University of Electronic Science and Technology of China 1.基本光波导单元结构-定向耦合器 1956 LPo1 LPo1 LPoi LP11a LPoi LP11b 图7-3.波导中几个低阶模的场分布特征 5University of Electronic Science and Technology of China 5 1. 基本光波导单元结构-定向耦合器 图7-3. 波导中几个低阶模的场分布特征