Theoretical modeling and analysis of a passively Q-switched Er-doped fiber laser with Tm-doped fiber saturable absorber

A theoretical model concerning the 3H6→3F4 transition of Tm ions for passive Q-switching of an Er-doped fiber laser is built. Related population transitions of the passive Q-switching mechanism are simulated and described. Effects of pump power, output reflectivity and cavity length on the laser performance are investigated and analyzed. Numerical results indicate that pump power and output reflectivity are major factors affecting the laser output, while the cavity length mainly determines the pulse duration. Besides, high repetition rate operation is achievable with 3H6→3F4 transition of Tm ions at the expense of the output pulse energy.