High-efficiency and tunable circular polarization selectivity in photosensitive silicon-based zigzag array metasurface

Abstract

In this paper, we demonstrate giant and tunable polarization selectivity ofcircularly polarized light (CPL) in transmission and reflection modes simultaneously by using photosensitive silicon-based zigzag metasurface. At 3.42 THz, the metasurface provides circular dichroism of transmission/reflection (CDT/CDR) of 0.89/−0.83 for forward-incident CPL and −0.86/0.69 for backward-incident CPL. Multipole expansion and Jones matrix deduction are performed to analyze the physical mechanism of polarization selectivity. To verify the actual control effect of polarization selectivity, a dynamic chiral imaging utilizing the proposed structure and its enantiomer is provided. By applying extra optical pumping to silicon, the switching between showing and hiding pre-designed pattern in transmission field is realized without refabricating the structures. The proposed metasurface with high-efficiency circular polarization selectivity has profound implications for photonic integrated devices.