  Inspired by recent developments in self-assembled chiral nanostructures, we
have explored the possibility of using spherical particles packed in cylinders
as building blocks for chiral photonic crystals. In particular, we focused on
an array of parallel cylinders arranged in a perfect triangular lattice, each
containing an identical densest sphere packing structure. Despite the
non-chirality of both the spheres and cylinders, the self-assembled system can
exhibit chirality due to spontaneous symmetry breaking during the assembly
process. We have investigated the circular dichroism effects of the system and
have found that, for both perfect electric conductor and dielectric spheres,
the system can display dual-polarization photonic band gaps for circularly
polarized light at normal incidence along the axis of the helix. Further, we
have examined how the polarization band gap size depends on the dielectric
constant of the spheres and the packing fraction of the cylinders. Our study
suggests that a cluster formed by spheres self-assembling inside parallel
cylinders with appropriate material parameters can be a promising approach to
creating chiral photonic crystals.
