Fluctuation reduction in a rational harmonic mode-locked fiber ring laser using carrier-suppressed return-to-zero modulation format

Abstract

The authors experimentally demonstrate stable pulse generation from a rational harmonic mode-locked fiber ring laser that employs carrier-suppressed return-to-zero (CS-RZ) format as a modulation waveform. We obtain the CS-RZ format by tuning the bias voltage of the LN intensity modulator and the RF driving amplitude. The rational mode-locking is realized by detuning the modulation frequency in the laser system. We have observed the rational harmonic mode-locking of up to the fifth order. The most stable pulses are generated at the rational harmonic order of two, where the stability of the output pulses is evaluated by the sum of the normalized standard deviation of the voltage and that of the time of the pulse leading edge.