Low-threshold, self-tuned and passively mode-locked coupled-cavity all-fiber lasers

Low threshold, self-tuned, and passively mode-locked fiber lasers with compact all-fiber coupled-cavity structures have been investigated experimentally. It is shown that the Bragg gratings used in a coupled-cavity fiber laser must be matched in their spectral characteristics for the mode-locking of the laser. Stable mode-locked optical pulses as short as 60 ps at a repetition rate of 213 MHz have been generated without the need of cavity length stabilization.