Dear Jaime,
You could use the optical spectrum analyzer to measure the laser linewidth. The DM laser has two modes of operation: digital and analog. You may try to control the DM laser parameters in the “Measurement” tab in the component properties window to control its bandwidth. The optical linewidth can be used to calculate the electrical linewidth.
You may use the new component (Electrical Transfer Function Visualizer) in OptiSystem 20 to measure the laser frequency response in a setup.
Regards,
Ahmad