Artificially embedding defects into three-dimensional photonic crystals as designed, is a necessary way to introduce certain optical properties. Normally, donor defects or acceptor defects, with the difference size or dielectric constant with the surrounding units, result in corresponding defect modes in photonic band gap. In previous reports, size defect and dielectric defect are always introduced simultaneously, which makes it difficult to clarify the mode of defect. In this work, combining convective self-assembly and L-B film method, we embedded a monolayer of hollow silica microspheres as a planar defect layer in three dimensional photonic crystals of solid silica microspheres, or in the contrast, embedded monolayer of solid microspheres into colloidal crystals of hollow spheres. Since the sizes of solid and hollow silica microspheres are controlled as almost the same, in the fabricated colloidal photonic crystals with the embedded planar defect, namely sandwich structure, there is only dielectric defects existing, without size defects in periodic superlattices.
