Broadband terahertz circular polarizers with single- and double-helical array metamaterials

A new broadband terahertz circular polarizer with a double-helix structure is proposed in this paper. Furthermore, we systematically simulated the performance of single- and double-helix circular polarizers. Our numerical simulation results show that the function regions of double-helical metamaterials are about 50% broader than those of the single-helical metamaterials in terahertz. We also analyzed the dependence of the performance of the single- and double-helix metamaterials on different structure parameters. Following the antenna theory and the metal wire grating theory, proper explanations were given to interpret the changes of performance with various structure parameters and the difference between the single and double helix.