1D chirality in all-photodesigned THz metamaterials

We suggest that all-photodesigned metamaterials, sub-wavelength custom patterns of photoexcited carriers on a semiconductor, can display an exotic extrinsic electromagnetic chirality in terahertz (THz) frequency range. We consider a photo-induced periodic pattern exhibiting 1D geometrical chirality (its mirror image can not be superposed onto itself by translations without rotations) and we prove that, in the long wavelength limit, te considered metamaterial configurations show an electromagnetic extrinsic chirality whose strength can be easily tune by recasting the optical illumination. Due to their extreme reconfigurability, we believe that the 1D chiral all-photodesigned metamaterials could offer opportunities for designing new reconfigurable devices for THz wave polarization manipulation.