Optically tunable all-silicon chiral metasurface in terahertz band

The chiral optical response represents interactions of circularly polarized light with matter. Chiral metamaterials are widely applied in polarization imaging, optical sensing, and other fields due to their strong ability to manipulate light and form giant circular polarization differential transmittance (CPDT). Here, we propose all-silicon chiral metasurfaces for highly efficient CPDT in the terahertz band. In addition to characterizing the static chiral properties of our proposed metasurface, dynamic chiral behaviors are also characterized by optical pumping (1064 nm continuous wave), and a giant amplitude modulation depth is obtained. The measured results agree well with the simulations. In addition, the application of our chiral metasurface in polarization multiplexed near-field image display is also exhibited. Such chiral metasurface could find many potential applications in photon-spin selective devices, such as circularly polarized light detectors and chiral sensors.