Introduction to the influence of the Kerr-nonlinearity (KNL) on field propagating in a standard single-mode fiber (SSFM)

Constants:
$c_0=299792458\,\mathrm{m}/\mathrm{s}$ (speed of light)
$\lambda_0 = 1550\,\mathrm{nm}$ (reference wavelength)
$f_\mathrm{sim} = 1\,\mathrm{TS/s}$ (simulation rate)

Parameters (with default values):
$\gamma=1.27\,\mathrm{W}^{-1}\mathrm{km}^{-1}$ (nonlinearity coefficent)
$R_s = 20\,\mathrm{GBd}$ (symbol rate)