ACTIVE HARMONIC MODELOCKING OF AN ERBIUM FIBER LASER WITH INTRACAVITYFABRY-PEROT FILTERS

We present both experimental and theoretical investigations of the ope ration of a harmonically modelocked erbium fiber ring laser stabilized by an intracavity bit-rate etalon, Our model analyzes the effects of cavity components and operating parameters on laser stability and outp ut pulse characteristics. The model predicts the output pulsewidth var iation with laser cavity parameters such as cavity length, dispersion, and finesse of intracavity Fabry-Perot etalons, If the laser cavity l ength is not optimized, a maximum 50% increase in pulsewidth can occur at 5 Gb/s pulse rate, A repetition rate etalon with a finesse of 50 i s sufficient to provide a side-mode suppression ratio of over 50 dB in the laser output, We also discuss how detuning from the optimal modul ation frequency increases the excess noise that affects the laser stab ility, The theory predicts a maximum detuning range of +/- 100 kHz, wh ich agrees with the experimental observations. These theoretical resul ts can guide the design of similar lasers over a wide range of operati ng parameters.