M-Z光波导是有机聚合物电光调制器的重要结构单元。将有效折射率法与二维差分束传播法相结合,利用有效折射率法计算了聚合物脊形波导的横向折射率分布及有效折射率。由Maxwell方程出发,结合辐射透明边界条件,采用Crank-Nicholson差分格式,得出有限差分束传播法的计算格式。通过对M-Z型波导结构中TM模的传播及损耗特性进行理论分析,研究了以IPC-E(20wt%)/PSU作为芯层材料的脊形M-Z波导,并对其结构进行了优化设计,得到了较为满意的结构参数。

Mach-Zehnder optical waveguide is an important component in electro-optic polymer modulators. Approach of EIM and 2D-BPM are combined in this paper, and using effective index method (EIM) to calculate the transverse refractive index distribution and the effective index of polymeric ridge waveguide. Then proceeding from the Maxwell equation, the basic computing scheme of the finite difference beam propagation method (FD-BPM) is obtained by utilizing the transparent boundary condition and the Crank-Nicholson difference scheme. The TM mode light wave propagation and loss characteristics of the M-Z waveguide are theoretically analyzed, particularly the M-Z waveguide using IPC-E(20wt%)/PSU as its core layer. The structure of waveguide is optimized, and satisfactory results are obtained with the method proposed.