Chiral optical response of all–dielectric metasurface in terahertz band

Abstract:

It is difficult to excite large chiral optical responses for metasurfaces based on single-layer metal resonators under normal incidence, because they are difficult to excite in-plane magnetic dipole moment that are not orthogonal to the electric dipole moment. The displacement current excited by optical field in the dielectric meta-atoms may induce an in-plane magnetic moment to achieve chiral optical responses. A huge chiral response is achieved in terahertz band based on the lossless all-silicon metasurface. The leaky waveguide mode in the chiral silicon pillar excites the in-plane magnetic dipole moment, which triggers the spin-selected backward electromagnetic radiation, and then realizes the chiral optical response of terahertz wave. A polarization-dependent TDS system is built by using wire grid polarizers，and the peak value of circular dichroism in the transmission spectrum reaches 0.2. This simple-prepared all-silicon metasurface provides a new idea for the design of terahertz chiral metadevices, and it is expected to be applied in the fields of terahertz imaging and spectral detection.