Photonic band gaps in square photonic crystal slabs of core–shell-type dielectric nanorod heterostructures

A new type of core–shell-type photonic crystal (PC) slab composed of a nanorod heterostructure array in a square lattice is studied. Using the plane-wave numerical expansion method, we analyze the band diagrams in two different models, and reveal that the photonic band gap is considerably enhanced in size when the refractive index of the core is larger than the shell. The effects of structural parameters on the band gaps are also studied. The results show that there exist optimal structural parameters to open large gaps.