fabrication. In this paper, a gradient phase discontinuity all-dielectric metasurface consisting of arrays of silicon cube resonator is designed. By adjusting the dimension of the silicon cube resonator, a 2 pi transmission phase covered from -3 pi/4 to pi with pi/4 phase intervals is realized in a frequency from 9.7 GHz to 11.8 GHz. We demonstrate the all-dielectric metasurface can produce the anomalous refraction, vortex beams, and wave-focusing in the microwave and infrared band, respectively. It can be expected that the proposed metasurfaces can find wide applications in communication, designing integrated optical devices, and focusing lenses.