设计了一种基于光纤饱和吸收效应的环形单纵模光纤激光器结构, 以可调谐光纤布拉格光栅作为波长选择器件, 与2 m未抽运掺铒光纤一起位于环形腔反射臂上。采用980 nm激光二极管注入环形腔抽运高掺铒光纤形成激光增益, 在饱和吸收体中形成驻波干涉, 实现1550 nm波段单纵模激光输出, 可调谐范围达42 nm。饱和吸收体对激光的吸收系数随抽运光强的增加而减小, 形成了输出激光的光学双稳态特性。为了提高单纵模激光的稳定性、抑制跳模产生的噪声, 采用一只抽运源通过光纤分路器分光, 同时抽运光纤激光器和光纤放大器, 实现了24 mW稳定的单纵模激光输出, 功率稳定性优于±0.005 dB, 工作效率可达18.5%。以12.5 Gb/s高速码率调制, 传输42 km无误码, 在未来大容量通信领域具有潜在应用价值。

A single-longitudinal mode fiber laser with fiber saturable absorber is designed. Tunable fiber Bragg grating as the wavelength selector is in the ring cavity with a 2 m-long unpumped erbium-doped fiber. A section of high concentration erbium-doped fiber is pumped by a 980 nm laser diode and the standing-wave interference is produced in the saturable absorber. Single-longitudinal mode laser at 1.55 μm band is observed and the output range is 42 nm. The optical bistable is observed because the absorption for laser reduces with the increasing of the pump power. Only one laser simultaneously pumps fiber amplifier and laser through a splitter for enhancing stability and decreasing noise. The output power exceeds 24 mW and the stability is less than ±0.005 dB. The laser slope efficiency is 18.5%. A 12.5 Gb/s codes rate is used in the fiber laser transmission experiment. The signal is transmitted in 42 km without regeneration. This fiber laser has potential applications in the field of the high capacity communications.