Single-Longitudinal-Mode Brillouin/Erbium Fiber Laser With High Linewidth-Reduction Ratio

Saturable-absorber-based autotracking filter is incorporated for the first time in hybrid Brillouin/erbium fiber laser to achieve a single-longitudinal-mode operation. We experimentally demonstrate a linewidth-reduction ratio of 166 with a 150-m Brillouin gain media. At the same time, with the intracavity erbium-doped fiber amplifier (EDFA) to compensate the loss introduced by the mode-selection elements, Brillouin pump threshold is as low as 3 mW under 120 mW of 980-nm pump power and the maximum output power is 7 mW. Moreover, the autotracking filter also helps to suppress self-lasing and enables tuning range over the entire
$C$
-band.