接上篇的波导结构继续进行分析。
使用lumerical脚本语言创建绘制波导、配置一维模式求解器的各项参数、执行网格收敛性测试、在z span进行多次模拟进行收敛性测试、进行一维平板波导的模式相关计算和分析及通过改变波导的厚度来扫描不同厚度下多个模式的有效折射率以及 TE 极化分数（代码均有详细注释）。
一、绘制波导结构
1.1 代码实现
wg_2D_draw
#按照设定的参数依次绘制波导结构中的各个部分，如包层、埋氧层、硅晶圆、波导本身
#以及肋形波导所需的平板层等#用于在 Lumerical MODE 软件中初始化新的模式或项目，并关闭重绘功能
#为了提高性能或避免不必要的图形更新，直到所有设置完成后再统一显示图形
newmode; newmode; redrawoff;#分别定义了包层、硅层、埋氧层的厚度
thick_Clad = 2.0e-6;
thick_Si = 0.22e-6;
thick_BOX = 2.0e-6;
#用于定义肋形波导中平板层的厚度，初始设置为 0 表示当前考虑的是条形波导，
#若改为其他值（如0.22e-6）则可用于模拟肋形波导。
thick_Slab = 0; # for strip waveguides
# thick_Slab = 0.13e-6; # for rib waveguides
width_ridge = 0.5e-6;
# 定义 materials
material_Clad = "SiO2 (Glass) - Const";
material_BOX = "SiO2 (Glass) - Const";
material_Si = "Si (Silicon) - Dispersive & Lossless";
materials; # 运行脚本 add materialswidth_margin = 2.0e-6; # space to include on the side of the waveguide
height_margin = 1.0e-6; # space to include above and below the waveguide
# calculate simulation volume
# propagation in the x-axis direction; z-axis is wafer-normal
#确定了模拟区域的范围
Xmin = -2e-6; Xmax = 2e-6; # length of the waveguide
#其中 Zmin 是在硅层下方预留一定空间（-height_margin），Zmax 是在硅层
#上方预留一定空间（thick_Si + height_margin）
Zmin = -height_margin; Zmax = thick_Si + height_margin;
Y_span = 2*width_margin + width_ridge; Ymin = -Y_span/2;
Ymax = -Ymin;#绘制包层
addrect; set("name","Clad"); set("material", material_Clad);
set("y", 0); set("y span", Y_span+1e-6);
set("z min", 0); set("z max", thick_Clad);
set("x min", Xmin); set("x max", Xmax);
#关于网格划分顺序的操作，将包层的网格划分顺序设置为类似 “置于底层” 的效果，使其作为背景显示
set("override mesh order from material database",1);
set("mesh order",3);
set("alpha", 0.05);#绘制埋氧层
# draw buried oxide
addrect; set("name", "BOX"); set("material", material_BOX);
set("x min", Xmin); set("x max", Xmax);
set("z min", -thick_BOX); set("z max", 0);
set("y", 0); set("y span", Y_span+1e-6);
set("alpha", 0.05);#绘制硅晶圆
# draw silicon wafer
addrect; set("name", "Wafer"); set("material", material_Si);
set("x min", Xmin); set("x max", Xmax);
set("z max", -thick_BOX); set("z min", -thick_BOX-2e-6);
set("y", 0); set("y span", Y_span+1e-6);
set("alpha", 0.1);# draw waveguide
addrect; set("name", "waveguide");
set("material",material_Si);
set("y", 0); set("y span", width_ridge);
set("z min", 0); set("z max", thick_Si);
set("x min", Xmin); set("x max", Xmax);#绘制肋形波导平板层
# draw slab for rib waveguides
addrect; set("
