Broadband Photonic Crystal Waveguide Bends in Two-Dimensional Triangular Lattice

• Main Authors: Yu-Jia Lin, 林裕佳
• Other Authors: Rei-Shin Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/11101677277923545548

碩士 === 龍華科技大學 === 電機工程研究所 === 97 === In this work, design and analysis of broadband photonic crystal (PhC) waveguide bend in two-dimensional triangular lattice is presented. By modifying a waveguide bend with a reflecting plane consisting of circular air holes, two better structures are obtained. The first is designed by enlarging the radii of the circular air holes of the reflecting plane. The second is designed by making the line-defect waveguide single- mode. The design purpose is to make the transmission efficiency of a launched pulse through the PhC waveguide bend as high as possible. Transmission results are compared to those obtained for a simple PhC bend and a bend with a rectangular reflecting plane. Simulation results show that transmission efficiency is dramatically enhanced to 99% for the bend with a reflecting plane consisting of circular air holes, compared to only 1~8% for a simple PhC bend. As for the method of analysis, the plane wave expansion method is employed to calculate the photonic bandgap. And the 1.55 μm wavelength is required to be within the photonic bandgap to ensure the light-guiding condition. The finite-difference time-domain method is employed to simulate light propagation and to calculate transmission efficiency. It is shown that the proposed PhC waveguide bends exhibit the advantages of simple structures, high transmission, and broadband characteristics.