| Summary: | 碩士 === 國立臺北科技大學 === 光電工程系研究所 === 100 === Due to the development of metamaterials growing to three-dimensional structure, broadband and wide-angle absorption is a goal for every researcher. In this paper, we use the electron beam evaporation with glancing angle deposition and bideposition technology to fabricate dielectric-metal composite three dimensional octagon nanostructure for different size and thickness which can reach the broadband and wide-angle absorption. We use SEM to observe samples’ top view and cross section is similar to helical and the metal part looks like crescent moon. The film’s thickness can be known with the cross section. The 1, 1.5, 2 period SiO2-Al and SiO2-Ag composite three dimensional octagon nanostructure were fabricated.
In the optical measurement, we measured every size of the sample with transmittance and reflectance visible spectrum for p(s) polarization, the incident angle is 0°~75°. The result show that 2 period SiO2-Al octagon helical structure exhibited high absorption of average above 90% at visible light and incident angle 0°~75° for p polarization and s polarization. In addition, we used FDTD to simulate the crescent aluminum’s electric field resonance to realize the samples’ property of absorption and use the commercial software “Wavse32” to fit the effective refractive index of 2 period SiO2-Al octagon helical structure. Finally, the circular property of 2 period SiO2-Al octagon helical was observed by measure the ellipsometric parameters (Ψ and Δ).
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