Active controllable spin-selective terahertz asymmetric transmission based on all-silicon metasurfaces

A strong spin-selective asymmetric transmission metasurface usually relies on a multilayer metal frame or compound all-dielectric system. By contrast, an all-silicon metasurface has advantages of simple process, low cost, and easy optical modulation. However, there is little work to explore the spin-selective asymmetric transmission in terahertz band based on the all-silicon metasurface due to weak interaction between all-silicon materials and terahertz waves. Herein, we have achieved excellent spin-selective terahertz asymmetric transmission in the all-silicon metasurface by the ingenious chirality structure design, and the maximum circular dichroism can reach 0.4. Meanwhile, 1064nm continuous wave optical pumping modulates the asymmetric transmission amplitude of the all-silicon metasurface to achieve circular dichroism switch between On and Off. We have also developed terahertz chiral imaging applications based on the all-silicon metasurface with spin-selective asymmetric transmission, and the chiral imaging with On and Off switching characteristics can be realized via optically active control.

Automated summary

The study explores spin-selective asymmetric transmission in terahertz band using an all-silicon metasurface. By designing a chirality structure, excellent spin-selective terahertz asymmetric transmission with circular dichroism reaching up to 0.4 is achieved. Additionally, the all-silicon metasurface can be modulated by optical pumping to switch between On and Off for chiral imaging applications.