Characteristics of a Brillouin-erbium fiber laser based on Brillouin pump preamplification.

A single-mode Brillouin-erbium fiber laser (BEFL) is realized using only a 5 m single-mode fiber (SMF) as Brillouin gain medium, which to our best knowledge is the shortest SMF ever used to construct a BEFL. The Brillouin pump (BP) preamplification technique is adopted using a bidirectionally amplified erbium-doped fiber amplifier inside the BEFL cavity. This BEFL presents a high optical signal-to-noise ratio (40 dB), a large output power (10 mW), and a low 980 nm pump threshold (~15 mW). Experimental results indicate that this threshold increases with the BP power. Two lower and upper BP thresholds exist for the BEFL onset and turnoff, respectively, for a fixed 980 nm pump power. Moreover, the output power of this BEFL increases linearly with the 980 nm pump power at the same slope efficiency of ~10% for various BP powers, but decreases linearly with the BP power at the same slope efficiency of ~-26% for various 980 nm pump powers.