Dispersion-Tuned Harmonically Mode-Locked Fiber Laser

A dispersion-tuned harmonically mode-locked fiber laser is demonstrated using a reflective semiconductor optical amplifier (RSOA) and a chirped fiber Bragg grating. The laser is controlled by modulating the RSOA with a RF signal. The laser performance in terms of tunable bandwidth, pulsewidth, spectral width, output power, and optical signal to noise ratio (OSNR) is studied with respect to their dependence on the injected current levels to the RSOA. This letter indicates that lasing at higher harmonic order results in broaden temporal pulse width, larger spectral width, and lower OSNR. Narrower spectral width is obtained with lower modulation current causing less longitudinal modes to lase. A second synchronously gated RSOA is used to further amplify the laser with peak power up to 0 dBm with a constant output spectrum maintained at all wavelengths and reduced noise between pulses.