Resonant Coupling of TE Wave Incidence to Asymmetric Metal-Dielectric Multilayered Structures at Optical Frequencies

• Main Authors: Chiao-Wei Hsu, 徐喬威
• Other Authors: Yin-Jung Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/86518907113110269070

碩士 === 國立中央大學 === 光電科學與工程學系 === 101 === This thesis employs the transmission line theory and a commercial software package based on Finite-Difference-Time-Domain method to investigate the transverse electric (TE) wave incidence upon two-dimensional planar metal-dielectric multilayered structures at optical frequencies. Results from both approaches show that a minimum reflectance could occur due to the resonant coupling between the incident electromagnetic wave and a guided mode in the high-index layer. From the guided-wave theory, since the phase accumulated by the wave at two boundaries in the guiding layer determines the guidance condition, the resonant coupling is largely affected by the thickness and refractive index of the high-index layer. It changes with the thickness and refractive index of the high-index layer periodically. In addition, under the same structure, since the effective index becomes smaller when the operating wavelength is increased, a smaller incident angle is required to excite the guided mode. On the other hand, metal thickness also affects the full-width-at-half-maximum (FWHM) angle of the reflectance. If the metal thickness becomes thicker, the incident angle required for the resonant coupling gets closer to the critical angle and the FWHM angle is smaller. On the contrary, the required incident angle is closer to when the thickness of the metal is decreased and the corresponding FWHM angle increases. Nevertheless, when the thickness of the metal is large than 60 nm, the TE resonant coupling vanishes.