The ZnO thin films were prepared from zinc acetate dihydrate as main precursor by using sol-gel method and deposited by drainage and dip coating technique. Four different routes and coating techniques were used for the preparation of samples. The morphology, optical, and structural properties of the sol-gel made ZnO thin films were studied with respect to the preparation of sol-gel route, drainage and dip coating technique. The microstructure of the ZnO thin films and the powders were analyzed by X-ray diffraction. The ZnO thin films prepared in this study were amorphous while its powders were polycrystalline with various diffraction peaks in the X-ray diffraction patterns. The morphology of the film was examined by using scanning electron microscopy. The surface morphology of the ZnO thin films strongly depends on preparation route and deposition technique. The optical characteristics of the samples were obtained by using UV-Visible spectrophotometer at 200-900 nm wavelength. The optical constants (refractive index, extinction coefficient etc.) of the ZnO thin films depend on preparation conditions. The photoluminescence spectra of the ZnO films show the band-edge and sub-band transitions.

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The aim of this paper was to propose and design an all optical four-channel demultiplexer using two-dimensional photonic crystals. To do so a resonant cavity was created by reducing the radius of the two adjacent rods. The radius of these defect rods was about 85 nm. The resonant cavity has a resonant mode at 1,557 nm. Then by using four resonant cavities with different radius values a four-channel optical demultiplexer was designed. The demultiplexer has four optical channels at λ1=1,537 nm, λ2=1,546 nm, λ3=1,553 nm and λ4=1,560 nm.

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