Low threshold, self-tuned, and passively mode-locked fiber lasers with
compact all-fiber coupled-cavity structures have been investigated ex
perimentally. It is shown that the Bragg gratings used in a coupled-ca
vity fiber laser must be matched in their spectral characteristics for
the mode-locking of the laser. Stable mode-locked optical pulses as s
hort as 60 ps at a repetition rate of 213 MHz have been generated with
out the need of cavity length stabilization.