Dual circular polarization gaps in helix photonic metamaterials.

Chiral structures exhibit strong interactions with circularly polarized light, and have been demonstrated to show many polarization-dependent properties. Various chiral structures exhibit some level of circular dichroism, where right-handed and left-handed circularly polarized waves experience different transmission. In this study, we use a dielectric helix array as a model system to examine the interactions of circularly polarized light with helical structures. Our results show that circular polarization band gaps can be formed in a dielectric helix array not only by light having the same handedness with the structure but also by light with the opposite handedness, resulting from additional chiral motifs induced by the arrangement of helices. Dual polarization band gaps can thus be tailored by varying the geometrical parameters, and circular-polarization dependent properties can be manipulated for optoelectronic devices and applications.