Refractive Index Description

The refractive index distribution can have different values for the x-polarized field from the y-polarized field, which allows for anisotropic materials. The refractive index can be specified in one of two ways:

• The refractive index can be created using a set of built-in polygon functions. Each polygon is a three dimensional shape. The refractive index value inside the polygon is specified by the user, and the refractive index outside the polygon is zero. Multiple polygons can be entered, they can overlap, and most geometries of interest can be constructed this way. Click here for a complete description. The background index is assumed to be 1.0, and every polygon adds an incremental value. This is the most standard way to specify the refractive index structure.
  
  
• An arbitrary two-dimensional refractive index profile can be uploaded as ASCII numeric values, which can then be extruded in the z-direction in a variety of ways. The two-dimensional profile must be uploaded as four separate text files. The first file defines the x-grid. It is simply a column of numbers. Similarly, the second file defines the y-grid. The third file contains the 2-D profile of the refractive index for the x-polarized field. The fourth file contains the 2-D profile of the refractive index for the y-polarized field. Once these files are uploaded, the 2D distribution can be invoked using the descriptor 'F' in the polygon entry box. The syntax for the 'F' descriptor is specified here.
  
  
• The two-dimensional function to be extruded can be transferred to this job from another job (BPM or Modesolver) instead of uploading as text files. When a field, refractive index or function is plotted from the other programs, there should be an option at the bottom of the screen for copying that distribution as the refractive index distribution for another program.