Electromagnetic Modeling of Fused Multi-Port Fiber-Optic Couplers

• Main Authors: Yao-Chun Tsai, 蔡耀群
• Other Authors: Hung-Chun Chang
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/00476588997311720498

碩士 === 國立臺灣大學 === 電信工程學研究所 === 90 === In this thesis we confirm the accuracy of the surface integral equation method (SIEM) used in the analysis of fused fiber couplers. This purpose is achieved by verifying the convergence characteristics of 2×2 and collinear 3×3 couplers. Then we use the SIEM to analyze the 4×4 fused fiber-optic coupler. The propagation constants and the modal field patterns can be calculated precisely by properly dividing the transverse boundary of the coupler. We calculate the propagation constants and the modal field patterns of 4×4 fused fiber couplers with different structure parameters. And the two-dimensional characteristics of 4×4 couplers have been understood well in this investigation. Furthermore, we develop a three-dimensional electromagnetic modeling to analyze the power transfer characteristics of 4×4 fused couplers. The longitudinally tapered structure is divided into many segments and approximated with the step-like functions. We find the propagation constants and the modal field patterns of each segment of the coupled structure by using the SIEM and sum up the coupling effect over the entire effective coupling region. Then, we can obtain the power transfer characteristics of 4×4 fused fiber couplers. In this thesis we employ this 3-D modeling to simulate 4×4 couplers with different structure parameters. We find that the coupler composed of four identical fibers forming a square shape can divide the input light into four equal parts.