High-efficiency Dual-band Bifocal Metalens Based on Reflective Metasurface

Achieving wavelength-independent behavior in a single metasurface is of great significance for electromagnetic integrated system. In this work, a novel dual-band meta-atom is proposed for reflecting the incident wave to its cross-polarized component with high efficiencies. Beside the phase modulation, the amplitude can also be tailored independently at two gigahertz frequencies. As a demonstration example, a dual-band bifocal reflective metalens is designed and numerically verified. The full-wave simulation results are in good agreement with the design goals.