Experimental investigations on spectrum width of square-wave pulses in passively mode-locked figure-8 fiber laser

摘要

We have proposed and demonstrated a nanosecond square-wave fiber laser working in the 1060nm band. The passively mode-locked fiber laser based on the nonlinear optical loop mirror has a peak power clamping effect which leads to the generation of nanosecond square-wave pulses. To investigate the spectrum width of the nanosecond square-wave pulse laser, we added couplers with different coupling ratio to the bidirectional ring of the figure-8 fiber laser and analyzed the laser output. The results show that a higher output coupling ratio leads to stronger peak power clamping effect, and the peak power of the square-wave pulse gets lower and the corresponding spectrum band width is narrower.