Similar structures, different characteristics: Optical performances of circular polarizers with single- and double-helical metamaterials

A novel metamaterial with double-helical wire structures was proposed to construct optical circular polarizers which have boarder wavelength bands than those with single-helical structures. In this work, we systematically studied the dependence of optical properties of the double- and single-helical circular polarizers on their length of helix-period, spacing of grid, number of helix-period, diameter of helix, and diameter of wire. The simulation results show that the double-helical circular polarizers have much broader operation bands than the single-helical ones but have considerably lower extinction ratios for all structural parameters. In addition, the influences of the structural parameters on the optical performances are quite distinct between the single- and double-helical structures. This paper summarized the main influences, which is of certain directive significance to related experimental studies.