Development of high-quality optical filters has received considerable attention because it's important device in the wavelength division multiplexing technique to realize optical communication with high speed and great capacity. In this work, the graded refractive index profiles are induced in the structure of designed multilayer filters by means of the concept of the functionally graded materials (FGM). Optical characterization of designed and fabricated novel filters with graded refractive index profiles in the SiO2-TiO2 system was investigated. Designed reflection filters have the symmetrical structure with graded refractive index profiles combining with the layers modifying index difference and exhibit higher optical performance than unmodified rugate filter. Designed transmission filters exhibit almost 100% transmittance at the designated wavelength band which can be changed in the range from 1 to 50 nm and a wide reflection region with almost 100% reflectance. A designed 31-layer SiO2-TiO2 film with graded refractive index profiles was fabricated by helicon plasma sputtering and which has superior process controls and consequently better reproducibility. The measured transmittance spectrum exhibited a reflectance of 99.8% at a central wavelength of 730 nm and high transmittance over the wavelength region outside of the reflected band, which corresponded well with calculated one.
|ジャーナル||Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals|
|出版ステータス||Published - 1998|
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