Mode-locked femtosecond polarization-maintaining Yb-doped fiber laser with a figure-nine configuration

In the present work, we demonstrated a mode-locked polarization-maintaining (PM) Yb-doped fiber laser based on the figure-of-nine configuration to generate similar to 100 fs pulses at 1 mu m. For the dispersion management, a pair of gratings was inserted into the laser resonator to compensate the group delay dispersion (GDD). The stable, self-started passive mode-locking operation was realized with a pulse duration of 122 fs and a full width at half maximum (FWHM) spectral width of 14.1 nm (3 dB bandwidth). The output power was 21 mW at a repetition rate of 34.4 MHz, corresponding to a pulse energy of 0.61 nJ and a peak power of 4.85 kW. Moreover, the theoretical investigation based on the nonlinear Schrodinger equation was implemented to explore the mode-locking properties. Numerical analyses were almost in agreement with the experimental results.