We use band-structure viewpoint to examine the formed PBG in the corner-cutting structure.The reason why the complete PBG of octagonal dielectric rods with square lattice is closed can be understand.

• 在切边结构的计算上，则是利用能带的观念去探讨能隙形成的决定因素，进而瞭解八边形柱子无法在正方晶格中出现绝对光子能隙的原因。