单调变化的渐变折射率波导的表面折射率大于波导基模的有效折射率,因而不能用传统的 m 线方法测量。利用分析转移矩阵(ATM)方法研究了渐变折射率波导中的表面等离子波,提出了一种确定波导近表面折射率的实验技术,在波导折射率分布的拟合中,得到了比传统逆WKB方法更为合理的结果。 The monotonically changing graded-index waveguide has a surface refractive index greater than the effective index of the waveguide fundamental mode and therefore can not be measured using the conventional m-line method. The surface plasmon wave in the graded-index waveguide was studied by the analytical transfer matrix (ATM) method. An experimental technique to determine the near-surface refractive index of the waveguide was proposed. In the fitting of waveguide refractive index distribution, Method is more reasonable result.