Generation of femtosecond pulses using actively mode-locked fiber ring laser

A new method to generate femtosecond optical pulses by an actively mode-locked fiber ring laser is presented. The fiber ring laser is operated by an optical intensity modulator and an erbium-doped fiber amplifier. The optical intensity modulator is driven by an electrical pulse generator, which produces a nanosecond open-time window for the mode-locked fiber ring laser. The mode-locking generates the ultrashort optical pulses with duration of about 420 fs and repetition rate of 9.188 MHz.