| Summary: | 碩士 === 國立中央大學 === 光電科學研究所 === 95 === Guided-mode resonance (GMR) effect occurring in waveguide grating causes the dramatic change of diffraction efficiency under particular conditions. It finds applications to the optical devices, such as filters and polarizers. Typically, GMR phenomenon cannot be realized by using single-layer grating, but can be realized in the structure consisting of a symmetrical waveguide gratings and thin-film layers. In this paper, we design a new type of optical filters. The structure uses only single asymmetric waveguide grating, without thin-film layers. The asymmetric waveguide is formed by periodically arranging more than two kinds of dielectric materials. This new type of filters can achieve the same effects as in the traditionally designed multilayer structures. In addition, they have the advantages of more compact sizes and are easier to be fabricated.
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