Laser-assisted chemical vapor deposition (LCVD), in combination with three-dimensional (3D) self-assembly of colloidal silica particles, was used to fabricate 3D core-shell photonic band gap (PBG) structures. Self-assembled multilayer silica particles were formed on silicon substrates using the isothermal heating evaporation approach. A continuous-wave CO_2 laser (10.6 μm wavelength) was used as the energy source in the LCVD to fabricate a silica-core-silicon-shell PBG structure. This technique is capable of fabricating structures with various PBGs by adjusting the silica particle size and Si-shell thickness using different LCVD parameters. This capability enables us to engineer positions and widths of PBGs by flexibly controlling the particle size and shell thicknesses. In the fabricated PBG structures, face-centered cubic structures consist of silica-core-silicon-shell "effective atoms." A series of PBG structures with designed PBGs was obtained under different experimental conditions. Incidence-angle-resolved spectroscopic ellipsometry was used to identify specific PBGs. The refractive indices of the effective atoms with different Si-shell thicknesses were calculated using the Bruggeman composite model. The plain-wave expansion method was used to simulate the photonic dispersion diagrams, which supported the experimental results.
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