| Summary: | 碩士 === 國立成功大學 === 光電科學與工程研究所 === 95 === This thesis is to study the transmission behavior of Transverse Magnetic (TM) wave through 2D single slit. Although there have been many research papers working on the excitation of surface plasmons in sub-wavelength single slits or periodical grating structures, there still lacks a complete explanation on the electromagnetic wave properties in such sub-wavelength structure. We use the finite-difference time-domain (FDTD) method and analytical solutions to make a detailed study on the transmission behavior of a single slit. Our study found that in the sub-wavelength slit of perfect electric conductor (PEC) or real metal, the transmission spectrum has resonant peaks similar to those found in the Fabry-Perot cavity. The slit width will affect the effective refractive index inside the slit channel, and will cause the red shift of the resonant peak. This red-shift is more significant for the real metal than the PEC single slits due to the dispersion relation of the surface plasmons generated on the real metal and dielectric interface. When the slit width becomes much smaller, there is a strong coupling between the two surface plasmon waves generated on the metal-dielectric interface on each side of the slit. This lead to further red shit behavior of the transmission resonant peak. When the slit width becomes large, the transmission behavior of the real metal and PEC will become similar.
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