Numerical analysis of pulse amplitude in rational harmonic mode locked ring fiber Laser

• 1、 Key Laboratory of Opto-electronic Information Acquisition and Manipulation, Ministry of Education

Abstract：The relation between modulating characteristic of Mach-Zehnder modulator and its direct-current bias voltage with modulation depth was demonstrated in detail. The linear modulation region was given precisely. By adjusting the direct-current bias voltage and modulation depth, the shape of transmission curve can be controlled. Equalization of pulse-amplitudes occurs only when the pulse gets the same transmission coefficient in the modulator. Mode locking pulse train and the modulator transmission curve were numerically investigated based on time-domain analysis. The modulation frequency was at 5GHz. Pulse trains and modulation curves with mode-locking cases from second order to seventh order were simulated and analyzed using Matlab software. The numerical result shows that: amplitude equalized pulses were obtained both in the linear region and the nonlinear region. When the rational harmonic mode-locking order p is larger than four, the value of modulation depth affects the pulse-amplitude equalization severely. The physical figure in the paper is laconic and is helpful to get amplitude equalized mode-locked pulses in experiment.

Keywords： laser rational harmonic mode-locked transmission curve pulse-amplitude equalization