Repetition rate and wavelength tunable all-optical actively mode-locked fiber ring laser based on a reflective semiconductor optical amplifier

A repetition rate and wavelength tunable fiber ring laser that utilises a reflective semiconductor optical amplifier as both a gain and mode-locking element is presented. 10.3 ps pulses at 10 GHz repetition rate are obtained across a 30 nm tuning range covering the entire C-band. The repetition rate is tunable up to 30 GHz via rational harmonic mode-locking. A comparison is made with using a conventional semiconductor optical amplifier as the gain and mode-locking element. It is shown that the reflective semiconductor optical amplifier requires in excess of 5 dB less average pump pulse power in order to achieve the optimum mode-locking condition, for achieving the narrowest output pulse width, thereby relaxing the requirement for a complex and expensive pump pulse source.