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

• The metasurface realized giant and tunable circular polarization selectivity in transmission and reflection modes simultaneously. • The polarization-selective characteristics of forward-incident light are different from those of backward-incident light. • Multipole expansion and Jones matrix deduction are performed to analyze the physical mechanism of polarization selectivity. • A dynamic chiral imaging utilizing the proposed structure and its enantiomer is provided. In this paper, we demonstrate giant and tunable polarization selectivity of circularly 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.