| As the applications multiply for compact sources of ultrashort pulses, it is necessary to develop a full understanding of the advantages and limitations of the different mode-locking techniques. With the current emphasis on increasing the capacity of the communications infrastructure, picosecond and sub-picosecond pulsed fiber lasers have attracted increasing interest especially in light of the efficiency of erbium fiber amplifiers. With this in mind, a comparative, experimental study of the mode-locking processes of three erbium-doped fiber lasers was conducted. An actively mode-locked fiber ring laser and a passively mode-locked Fabry-Perot fiber laser employing a multiple quantum well saturable absorber were constructed as a precursor to developing a hybrid laser source which would combine the most desirable features of the individual lasers.;The actively mode-locked laser produced picosecond pulses at repetition rates ranging from 1.5 MHz to 5.0 GHz and was tunable over the whole erbium gain bandwidth. The passively mode-locked laser utilized the nonlinear transmission of the multiple quantum well saturable absorber to start and sustain mode-locked operation. Additionally, the two lasers were integrated to form a hybrid mode-locked laser. By injecting a portion of the ring laser's output directly into the Fabry-Perot cavity, the output of the two lasers would synchronize at the fundamental cavity frequency. |
