The Effects of Bandpass Filtering on the Dissipative Soliton Generation in a Passively Mode-locked Fiber Laser

We numerically investigate the evolution of a dissipative soliton in erbium-doped fiber (EDF) mode-locked lasers operating in the net normal cavity dispersion regime. The pulse evolution in the laser cavity is analyzed by using a simulation based on the generalized nonlinear Schrodinger equation, including the gain medium; the saturable absorber and the bandpass filter for efficient laser mode-locking. The analysis particularly focused on the function of bandpass filtering; which played a crucial role in balancing the pulse evolution against the dispersive propagation in a normal dispersion waveguide. The characteristics of the laser output spectra are analyzed for various bandwidths of the filter with other parameters fixed. As a result: we obtained a maximum spectral bandwidth of 20 inn in the laser output for a 13-nm bandwidth of the filter; the pulse duration was about, 200 fs. Our results imply the possibility for realizing sub-picosecond (ps) pulse generation in a dissipative soliton laser system possessing a large net normal cavity dispersion.