Optical transmission spectra of two-dimensional quasiperiodic photonic crystals based on Penrose-tiling and octagonal-tiling systems

We measured and calculated optical transmission spectra of two-dimensional quasiperiodic photonic crystals based on 5- and 8-fold symmetric patterns (Penrose and octagonal patterns). In our photonic crystals, dielectric cylindrical rods stood perpendicular to a basal plane on vertices of tiles in the patterns in air. In the TM mode, where electric fields of incident light are parallel to the rods, we found an isotropic photonic band gap even when the dielectric constant is as small as 2.4. Besides, we observed several dips depending on the incident direction of the light, which may be due to long-range multiple scattering.