Stable, self-starting, passively mode-locked fiber ring laser of the 3 μm class.

We report a passively mode-locked Ho(3+)Pr(3+)-doped fluoride fiber laser, producing 6 ps pulses at a repetition rate of 24.8 MHz, with a peak power of 465 W. For the first time, a ring cavity was demonstrated in a fluoride fiber laser arrangement which was essential to the generation of stable and self-starting mode-locked pulses.