Abstract: Close packed and non-close packed photonic crystals of SiO²microspheres were prepared with the help of modified vertical method, the thermal sintering technique and the etching technique. The structure of the non-closed packed opals was compared with that of close packed opals via scanning electron microscopy. We performed photonic band-structure calculations by a plane wave expansion method of the two kinds of structures. The calculations indicate that the photonic bandgaps at points L and X of the Brillouin zone in non-close packed structure were opened more easily than that in close packed structure. 

Key words: close packed, non-close packed, photonic crystals, photonic bandgaps