Metamaterial-based design for a half-wavelength plate in the terahertz range

In this work, a new design aimed to perform as a half-wavelength plate in the terahertz regime is presented. The fabricated samples exhibit a phase difference of 180° at 0.73 THz between the two principal polarisations that matches with the modelling results. The experimentally determined transmittances of the two polarisations were around 61 %, which is below theoretical predictions of reaching more than 90 %. The difference between the two results is explained, and possibilities for increasing the transmittance are presented.