Hello,
The optical fiber component is a unidirectional component, while the nonlinear optical fiber component is a bidirectional component. Also, in the nonlinear component, there is no dispersion effects considered. Finally, the nonlinear effects in the nonlinear fiber component is most comprehensive compared to the Optical Fiber component.
If you’d like to include the dispersion effects to all nonlinear effects, use the Bidirectional Optical Fiber component. Make sure to connect a null optical component to the input that is not used.
Regards,
Ahmad