Development of

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Recently, engineers develop technology and materials for opto-telecommunication, because they will satisfy demands. One of the most important physical properties for the materials is refractive index. Refractive index depends on linear polarizability by the Lorenlz-Lorenz equation. The photochemical reaction which breaks the π-conjugated system can reduce the refractive index of the material because the linear polarizability decreases. The linear, polarizability variations in the nitrone derivatives were predicted by MOPAC calculation. Furthermore, we demonstrate that a photochemical reaction can create various distributions of refractive index in the polymer.We prepared the PMMA films containing the nitrone derivatives by spin-coating method. UV irradiation decreased refractive indices of the film exponentially with the irradiation time. The change in the refractive index was large enough to apply to optical devices. Electronic structural change of DMAPN and refractive indices of the … More film before and after UV irradiation were evaluated by UV absorption spectra and m-line method, respectively. The UV irradiation decreased λ_<max> at 380 nm in the absorption spectra, which is attributed to nitrone, and the refractive indices exponentially with irradiation time. The change of refractive indices reached 0.028. It is shown that the relative variation of refractive index can be predicted based on calculated polarizability variation, in the case of photoisomerization like the reaction of nitrone to oxadirizine.The refractive index profile upon depth of the film was investigated by measuring refractive indices of stacked DMAPN/PMMA films. When UV with a power of 10.7 mW/cm^2 irradiated upon three stacked DMAPN/PMMA films for 35 s, variation of the refractive index change showed a quadratic profile. The refractive index profile with various irradiation times can be accounted with the combination of the chemical kinetics with the steady state approximation and Lambert-Beer's law. Thus, the photochemical reaction can be used to control the refractive index distribution in polymer. Less