In brief, the program calculates the distribution of optical fiber modes by solving the overall model. The script requires the definition of the refractive index distribution values. Through several lines of code, it sequentially reads the refractive index values and interpolates to plot the refractive index function n_f(r) graph. 

The following are the graphs related to the characteristics of the optical fiber modes after the program runs: 

Figure 1 is the radial function graph, where different colored curves correspond to different values of ι. The graph also indicates the refractive index distribution and the effective refractive index of the modes.

Figure 2 shows the intensity distribution pattern of the selected mode.

Figure 3 shows the relationship curve between the number of modes and wavelength. At a wavelength of 1.96 um, only a single mode exists.

Figure 4 shows that the effective refractive index is related to the wavelength. When the refractive index increases to the size of the cladding refractive index, it corresponds to the cutoff wavelength.

Figure 5 shows the power of all modes and wavelengths corresponding to the core.