Experimental study on passive mode-locked Yb³⁺ doped fiber laser with F-P cavity

The oscillator utilized a linear (F-P) cavity in which the halfwave plates and polarization splitters were placed to introduce polarization rotation. Combining the self-starting of semiconductor saturable absorber mirror, the passive mode-locked operation was achieved. The grating pair, providing negative group velocity dispersion, compensated the positive dispersion of fiber to compress the pulse. The stable mode-locked was operated with a pump power of 300 mW and the distance between the grating pair was 10 cm. The mode-locked output power was 28 mW while the pulse repetition was 20 MHz and the output spectrum width was 15 nm. The pulse width was less than 100 fs calculated by the formula that time bandwidth product equal to 0.315.