| Photonic crystal (PC) is characterized by its photonic bandgap (PBG), where the transport of light or electromagnetic with the frequency falling in the gap is strictly forbidden. The properties of PCs are determined by the photonic band structures (PBS), which rely on the constituent materials (refraction indices) and their spatial structures. PCs are usually composed by two dielectric materials with different refractive indices. Once the constituent materials are chosen, the properties of the PCs are controlled by structure design. Based on the optical constants of thin films obtained by experiments, this work studies the PBS of various structures, and focuses on the relationship between structure and broadening of PBGs of one-dimensional photonic crystals.Firstly, TiO2 and SiO2 thin films were prepared on glass substrate by RF magnetron sputtering, respectively. The optical constants were determined from the transmittance spectra by envelope method. The dispersive refractive indices and extinction coefficients were obtained as well. These simulated results were verified by comparing the calculated spectra with the measured ones, which presented little difference, showing that the simulated optical constants are reliable.Secondly, we took TiO2 and SiO2 thin films as compositional layers, designed period structures, structures with defect layers as well as their heterostructures, and simulated their PBSs using transfer matrix method (TMM). The effects of defect layer number on width of PBG were investigated. The PBG is found to be broadened in heterostructure consisting of periodic structures and defective structures.Finally, in order to verify the simulated and calculated results, we experimentally prepared some samples by RF magnetron sputtering according to the theoretical designs and measured the optical properties. It was seen that the calculated results were well consistent with the experiment ones. The results were analyzed and discussed as well.
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