| Summary: | 碩士 === 義守大學 === 電機工程學系 === 91 === In this thesis, the Floquet-Bloch theory (FBT) is used to simulate the periodic dielectric waveguide with multi-layer gratings and deep-etched gratings. The Runge-kutta method (RKM) and the Eigenvalue Technique (EVT) are applied to solve the characteristic equation of the waveguide structure. The propagation constant, the transmission coefficient, the reflection coefficient and the radiation loss in the first Bragg and the second Bragg condition are calculated in this study. The grating consisted of multi-layer is considered in this thesis. If the layer with higher index in gratings is closer to the core, the coupling become stronger. In the structure of deep-etched grating, the derivation of the characteristic equation plays a very important role in the analysis of the waveguide structure because of the truncation error. A special characteristic equation is developed to simulate the structure with deep-etched grating. It shows that the higher the grating, the stronger the coupling effect. However, the radiation loss caused by the discontinuity of grating and non-grating region is increased.
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