0.5-GHz Repetition Rate Fundamentally Tm-Doped Mode-Locked Fiber Laser

We demonstrate a passively mode-locked Tm-doped silica fiber laser with 535-MHz fundamental repetition rate by employing a semiconductor saturable absorber mirror. With in-band pumping at 1590 nm, the stable mode-locked fiber laser produces up to 50 mW at an incident pump power of 558 mW. The laser operating at 1938 nm has a spectral bandwidth of 0.72 nm. After amplification, the laser pulse width is measured to be
$\sim 7.9$
ps, and the time-bandwidth product is
$\sim 0.46$
.