Pulse-amplitude equalization in a rational harmonic mode-locked fiber laser using nonlinear modulation

In this letter, a simple technique for the pulse-amplitude equalization of high repetition rate pulses generated from a rational harmonic mode-locked fiber ring laser was demonstrated. The principle is based on nonlinear modulation of the modulator and a theoretical explanation based on time-domain analysis was given. Amplitude equalized short pulses up to the seventh rational harmonic mode-locking were obtained with an optimum bias level and modulation depth of the modulator, which agrees well with the simulation result and demonstrates the efficiency of this method.